15 hours - dchsbennett.files.wordpress.com · Biology guide 29 Core Topic 1: Cell biology 15 hours Essential idea: The evolution of multicellular organisms allowed cell specialization

29Biology guide 29

Core Topi

c 1:

Cel

l bio

logy

15

hou

rs

Esse

ntia

l ide

a: T

he e

volu

tion

of m

ultic

ellu

lar o

rgan

ism

s al

low

ed c

ell s

peci

aliz

atio

n an

d ce

ll re

plac

emen

t.

1.1

Intr

oduc

tion

to c

ells

Nat

ure

of s

cien

ce:

Look

ing

for t

rend

s an

d di

scre

panc

ies—

alth

ough

mos

t org

anis

ms

conf

orm

to c

ell t

heor

y, th

ere

are

exce

ptio

ns. (

3.1)

Ethi

cal i

mpl

icat

ions

of r

esea

rch—

rese

arch

invo

lvin

g st

em c

ells

is g

row

ing

in im

port

ance

and

rais

es e

thic

al is

sues

. (4.

5)

Und

erst

andi

ngs:

• A

ccor

ding

to th

e ce

ll th

eory

, liv

ing

orga

nism

s ar

e co

mpo

sed

of c

ells

.

• O

rgan

ism

s co

nsis

ting

of o

nly

one

cell

carr

y ou

t all

func

tions

of l

ife in

that

cel

l.

• Su

rfac

e ar

ea to

vol

ume

ratio

is im

port

ant i

n th

e lim

itatio

n of

cel

l siz

e.

• M

ultic

ellu

lar o

rgan

ism

s ha

ve p

rope

rtie

s th

at e

mer

ge fr

om th

e in

tera

ctio

n of

th

eir c

ellu

lar c

ompo

nent

s.

• Sp

ecia

lized

tiss

ues

can

deve

lop

by c

ell d

iffer

entia

tion

in m

ultic

ellu

lar

orga

nism

s.

• D

iffer

entia

tion

invo

lves

the

expr

essi

on o

f som

e ge

nes

and

not o

ther

s in

a

cell’

s ge

nom

e.

• Th

e ca

paci

ty o

f ste

m c

ells

to d

ivid

e an

d di

ffer

entia

te a

long

diff

eren

t pa

thw

ays

is n

eces

sary

in e

mbr

yoni

c de

velo

pmen

t and

als

o m

akes

ste

m c

ells

su

itabl

e fo

r the

rape

utic

use

s.

Inte

rnat

iona

l-m

inde

dnes

s:

• St

em c

ell r

esea

rch

has

depe

nded

on

the

wor

k of

team

s of

sci

entis

ts in

man

y co

untr

ies

who

sha

re re

sults

ther

eby

spee

ding

up

the

rate

of p

rogr

ess.

H

owev

er, n

atio

nal g

over

nmen

ts a

re in

fluen

ced

by lo

cal,

cultu

ral a

nd re

ligio

us

trad

ition

s th

at im

pact

on

the

wor

k of

sci

entis

ts a

nd th

e us

e of

ste

m c

ells

in

ther

apy.

Theo

ry o

f kno

wle

dge:

• Th

ere

is a

diff

eren

ce b

etw

een

the

livin

g an

d th

e no

n-liv

ing

envi

ronm

ent.

How

are

we

able

to k

now

the

diff

eren

ce?

Uti

lizat

ion:

• Th

e us

e of

ste

m c

ells

in th

e tr

eatm

ent o

f dis

ease

is m

ostly

at t

he e

xper

imen

tal

stag

e, w

ith th

e ex

cept

ion

of b

one

mar

row

ste

m c

ells

. Sci

entis

ts, h

owev

er,

antic

ipat

e th

e us

e of

ste

m c

ell t

hera

pies

as

a st

anda

rd m

etho

d of

trea

ting

a w

hole

rang

e of

dis

ease

s in

the

near

futu

re, i

nclu

ding

hea

rt d

isea

se a

nd

diab

etes

.

Topic 1: Cell biology

Biology guide30

1.1

Intr

oduc

tion

to c

ells

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: Q

uest

ioni

ng th

e ce

ll th

eory

usi

ng a

typi

cal e

xam

ples

, inc

ludi

ng

stria

ted

mus

cle,

gia

nt a

lgae

and

ase

ptat

e fu

ngal

hyp

hae.

• A

pplic

atio

n: In

vest

igat

ion

of fu

nctio

ns o

f life

in P

aram

eciu

m a

nd o

ne n

amed

ph

otos

ynth

etic

uni

cellu

lar o

rgan

ism

.

• A

pplic

atio

n: U

se o

f ste

m c

ells

to tr

eat S

targ

ardt

’s di

seas

e an

d on

e ot

her

nam

ed c

ondi

tion.

• A

pplic

atio

n: E

thic

s of

the

ther

apeu

tic u

se o

f ste

m c

ells

from

spe

cial

ly c

reat

ed

embr

yos,

from

the

umbi

lical

cor

d bl

ood

of a

new

-bor

n ba

by a

nd fr

om a

n ad

ult’s

ow

n tis

sues

.

• Sk

ill: U

se o

f a li

ght m

icro

scop

e to

inve

stig

ate

the

stru

ctur

e of

cel

ls a

nd

tissu

es, w

ith d

raw

ing

of c

ells

. Cal

cula

tion

of th

e m

agni

ficat

ion

of d

raw

ings

an

d th

e ac

tual

siz

e of

str

uctu

res

and

ultr

astr

uctu

res

show

n in

dra

win

gs o

r m

icro

grap

hs. (

Prac

tical

1)

Gui

danc

e:

• St

uden

ts a

re e

xpec

ted

to b

e ab

le to

nam

e an

d br

iefly

exp

lain

thes

e fu

nctio

ns

of li

fe: n

utrit

ion,

met

abol

ism

, gro

wth

, res

pons

e, e

xcre

tion,

hom

eost

asis

and

re

prod

uctio

n.

• Ch

lore

lla o

r Sce

nede

smus

are

sui

tabl

e ph

otos

ynth

etic

uni

cells

, but

Eug

lena

sh

ould

be

avoi

ded

as it

can

feed

het

erot

roph

ical

ly.

• Sc

ale

bars

are

use

ful a

s a

way

of i

ndic

atin

g ac

tual

siz

es in

dra

win

gs a

nd

mic

rogr

aphs

.

Aim

s:

• A

im 8

: The

re a

re e

thic

al is

sues

invo

lved

in s

tem

cel

l res

earc

h, w

heth

er

hum

ans

or o

ther

ani

mal

s ar

e us

ed. U

se o

f em

bryo

nic

stem

cel

ls in

volv

es

the

deat

h of

ear

ly-s

tage

em

bryo

s, b

ut if

ther

apeu

tic c

loni

ng is

suc

cess

fully

de

velo

ped

the

suff

erin

g of

pat

ient

s w

ith a

wid

e va

riety

of c

ondi

tions

cou

ld

be re

duce

d.

Topic 1: Cell biology

Biology guide 31

Esse

ntia

l ide

a: E

ukar

yote

s ha

ve a

muc

h m

ore

com

plex

cel

l str

uctu

re th

an p

roka

ryot

es.

1.2

Ult

rast

ruct

ure

of c

ells

Nat

ure

of s

cien

ce:

Dev

elop

men

ts in

sci

entif

ic re

sear

ch fo

llow

impr

ovem

ents

in a

ppar

atus

—th

e in

vent

ion

of e

lect

ron

mic

rosc

opes

led

to g

reat

er u

nder

stan

ding

of c

ell s

truc

ture

. (1.

8)

Und

erst

andi

ngs:

• Pr

okar

yote

s ha

ve a

sim

ple

cell

stru

ctur

e w

ithou

t com

part

men

taliz

atio

n.

