Dna structure 12.1 and 12.2 students

End of 12.1 and 12.2

Nucleotides are made

up of 3 things:

1. 5 carbon sugar

2. Nitrogenous

(containing nitrogen)

bases

3. Phosphate group

Nucleic Acids (like

DNA and RNA)

The nucleic acid DNA consists of the

following: 1. Deoxyribose- sugar

2. A phosphate group

3. A series of 4 nitrogenous bases: cytosine, adenine, thymine,

guanine

The nucleic acid RNA

consists of the

following:

1. Ribose- sugar

2. A phosphate group

3. A series of 4

nitrogenous bases:

adenine, uracil,

guanine, cytosine

Adenine and Guanine

are considered purine

Thymine, Cytosine,

and Uracil are

considered

pyrimidines

DNA is compared to a

twisted ladder

Ladder Rails- consist of

alternating deoxyribose

(sugar) and phosphate

group

A purine base always

bonds with pyrimidine

Bases are held together

by hydorgen bonds

The direction or orientation of the

The carbon in the sugar molecules are numbered

The leading strand starts with the 3’ (five prime) end

The lagging strand runs in the reverse direction

This orientation of the

Length of a human

chromosome ranges

from

If a DNA strand 140

million nucleotides

long

In order for all of the

DNA to fit into

microscopic cells, the

The phosphate

groups in DNA create

a negative charge

The structure of DNA

wound around

DNA replication is

considered

semiconservative

replication- because

this process consists

DNA replication

occurs during

interphase of the cell

cycle-

There are 3 main

stages to

semiconservative

replication:

Helicase- is an

enzyme used to

When DNA is

unzipped, the

hydrogen bonds

between the bases

DNA polymerase-

enzyme that catalyzes

the addition of

appropriate nucleotides

There are a plethora of

nucleotides floating in

the cell waiting to be

DNA polymerase

ensures that each base

binds to its compliment

DNA polymerase adds

the nucleotide bases

to the 3’ end of the

In this way, the

templates allow

identical copies of

The leading strand is replicated from 3’ to 5’ end

The lagging strand is synthesized discontinously in segments called Okazaki fragments by the DNA

The lagging strand is oriented in the 5’ to 3’

DNA ligase- is an

enzyme that connects

all the fragments of