1. Cell Cycle and DNA

2. Why are cells small? Diffusion DNA Surface area-to-volume ratio
Fast and efficient over small distances
Slow and inefficient over large distances
DNA
Blueprint for proteins
More cytoplasm needs more proteins therefore we would need more DNA
Surface area-to-volume ratio
A cell’s volume increases much faster than its surface area
Plasma membrane does not have enough area to allow all the oxygen, waste and nutrients to diffuse

3.                                                       
Parameters
Case I
Case II
Case III
Case IV
Length (L) 1 2 3 4
Face Area (L2) 9 16
Volume (L3) 8 27 64
Surface Area(L2 x 6 faces) 6 24 54 96
Area/Volume ratio
1.5

4. G1 S First stage of interphase Rapid growth and metabolic activity
-DNA synthesis – DNA copies itself
-Middle of Interphase
First stage of interphase
Rapid growth and metabolic activity

5. G2 Cell prepares for mitosis (cell division)
In animal cells, centrioles begin to form spindle fibers which aid during cell division
End of Interphase

6. M Cell divides into 2 identical daughter cells over 4 stages (PMAT)
Cells are identical to each other and to the parent cells

7. MITOSIS YouTube: Click

8. Review of Mitosis
Prophase
Metaphase
Anaphase
Telophase

9. DNA Deoxyribose nucleic acid Holds genetic information
Found in the nucleus
Chromosomes are made up of long strands of DNA
Genes are found on the chromosomes

10. CHROMATIN

11. In the nucleus, the DNA double helix is packaged by special proteins (histones) to form a complex called chromatin. The chromatin undergoes further condensation to form the chromosome. So while the chromatin is a lower order of DNA organization, chromosomes are the higher order of DNA organization. An organism’s genetic content is counted in terms of the chromosome pairs present. e.g. humans have 23 pairs (so 46 total) of chromosomes.

12. DNA Structure DNA is a polymer of nucleotides 3 Parts of a nucleotide
(1) Simple Sugar – deoxyribose
(2) Phosphate group
(3) Nitrogen Base (4 Kinds)

13. The 4 Kinds of Bases Adenine (A) always pairs with Thymine (T)
Guanine (G) always pairs with Cytosine (C)

14. DNA in the Cell Cycle

15. Bonding in DNA Covalent Bond Covalent Bond
holds the phosphate of one nucleotide to the sugar of another nucleotide
Making the outside of the DNA ladder
Covalent Bond

16. Bonding in DNA Hydrogen Bond
Hold the nitrogen bases together
Making the rungs of the ladder
Together the Covalent and Hydrogen bonds create the double helix (twisted ladder)

17. Scientists James Watson and Francis Crick
Won a Nobel Prize in 1953 for discovering the double helix shape of DNA

18. Scientists (continued)
Rosalind Franklin
Had information that Watson and Crick “borrowed” to piece together the shape of DNA (was given no credit)
VIDEO

19. DNA Replication Making a copy of DNA 3 Steps
(1) DNA unwinds – helicase unzips the DNA
(2) Free nucleotides in the nucleus pair up with exposed bases from the unzipped DNA
(3) Phosphates and sugars pair up forming a backbone for the free nucleotides