• Eu

kary

otes

hav

e a

com

part

men

taliz

ed c

ell s

truc

ture

.

• El

ectr

on m

icro

scop

es h

ave

a m

uch

high

er re

solu

tion

than

ligh

t mic

rosc

opes

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: S

truc

ture

and

func

tion

of o

rgan

elle

s w

ithin

exo

crin

e gl

and

cells

of

the

panc

reas

and

with

in p

alis

ade

mes

ophy

ll ce

lls o

f the

leaf

.

• A

pplic

atio

n: P

roka

ryot

es d

ivid

e by

bin

ary

fissi

on.

• Sk

ill: D

raw

ing

of th

e ul

tras

truc

ture

of p

roka

ryot

ic c

ells

bas

ed o

n el

ectr

on

mic

rogr

aphs

.

• Sk

ill: D

raw

ing

of th

e ul

tras

truc

ture

of e

ukar

yotic

cel

ls b

ased

on

elec

tron

m

icro

grap

hs.

• Sk

ill: I

nter

pret

atio

n of

ele

ctro

n m

icro

grap

hs to

iden

tify

orga

nelle

s an

d de

duce

the

func

tion

of s

peci

aliz

ed c

ells

.

Gui

danc

e:

• D

raw

ings

of p

roka

ryot

ic c

ells

sho

uld

show

the

cell

wal

l, pi

li an

d fla

gella

, and

pl

asm

a m

embr

ane

encl

osin

g cy

topl

asm

that

con

tain

s 70

S rib

osom

es a

nd a

nu

cleo

id w

ith n

aked

DN

A.

• D

raw

ings

of e

ukar

yotic

cel

ls s

houl

d sh

ow a

pla

sma

mem

bran

e en

clos

ing

cyto

plas

m th

at c

onta

ins

80S

ribos

omes

and

a n

ucle

us, m

itoch

ondr

ia a

nd

othe

r mem

bran

e-bo

und

orga

nelle

s ar

e pr

esen

t in

the

cyto

plas

m. S

ome

euka

ryot

ic c

ells

hav

e a

cell

wal

l.

Inte

rnat

iona

l-m

inde

dnes

s:

• M

icro

scop

es w

ere

inve

nted

sim

ulta

neou

sly

in d

iffer

ent p

arts

of t

he w

orld

at

a tim

e w

hen

info

rmat

ion

trav

elle

d sl

owly

. Mod

ern-

day

com

mun

icat

ions

hav

e al

low

ed fo

r im

prov

emen

ts in

the

abili

ty to

col

labo

rate

, enr

ichi

ng s

cien

tific

en

deav

our.

Theo

ry o

f kno

wle

dge:

• Th

e w

orld

that

we

inha

bit i

s lim

ited

by th

e w

orld

that

we

see.

Is th

ere

any

dist

inct

ion

to b

e dr

awn

betw

een

know

ledg

e cl

aim

s de

pend

ent u

pon

obse

rvat

ions

mad

e by

sen

se p

erce

ptio

n an

d kn

owle

dge

clai

ms

depe

nden

t up

on o

bser

vatio

ns a

ssis

ted

by te

chno

logy

?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Ph

ysic

s To

pic

4.4

Wav

e be

havi

our

Topi

c C

.1 In

trod

uctio

n to

imag

ing

Topi

c C

.3 F

ibre

optic

s

Aim

s:

• A

im 8

: Dev

elop

men

ts in

sci

ence

, suc

h as

ele

ctro

n m

icro

scop

y, c

an h

ave

econ

omic

ben

efits

as

they

giv

e co

mm

erci

al c

ompa

nies

opp

ortu

nitie

s to

m

ake

prof

its, b

ut th

is c

an a

ffec

t coo

pera

tion

betw

een

scie

ntis

ts.

Topic 1: Cell biology

Biology guide32

Esse

ntia

l ide

a: T

he s

truc

ture

of b

iolo

gica

l mem

bran

es m

akes

them

flui

d an

d dy

nam

ic.

1.3

Mem

bran

e st

ruct

ure

Nat

ure

of s

cien

ce:

Usi

ng m

odel

s as

repr

esen

tatio

ns o

f the

real

wor

ld—

ther

e ar

e al

tern

ativ

e m

odel

s of

mem

bran

e st

ruct

ure.

(1.11

)

Fals

ifica

tion

of th

eorie

s w

ith o

ne th

eory

bei

ng s

uper

sede

d by

ano

ther

—ev

iden

ce fa

lsifi

ed th

e D

avso

n-D

anie

lli m

odel

. (1.

9)

Und

erst

andi

ngs:

• Ph

osph

olip

ids

form

bila

yers

in w

ater

due

to th

e am

phip

athi

c pr

oper

ties

of

phos

phol

ipid

mol

ecul

es.

• M

embr

ane

prot

eins

are

div

erse

in te

rms

of s

truc

ture

, pos

ition

in th

e m

embr

ane

and

func

tion.

• Ch

oles

tero

l is

a co

mpo

nent

of a

nim

al c

ell m

embr

anes

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

hole

ster

ol in

mam

mal

ian

mem

bran

es re

duce

s m

embr

ane

fluid

ity a

nd p

erm

eabi

lity

to s

ome

solu

tes.

• Sk

ill: D

raw

ing

of th

e flu

id m

osai

c m

odel

.

• Sk

ill: A

naly

sis

of e

vide

nce

from

ele

ctro

n m

icro

scop

y th

at le

d to

the

prop

osal

of

the

Dav

son-

Dan

ielli

mod

el.

• Sk

ill: A

naly

sis

of th

e fa

lsifi

catio

n of

the

Dav

son-

Dan

ielli

mod

el th

at le

d to

the

Sing

er-N

icol

son

mod

el.

Gui

danc

e:

• A

mph

ipat

hic

phos

phol

ipid

s ha

ve h

ydro

phili

c an

d hy

drop

hobi

c pr

oper

ties.

• D

raw

ings

of t

he fl

uid

mos

aic

mod

el o

f mem

bran

e st

ruct

ure

can

be tw

o di

men

sion

al ra

ther

than

thre

e di

men

sion

al. I

ndiv

idua

l pho

spho

lipid

m

olec

ules

sho

uld

be s

how

n us

ing

the

sym

bol o

f a c

ircle

with

two

para

llel

lines

att

ache

d. A

rang

e of

mem

bran

e pr

otei

ns s

houl

d be

sho

wn

incl

udin

g gl

ycop

rote

ins.

Theo

ry o

f kno

wle

dge:

• Th

e ex

plan

atio

n of

the

stru

ctur

e of

the

plas

ma

mem

bran

e ha

s ch

ange

d ov

er

the

year

s as

new

evi

denc

e an

d w

ays

of a

naly

sis

have

com

e to

ligh

t. U

nder

w

hat c

ircum

stan

ces

is it

impo

rtan

t to

lear

n ab

out t

heor

ies

that

wer

e la

ter

disc

redi

ted?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

2.3

Carb

ohyd

rate

s an

d lip

ids

Topi

c 2.

6 St

ruct

ure

of D

NA

and

RN

A

Topic 1: Cell biology

Biology guide 33

Esse

ntia

l ide

a: M

embr

anes

con

trol

the

com

posi

tion

of c

ells

by

activ

e an

d pa

ssiv

e tr

ansp

ort.

1.4

Mem

bran

e tr

ansp

ort

Nat

ure

of s

cien

ce:

Expe

rimen

tal d

esig

n—ac

cura

te q

uant

itativ

e m

easu

rem

ent i

n os

mos

is e

xper

imen

ts a

re e

ssen

tial.

