DNA Replication

1
DNA
THE INSTRUCTION MANUAL FOR BUILDING A BODY
2

What Is DNA?
 DNA stands for DeoxyriboNucleic Acid and is the
basic substance of heredity.  
DNA is a set of instructions for building your
body and controls everything about the way you
look and function.
3
WHERE IS THE DNA STORED?
The DNA is stored in the nucleus of nearly all
your cells.
4
(Get itWatson and Crick? Whats in the creek?)
Whats in the creek?

• In 1953, James Watson and Francis Crick figured
  out the structure of DNA. Their discovery
  revealed important information about how DNA
  copies itself.

5
These scientist won a Nobel Prize in 1962 for
work on the DNAs structure.

Rosalind Franklin was actually the 1st scientist
to produce the pictures of DNA , but died before
the Nobel Prize was given.
6
Rosalind Franklin
7
The Structure of DNA
A DNA molecule looks like a twisted ladder.
Because of its shape, a DNA molecule is often
called a double helix. A helix is a shape that
twists.
8
The DNA Double Helix Molecule
Looks like a twisted ladder
The sides of the ladder are made of sugar
molecules and phosphates
The rungs of the ladder are formed by pairs of
nitrogen bases. Nitrogen bases are molecules that
contain the element nitrogen and other elements.
9

• Within the nucleus of every cell are long strings
  of DNA, the code that holds all the information
  needed to make and control every cell within a
  living organism.

10

• The two sides of the DNA ladder are made up of
  molecules of a sugar called deoxyribose,
  alternating with molecules known as phosphates.

11

• There are four kinds of nitrogen bases Adenine
  (ad uh neen), Thymine (thy meen), Guanine (gwah
  neen), and Cytosine (sy tuh seen). The capital
  letters A, T, G, and C are used to represent the
  four bases.

12
Nitrogen bases

• Adenine always pairs with Thymine and Guanine
  always pairs with Cytosine

• Adenine A
• Thymine T
• Guanine G
• Cytosine C

• The genetic code is the order of the nitrogen
  bases and the set of instructions for making a
  person.
• This is known as the HUMAN GENOME

13

• The bases on one side of the DNA ladder match up
  in a specific way with the bases on the other
  side. Adenine (A) - Thymine (T),
• Guanine (G) -Cytosine (C)
• This pairing pattern is the key to understanding
  how DNA replication occurs.

14
Nucleotide
15
example
ATTCGAACGACCTG
TAAGCTTGCTGGAC
Try your own
GTAACTGGAACTAG
CATTGACCTTGATC
16
DNA Replication

• A cell makes a copy of its DNA during interphase
  before mitosis occurs.
• DNA replication ensures that each daughter cell
  will have all of the genetic information it needs
  to carry out its activities.

17

• During DNA replication, special enzymes move up
  along the DNA ladder, unzipping the molecule as
  it moves along.

18
A DNA molecule unzips between its paired bases.
New bases pair with the base on each strand. As a
result, two identical DNA molecules form.
19

• When the enzyme has passed the end of the DNA,
  two identical molecules of DNA are left behind.
  Each contains one side of the original DNA and
  one side made of "new" nucleotides.

20
Nucleotides

• Units which, when linked to sugar, make up one
  side of the DNA ladder

21

• New nucleotides move in and go to each side of
  the unzipped ladder. The bases on these
  nucleotides are very particular about what they
  connect to.

22

• Cell division occurs at least
• 10 million times every
• second in an adult human
• body.

23

• About 1 trillion mitoses occur in an adult human
  every 24 hours

24
Mustakes afe boind to happwn!

• It is possible that mistakes were made along the
  way -- in other words, that a base pair in one
  DNA molecule doesn't match the corresponding pair
  in the other molecule.

25

• On average, one mistake may exist in every
  billion base pairs. That's the same as typing out
  the entire Encyclopaedia Britannica five times
  and typing in a wrong letter only once!

26
Lets check out this DNA activity.A Science
Odyssey You Try It DNA Workshop