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56 Cards in this Set

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