(3.1)

Und

erst

andi

ngs:

• Pa

rtic

les

mov

e ac

ross

mem

bran

es b

y si

mpl

e di

ffus

ion,

faci

litat

ed d

iffus

ion,

os

mos

is a

nd a

ctiv

e tr

ansp

ort.

• Th

e flu

idity

of m

embr

anes

allo

ws

mat

eria

ls to

be

take

n in

to c

ells

by

endo

cyto

sis

or re

leas

ed b

y ex

ocyt

osis

. Ves

icle

s m

ove

mat

eria

ls w

ithin

cel

ls.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: S

truc

ture

and

func

tion

of s

odiu

m–p

otas

sium

pum

ps fo

r act

ive

tran

spor

t and

pot

assi

um c

hann

els

for f

acili

tate

d di

ffus

ion

in a

xons

.

• A

pplic

atio

n: T

issu

es o

r org

ans

to b

e us

ed in

med

ical

pro

cedu

res

mus

t be

bath

ed in

a s

olut

ion

with

the

sam

e os

mol

arity

as

the

cyto

plas

m to

pre

vent

os

mos

is.

• Sk

ill: E

stim

atio

n of

osm

olar

ity in

tiss

ues

by b

athi

ng s

ampl

es in

hyp

oton

ic a

nd

hype

rton

ic s

olut

ions

. (Pr

actic

al 2

)

Gui

danc

e:

• O

smos

is e

xper

imen

ts a

re a

use

ful o

ppor

tuni

ty to

str

ess

the

need

for a

ccur

ate

mas

s an

d vo

lum

e m

easu

rem

ents

in s

cien

tific

exp

erim

ents

.

Uti

lizat

ion:

• Ki

dney

dia

lysi

s ar

tific

ially

mim

ics

the

func

tion

of th

e hu

man

kid

ney

by u

sing

ap

prop

riate

mem

bran

es a

nd d

iffus

ion

grad

ient

s.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

6.5

Neu

rons

and

syn

apse

s

Aim

s:

• A

im 8

: Org

an d

onat

ion

rais

es s

ome

inte

rest

ing

ethi

cal i

ssue

s, in

clud

ing

the

altr

uist

ic n

atur

e of

org

an d

onat

ion

and

conc

erns

abo

ut s

ale

of h

uman

org

ans.

• A

im 6

: Dia

lysi

s tu

bing

exp

erim

ents

can

act

as

a m

odel

of m

embr

ane

actio

n.

Expe

rimen

ts w

ith p

otat

o, b

eetr

oot o

r sin

gle-

celle

d al

gae

can

be u

sed

to

inve

stig

ate

real

mem

bran

es.

Topic 1: Cell biology

Biology guide34

Esse

ntia

l ide

a: T

here

is a

n un

brok

en c

hain

of l

ife fr

om th

e fir

st c

ells

on

Eart

h to

all

cells

in o

rgan

ism

s al

ive

toda

y.

1.5

The

orig

in o

f cel

ls

Nat

ure

of s

cien

ce:

Test

ing

the

gene

ral p

rinci

ples

that

und

erlie

the

natu

ral w

orld

—th

e pr

inci

ple

that

cel

ls o

nly

com

e fr

om p

re-e

xist

ing

cells

nee

ds to

be

verif

ied.

(1.9

)

Und

erst

andi

ngs:

• Ce

lls c

an o

nly

be fo

rmed

by

divi

sion

of p

re-e

xist

ing

cells

.

• Th

e fir

st c

ells

mus

t hav

e ar

isen

from

non

-livi

ng m

ater

ial.

• Th

e or

igin

of e

ukar

yotic

cel

ls c

an b

e ex

plai

ned

by th

e en

dosy

mbi

otic

theo

ry.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: E

vide

nce

from

Pas

teur

’s ex

perim

ents

that

spo

ntan

eous

ge

nera

tion

of c

ells

and

org

anis

ms

does

not

now

occ

ur o

n Ea

rth.

Gui

danc

e:

• Ev

iden

ce fo

r the

end

osym

biot

ic th

eory

is e

xpec

ted.

The

orig

in o

f euk

aryo

te

cilia

and

flag

ella

doe

s no

t nee

d to

be

incl

uded

.

• St

uden

ts s

houl

d be

aw

are

that

the

64 c

odon

s in

the

gene

tic c

ode

have

th

e sa

me

mea

ning

s in

nea

rly a

ll or

gani

sms,

but

that

ther

e ar

e so

me

min

or

varia

tions

that

are

like

ly to

hav

e ac

crue

d si

nce

the

com

mon

orig

in o

f life

on

Eart

h.

Theo

ry o

f kno

wle

dge:

• Bi

olog

y is

the

stud

y of

life

, yet

life

is a

n em

erge

nt p

rope

rty.

Und

er w

hat

circ

umst

ance

s is

a s

yste

ms

appr

oach

pro

duct

ive

in b

iolo

gy a

nd u

nder

w

hat c

ircum

stan

ces

is a

redu

ctio

nist

app

roac

h m

ore

appr

opria

te?

How

do

scie

ntis

ts d

ecid

e be

twee

n co

mpe

ting

appr

oach

es?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

5.1

Evid

ence

for e

volu

tion

Aim

s:

• A

im 6

: Pas

teur

’s ex

perim

ent c

an b

e re

peat

ed u

sing

mod

ern

appa

ratu

s.

Topic 1: Cell biology

Biology guide 35

Esse

ntia

l ide

a: C

ell d

ivis

ion

is e

ssen

tial b

ut m

ust b

e co

ntro

lled.

1.6

Cell

divi

sion

Nat

ure

of s

cien

ce:

Sere

ndip

ity a

nd s

cien

tific

dis

cove

ries—

the

disc

over

y of

cyc

lins

was

acc

iden

tal.

(1.4

)

Und

erst

andi

ngs:

• M

itosi

s is d

ivis

ion

of th

e nu

cleu

s int

o tw

o ge

netic

ally

iden

tical

dau

ghte

r nuc

lei.

• Ch

rom

osom

es c

onde

nse

by s

uper

coili

ng d

urin

g m

itosi

s.

• Cy

toki

nesi

s oc

curs

aft

er m

itosi

s an

d is

diff

eren

t in

plan

t and

ani

mal

cel

ls.

• In

terp

hase

is a

ver

y ac

tive

phas

e of

the

cell

cycl

e w

ith m

any

proc

esse

s oc

curr

ing

in th

e nu

cleu

s an

d cy

topl

asm

.

• Cy

clin

s ar

e in

volv

ed in

the

cont

rol o

f the

cel

l cyc

le.

• M

utag

ens,

onc

ogen

es a

nd m

etas

tasi

s ar

e in

volv

ed in

the

deve

lopm

ent o

f pr

imar

y an

d se

cond

ary

tum

ours

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: T

he c

orre

latio

n be

twee

n sm

okin

g an

d in

cide

nce

of c

ance

rs.

• Sk

ill: I

dent

ifica

tion

of p

hase

s of

mito

sis

in c

ells

vie

wed

with

a m

icro

scop

e or

in

a m

icro

grap

h.

• Sk

ill: D

eter

min

atio

n of

a m

itotic

inde

x fr

om a

mic

rogr

aph.

Gui

danc

e:

• Th

e se

quen

ce o

f eve

nts

in th

e fo

ur p

hase

s of

mito

sis

shou

ld b

e kn

own.

• Pr

epar

atio

n of

tem

pora

ry m

ount

s of

root

squ

ashe

s is

reco

mm

ende

d bu

t ph

ases

in m

itosi

s ca

n al

so b

e vi

ewed

usi

ng p

erm

anen

t slid

es.

