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Cell CycleA. The Cell Theory:

1. All organisms are composed of one or more cells.

2. The cell is the basic unit of life.

3. All cells come from existing cells.

B. Cells go through a Cell Cycle to:

1. Grow 2. Repair 3. Replace 4. Create haploid cells that can combine to make an organism

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Cell Cycle - Interphase:

G1 - growth: increase size of cell

G0 - resting phase (*neurons, liver, muscle cells)

S - growth as in DNA Synthesis (replication)

G2 - growth: organelles and biochemicals

- M Phase (Mitotic Phase)

Mitosis: division of nuclear material

Prophase, Metaphase, Anaphase, Telophase

Cytokinesis: division of cytoplasm & organelles

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Cell Cycle

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Cell Cycle Regulation

Can DNA synthesis begin?

Did DNA replicate properly?

Can sister chromatids

separate properly?

• Promoting factors– Cyclins

• regulatory proteins for the cell cycle

– Cdks

• cyclin-dependent kinases

• enzyme activates cellular proteins

– MPF

• maturation (mitosis) promoting factor

• combo of a cdk (enzyme) and cyclin (substrate)

– APC

• anaphase promoting complex

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Faulty Cell Cycle Regulation

unlimited growth

turn on growth promoter genes

ignore checkpoints

turn off tumor suppressor genes

escape apoptosis

turn off suicide genes

immortality = unlimited divisions

turn on chromosome maintenance genes

promotes blood vessel growth

turn on blood vessel growth genes

overcome anchor & density dependence

turn off touch sensor gene

DNA damage is causedby heat, radiation, or chemicals.

p53 allows cellswith repairedDNA to divide.

Step 1 Step 3p53 triggers the destruction of cells damaged beyond repair.

NORMAL p53

Cell division stops, and p53 triggers enzymes to repair damaged region.

Step 2

DNA repair enzymep53protein

p53protein

DNA Polymerase I

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Mitosis1 divisiondaughter cells genetically identical to parent cellproduces 2 cells2n 2nDiploid Diploidproduces cells for growth & repairNo homologous chromosomes pairingno crossing over

Meiosis2 divisionsdaughter cells genetically different from parentproduces 4 cells2n 1nDiploid Haploidproduces gametes for reproduction Homologous chromosomes and tetradscrossing over Synapse (homologous chr togetherChiasma

Nondisjunction

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Mitosis vs Meiosis

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Nondisjunction

4 genetically unique cells1 egg3 smaller polar bodies

4 genetically unique sperm

Synapsis - pairing of homologous chromosomesChiasma - point where crossing over occurs

Haploid (n) or Diploid (2N)?

Haploid (n) or Diploid (2N)?

Haploid (n) or Diploid (2N)?

Haploid (n) or Diploid (2N)?

Meiosis - production of gametesfrom a Germ Cell Interphase

Prophase I

Metaphase I

Anaphase I

Prophase II

Metaphase II

Anaphase II

Telophase II

Telophase I

No Interphase between Meiosis Iand Meiosis II, means that G1, S, and G2 do not occur.

What is the end result in termsOf the chromosome number?

What 3 things happen here?

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tetradHomologous chromosomes

Crossing over

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Karyotype Pedigree

?

Crossing Over

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Writing Prompt

• 1. What are the phases of the cell cycle and what is occurring?– Sentence starter: A cell that has divided goes into ___ phase where…

• 2. Not all cells move through the cell cycle in the same way. Give     examples of three different cells and their destiny.– Sentence starter: The frequency of cell division varies with cell type,

one example is …

• 3. Discuss the 3 checkpoints of the cell cycle, where they take     place, what indicates the cells readiness to continue, and what     chemicals triggers the “go ahead.”– Sentence starter: In the cell cycle, there are three defined checkpoints

for cells, the first one…

Genetics

Overview

Inheritance

• Genetic Information

• Passes on as genes at a certain location on a chromosome (locus)

• Chromosomes are paired– Autosomal (22 pairs)– Sex-Linked (1 pair)

Terms

• Traits - Alleles• Dominant - Recessive• Genotype - Phenotype• Homozygous - Heterozygous• Pure - Hybrid• P generation - Filial generations• Gametes - Offspring• Law of Segregation• Law of Inheritance

Terms

• Codominant• Incomplete dominance• Epistasis• Pleiotropy• Multiple alleles• Polygenic• Sex-linked

Locus

Punnett SquaresPunnett Squares show:

1. The alleles in the gametes of each parent,

2. Possible results of genetic crosses, and

3. The genotypes of the offspring.

Steps to Creating and Using Punnett Squares:

1. Identify the trait and possible alleles (dominant and recessive)

2. Determine the genotype of the parents

3. Create the Punnett Square - each trait needs 2 boxes to represent it

4. Put the male across the top, Female along the side.

5. Fill in the Punnett Square representing the offspring produced

6. Determine the Genotype Ratio (GR) of the offspring.

7. Determine the Phenotype Ratio (PR) of the offspring.

Punnett Squares

• Monohybrid

Dihybrid

FOIL Method

Two-Point Cross Data

BV bv Bv bV

bv BbVv

bbvv Bbvv bbVv

Expected Results

575 575 575 575

Actual Results

965 944 206 185

Calculations Parental Genotypes

965 (42%) +944 (41%) = 1909 1909/2300 = 83%

Recombinant Genotypes 206 (9%)+185 (8%) = 391 391/2300 = 17%

If independent assortment was to occur, the percentages would be 25% a piece.

Based on the data, the recombinants arose because of crossing over

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If the majority of the offspring have a genotype similar to one of the parents, then the genes are linked.

If the majority of the offspring have a recombinant genotype, then the genes are unlinked.