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DNA Lecture 009
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DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

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Page 1: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

DNALecture 009

Page 2: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Gregor Mendel

Page 3: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Rosalind Franklin Frances Crick & James Watson

X-ray diffraction photograph of DNA, 1953

Proposed double helix model 1953

Page 4: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Cell

Page 5: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Nucleus

Page 6: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

DNA

Page 7: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

What is DNA?What is DNA?• DNA, or deoxyribonucleic acid, is the genetic

instruction set.

• It is composed of a linear sequence of units called nucleotides.

• There are four different kinds of nucleotides (designated by the letters A, G, C, & T; sometimes called “bases”).

• An individual DNA strand (or chromosome) may consist of 100,000’s of nucleotides.

• The sequence of the nucleotides of a DNA strand determines the genetic code.

Page 8: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Polymers made up of individual nucleotides

Nucleotides contain• Phosphate group• Five carbon sugar• Ring shaped nitrogen base

DNA contains information for almost all cell activities

Page 9: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Nitrogen Base

Page 10: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

adenine guanine

Purines

Page 11: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

cytosine thymine

Pyrimidines

Page 12: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Deoxyribose

Page 13: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.
Page 14: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

DNA is Double StrandedDNA is Double Stranded

Page 15: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Base Pairing in DNA

Base Pairing in DNA

Page 16: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.
Page 17: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.
Page 18: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

ChromosomesChromosomes

Page 19: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Chromosomes Come in PairsChromosomes Come in Pairs

Page 20: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Beliefs about Heredity

Fig. 1. De la propagation du genre humain, ou manuel indispensable pour ceux qui veulent avoir de beaux enfants de l’un ou l’autre sexe (Paris, Year VII). Image courtesy of the Bibliothèque Interuniversitaire de Médecine, Paris.

Page 21: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Homunculus

How is “heredity passed on:

Spermist vs Ovists

Spermist conception of a

human sperm

Page 22: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Homunculus

Leeuwenhoek’s black male and white female rabbit experiments: spermist “proof”

Page 23: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Darwin

What he got right. What he got wrong.

• Acquired characteristics

Ex. Blind cave animals

• Sex. Repro.- gemmules from all over body are packed in sperm and egg

• Blended inheritance

• Likes produce likes• Change can be

permanent• There is no limit to

cumulative change

Page 24: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Mendel’s Three Principles

• Dominance

• Segregation

• Independent Assortment

The foundation of “classical” scienceThe foundation of “classical” science

(1822-1884)

Page 25: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

• Genes- genetic material on a chromosome that codes for a specific trait

• Genotype- the genetic makeup of the organism

• Phenotype- the expressed trait• Allel- an alternative form of a

gene

Genetic Definitions

Page 26: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Dominance Mechanism

• Two alleles are carried for each trait

• In true-breeding individuals, both alleles are the same (homozygous).

• Hybrids, on the other hand, have one of each kind of allele (heterozygous).

• One trait is dominant, the other trait is recessive

Page 27: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Dominance

• Traits of both parents inherited, but one shows over the other

• Traits are not blended

Page 28: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Segregation

• Half the gametes (egg or sperm) will carry the traits of one parent and half the traits for the other parent

Pairs of alleles are separated (=segregated) during meiosisPairs of alleles are separated (=segregated) during meiosis

Page 29: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Two different parental characteristics will be inherited independently of one another during gamete formation.

Independent Assortment

Example: flower color and leaf shape

Page 30: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Complexities

• Multiple genes for one trait

• Example: eye color

• Blended traits (“incomplete dominance”)

• Influence of the environment (UV, smoking, alcoholism)

Page 31: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Complexities

• Co-dominance-neither allele is recessive and the phenotypes of both alleles are expressed.

• Blood types- AB (not O); sickle cell anemia

heterochromia

Page 32: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Disorders

Down’s Syndrome (chrom 21)

Huntington’s (chrom 4)

Alzheimer’s (chrom 1, 10, 14, 19, 21)

Page 33: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genetic Information

Genes are traits

“Eye color”

Ear lobe connectedness

Genes produce proteins

Enzymes are proteins

Page 34: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Homologous Chromosomes

allele: specific traitallele: specific trait

gene: locationgene: location

Page 35: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Allele Example

Gene = “eye color”