• To

avo

id c

onfu

sion

in te

rmin

olog

y, te

ache

rs a

re e

ncou

rage

d to

refe

r to

the

two

part

s of

a c

hrom

osom

e as

sis

ter c

hrom

atid

s, w

hile

they

are

att

ache

d to

ea

ch o

ther

by

a ce

ntro

mer

e in

the

early

sta

ges

of m

itosi

s. F

rom

ana

phas

e on

war

ds, w

hen

sist

er c

hrom

atid

s ha

ve s

epar

ated

to fo

rm in

divi

dual

st

ruct

ures

, the

y sh

ould

be

refe

rred

to a

s ch

rom

osom

es.

Inte

rnat

iona

l-m

inde

dnes

s:

• Bi

olog

ists

in la

bora

torie

s th

roug

hout

the

wor

ld a

re re

sear

chin

g in

to th

e ca

uses

and

trea

tmen

t of c

ance

r.

Theo

ry o

f kno

wle

dge:

• A

num

ber o

f sci

entif

ic d

isco

verie

s ar

e cl

aim

ed to

be

inci

dent

al o

r se

rend

ipito

us. T

o w

hat e

xten

t mig

ht s

ome

of th

ese

scie

ntifi

c di

scov

erie

s be

th

e re

sult

of in

tuiti

on ra

ther

than

luck

?

Uti

lizat

ion:

• Th

e m

itotic

inde

x is

an

impo

rtan

t pro

gnos

tic to

ol fo

r pre

dict

ing

the

resp

onse

of

can

cer c

ells

to c

hem

othe

rapy

.

Aim

s:

• A

im 8

: The

toba

cco

indu

stry

cou

ld b

e di

scus

sed.

Sup

pres

sion

of t

he re

sults

of

rese

arch

by

toba

cco

com

pani

es in

to th

e he

alth

eff

ects

of s

mok

ing

toba

cco

was

une

thic

al. S

mok

ing

caus

es c

onsi

dera

ble

soci

al h

arm

, but

, with

the

exce

ptio

n of

law

s on

pro

duct

ion

and

supp

ly in

Bhu

tan,

has

nev

er b

een

mad

e ill

egal

.

Biology guide36

Core Topi

c 2:

Mol

ecul

ar b

iolo

gy

21 h

ours

Esse

ntia

l ide

a: L

ivin

g or

gani

sms

cont

rol t

heir

com

posi

tion

by a

com

plex

web

of c

hem

ical

reac

tions

.

2.1

Mol

ecul

es to

met

abol

ism

Nat

ure

of s

cien

ce:

Fals

ifica

tion

of th

eorie

s—th

e ar

tific

ial s

ynth

esis

of u

rea

help

ed to

fals

ify v

italis

m. (

1.9)

Und

erst

andi

ngs:

• M

olec

ular

bio

logy

exp

lain

s liv

ing

proc

esse

s in

term

s of

the

chem

ical

su

bsta

nces

invo

lved

.

• Ca

rbon

ato

ms

can

form

four

cov

alen

t bon

ds a

llow

ing

a di

vers

ity o

f sta

ble

com

poun

ds to

exi

st.

• Li

fe is

bas

ed o

n ca

rbon

com

poun

ds in

clud

ing

carb

ohyd

rate

s, li

pids

, pro

tein

s an

d nu

clei

c ac

ids.

• M

etab

olis

m is

the

web

of a

ll th

e en

zym

e-ca

taly

sed

reac

tions

in a

cel

l or

orga

nism

.

• A

nabo

lism

is th

e sy

nthe

sis

of c

ompl

ex m

olec

ules

from

sim

pler

mol

ecul

es

incl

udin

g th

e fo

rmat

ion

of m

acro

mol

ecul

es fr

om m

onom

ers

by c

onde

nsat

ion

reac

tions

.

• Ca

tabo

lism

is th

e br

eakd

own

of c

ompl

ex m

olec

ules

into

sim

pler

mol

ecul

es

incl

udin

g th

e hy

drol

ysis

of m

acro

mol

ecul

es in

to m

onom

ers.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s: Ch

emis

try

To

pic

4 Ch

emic

al b

ondi

ng a

nd s

truc

ture

O

ptio

n B

Bioc

hem

istr

y

Aim

s:

• A

im 7

: IC

T ca

n be

use

d fo

r mol

ecul

ar v

isua

lizat

ion

of c

arbo

hydr

ates

, lip

ids

and

prot

eins

in th

is s

ub-t

opic

and

in 2

.3 a

nd 2

.4.

• A

im 6

: Foo

d te

sts

such

as

the

use

of io

dine

to id

entif

y st

arch

or B

ened

ict’s

re

agen

t to

iden

tify

redu

cing

sug

ars

coul

d be

car

ried

out.

Topic 2: Molecular biology

Biology guide 37

2.1

Mol

ecul

es to

met

abol

ism

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

rea

as a

n ex

ampl

e of

a c

ompo

und

that

is p

rodu

ced

by li

ving

or

gani

sms

but c

an a

lso

be a

rtifi

cial

ly s

ynth

esiz

ed.

• Sk

ill: D

raw

ing

mol

ecul

ar d

iagr

ams

of g

luco

se, r

ibos

e, a

sat

urat

ed fa

tty

acid

an

d a

gene

raliz

ed a

min

o ac

id.

• Sk

ill: I

dent

ifica

tion

of b

ioch

emic

als

such

as

suga

rs, l

ipid

s or

am

ino

acid

s fr

om

mol

ecul

ar d

iagr

ams.

Gui

danc

e:

• O

nly

the

ring

form

s of

D-r

ibos

e, a

lpha

–D-g

luco

se a

nd b

eta-

D-g

luco

se a

re

expe

cted

in d

raw

ings

.

• Su

gars

incl

ude

mon

osac

char

ides

and

dis

acch

arid

es.

• O

nly

one

satu

rate

d fa

t is

expe

cted

and

its

spec

ific

nam

e is

not

nec

essa

ry.

• Th

e va

riabl

e ra

dica

l of a

min

o ac

ids

can

be s

how

n as

R. T

he s

truc

ture

of

indi

vidu

al R

-gro

ups

does

not

nee

d to

be

mem

oriz

ed.

• St

uden

ts s

houl

d be

abl

e to

reco

gniz

e fr

om m

olec

ular

dia

gram

s th

at

trig

lyce

rides

, pho

spho

lipid

s an

d st

eroi

ds a

re li

pids

. Dra

win

gs o

f ste

roid

s ar

e no

t exp

ecte

d.

• Pr

otei

ns o

r par

ts o

f pol

ypep

tides

sho

uld

be re

cogn

ized

from

mol

ecul

ar

diag

ram

s sh

owin

g am

ino

acid

s lin

ked

by p

eptid

e bo

nds.

Topic 2: Molecular biology

Biology guide38

Esse

ntia

l ide

a: W

ater

is th

e m

ediu

m o

f life

.

2.2

Wat

er

Nat

ure

of s

cien

ce:

Use

theo

ries

to e

xpla

in n

atur

al p

heno

men

a—th

e th

eory

that

hyd

roge

n bo

nds

form

bet

wee

n w

ater

mol

ecul

es e

xpla

ins

the

prop

ertie

s of

wat

er. (

2.2)

Und

erst

andi

ngs:

• W

ater

mol

ecul

es a

re p

olar

and

hyd

roge

n bo

nds

form

bet

wee

n th

em.

• H

ydro

gen

bond

ing

and

dipo

larit

y ex

plai

n th

e co

hesi

ve, a

dhes

ive,

ther

mal

an

d so

lven

t pro

pert

ies

of w

ater

.

• Su

bsta

nces

can

be

hydr

ophi

lic o

r hyd

roph

obic

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

ompa

rison

of t

he th

erm

al p

rope

rtie

s of

wat

er w

ith th

ose

of

met

hane

.

