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56 Cards in this Set
- Front
- Back
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feature that can be inherited (ex: flower color)
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character
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alternative forms of a character (ex: purple or white flower color)
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trait
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inheritable sequence of DNA that encodes a protein (or RNA molecule) that determines a character
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gene
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1 or 2 or more alternative forms of a gene that result in the different traits of a character
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allele
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location of a gene on a chromosome
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locus
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total set of genes present
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genotype
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realized expression of a gene; observable trait
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phenotype
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one set of chromosome
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haploid
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two copies of chromosomes
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diploid
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diploid individual with identical alleles on both chromosomes
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homozygote
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diploid individual carrying two different alleles on both chromosomes
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heterozygote
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dictates appearace of heterozygotes
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dominant allele
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phenotype not seen in heterozygotes
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recessive allele
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law of segregation
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1. the two alleles for a heritable character segregate during gamete formation and end up in different gametes
2. different traits of a character segregate independently of each other in crosses |
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law of independent assortment
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the emergence of one trait will not affect the emergence of another
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individual alleles have more than one effect
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pleiotropy
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one gene interferes with the expression of another
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epistasis
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additive effect of 2 or more genes on a single phenotypic character (Ex: skin color)
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polygenic inheritance
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both alleles affect the phenotype (type of dominance)
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codominance
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heterozygote unlike either parent (Ex: red x white snapdragons = pink snapdragons)
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incomplete dominance
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found when determining ABO blood groups
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multiple alleles
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effect of environment on phenotype
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phenotypes of organisms of the same genetic variety range may alter depending on the environment
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the chromosomal basis of Mendel's laws?
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- two alleles separate during gamete production
- phenotypes are inherited independently of each other |
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the cause of genetic disorders
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alleles that causes genetic disorder codes; malfunctional protein or no protein at all
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normal phenotype because one copy of 'normal allele' produces enough protein
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heterozygote
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sickle cell anemia
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- common among Africans
- single amino acid change (GLU -> VAL) in hemoglobin - heterozygotes have no phenotype |
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how sickle-cell anemia confers resistance to malaria
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<i>Plasmodium</i> spends part of its life cycle in RBC; the presence of sickle cells interrupts the cycle (heterozygote advantage)
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Huntington's disease
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- affected individuals have degenerative disease of the nervous system
- lethal dominant allele can escape elimination (usually too late to be detected) - by the time symptoms are evident, individual may have transmitted allele to offspring |
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rule of multiplication
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probability of two or more independent events occurring together in a specific combination; determined by multiplying the probability of the individual events
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rule of addition
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probability of an event that can occur in two or more different ways; determined by adding the separate possibilities
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where sex-linked genes are located
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sex chromosomes
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Duchenne muscular dystrophy
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- progressive weakening of muscles/loss of coordination
- caused by the absence of dystrophin, gene locus on X |
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hemophilia
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- blood slow to clot
- caused by absence of 1 or 2 clotting factors - 2 clotting factors on X chromosome |
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x inactivation
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- inactive x condenses into a Barr body, which lies inside the nuclear membrane
- inactivation varies randomly from cell to cell |
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mishap in chromosome distribution; sister chromatids fail to separate properly
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nondisjunction
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How many pairs of autosomes in human chromosomes? Sex chromosomes?
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22; 1
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humans who have lost one copy of an autosome; will not survive development
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monosomics
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humans who have gained an extra chromosome; will not survive development, unless in 5 smallest
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trisomics
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trisomy 13, 15, 18
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severe development difficulties; infants die within a few months
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trisomy 21, 22
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survive to adulthood but with compromised or delayed mental and skeletal development
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cause of Down syndrome (which trisomy?)
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trisomy 21 occurs after nondisjuction of chromosome 21 during egg formation
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abnormal number of a particular chromosome
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aneuploidy
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XXX
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sterile, but otherwise normal
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XO
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Turner syndrome (sterile female, pre-pubescent)
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XXY
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Klinefelter syndrome (sterile male with female characteristics)
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OY
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not viable
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XYY
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Jacob's syndrome (karotype 20x higher among males in prison, psychiatric hospitals)
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four types of changes in chromosomal structure
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1. deletion
2. duplication 3. inversion 4. translocation |
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associated with chronic myelogenous leukemia (CML)
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translocation (exchange of nonhomologous parts of chromosome 9 with chromosome 22)
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Cri du chat
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- mental retardation, death in early infancy/childhood
- caused by deletion of chromosome 5 |
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the inactive X chromosome in a female cell
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Barr Body
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more than one genotype present
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mosaic
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What did Frederick Griffith discover while studying Stretococcus pnemoniae?
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heat-killed S strain transforms live R strain into pathogentic bacteria
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S (smooth strain)
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encapsulated, pathogenic
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R (rough strain)
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no polysac coat, harmless
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What did Avery, MacLeod, and McCarty discover?
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- 'transforming principle'
- used chemicals to identify macromolecule capable of transformation - lipid/protein extraction -> transformation |
