ap bio unit 5

Cards (47)

  • both DNA and RNA carry genetic information
  • prokaryotes DO SHOW genetic variation even if they don't participate in sexual reproduction
  • linked genes: genes located very close to other genes on the same chromosome can be inherited together
  • meiosis: production of gametes (sex cells) from diploid cells
    • daughter cells have HALF the chromosomes
    • diploid to haploid
    • when the sperm and egg join in fertilization, the two haploid sets of chromosomes form a complete diploid set: a new genome
  • homologous chromosomes: the similar but nonidentical chromosome pairs an organism receives from its two parents
  • meiosis 1: homologous chromosomes separate
    meiosis 2: sister chromatids separate
  • prophase 1 of meiosis:
    • chromosomes condense and become visible
    • chromosomes pair up and crossing over occurs
    • common for multiple crossing overs to occur
  • metaphase 1 of meiosis:
    • homologous pairs, NOT individual chromosomes, line up at the metaphase plate for separation
    • RANDOM ORIENTATION
  • anaphase 1 of meiosis:
    • same as mitosis, however, each sister chromatid is still attached to one another
  • telophase 1 in meiosis:
    • same as mitosis
    • newly formed cells are HAPLOID
    • each chromosome has 2 (non-identical) sister chromatids
  • meiosis II:
    • mitosis but with haploid cells
    • the sister chromatids separate, making haploid cells with NON-DUPLICATED chromosomes
  • reasons for genetically different gametes:
    • crossing over in prophase 1
    • random orientation of homologous pairs in metaphase 1
  • end of meiosis 1: 2 haploid cells
    end of meiosis 2: 4 haploid cells
  • mitosis produces genetically IDENTICAL daughter cells, but meiosis produces genetically UNIQUE daughter cells
  • mendel's pea plant experiment results:
    • P generation: tall x short
    • F1 generation: all tall
    • F2 generation: 3 tall: 1 short
  • law of segregation:
    • only 1 of the 2 gene copies present in an organism is distributed to each gamete that it makes and the allocation of the gene copies is random
    • occurs in anaphase 1
  • law of independent assortment:
    • inheriting an allele has nothing to do with inheriting an allele for any other trait
    • occurs during metaphase 1
  • monohybrid cross: heterozygous for one gene
    dihybrid cross: heterozygous for two genes
  • independent events- the occurrence of one event does NOT affect the occurrence of another (rolling a 1 on the first dice and a 6 on the second dice)
    mutually exclusive- two events cannot occur at the same time (rolling a 1 and 6 at the same time)
  • codominance: two alleles may be simultaneously expressed when both are present
    • ex. red and white flowers
  • incomplete dominance: two alleles may produce an intermediate phenotype when both are present
    • ex. pink flowers
  • sex linkage: genes carried on sex chromosomes, such as the X chromosome of humans
    • show different inheritance patterns than genes on autosomal (non-sex) chromosomes
  • epistasis: the alleles of one gene may mask or conceal the alleles of another gene
  • polygenic inheritance: characteristics that are controlled by a number of different genes
    • polygenic traits include height, skin color, hair color, and eye color
  • when doing punnett squares between males and females, the Y chromosome has NO ALLELE on it
  • X-linked human genetic disorders are much more common in males than in females due to the X-linked inheritance pattern (the X chromosome from the mom is the ONLY allele that shows up in males)
  • hemizygous: males are hemizygous for X-linked genes because he has no other gene copy
    • even if the allele is recessive in females, the male will still express that allele
  • recombination frequency = (recombinants/total offspring) x 100%
  • autosomal chromosome: trait that is located on a NON-SEX chromosome (ex. Aa, RR)
  • autosomal dominant trait: present in every generation, not SEX-LINKED
  • x-linked recessive trait: not necessarily present in every generation, MORE MALES THAN FEMALES
  • the offspring inherits mitochondrial AND nuclear DNA from their MOTHER, while they ONLY inherit nuclear DNA from their FATHER
  • the larger the recombination frequency, the FURTHER the genes are
  • mitochondrial and chloroplast DNA are both inherited from the MOTHER
  • phenotypic plasticity: the ability of an organism to change its phenotype in response to environmental change
    • allows organisms to better fit a particular environment
  • euploid- contains chromosomes correctly organized into complete sets
    aneuploid- missing one or more chromosomes
    • monosomy- 2n-1
    • trisomy- 2n+1
  • nondisjunction- when homologous chromosomes or sister chromatids fail to separate during meiosis I or II, or during mitosis
  • down syndrome- trisomy 21, 3 copies of chromosome 21
  • chromosomal rearrangement:
    • duplication- part is copied
    • deletion- part is removed
    • inversion- region is flipped around (opposite direction)
    • translocation- piece of one chromosome gets attached to another
    • reciprocal translocation- swapping of segments
  • horizontal gene transfer where genetic information is shared between organisms WITHOUT MATING