• A

pplic

atio

n: U

se o

f wat

er a

s a

cool

ant i

n sw

eat.

• A

pplic

atio

n: M

odes

of t

rans

port

of g

luco

se, a

min

o ac

ids,

cho

lest

erol

, fat

s,

oxyg

en a

nd s

odiu

m c

hlor

ide

in b

lood

in re

latio

n to

thei

r sol

ubili

ty in

wat

er.

Gui

danc

e:

• St

uden

ts s

houl

d kn

ow a

t lea

st o

ne e

xam

ple

of a

ben

efit

to li

ving

org

anis

ms

of e

ach

prop

erty

of w

ater

.

• Tr

ansp

aren

cy o

f wat

er a

nd m

axim

um d

ensi

ty a

t 4°C

do

not n

eed

to b

e in

clud

ed.

• Co

mpa

rison

of t

he th

erm

al p

rope

rtie

s of

wat

er a

nd m

etha

ne a

ssis

ts in

the

unde

rsta

ndin

g of

the

sign

ifica

nce

of h

ydro

gen

bond

ing

in w

ater

.

Inte

rnat

iona

l-m

inde

dnes

s:

• Th

ere

are

chal

leng

es fo

r the

incr

easi

ng h

uman

pop

ulat

ion

in s

harin

g w

ater

re

sour

ces

equi

tabl

y fo

r drin

king

and

irrig

atio

n, e

lect

ricity

gen

erat

ion

and

a ra

nge

of in

dust

rial a

nd d

omes

tic p

roce

sses

.

Theo

ry o

f kno

wle

dge:

• Cl

aim

s ab

out t

he “m

emor

y of

wat

er” h

ave

been

cat

egor

ized

as

pseu

dosc

ient

ific.

Wha

t are

the

crite

ria th

at c

an b

e us

ed to

dis

tingu

ish

scie

ntifi

c cl

aim

s fr

om p

seud

osci

entif

ic c

laim

s?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

4.3

Carb

on c

yclin

gTo

pic

4.4

Clim

ate

chan

gePh

ysic

s To

pic

3.1

Ther

mal

con

cept

s

Aim

s:

• A

im 6

: Pro

bes

can

be u

sed

to d

eter

min

e th

e ef

fect

of d

iffer

ent f

acto

rs li

kely

to

influ

ence

coo

ling

with

wat

er.

Topic 2: Molecular biology

Biology guide 39

Esse

ntia

l ide

a: C

ompo

unds

of c

arbo

n, h

ydro

gen

and

oxyg

en a

re u

sed

to s

uppl

y an

d st

ore

ener

gy.

2.3

Carb

ohyd

rate

s an

d lip

ids

Nat

ure

of s

cien

ce:

Eval

uatin

g cl

aim

s—he

alth

cla

ims

mad

e ab

out l

ipid

s in

die

ts n

eed

to b

e as

sess

ed. (

5.2)

Und

erst

andi

ngs:

• M

onos

acch

arid

e m

onom

ers

are

linke

d to

geth

er b

y co

nden

satio

n re

actio

ns to

fo

rm d

isac

char

ides

and

pol

ysac

char

ide

poly

mer

s.

• Fa

tty

acid

s ca

n be

sat

urat

ed, m

onou

nsat

urat

ed o

r pol

yuns

atur

ated

.

• U

nsat

urat

ed fa

tty

acid

s ca

n be

cis

or t

rans

isom

ers.

• Tr

igly

cerid

es a

re fo

rmed

by

cond

ensa

tion

from

thre

e fa

tty

acid

s and

one

gly

cero

l.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: S

truc

ture

and

func

tion

of c

ellu

lose

and

sta

rch

in p

lant

s an

d gl

ycog

en in

hum

ans.

• A

pplic

atio

n: S

cien

tific

evi

denc

e fo

r hea

lth ri

sks

of tr

ans

fats

and

sat

urat

ed

fatt

y ac

ids.

• A

pplic

atio

n: L

ipid

s ar

e m

ore

suita

ble

for l

ong-

term

ene

rgy

stor

age

in h

uman

s th

an c

arbo

hydr

ates

.

• A

pplic

atio

n: E

valu

atio

n of

evi

denc

e an

d th

e m

etho

ds u

sed

to o

btai

n th

e ev

iden

ce fo

r hea

lth c

laim

s m

ade

abou

t lip

ids.

• Sk

ill: U

se o

f mol

ecul

ar v

isua

lizat

ion

soft

war

e to

com

pare

cel

lulo

se, s

tarc

h an

d gl

ycog

en.

• Sk

ill: D

eter

min

atio

n of

bod

y m

ass

inde

x by

cal

cula

tion

or u

se o

f a n

omog

ram

.

Gui

danc

e:

• Th

e st

ruct

ure

of s

tarc

h sh

ould

incl

ude

amyl

ose

and

amyl

opec

tin.

• N

amed

exa

mpl

es o

f fat

ty a

cids

are

not

requ

ired.

• Su

cros

e, la

ctos

e an

d m

alto

se s

houl

d be

incl

uded

as

exam

ples

of

disa

ccha

rides

pro

duce

d by

com

bini

ng m

onos

acch

arid

es.

Inte

rnat

iona

l-m

inde

dnes

s:

• Va

riatio

n in

the

prev

alen

ce o

f diff

eren

t hea

lth p

robl

ems

arou

nd th

e w

orld

co

uld

be d

iscu

ssed

incl

udin

g ob

esity

, die

tary

ene

rgy

defic

ienc

y, k

was

hior

kor,

anor

exia

ner

vosa

and

cor

onar

y he

art d

isea

se.

Theo

ry o

f kno

wle

dge:

• Th

ere

are

conf

lictin

g vi

ews

as to

the

harm

s an

d be

nefit

s of

fats

in d

iets

. How

do

we

deci

de b

etw

een

com

petin

g vi

ews?

Uti

lizat

ion:

• Po

tato

es h

ave

been

gen

etic

ally

mod

ified

to re

duce

the

leve

l of a

myl

ose

to

prod

uce

a m

ore

effe

ctiv

e ad

hesi

ve.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yO

ptio

n B:

Bio

tech

nolo

gy a

nd b

ioin

form

atic

s

Aim

s:

• A

im 8

: The

re a

re s

ocia

l im

plic

atio

ns o

f obe

sity

.

Topic 2: Molecular biology

Biology guide40

Esse

ntia

l ide

a: P

rote

ins

have

a v

ery

wid

e ra

nge

of fu

nctio

ns in

livi

ng o

rgan

ism

s.

2.4

Prot

eins

Nat

ure

of s

cien

ce:

Look

ing

for p

atte

rns,

tren

ds a

nd d

iscr

epan

cies

—m

ost b

ut n

ot a

ll or

gani

sms

asse

mbl

e pr

otei

ns fr

om th

e sa

me

amin

o ac

ids.

(3.1)

Und

erst

andi

ngs:

• A

min

o ac

ids

are

linke

d to

geth

er b

y co

nden

satio

n to

form

pol

ypep

tides

.

• Th

ere

are

20 d

iffer

ent a

min

o ac

ids

in p

olyp

eptid

es s

ynth

esiz

ed o

n rib

osom

es.

• A

min

o ac

ids

can

be li

nked

toge

ther

in a

ny s

eque

nce

givi

ng a

hug

e ra

nge

of

poss

ible

pol

ypep

tides

.

• Th

e am

ino

acid

seq

uenc

e of

pol

ypep

tides

is c

oded

for b

y ge

nes.

• A

pro

tein

may

con

sist

of a

sin

gle

poly

pept

ide

or m

ore

than

one

pol

ypep

tide

linke

d to

geth

er.

