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What impacts have genetics technology had on our society?
- Recombinant DNA Technology: ability to insert DNA fragments into bacteria to have them produce a given product (insulin)
- Agriculture: viral resistance, nutritional enhancement, herbicide resistance
- Medical: genetic testing, gene therapy, pharmacogenetics
- Legal: Forensic DNA applications
- Bioethics: savior siblings, stem cell therapy, preimplantation genetic diagnosis
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Define eugenics and describe the difference between positive and negative eugenics.
- Practices involved in improving the genetic composition of a population
- Positive eugenics is aimed at encouraging reproduction among the genetically advantaged
- Negative eugenics is aimed at lowering fertility among the genetically disadvantaged
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List chromosome designation terms (arms, and centromere location)
- p arm: petite arm (smaller)
- q arm: longer arm
- metacentric: centromere in middle
- submetacentric: centromere between middle and end
- acrocentric: centromere close to end
- telocentric: centromere at end
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Stages, substages, and checkpoints of cell cycle
- Interphase (G0, G1, S, and G2) and mitosis (prophase, prometaphase, metaphase, anaphase, telophase)
- G0: Nondividing cells
- G1: Cells become committed to division or enter G0
- G1/S checkpoint: monitors cell size and DNA integrity
- S: DNA is synthesized
- G2:
- G2/M checkpoint: Cell monitors DNA synthesis and damage
- M checkpoint: (during mitosis) Cell monitors spindle formation and attachment to kinetochores
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Stages of mitosis
- Prophase: chromosomes coil up and shorten; centrioles divide and move apart
- Prometaphase: chromosomes are clearly double structures; centrioles reach the opposite poles; spindle fibers form
- Metaphase: Centromeres align on metaphase plate
- Anaphase: Centromeres split and daughter chromosomes migrate to opposite poles
- Telophase: Daughter chromosomes arrive at the poles; cytokinesis commences
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Stages of meiosis
- (Prophase I) Leptonema: chromasomes become visible, chromomeres aid in homology search
- (Prophase I) Zygonema: chromasomes continue to condense, homologous chromosomes align, synaptonemal complex forms between homologs, at end # of bivalents = haploid number of species
- (Prophase I) Pachynema: Homologs undergo more intimate pairing (synapsis), each bivalent contains two pairs of sister chromatids (paternal/maternal), nonsister chromatids cross over at chiasma,
- (Prophase I) Diplonema: result of crossing over is visible
- (Prophase I) Diakinesis: nucleolus/envelope break down and centromeres of each tetrad attach to spindle fibers
- Metaphase I: tetrads are alligned at equator
- Anaphase I: One half of each tetrad is pulled toward each pole (separation of homologous chromosomes)
- Telophase I: Cytokinesis commences
- Prophase II: Each diad (sister chromatids) moves toward center plate
- Metaphase II: each dyad is aligned at equitorial plate
- Anaphase II: Sister chromatids are pulled to opposite poles (# of dyads = haploid #)
- Telophase II: One member of each pair of homologous chromosomes present at each pole, cytokinesis occurs
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Oogenesis vs. Spermatogenesis
- Spermatogensis: spermatogonium (diploid) -> primary spermatocyte (first meiotic division) -> secondary spermatocyte (second meiotic division) -> spermatids (4 total) -> spermatozoa (fully motile)
- Oogenesis: Oogonium (diploid) -> primary oocyte -> secondary oocyte/first polar body -> ootid/second polar body -> mature ovum
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Mendel's experimental design
- Didn't allow random pollination
- Used true-breed plants
- Pisum Satvium (pea plant)
- P1 (parental strains) -> F1 (Parental cross) -> F2 (selfed F1)
- "luckily" chose traits that were not on the same chromosome
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Mendel's 4 postulates
- 1. Inheritable unit factors exist in pairs
- 2. Dominance/Recessiveness
- 3. Segregation
- 4. Independent assortment of traits
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What is a test cross?
Determination of the genotype (AA vs Aa) of something showing the dominant trait by crossing with recessive.
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binomial theorum
- P= (N!/s!t!)(asbt)
- N = total # of events
- a = outcome #1 probability
- b = outcome #2 probability
- s = outcome #1 amount
- t = outcome #2 amount
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What are the extensions of mendelian genetics?
- Incomplete dominance: phenotype is intermediate
- Codominance: both alleles are equally expressed
- Multiple alleles: more than 2 alleles in a population
- epistasis: alleles at one locus override expression of alleles at a different locus (epistatic vs hypostatic)
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sex limited vs sex influenced vs sex linked w/ examples
- Sex-limited: Occurs only in one sex (development of ovaries)
- Sex-influenced: gene is on autosomal chromosome but phenotype influenced by sex hormones (male pattern baldness)
- Sex-linked:Genes on the sex chromosomes
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Examples of X-linked conditions
- colorblindness
- hemophilia
- icthyosis
- lesh-nyhan syndrome
- muscular dystrophy
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Penetrance vs expressivity
- Penetrance: the chance that the genotype will be properly reflected in the phenotype (% likliness)
- Expressivity: Degree to which you express a trait can vary
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Genomic imprinting and uniparental disomy
- Genomic imprinting Examples: Prader-Willi, Angelman syndrom
- Genomic imprinting: During meiosis one gene is silenced (either M or F), and the others end up with the unsilenced gene.
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epigenetics and the human epigenomic project
- Epigenetics involves the changing of gene expression without the altering of DNA (methylation, coformation, etc)
- HEP: attempt to catalog methylation sites in all human chromosomes in different tissues.
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Complementation test analysis
- Analytical process to determine whether there is genetic heterogeneity for a particular trait (more than one gene gives phenotype)
- If mutations are on the same gene they will NOT compliment (no wild type appears)
- If mutations are on different genes they will complement (wild type appears)
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Mechanisms that exist for sex determination
- Heterogametic sex chromosomes
- Ratio of autosomes to X chromsomes (Drosophila)
- Temperature (reptiles)
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