DNA

1
DNA What Is It?

• Write down everything you know about DNA on the
  back of the notetaking worksheet

2
What is it?

• D Deoxyribo
• N nucleic
• A Acid
• Deoxyribonucleic Acid

3
Length of Cell Cycle

• Length of cell cycle depends on the type of cell.
• Liver cell takes 22 hours to divide, some cells,
  like nerve cells, stay in interphase for years.
• (liver cell)

4
DNA Replication

• Ensures that each daughter cell has genetic
  information to carry out its activities.
• DNA carries all the cells instructions.
• DNA is passed from parent cell to daughter cells.

5
Structure of DNA

• DNA molecule looks like a twisted ladder
• The molecule is known as a double helix
• Sides of molecule are made of sugar (deoxyribose)
  and phosphate
• Rung of molecule is made of nitrogen base pairs

6
DNA Structure Continued

• Rung of molecule is made of nitrogen bases
• Names of bases
• (A) adenine
• (T) thymine
• (G) guanine
• (C) cytosine

7
DNA Structure Continued

• One unit made up of a phosphate, sugar and
  nitrogen base is called a Nucleotide.
• Nucleotide base sugar phosphate

8
Replication Process

• Replication starts by the molecule unwinding and
  separating.
• They separate between the nitrogen pairs (on the
  rungs)
• Free floating nitrogen bases pair up with bases
  on each half of the DNA molecule.
• A always pairs with T
• G always pairs with C
• The order will exactly match the parent DNA
  molecule

9
Answer the following questions on a sheet of
paper.

1. What does the length of the cell cycle depend on?
2. What does DNA stand for?
3. Name 2 reasons DNA replication is so important.
4. Describe what a DNA molecule looks like.
5. What is another name for a DNA molecule?

10

• 6. What are the sides of the DNA molecule
  composed of?
• 7. What are the rungs of the DNA molecule
  composed of?
• 8. What are the names of the rungs of a DNA
  molecule?
• 9. What is a nucleotide and what are they made
  of?

11

• 10. Draw a picture of a DNA molecule and label
  each part.
• 11. List the steps of DNA replication.
• 12. Describe which base pairs always pair up
  together during replication.