• Th

e am

ino

acid

seq

uenc

e de

term

ines

the

thre

e-di

men

sion

al c

onfo

rmat

ion

of

a pr

otei

n.

• Li

ving

org

anis

ms

synt

hesi

ze m

any

diff

eren

t pro

tein

s w

ith a

wid

e ra

nge

of

func

tions

.

• Ev

ery

indi

vidu

al h

as a

uni

que

prot

eom

e.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: R

ubis

co, i

nsul

in, i

mm

unog

lobu

lins,

rhod

opsi

n, c

olla

gen

and

spid

er s

ilk a

s ex

ampl

es o

f the

rang

e of

pro

tein

func

tions

.

• A

pplic

atio

n: D

enat

urat

ion

of p

rote

ins

by h

eat o

r by

devi

atio

n of

pH

from

the

optim

um.

• Sk

ill: D

raw

ing

mol

ecul

ar d

iagr

ams

to s

how

the

form

atio

n of

a p

eptid

e bo

nd.

Uti

lizat

ion:

• Pr

oteo

mic

s an

d th

e pr

oduc

tion

of p

rote

ins

by c

ells

cul

ture

d in

ferm

ente

rs

offe

r man

y op

port

uniti

es fo

r the

food

, pha

rmac

eutic

al a

nd o

ther

indu

strie

s.

Aim

s:

• A

im 7

: IC

T ca

n be

use

d fo

r mol

ecul

ar v

isua

lizat

ion

of th

e st

ruct

ure

of

prot

eins

.

• A

im 8

: Obt

aini

ng s

ampl

es o

f hum

an b

lood

for i

mm

unol

ogic

al,

phar

mac

eutic

al a

nd a

nthr

opol

ogic

al s

tudi

es is

an

inte

rnat

iona

l end

eavo

ur

with

man

y et

hica

l iss

ues.

Topic 2: Molecular biology

Biology guide 41

2.4

Prot

eins

Gui

danc

e:

• Th

e de

taile

d st

ruct

ure

of th

e si

x pr

otei

ns s

elec

ted

to il

lust

rate

the

func

tions

of

pro

tein

s is

not

nee

ded.

• Eg

g w

hite

or a

lbum

in s

olut

ions

can

be

used

in d

enat

urat

ion

expe

rimen

ts.

• St

uden

ts s

houl

d kn

ow th

at m

ost o

rgan

ism

s us

e th

e sa

me

20 a

min

o ac

ids

in th

e sa

me

gene

tic c

ode

alth

ough

ther

e ar

e so

me

exce

ptio

ns. S

peci

fic

exam

ples

cou

ld b

e us

ed fo

r illu

stra

tion.

Topic 2: Molecular biology

Biology guide42

Esse

ntia

l ide

a: E

nzym

es c

ontr

ol th

e m

etab

olis

m o

f the

cel

l.

2.5

Enzy

mes

Nat

ure

of s

cien

ce:

Expe

rimen

tal d

esig

n—ac

cura

te, q

uant

itativ

e m

easu

rem

ents

in e

nzym

e ex

perim

ents

requ

ire re

plic

ates

to e

nsur

e re

liabi

lity.

(3.2

)

Und

erst

andi

ngs:

• En

zym

es h

ave

an a

ctiv

e si

te to

whi

ch s

peci

fic s

ubst

rate

s bi

nd.

• En

zym

e ca

taly

sis

invo

lves

mol

ecul

ar m

otio

n an

d th

e co

llisi

on o

f sub

stra

tes

with

the

activ

e si

te.

• Te

mpe

ratu

re, p

H a

nd s

ubst

rate

con

cent

ratio

n af

fect

the

rate

of a

ctiv

ity o

f en

zym

es.

• En

zym

es c

an b

e de

natu

red.

• Im

mob

ilize

d en

zym

es a

re w

idel

y us

ed in

indu

stry

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: M

etho

ds o

f pro

duct

ion

of la

ctos

e-fr

ee m

ilk a

nd it

s ad

vant

ages

.

• Sk

ill: D

esig

n of

exp

erim

ents

to te

st th

e ef

fect

of t

empe

ratu

re, p

H a

nd

subs

trat

e co

ncen

trat

ion

on th

e ac

tivity

of e

nzym

es.

• Sk

ill: E

xper

imen

tal i

nves

tigat

ion

of a

fact

or a

ffec

ting

enzy

me

activ

ity.

(Pra

ctic

al 3

)

Gui

danc

e:

• La

ctas

e ca

n be

imm

obili

zed

in a

lgin

ate

bead

s an

d ex

perim

ents

can

then

be

carr

ied

out i

n w

hich

the

lact

ose

in m

ilk is

hyd

roly

sed.

• St

uden

ts s

houl

d be

abl

e to

ske

tch

grap

hs to

sho

w th

e ex

pect

ed e

ffec

ts o

f te

mpe

ratu

re, p

H a

nd s

ubst

rate

con

cent

ratio

n on

the

activ

ity o

f enz

ymes

. Th

ey s

houl

d be

abl

e to

exp

lain

the

patt

erns

or t

rend

s ap

pare

nt in

thes

e gr

aphs

.

Theo

ry o

f kno

wle

dge:

• D

evel

opm

ent o

f som

e te

chni

ques

ben

efits

par

ticul

ar h

uman

pop

ulat

ions

m

ore

than

oth

ers.

For

exa

mpl

e, th

e de

velo

pmen

t of l

acto

se-f

ree

milk

av

aila

ble

in E

urop

e an

d N

orth

Am

eric

a w

ould

hav

e gr

eate

r ben

efit

in A

fric

a/A

sia

whe

re la

ctos

e in

tole

ranc

e is

mor

e pr

eval

ent.

The

deve

lopm

ent o

f te

chni

ques

requ

ires

finan

cial

inve

stm

ent.

Shou

ld k

now

ledg

e be

sha

red

whe

n te

chni

ques

dev

elop

ed in

one

par

t of t

he w

orld

are

mor

e ap

plic

able

in

anot

her?

Uti

lizat

ion:

• En

zym

es a

re e

xten

sive

ly u

sed

in in

dust

ry fo

r the

pro

duct

ion

of it

ems

from

fr

uit j

uice

to w

ashi

ng p

owde

r.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

8 A

HL

Met

abol

ism

, cel

l res

pira

tion

and

phot

osyn

thes

is

Topic 2: Molecular biology

Biology guide 43

Esse

ntia

l ide

a: T

he s

truc

ture

of D

NA

allo

ws

effic

ient

sto

rage

of g

enet

ic in

form

atio

n.

2.6

Stru

ctur

e of

DN

A a

nd R

NA

Nat

ure

of s

cien

ce:

Usi

ng m

odel

s as

repr

esen

tatio

n of

the

real

wor

ld—

Cric

k an

d W

atso

n us

ed m

odel

mak

ing

to d

isco

ver t

he s

truc

ture

of D

NA

. (1.

10)

Und

erst

andi

ngs:

• Th

e nu

clei

c ac

ids

DN

A a

nd R

NA

are

pol

ymer

s of

nuc

leot

ides

.

• D

NA

diff

ers

from

RN

A in

the

num

ber o

f str

ands

pre

sent

, the

bas

e co

mpo

sitio

n an

d th

e ty

pe o

f pen

tose

.

• D

NA

is a

dou

ble

helix

mad

e of

two

antip

aral

lel s

tran

ds o

f nuc

leot

ides

link

ed

by h

ydro

gen

bond

ing

betw

een

com

plem

enta

ry b

ase

pairs

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

rick

and

Wat

son’

s el

ucid

atio

n of

the

stru

ctur

e of

DN

A u

sing

m

odel

mak

ing.

