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G-banding
- Giemsa stain
- Reflects how condensed the chromosome is.
- Dark - heterochromatin
- Light - euchromatin
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Deletions
- usually bad (dep on size) lethal
- *loss
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Duplication
- - Tolerated better
- - Through evolution can also be beneficial
- - Gain
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Relocations
- depends- If gene was moved away from its promoter can be bad.
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Inversions
- -2 types
- 1. Paracentric
- 2. Pericentric
- -inversion spans centromere
- -Don't tend to have phenotypic consequences
- (balanced rearrangement of genetic material)
- -where/when there are issues:
- 1. If break pt disrupts gene seq.
- 2. If new location of gene places it under diff. (abnormal) expression regulation.
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Translocation
- - There are many different types
- Focus on one.
- - Reciprocal (or "balanced") - minimal phenotypic consequence.
- 2 common ways this happens
- - Chromosomes break (non-homologous)
- double stranded (ds) break-DNA repair enzymes recognize, attach pieces to wrong chromosomes. They don't recognize homologous so they don't reattach correctly.
- - UV, irradiation (environment damage)
- - by-products --O2 radicals
- 2. Non-homologous chromosomes pair accidently @ cell division
- - cross-over
- PC= "pair-centers"
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PC
- = "pair-centers"
- help organize chromosomal pairs.
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Chromosome # variation
- Dipliod vs. {tripliod, tetrapliod - polypliod}
- "ploidy" changes
- sturgeon - octapliod
- - 12-ploid
- "polypliod"- normal for some organismal
- ex. human liver - increase expression
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aneupliod
- trisomic, tetrasomic
- Abnormal number of individual chromosomes
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In humans (aneuploid)
- XXY
- XYY
- XXX
- X_
- Much more tolerated in human sex chromosomes because dosage compensation and few genes in Y.
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Increase affects probability
- Age of mother
- - eggs are held at prophase I
when there are errors- non-dusjunction
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disjunction
- part of normal process.
- mitotic non-disjunction = aneuploid areas on body.
- meiotic non-disjunction = aneupliod organism
- **** find definition pic**********
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causes of non-disjunction
- random/spontaneous
- -often involve interference w/ microtubule polymerization.
- - more non-disjunction @ meiosis I
- in vitro (experimentally)
- - chemicals called mitotic inhibitors colchicine colcemid
- ****Find a diagram on non-disjuction***
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