Chapter 12 DNA Structure And Replication

Topics: DNA, DNA replication, Base pair Pages: 14 (1376 words) Published: April 15, 2015
Bell WorkWhat are the four macromolecules that compose

all life?

BellworkIf your DNA is 23.5 % adenine. How much

Guanine is there?

Chapter 12- DNA Structure
and Replication
The Recipe Book

Nucleic Acids- Function
Nucleic acids function is storing, copying, and

transmitting instructions for making proteins.
DNA and RNA are nucleic acids!!!
Monomer of Nucleic Acids- Nucleotides
Think of DNA as a recipe book
What is DNA and how does it work?

DNA Storage
DNA stores instructions for making

proteins
The total human genome contains 3 billion

base pairs, enough to fill 1,700 books!
The human genome contains about 25,000-

30,000 separate genes
One single gram of DNA can store 700TB of

data , which is 734003200 MB or over 70
million Taylor Swift songs
Genetic Sequencing Site -

https://www.23andme.com/

Nucleotide- 3 parts

DNA- Nucleotide Structure
 5-carbon Sugar- D stands for deoxyribose.

This connects to other nucleotides’
phosphate groups.
Phosphate Group- used to form phosphate

backbone of a nucleic acid.
Nitrogen Base- functional part of DNA.

Makes up the “coded” message

Four Nucleotides- A,T,G,C
Purines

Pairs
With

Pairs
With

Pyramidines

Nitrogen Base Pairing Rules
Adenine pairs with Thymine ( 2 hydrogen bonds )
A-T
Guanine pairs with Cytosine (3 hydrogen bonds )
G-C
Connected by hydrogen bonding between bases
Allows unzipping and rezipping of DNA
There is a 5th Base, Uracil,- FOUND ONLY IN RNA

DNA Structure

Nitrogen
Base

3’ to 5’

3’ to 5’

Covale
nt
Bonds

DNA Structure
Complementary bases pairing keeps DNA

information conserved, reduces mutation
Hydrogen bonds hold strands together and

allow DNA to be unzipped and rezipped
Nucleotides are connected by covalent

bonds between sugars and phosphate to
create sugar phospate backbone

DNA-Twisted Ladder Structure

DNA- Anti-Parallel Strands
P
o
i
n
t
e
d
d
o
w
n

Notice how the strands are running in opposite

directions! (Sugars are upside-down on the right)

Watson, Crick, and Rosalind
Franklin

DNA code is Universal
DNA functions by storing and transporting the genetic

instructions for making proteins within all organisms.
These instructions often overlap between species or
even kingdoms of organisms because of their
evolutionary history
The fact that all organisms use DNA and DNA is
passed form parent to offspring provides strong
evidence for evolution
Your DNA is….
99% chimp
 95% Dog or Cat
 88% Mouse
75% Chicken
50% Banana
http://www.wellcomecollection.org/interactives/comparey

ourdna/

MIT Open Source Class
https://

www.youtube.com/watch?v=P-Ry4rRdDbk
Backstreet Boys DNA Song-

http://www.youtube.com/watch?v=hyI2mYfbb
xk

BellworkDraw and label 4 nucleotides of DNA in two

strands including the three major parts, the
covalent bonds, and where hydrogen bonds
will form.

BellworkDraw and label 4 nucleotides of DNA in two

strands including the three major parts, the
covalent bonds, and hydrogen
bonds.
Hydroge
n Bonds

Phosphat
e

Nitrogen Base

5-C
Deoxyribose

Covalent
Bond

Bell Work
Which of the following includes all the others?
Chromatin
Nucleosomes
DNA molecules
Histones
Chromosome

Lecture Part 2- DNA Replication

Calculating Nitrogen Base %
Since for every A there is a

T and for every G there is a
C. You can calculate the %
of every nitrogen base if
you only have one base %.
A + T + G + C =100%

Nitrogen
Base

Percent

A

A = T and G = C
A+G= 50% and T+C= 50%

T
G
C

34.5 %

Cell Cycle and Chromosomes
• During the S phase of cell
cycle, chromosomes are
replicated
• This creates duplicated
chromosomes with two
identical sister chromatids
• These sister chromatids
will be separated during
Anaphase of mitosis.

Semi-conservative- DNA
Replication
DNA...
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