biol exam 3 fitb

• Bacterial cell division is also called

  binary fission
• Cells


  need to replicate DNA (S phase), and ensure proper growth (G1 & G2) prior to celldivision (mitosis)
• Cell cycle (eukaryotic)


  constitutes of first gap (G1), DNA synthesis (S), second gap(G2), and cell division when the duplicated genome is equally distributed in the two daughter cells
• Chromosomes


  are replicated by using each strand as a template to generate two copiesof DNA
• Replication of chromosomes occurs during

  the DNA synthesis (S) phase
• Eukaryotic cell cycle is

  G1+S+G2 phases = Interphase, where cells are preparing forcell division followed by mitosis with various phases
• Each phase of mitosis (and meiosis) are defined based on

  chromosome status and location.
• Kinetochore reduce microtubule length by


  removing tubulin from the positive end
• Cytokinesis is


  division of a cell that has separated the two copies of DNA into two poles
• Cell cycle checkpoints


  ensure that "all is good" at end of each phase
• Mitosis promoting factor (MPF) contains


  cyclin and cdk, which initiates G2 to Mtransition
• Cdk


  in activated MPF phosphorylates Rb, which releases E2F and initiates S-phase
• Dysregulation of cell cycle that leads to uncontrolled proliferation results in

  cancer
• Cancer cells


  often grow as a benign tumor, but when those cells gain capacity to invade other tissues (metastasis), cancer can spread all over
• Meiosis


  produces gametes with extensive genetic variation for sexual reproduction
• Summary of Meiosis I and Meiosis II

  where the steps are similar to Mitosis, but theDNA amount is reduced (one allele for each gene)
• Mendelian genetics:


  a single gene determines a specific trait
• Locus is a


  location where a particular gene is on the chromosome
• Gametes (egg or sperm)


  have only one allele for each gene, while all other cells have two alleles (mom+dad) of each gene
• Haploid states (in humans)

  occurs ONLY during gametogenesis and in gametes
• All cells in most animals are

  diploid, except during gametogenesis and in gametes
• Meiosis


  produces haploid gametes
• Alleles are


  different version of the same gene. There may be 100s of alleles in the population. Some could be "better," "nonconsequential," "worse," "unique," etc....
• The number of centromeres are

  reduced by ½ during Anaphase I, and two "non-identical sister" chromatids are split in Anaphase II
• Independent assortment of chromosomes means

  different chr #x is sorted independent of chr #y
• Ploidy and chromosome number are

  counted as number of centromeres.
• DNA amount (# of copies of alleles)


  doubles during S-phase.
• The two replicated homologous chromosomes form a

  tetrad that can form random synapsis(cross-over sites) mediated by synaptonemal complex
• Genetic variation increases due to

  crossover at chiasma during Prophase I
• Homologous chromosomes are


  randomly assorted during Meiosis I
• Meiosis I yields a

  haploid (n) number of centromeres with two connected "non-identicalsister" chromatids
• The "non-identical sister" chromatids are

  split during Meiosis II (yields haploid genome)
• Offspring genotypes are


  unique (one in infinite) because of crossovers and gamete selection
• Aneuploidy and polyploidy occurs due to

  Nondisjunction
• Spectral karyotyping (fluorescent staining of chr) allows for

  easy identification of homologous chromosomes
• Down's Syndrome (Trisomy 21) is an example of

  polyploidy
• In Mendel's experiments, dominant and recessive traits in peas were

  inherited independently of each other and gender
• Peas can


  self-fertilize or cross-fertilize, which allows to evaluation of inheritance
• Terms related to Mendelian genetics are


  applicable to most aspects of genetics
• Punnett squares allow for

  estimation of probability of a particular genotype and phenotype