Transcript Chapter 13: The Cell Cycle

Chapter 12: The Cell Cycle
Eukaryotic Cells
• Somatic cells
– Diploid
• Gametes
– Haploid
• Genome
– Chromatin
• Chromosomes
• Sister Chromatid
The Mitotic Cell Cycle
Prophase-Prometaphase
Prophase
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Chromatin condenses
Nucleoid disappears
2 sister chromatids
Mitotic spindle forms
Centrosome
Animals
– Centrioles moves
apart to poles
Prometaphase
• Microtubles attach to
kinetochore
• Chromosomes begin
to move
Metaphase- Anaphase-Telophase
Metaphase
• Chromosomes line up
along the metaphase
plate
Anaphase
• Chromosomes move
to opposite poles
• Each ½ sister
chromatid is now
considered to be a
complete
chromosome
Telophase
• Nuclei form
• Nucleoli reappear
• Chromatin uncoils
Cytokinesis
• Part of cell cycle, but not considered to be
part of mitosis
Regulation
Cyclins and Protein Kinases
• Cyclin
• Protein kinase
– Cyclin-dependent
kinase
– Mitosis promoting
factor
– Promotes mitosis
Density Dependent Inhibition
• Crowded cells stop
dividing
– Cancer
Growth Factors
• Protein released by certain cells
– Stimulates division
Cancer
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Disorder of Cell division
– Divides indefinitely (1951)
Transformation
– Benign
– Malignant
• Cancer
• Metastasis
Henrietta Lacks
Chapter 13: Meiosis and
Sexual Life Cycles
Heredity
• Acquiring genes
– Gene
• DNA
– Unique Sequence
– Locus
Reproduction
• Asexual
– Mitotic division
• Offspring
– Hydras
• Clone
• Sexual
– Combination of genes
• Greater variation
Life Cycle
• Conception to production
of offspring
• Humans
– Somatic cells- Diploid
• Produced by mitosis
• 23 pairs of
chromosomes
– Sex chromosomes
» Males
– Autosomes
– Gametes- Haploid
• Produced by meisosis
• 22 autosomes, 1 sex
chromosomes
Life Cycle
• Ovaries
• Testes
• 2 haploid forms a
diploid
– Fertilization
Meiosis
• 2 consecutive cell
division
– 4 daughter cells
• Interphase
– Forms 2 sister
chromatids
• Meiosis I
• Meiosis II
Meiosis I
Meiosis II
Comparison of Mitosis and Meiosis
Comparison of Mitosis and Meiosis
Origins of Genetic Variation
• Independent assortment
– 50/50 chance
– 2 possible outcomes for each of the 23 pairs
• Possible combinations
Origins of Genetic Variation
• Crossing over
– Combine genes from 2
parents
• Occurrence
• Trade places
– Event per pair
• Genetic exchanges
Origins of Genetic Variation
• Mutations
– Evolutionary adaptation
• Random fertilization
– Possible combinations
• Combine crossing over, independent
assortment and random
fertilization…endless combinations.
• In other words, you are unique…and
special! 