• Sk

ill: D

raw

ing

sim

ple

diag

ram

s of

the

stru

ctur

e of

sin

gle

nucl

eotid

es a

nd

of D

NA

and

RN

A, u

sing

circ

les,

pen

tago

ns a

nd re

ctan

gles

to re

pres

ent

phos

phat

es, p

ento

ses

and

base

s.

Gui

danc

e:

• In

dia

gram

s of

DN

A s

truc

ture

, the

hel

ical

sha

pe d

oes

not n

eed

to b

e sh

own,

bu

t the

two

stra

nds

shou

ld b

e sh

own

antip

aral

lel.

Ade

nine

sho

uld

be s

how

n pa

ired

with

thym

ine

and

guan

ine

with

cyt

osin

e, b

ut th

e re

lativ

e le

ngth

s of

th

e pu

rine

and

pyrim

idin

e ba

ses

do n

ot n

eed

to b

e re

calle

d, n

or th

e nu

mbe

rs

of h

ydro

gen

bond

s be

twee

n th

e ba

se p

airs

.

Theo

ry o

f kno

wle

dge:

• Th

e st

ory

of th

e el

ucid

atio

n of

the

stru

ctur

e of

DN

A il

lust

rate

s th

at

coop

erat

ion

and

colla

bora

tion

amon

g sc

ient

ists

exi

sts

alon

gsid

e co

mpe

titio

n be

twee

n re

sear

ch g

roup

s. T

o w

hat e

xten

t is

rese

arch

in s

ecre

t ‘an

ti-sc

ient

ific’

? W

hat i

s th

e re

latio

nshi

p be

twee

n sh

ared

and

per

sona

l kno

wle

dge

in th

e na

tura

l sci

ence

s?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

2.2

Wat

er

Topi

c 3.

5 G

enet

ic m

odifi

catio

n an

d bi

otec

hnol

ogy

Topi

c 7

Nuc

leic

aci

ds

Topic 2: Molecular biology

Biology guide44

Esse

ntia

l Ide

a: G

enet

ic in

form

atio

n in

DN

A c

an b

e ac

cura

tely

cop

ied

and

can

be tr

ansl

ated

to m

ake

the

prot

eins

nee

ded

by th

e ce

ll.

2.7

DN

A re

plic

atio

n, tr

ansc

ript

ion

and

tran

slat

ion

Nat

ure

of s

cien

ce:

Obt

aini

ng e

vide

nce

for s

cien

tific

theo

ries—

Mes

elso

n an

d St

ahl o

btai

ned

evid

ence

for t

he s

emi-c

onse

rvat

ive

repl

icat

ion

of D

NA

. (1.

8)

Und

erst

andi

ngs:

• Th

e re

plic

atio

n of

DN

A is

sem

i-con

serv

ativ

e an

d de

pend

s on

com

plem

enta

ry

base

pai

ring.

• H

elic

ase

unw

inds

the

doub

le h

elix

and

sep

arat

es th

e tw

o st

rand

s by

bre

akin

g hy

drog

en b

onds

.

• D

NA

pol

ymer

ase

links

nuc

leot

ides

toge

ther

to fo

rm a

new

str

and,

usi

ng th

e pr

e-ex

istin

g st

rand

as

a te

mpl

ate.

• Tr

ansc

riptio

n is

the

synt

hesi

s of

mRN

A c

opie

d fr

om th

e D

NA

bas

e se

quen

ces

by R

NA

pol

ymer

ase.

• Tr

ansl

atio

n is

the

synt

hesi

s of

pol

ypep

tides

on

ribos

omes

.

• Th

e am

ino

acid

seq

uenc

e of

pol

ypep

tides

is d

eter

min

ed b

y m

RNA

acc

ordi

ng

to th

e ge

netic

cod

e.

• Co

dons

of t

hree

bas

es o

n m

RNA

cor

resp

ond

to o

ne a

min

o ac

id in

a

poly

pept

ide.

• Tr

ansl

atio

n de

pend

s on

com

plem

enta

ry b

ase

pairi

ng b

etw

een

codo

ns o

n m

RNA

and

ant

icod

ons

on tR

NA

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

se o

f Taq

DN

A p

olym

eras

e to

pro

duce

mul

tiple

cop

ies

of D

NA

ra

pidl

y by

the

poly

mer

ase

chai

n re

actio

n (P

CR).

• A

pplic

atio

n: P

rodu

ctio

n of

hum

an in

sulin

in b

acte

ria a

s an

exa

mpl

e of

the

univ

ersa

lity

of th

e ge

netic

cod

e al

low

ing

gene

tran

sfer

bet

wee

n sp

ecie

s.

• Sk

ill: U

se a

tabl

e of

the

gene

tic c

ode

to d

educ

e w

hich

cod

on(s

) cor

resp

onds

to

whi

ch a

min

o ac

id.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

3.5

Gen

etic

mod

ifica

tion

and

biot

echn

olog

yTo

pic

7.2

Tran

scrip

tion

and

gene

exp

ress

ion

Topi

c 7.

3 Tr

ansl

atio

n

Aim

s:

• A

im 8

: The

re a

re e

thic

al im

plic

atio

ns in

alte

ring

the

geno

me

of a

n or

gani

sm

in o

rder

to p

rodu

ce p

rote

ins

for m

edic

al u

se in

hum

ans.

Topic 2: Molecular biology

Biology guide 45

2.7

DN

A re

plic

atio

n, tr

ansc

ript

ion

and

tran

slat

ion

• Sk

ill: A

naly

sis

of M

esel

son

and

Stah

l’s re

sults

to o

btai

n su

ppor

t for

the

theo

ry

of s

emi-c

onse

rvat

ive

repl

icat

ion

of D

NA

.

• Sk

ill: U

se a

tabl

e of

mRN

A c

odon

s an

d th

eir c

orre

spon

ding

am

ino

acid

s to

ded

uce

the

sequ

ence

of a

min

o ac

ids

code

d by

a s

hort

mRN

A s

tran

d of

kn

own

base

seq

uenc

e.

• Sk

ill: D

educ

ing

the

DN

A b

ase

sequ

ence

for t

he m

RNA

str

and.

Gui

danc

e:

• Th

e di

ffer

ent t

ypes

of D

NA

pol

ymer

ase

do n

ot n

eed

to b

e di

stin

guis

hed.

Topic 2: Molecular biology

Biology guide46

Esse

ntia

l ide

a: C

ell r

espi

ratio

n su

pplie

s en

ergy

for t

he fu

nctio

ns o

f life

.

2.8

Cell

resp

irat

ion

Nat

ure

of s

cien

ce:

Ass

essi

ng th

e et

hics

of s

cien

tific

rese

arch

—th

e us

e of

inve

rteb

rate

s in

resp

irom

eter

exp

erim

ents

has

eth

ical

impl

icat

ions

. (4.

5)

Und

erst

andi

ngs:

• Ce

ll re

spira

tion

is th

e co

ntro

lled

rele

ase

of e

nerg

y fr

om o

rgan

ic c

ompo

unds

to

pro

duce

ATP

.

• AT

P fr

om c

ell r

espi

ratio

n is

imm

edia

tely

ava

ilabl

e as

a s

ourc

e of

ene

rgy

in th

e ce

ll.

• A

naer

obic

cel

l res

pira

tion

give

s a

smal

l yie

ld o

f ATP

from

glu

cose

.

• A

erob

ic c

ell r

espi

ratio

n re

quire

s ox

ygen

and

giv

es a

larg

e yi

eld

of A

TP fr

om

gluc

ose.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

se o

f ana

erob

ic c

ell r

espi

ratio

n in

yea

sts

to p

rodu

ce e

than

ol

and

carb

on d

ioxi

de in

bak

ing.

