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L10: Mitosis & Meiosis
BIOL 153/LBlack Hills State Univ.Ramseys
I. Eukaryotic chromosomesA. Structural components
1. Chromatin
DNA and associated proteins
2. Nucleosomes
chromotin packing unit ('beads on a string')
3. Fibers, looped domains, condensed coils
higher order organization of chromatin
Fig. 8-4Raven p. 154
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I. Eukaryotic chromosomesB. Location
1. In nucleus
1. In nucleus
interphase and early prophase
1. In nucleus
interphase and early prophase
2. Across cell
1. In nucleus
interphase and early prophase
2. Across cell
late prophase, metaphase, anaphase
1. In nucleus
interphase and early prophase
2. Across cell
late prophase, metaphase, anaphase
chromosomes spend most time in nucleus (interphase)
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nuclear envelope degrades during prophase
nuclear envelope reforms during telophase
I. Eukaryotic chromosomesC. Size and content
1. Nucleotides: huge variation in base pairs
• flowering plants: very high• mammals: kinda high• birds: low
1. Nucleotides: huge variation in base pairs
• flowering plants: very high• mammals: kinda high• birds: low
2. Length:0.5 g DNA stretches earth to sun!
Wake-robin Trillium
~68 m of DNA
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Homo sapiens
~2 m of DNA
I. Eukaryotic chromosomesD. Genes
1. A gene specifies amino acid order in a protein
2. Allele = alternate version of gene
3. Locus = specific gene location on chromosome
I. Eukaryotic chromosomeE. Ploidy
1. Haploid: 1 set of chromosomes
2. Diploid : 2 sets of chromosomes
3. Polyploid: >2 sets of chromosomes
4. Homologous chromosomes
chromosomes with same genes, in same order (may have different alleles)
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hypothetical organism with only three chromosomes:
Haploid Diploid
Haploid Diploid Triploid Tetraploid Haploid Diploid Triploid TetraploidPolyploid
Haploid Diploid Triploid TetraploidPolyploid
homologous
Haploid Diploid Triploid TetraploidPolyploid
homologous homologous homologous
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one particular chromosome in hypothetical diploid organism:
homologous chromosomes
2 different alleles
2 different alleles
1 allele (only)
2 different alleles
homologous chromosomes
II. Mitosis overview A. Location
somatic (body) cells
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B. Goal
make exact chromosome replicates(occurs with cell division)
C. Examples
C. Examples
animal developmentchicken egg
plant growthash seedling
if mitosis makes exact copies...
how do bloody blobs become chicks?how do seeds become trees?
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III. Meiosis overview A. Location
gametic (reproductive) cells
B. Goal
reduce (half) chromosome number(occurs with cell division)
C. Examples
testes à sperm
ovary à egg
anther à pollen
IV. Shared features of mitosis & meiosis A. Naming of stages
[I]P-MAT
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A. Naming of stages
[Interphase]ProphaseMetaphaseAnaphaseTelophase
[I]P-MAT
B. DNA replication
Interphase
C. DNA condensing
Prophase
D. Lining up of chromosomes
Metaphase
E. Separation (chromatids/chromosomes)
Anaphase
V. Particular features of meiosis
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A. Two rounds of division
P-MAT I P-MAT II"Reductional Division" "Equational Division"
A. Two rounds of division
P-MAT I P-MAT II"Reductional Division" "Equational Division"
reduces chromosome # in half divides chromatids
Meiosis I"Reductional Division"
Meiosis II"Equational Division"
B. Crossing over of homologous chromosomes (recombination)
Prophase I
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C. Separation of homologous chromosomes(reduction)
Anaphase I & Telophase I
