1. 12-1 and 12-2 DNA Structure and Replication
Pgs
Block 1

2. DNA – a nucleic acid made of a polymer of nucleotides.
Deoxyribonucleic acid
Nucleotide has three parts: phosphate group, nitrogen base, and deoxyribose (sugar).

3. DNA – shape described as a double helix or spiral staircase.
Sugar-phosphate backbone
Nucleotides in the center being held together with hydrogen bonds.

4. Nucleotide bases Adenine (A) Cytosine (C) Guanine (G) Thymine (T)
Each nucleotide above has a unique nitrogen base.

5. Pairing of nucleotides:
Adenine and Thymine are always paired together.
Cytosine and Guanine are always paired together.

6. How do chromosomes and DNA differ between prokaryotes and eukaryotes?
Contains 1000x more DNA than in prokaryote.
DNA found on multiple chromosomes housed in the cell’s nucleus.
Lack nuclei
DNA molecule forms the cell’s chromosome.
Figure 12-8

7. Human Cell’s DNA
The nucleus of a human cell contains more than a meter of DNA.

8. How is DNA packaged? Nucleosomes Chromosomes DNA Coils Supercoils
Histones

9. DNA replication: DNA is being copied.
Enzymes unzip the DNA strand and two strands are formed from the original strand.
Occurs during the S phase of the cell cycle.

11. Important contributions were made by:
Erwin Chargaff
Rosalind Franklin
Watson and Crick

12. Erwin Chargaff American biochemist
Equal amounts of adenine and thymine are present in DNA
This was also true for cytosine and guanine.

13. Rosalind Franklin English scientist
Examined DNA using X-ray diffraction
Provided important clues to Watson and Crick.

14. Watson and Crick Major breakthrough
Determined the shape of DNA to be a double helix.
DNA looks like a spiral staircase.

15. How does this relate to chromosomes?
Chromosomes are made of chromatin.
Chromatin is made of DNA and different proteins.
Histones (a type of protein) bind to DNA and helps to fold and package it so it fits into the nucleus.

16. Chromosomes (small), and Genes (smaller), and DNA (smallest).
DNA is the molecule that makes up the chromosome and genes.
The genes are locations or bands found on the chromosomes.
The chromosomes are the X shaped structures we see during cell division.
All found inside the nucleus.