• A

pplic

atio

n: L

acta

te p

rodu

ctio

n in

hum

ans

whe

n an

aero

bic

resp

iratio

n is

us

ed to

max

imiz

e th

e po

wer

of m

uscl

e co

ntra

ctio

ns.

• Sk

ill: A

naly

sis

of re

sults

from

exp

erim

ents

invo

lvin

g m

easu

rem

ent o

f re

spira

tion

rate

s in

ger

min

atin

g se

eds

or in

vert

ebra

tes

usin

g a

resp

irom

eter

.

Gui

danc

e:

• D

etai

ls o

f the

met

abol

ic p

athw

ays

of c

ell r

espi

ratio

n ar

e no

t nee

ded

but t

he

subs

trat

es a

nd fi

nal w

aste

pro

duct

s sh

ould

be

know

n.

• Th

ere

are

man

y si

mpl

e re

spiro

met

ers

whi

ch c

ould

be

used

. Stu

dent

s ar

e ex

pect

ed to

kno

w th

at a

n al

kali

is u

sed

to a

bsor

b CO

2, so

redu

ctio

ns in

vo

lum

e ar

e du

e to

oxy

gen

use.

Tem

pera

ture

sho

uld

be k

ept c

onst

ant t

o av

oid

volu

me

chan

ges

due

to te

mpe

ratu

re fl

uctu

atio

ns.

Aim

s:

• A

im 8

: The

eth

ics

of th

e us

e of

ani

mal

s in

exp

erim

ents

cou

ld b

e di

scus

sed

in re

latio

n to

resp

irom

eter

exp

erim

ents

. Lar

ge-s

cale

use

of f

ood

plan

ts fo

r bi

ofue

ls a

nd th

e re

sulti

ng im

pact

on

food

pric

es h

as e

thic

al im

plic

atio

ns.

Topic 2: Molecular biology

Biology guide 47

Esse

ntia

l ide

a: P

hoto

synt

hesi

s us

es th

e en

ergy

in s

unlig

ht to

pro

duce

the

chem

ical

ene

rgy

need

ed fo

r life

.

2.9

Phot

osyn

thes

is

Nat

ure

of s

cien

ce:

Expe

rimen

tal d

esig

n—co

ntro

lling

rele

vant

var

iabl

es in

pho

tosy

nthe

sis

expe

rimen

ts is

ess

entia

l. (3

.1)

Und

erst

andi

ngs:

• Ph

otos

ynth

esis

is th

e pr

oduc

tion

of c

arbo

n co

mpo

unds

in c

ells

usi

ng li

ght

ener

gy.

• Vi

sibl

e lig

ht h

as a

rang

e of

wav

elen

gths

with

vio

let t

he s

hort

est w

avel

engt

h an

d re

d th

e lo

nges

t.

• Ch

loro

phyl

l abs

orbs

red

and

blue

ligh

t mos

t eff

ectiv

ely

and

refle

cts

gree

n lig

ht m

ore

than

oth

er c

olou

rs.

• O

xyge

n is

pro

duce

d in

pho

tosy

nthe

sis

from

the

phot

olys

is o

f wat

er.

• En

ergy

is n

eede

d to

pro

duce

car

bohy

drat

es a

nd o

ther

car

bon

com

poun

ds

from

car

bon

diox

ide.

• Te

mpe

ratu

re, l

ight

inte

nsity

and

car

bon

diox

ide

conc

entr

atio

n ar

e po

ssib

le

limiti

ng fa

ctor

s on

the

rate

of p

hoto

synt

hesi

s.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

hang

es to

the

Eart

h’s

atm

osph

ere,

oce

ans

and

rock

dep

ositi

on

due

to p

hoto

synt

hesi

s.

• Sk

ill: D

raw

ing

an a

bsor

ptio

n sp

ectr

um fo

r chl

orop

hyll

and

an a

ctio

n sp

ectr

um fo

r pho

tosy

nthe

sis.

• Sk

ill: D

esig

n of

exp

erim

ents

to in

vest

igat

e th

e ef

fect

of l

imiti

ng fa

ctor

s on

ph

otos

ynth

esis

.

• Sk

ill: S

epar

atio

n of

pho

tosy

nthe

tic p

igm

ents

by

chro

mat

ogra

ph. (

Prac

tical

4)

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

2.5

Enzy

mes

Topic 2: Molecular biology

Biology guide48

2.9

Phot

osyn

thes

is

Gui

danc

e:

• St

uden

ts s

houl

d kn

ow th

at v

isib

le li

ght h

as w

avel

engt

hs b

etw

een

400

and

700

nano

met

res,

but

they

are

not

exp

ecte

d to

reca

ll th

e w

avel

engt

hs o

f sp

ecifi

c co

lour

s of

ligh

t.

• W

ater

free

of d

isso

lved

car

bon

diox

ide

for p

hoto

synt

hesi

s ex

perim

ents

can

be

pro

duce

d by

boi

ling

and

cool

ing

wat

er.

• Pa

per c

hrom

atog

raph

y ca

n be

use

d to

sep

arat

e ph

otos

ynth

etic

pig

men

ts b

ut

thin

laye

r chr

omat

ogra

phy

give

s be

tter

resu

lts.

49Biology guide 49

Core Topi

c 3:

Gen

etic

s 15

hou

rs

Esse

ntia

l ide

a: E

very

livi

ng o

rgan

ism

inhe

rits

a bl

uepr

int f

or li

fe fr

om it

s pa

rent

s.

3.1

Gen

es

Nat

ure

of s

cien

ce:

Dev

elop

men

ts in

sci

entif

ic re

sear

ch fo

llow

impr

ovem

ents

in te

chno

logy

—ge

ne s

eque

ncer

s ar

e us

ed fo

r the

seq

uenc

ing

of g

enes

. (1.

8)

Und

erst

andi

ngs:

• A

gen

e is

a h

erita

ble

fact

or th

at c

onsi

sts

of a

leng

th o

f DN

A a

nd in

fluen

ces

a sp

ecifi

c ch

arac

teris

tic.

• A

gen

e oc

cupi

es a

spe

cific

pos

ition

on

a ch

rom

osom

e.

• Th

e va

rious

spe

cific

form

s of

a g

ene

are

alle

les.

• A

llele

s di

ffer

from

eac

h ot

her b

y on

e or

onl

y a

few

bas

es.

• N

ew a

llele

s ar

e fo

rmed

by

mut

atio

n.

• Th

e ge

nom

e is

the

who

le o

f the

gen

etic

info

rmat

ion

of a

n or

gani

sm.

• Th

e en

tire

base

seq

uenc

e of

hum

an g

enes

was

seq

uenc

ed in

the

Hum

an

Gen

ome

Proj

ect.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: T

he c

ause

s of

sic

kle

cell

anem

ia, i

nclu

ding

a b

ase

subs

titut

ion

mut

atio

n, a

cha

nge

to th

e ba

se s

eque

nce

of m

RNA

tran

scrib

ed fr

om it

and

a

chan

ge to

the

sequ

ence

of a

pol

ypep

tide

in h

emog

lobi

n.

• A

pplic

atio

n: C

ompa

rison

of t

he n

umbe

r of g

enes

in h

uman

s w

ith o

ther

sp

ecie

s.

• Sk

ill: U

se o

f a d

atab

ase

to d

eter

min

e di

ffer

ence

s in

the

base

seq

uenc

e of

a

gene

in tw

o sp

ecie

s.

Inte

rnat

iona

l-m

inde

dnes

s:

• Se

quen

cing

of t

he h

uman

gen

ome

show

s th

at a

ll hu

man

s sh

are

the

vast

m

ajor

ity o

f the

ir ba

se s

eque

nces

but

als

o th

at th

ere

are

man

y si

ngle

nu

cleo

tide

poly

mor

phis

ms