KEY CONCEPT DNA structure is the same in all organisms.

1
KEY CONCEPT DNA structure is the same in all
organisms.
2
DNA is the molecule of Life

• Deoxyribonucleic Acid
• Contains genetic information for cell functions,
  growth, and division
• Shape Double Helix
• Watson Crick Discovered the shape of DNA

3

• DNA is made up of a long chain of nucleotides.
• Each nucleotide has three parts.
• a phosphate group
• a deoxyribose sugar
• a nitrogen-containing base

4

• DNA is composed of four types of nucleotides.

-Adenine -Thymine -Cytosine -Guanine
5
Watson and Crick determined the three-dimensional
structure of DNA by building models.

• DNA is a double helix that is made up of a
  sugar-phosphate backbone on the outside with
  bases on the inside.

6
Nucleotides always pair in the same way.

• The base-pairing rules show how nucleotides
  always pair up in DNA.

• A pairs with T
• C pairs with G

7

• The backbone is connected by covalent bonds.

• The bases are connected by hydrogen bonds.

8
DNA Replication

• Replication DNA making copies of itself
• DNA must be copied before a cell can divide
• Each new cell will have
• a complete set of DNA

9
DNA Replication Process

• Replication begins when the enzyme DNA helicase
  opens the DNA forming replication bubbles

10
DNA Replication- The Big Picture
Each Bubble has 2 Forks each fork has a leading
and lagging strand
11
DNA Replication DNA Polymerase

• The enzyme DNA polymerase
• brings new nucleotides to the
• replication fork
• - it pairs them according to base pairing
  rules A pairs with T
• C pairs with G

12
DNA Replication

• The process continues until 2 complete copies of
  the DNA are produced
• Each copy of the DNA contains one strand of DNA
  from the original DNA molecule and one new strand
  that was produced by replication
• Known as semi-conservative replication