1. Genetics
DNA and cell cycle
Video – Cell Structure

2. 4. 1 Cell Division and Genetic Material
Genetics:
The study of how heredity information is passed from one generation to the next.

3. Cell Theory
All living things are composed of one or more cells i.e. structural unit of life
Cells are the smallest functional units of living organisms
New cells come only from pre-existing cells by cell division

4. DNA Structure
DNA is the genetic information that an individual inherits from his/her parents.
DNA is double stranded and is called « Double helix »
During cell division (mitosis), DNA is replicated so that each new cell receives an identical copy of the genetic information.

5. DNA Structure
DNA is made up of many nucleotides joined together as a chain.
This chain is known as a polynucleotide or nucleic acid

6. DNA Structure Nitrogenous base: - A, T, C, G -bound to the sugar
Phosphate group:
-Binds to the deoxyribose to form the backbone of the DNA
Nitrogenous base: - A, T, C, G
-bound to the sugar
Pentose Sugar:
5 carbon ring
Deoxyribose

7. The Deoxyribose sugar on the DNA does not have an oxygen on the 2nd carbon.
RNA has a ribose sugar, which has an oxygen atom on the 2nd carbon.

8. Complementary base-pairing: Adenine – Thymine (one H bond)
Pyrimidine: (single ring)
- heterocyclic compound
- Cytosine, Thymine and Uracil
-Cytosine and thymine are found in DNA.
2) Purine: (double ring)
-heterocyclic compound
-2 ring structure
- Adenine & Guanine
Complementary base-pairing: Adenine – Thymine (one H bond)
Guanine – Cytosine (two H bonds)

9. DNA Structure
Genome: Complete DNA sequence of an organism.

10. Complementary Base Pairing
What would the complementary strand be?
A T T C G A A C T
a) T A A G G T C A G
b) T A A G C T T G A
c) G C C A T G G T C

11. Chromatin: uncoiled DNA
Chromosome: coiled DNA (many strands of chromatin)

12. Video

13. CELL cycle Process of growth and cell division
One complete cycle produces two new identical ( but smaller)daughter cells
One cycle takes approximately hours
All somatic cells undergo the cycle
3 main phases: Interphase, Mitosis and Cytokinesis

14. Cell cycle
5-6 hours
10 – 12 hours
4-6 hours
Less than 1 hour

15. interphase
Stage where the cell grows and makes copies of genetic information and prepares the cell for division. Cell is carrying out life functions.
G1 (Growth 1) : synthesizes new molecules
S (Synthesis): DNA is copied and is in the form of chromatin.
G2 (Growth 2): synthesizes more proteins that prepare for cell division.

16. mitosis
The copied genetic material separates and prepares for the physical separation of two new daughter cells.
The splitting of genetic information allows each new daughter cell to have identical genetic information.
Subdivided into 4 main phases.

18. 1) prophase Chromatin condenses into chromosome
Each chromosome exists as two copies of one chromosome
The chromosome arms are « sister chromatids » and are joined at the center by the centromere.
Nuclear membrane breaksdown and nucleolus disappears.
The centrioles begin to release spindle fibers and migrate to opposite poles

19. 2) metaphase
Spindle fibers attach to the centromere of the sister chromatids
The sister chromatids line up on the equator of the cell forming a metaphase plate.

20. 3) anaphase
Each centromere separates, causing the sister chromatids to separate. Spindle fibres contract.
Each chromosome migrates to the opposite pole.
One complete set of chromosomes is now at each pole of the cell.

21. 4) telophase Chromosomes unwind into chromatin
Spindle fibers break down
Nuclear membrane reforms around the new set of chromosomes
Nucleolus forms within each new nucleus.
Cleavage Furrow

22. cytokinesis Process of cytoplasmic division
The cytoplasm physically divides and creates two new daughter cells
The microfilaments on the cytoskeleton of the cell membrane pinch and separate the cytoplasm.
The cytoplasm divides equally between the two cells.

23. Plant cell Have a cell wall that is rigid
A cell plate forms between the two nuclei and separates the two daughter cells.
A new cell wall then forms around the cell plate.

24. homework
p. 168 :
2, 3,5,8, 9, 10, 11
Video