11/22/2015 cell cycle a. the cell theory: 1. all organisms are composed of one or more cells. 2. the...
TRANSCRIPT
04/20/23
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.