Ch. 6 - Heredity Flashcards
Homologous chromosomes: a pair of chromosomes that contains ____ (gene for gene). Each parent contributed ____ of the chromosome in the pair and thus different alleles may exist for a gene (dominant and recessive or incomplete dominance (color blending) / co-dominant such as blood type).
____
same genetic material
1
law of segregation: one member of each chromosome pair migrates to an ____ so that each gamete is ____ (aka each gamete has only one copy of each allele), occurs in ____.
opposite pole
haploid
anaphase I
Law of independent assortment: migration of homologues within one pair of homologous chromosomes ____ influence
the migration of homologues ____ (independent assortment of alleles)
does not
of other homologous pairs
incomplete Dominance: ____ of expressions of alleles (e.g. R red, R’ white, RR’ comes out pink) (unique hetero phenotype)
blending
Codominance: Both inherited alleles are ____ (e.g. blood types A and B or both can show up as AB if expressed)
completed expressed
Multiple alleles: Blood groups have ____, the codominant A and B and the O, leading to 4 possible genotypes (phenotypes?): AO (A type), BO (B type), AB (codominant AB type), OO (O type)
3 possible alleles
Epistasis: one gene affects phenotypic expression of ____. ____ (one gene controls (turn on/off) the production of pigment, and 2nd gene controls color or amount). If 1st gene codes for ____ => 2nd gene has no effect.
CCBx => black fur in mice ccxx => ____
2nd gene
pigmentation
no pigment
no pigment
Pleiotropy: single gene has ____ (gene in pea plants that expressed seed texture also influences phenotype of ____ and water uptake; ____ leads to different health conditions).
more than 1 phenotypic expression
starch metabolism
sickle cell anemia
Polygenic inheritance: the interaction of ____ to shape a ____ w/ continuous variation (____, skin color).
many genes
single phenotype
height
Linked genes: two or more genes that reside on the same chromosomes and thus cannot separate ____ because they are physically ____ (inherited together). Linked genes exhibit recombination about ____ of the time.
In a cross of BbVv x bbvv (says that BV and bv are linked and each is in a homologues). We only get BV or bv and no Bv or bV. However, if there is ____, we may get 18% of Bv and bV.
- Greater recombination frequencies (18% above) means ____ of genes apart on the same chromosome.
independently
connected
18%
recombination
farther distance
Sex-linked: refers to ____ resides on sex chromosome; when male (XY) receives an X from ____, whether it is dominant or recessive will be expressed because there is no copy on the Y chromosome.
single gene
mother
Sex-influenced: can be influenced by ____ carrying trait (e.g. Bb female not bald, Bb male is)
sex of individual
Penetrance: ____ an organism with a specific genotype will express a ____
probability
particular phenotype
Expressivity: term describing the ____ for a specific genotype
variation of phenotype
X-inactivation: during embryonic development in female mammals, one of two X chromosomes does not ____ => dark and coiled compact body chromosome (____) => cannot be ____. Thus, only the genes on the other X chromosome will be expressed. Either one can be inactivated => genes in the female will not be expressed similarly, so all cells in a female mammal not necessarily ____ (calico cats).
uncoil into chromatin
barr body
expressed
functionally identical
Hemophilia: cannot form blood clot. XHXh is a normal carrier. But if XH is ____ => Xh is expressed. (female x-inactivation)
inactivated
Nondisjunction: failure of one/more chromosomes pairs or chromatids to ____ during ____ (failure of two chromatids of a
single chromosome during anaphase) or ____(homologous chromosomes to separate during Meiosis I or sister chromatids to separate during Meiosis II; result in ____ or ____; ex Down syndrome) – note: specifically during ____!
separate mitosis meiosis trisomy monosomy
Mosaicism in cells that undergo ____ in ____ during embryonic development; fraction of body cells have extra or missing chromosome
nondisjunction
mitosis
Polyploidy: all chromosomes undergo ____ and produce gametes with ____ the number of chromosomes. Common in ____.
meiotic nondisjunction
twice
plants
Point mutation: single nucleotide changes causing substitution, insertion, deletion (latter 2 could cause frameshift). - ____ mutation: Purine to purine or pyrimidine to pyrimidine
- ____ mutation: purine to pyrimidine or vice versa
transition
transversion
Aneuploidy: genome with ____ chromosome XO ____, physically abnormal; ____ (XXY); Down Syndrome (Trisomy 21)
extra/missing nondisjunction trisomy 21 sex chromosome sterile klinefelter
Chromosomal abberations: chromosome segments are changed.
- Duplications: chromosome segment is repeated on ____.
- Inversions: chromosome segments are rearranged in ____.
- Translocation: segment is moved to ____. Can be ____ (two non-homologous chromosomes swap chunks) or ____ (one chromosome from a pair becomes attached to another from a pair – e.g. an extra chromosome 21 attached to 14 can cause Downs as well, ____)
same chromosome to another chromosome reciprocal robertsonian tripled 21 chunk
Chromosomal Breakage – spontaneous or induced (mutagenic agents, Xrays). Deficiency = ____
lost fragment
Mutagenic agents include cosmic rays, Xrays, UV rays, radioactivity, chemical compounds include ____ (inhibits ____ causing polyploidy), mustard gas. Mutagenic agents are generally also ____.
- Proto-oncogenes stimulate normal growth; if mutated become ____ cancer.
colchiline
spindle formation
carcinogenic
oncogenes
PKU (inability to product proper enzyme for ____; degradation
product ____ accumulates), cystic fibrosis (____ in tracts)
phenylalanine breakdown
phenylpyruvic acid
fluid buildup
Tay-sachs (____ defect; can’t breakdown ____ for normal brain fxn)
lysosome
lipids
sickle-cell (defective hemoglobin due to ____ mutation)
substitution
Huntingtons (____ nervous system disease)
degenerate
hemophilia (abnormal ____)
blood clotting
Turner’s doesn’t typically cause ____, but Downs, Kline, and Cri Du Chat (deletion on ____) do
mental retardation
chromosome 5
Extranuclear inheritance: extranuclear genes are found in ____ and ____. Defects in mito DNA can ____
cell’s ATP production. Mitochondria passed to zygote all come from ____, so all related diseases are ____.
Note that mitochondria have their own ____ that make mitochondrial proteins w/in mitochondrial matrix!
mitochondria chloroplasts reduce cell's ATP production mother mother inherited ~70S ribosomes
Homozygous: two copies of the same allele (AA or aa). Heterozygous: different alleles of the same gene (Aa).
Note that mitochondria have their own ____: one single copy of a gene instead of two. (male has XY sex chromosome
Note that mitochondria have their own ____).
hemizygous
hemizygous
- Lethal gene: cross between Aa and Aa, we get AA:2Aa:aa. If “aa” was lethal, we would have AA and Aa as ____ ratio.
1:2
f the phenotype “skips” generations be suspicious of an ____ disorder. If no skip, most likely an ____ disorder. Be suspicious for ____, if a father doesn’t have the phenotype, none of his ____ display it.
autosomal recessive
autosomal dominant
x-linked recessive
daughters
Mitochondrial DNA is an exception to the ____
universality of genetic code
