1. NEW UNIT! GENETICS

2. Hint: the bases are bonded to the sugars.
THE STRUCTURE OF DNA
Recall the structure of DNA
Monomer: _______________
Composed of: _________________________________________
4 Bases: _____________________________________________
Shape:
“Twisted ladder”: _______________
“Handrails”: ______________________
“Steps”: ________
Pairing: _____________
Nucleotide
Sugar Group, Phosphate Group, Base
Adenine, Thymine, Cytosine, Guanine
A T C G
Edible DNA!
At your table, there is a bag full of candy and toothpicks.
You will be building a model of DNA.
What rules must you follow when making your model?
Double Helix
Phosphate & Sugar
Bases
A – T, C – G
Hint: the bases are bonded to the sugars.

3. STRUCTURE OF DNA
Use your model to NEATLY draw a “flat” DNA molecule and label it with the following terms: sugar, phosphate, thymine, adenine, cytosine, guanine.

4. Some Terminology Somatic Cell
Any cell other than sex cells (sperm & ovum)
Eg. Skin cells, muscle cells, blood cells, etc.
Gene
A section of DNA associated with a particular inherited trait
Genome
The entire nucleotide sequence for a cell or organism
The human genome contains 46 (23 pairs) chromosomes – one comes from mother, one from father.
Estimated 20,000 – 25,000 genes

5. CHROMATIN AND CHROMOSOMES AND CHROMATIDS
Genetic material is called different things depending on what form it’s in.
Chromatin
Non-condensed form of
genetic material; composed of DNA and proteins
Chromosome
Condensed form of
Sister Chromatids
Pair of chromosomes condensed and attached by a centromere
Centromere
The point where two sister chromatids

6. Consider the Following
Humans begin life as ONE cell.
We become TRILLIONS of cells before being born due to cell division.
After we are born, cell division continues as we grow.
As adults, cell division replaces worn-out or damaged tissues.
Lining of digestive tract
New blood cells
Lining of the respiratory tract
Cells repair cuts
New skin cells

7. THE CELL CYCLE
The repeating series of events that occur as a cell grows and divides.
Interphase
G1 phase
S phase
G2 phase
Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

8. Next up, Mitosis!!! 1. INTERPHASE
The phase where a cell spends most of its life.
G1 phase
Growth
DNA is in chromatin form
One copy of each chromosome
S phase
Chromosomes are copied
(DNA replication)
G2 phase
Second growth phase
Prepares for mitosis
Next up, Mitosis!!!