Alleles

brownbluegreenlavender

Page 36: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Allele Examples

appearance

eye color:homozygous

Page 37: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Allele Examples

appearance

eye color:heterozygous,brown dominant over blue

Page 38: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genotype vs Phenotype

homozygous(dominant)

heterozygous

homozygous(recessive)

genotype phenotype

appearanceappearance

Phaner = visible

Page 39: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Punnett Square

If male & female are heterozygous for eye color

X

brown: 3/4 offspringblue: 1/4 offspring

male

female

Page 40: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Sickle Cell AnemiaEach parent carries one gene for sickle cell

S s

S sX

S

s

sS

S

S

S

s

s

S

s

s

Possible genotypes: 1SS 2Ss 1ss

Possible phenotypes:no sickle cell sickle cell

Page 41: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Autosomes and Sex Chromosomes

Page 42: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Red-Green Color BlindnessSex-linked trait

XC Y

XC Xc

X

XC

Xc

YXC

XC

XC

XC

Y

Xc

XC

Y

Xc

Normal male

Normal female recessive gene

Possible outcomes: XCXC XCXc XCY XcYNormal female

Normal Female(carrier)

Normal male

Color-blind male

Page 43: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

E unconnected earlobee connected earlobeE unconnected earlobee connected earlobe

alleleallele genegene

P EE x ee

gametes E e

F1 Ee

unconnected

connected

Page 44: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

F1 Ee x Ee

gametes1/2 E 1/2 e1/2 E 1/2 e

E

e

E e

EE Ee

Ee ee

F2 1 EE 2 Ee 1 ee

PunnettSquare

Page 45: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genotypes Phenotypes

Experiment to determinedominant vs. recessiveExperiment to determinedominant vs. recessive

Page 46: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genetic Sleuthing

My eye color phenotype is brown.

What is my genotype?

Page 47: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Where Does Genetic Diversity Come From?

Where Does Genetic Diversity Come From?

• MutationMutation• Chromosomal AberrationsChromosomal Aberrations• Genetic Recombination Genetic Recombination

(e.g., from sexual (e.g., from sexual reproduction)reproduction)

Page 48: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

mutationmutation

Sickle Cell Mutation

CTG ACT CCT GAG GAG AAG TCTLeu Thr Pro Glu Glu Lys Ser

CTG ACT CCT GAG GTG AAG TCTLeu Thr Pro Glu Val Lys Ser

NORMAL Hb

SICKLE CELL

Page 49: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Difference between Meiosis and MitosisDifference between Meiosis and Mitosis

Page 50: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Meiosis IMeiosis I

Interphase Prophase I Metaphase I Anaphase I Telephase I

Page 51: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Crossing Over of Nonsister Chromatids between Homologous Chromosomes

Page 52: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Meiosis IIMeiosis II

Prophase II Metaphase II Anaphase II Telephase II

Page 53: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.
Page 54: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genetic Testing

Page 55: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genetic Testing

• Predisposition to disease• Alzheimer's case (Feb. 2002)• Amniocentesis & Chorionic villa• Family history• >35 years old• Donor match• Paternity• Forensics

Page 56: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Gel electrophoresis

Page 57: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

• PCR way of copying specific DNA fragments from small sample DNA material "molecular photocopying"

• It’s fast, inexpensive and simple

Polymerase Chain Reaction

Page 58: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.
Page 59: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genetic Testing

Paternity Test $99

$299, looks at specific diseases

23 and me

Page 60: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Genetic TestingWould you want to know?

• Ethical concerns• Cost• Insurance companies

Page 61: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.
Page 62: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Tongue Roller

R = Tongue Rollerr = Unable to Roll Tongue

Page 63: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Widow’s Peak

W = Widows Peakw = Lack of Widow’s Peak

Page 64: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Free Ear Lobe Attached Ear Lobe

E = Free Ear Lobee = Attached Ear Lobe

Page 65: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Hitchhiker’s Thumb

Hi = Straight Thumbhi = Hitchhiker’s Thumb

Page 66: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Bent Little Finger

Bf = Bent Little Fingerbf = Straight Little Finger

Page 67: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Mid-digital Hair

M = Mid-Digital Hairm = Absence of Mid-Digital Hair

Page 68: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Dimples

D = Dimplesd = Absence of Dimples

Page 69: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Short Hallux

Ha = Short Halluxha = Long Hallux

Page 70: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

Short Index Finger

Ss = Short Index FingerS1 = Long Index Finger

*Sex-Influenced Trait*Sex-Influenced Trait

Page 71: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

http://www.youtube.com/watch?v=gCPuHzbb5hA

Page 72: DNA Lecture 009. Gregor Mendel Rosalind FranklinFrances Crick & James Watson X-ray diffraction photograph of DNA, 1953 Proposed double helix model 1953.

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