120 terms

DAT Bootcamp - Heredity

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a _____ is a distinct unit or sequence of genetic material that codes for a trait
gene
a gene _____ refers to where the gene is located within the genome
locus
for humans, _____ indicate which of the 23 chromosomes the gene is located on, as well as where it is located on that specific chromosome
gene loci
an _____ is an alternative version of a gene
allele
what are some typical allele examples?
eye color: blue, green, and brown eyes are different versions of the eye color gene
a _____ allele is the 'normal' copy of an allele
wild type
a _____ allele has an altered DNA sequence that can affect a gene's phenotype
mutant
the _____ refers to the actual DNA sequence of a gene
genotype
the _____ refers the observable characteristics of a gene's expression
phenotype
_____ are a pair of chromosomes (one maternal and one paternal) that contain all the same gene loci
homologous chromosomes
homologous chromosomes have the same gene loci, but they do not have to have the same _____
alleles
humans have 22 pairs of _____ chromosomes and 1 pair of _____ chromosomes
autosomal; sex
the sex chromosomes of a female are _____ because they are XX (genotype)
homologous
the sex chromosomes of a male are _____ because they are XY (genotype)
not homologous

(men are hemizygous)
an organism is considered to be _____ for a given gene if an identical allele is present on each homologous chromosome
homozygous
how many copies of the dominant allele do homozygous-dominant individuals carry?
2 (ex: BB)
how many copies of the recessive allele do homozygous-dominant individuals carry?
0 (ex: BB)
what is the phenotype of a heterozygous dominant individual?
dominant
how many copies of the dominant allele do heterozygous individuals carry?
1 (ex: Bb)
how many copies of the recessive allele do heterozygous individuals carry?
1 (ex: Bb)
what is the phenotype of a heterozygous individual?
dominant
how many copies of the dominant allele do homozygous-recessive individuals carry?
0 (ex: bb)
how many copies of the recessive allele do homozygous-recessive individuals carry?
2 (ex: bb)
what is the phenotype of a homozygous-recessive individual?
recessive
_____ refers to the condition of having a single copy of a gene instead of 2 - e.g.
hemizygous
men have 2 different sex chromosomes (XY), so they are _____ for genes on each chromosome
hemizygous
the law of _____ says that homologous chromosomes separate during _____, so each parent only passes 1 of their alleles to their offspring
segregation; anaphase I of meiosis
the law of _____ says that 1 chromosome does not affect another as they separate during _____
independent assortment; anaphase I of meiosis
the law of dominance says that _____ alleles will mask the effect of _____ alleles
dominant; recessive
a monohybrid cross mates individuals that are _____ for _____ gene(s)
heterozygous; a single
what is the phenotypic ratio for a monohybrid cross?
3:1
what is the genotypic ratio for a monohybrid cross?
1:2:1 for XX : Xx : xx
a dihybrid cross mates individuals that are _____ for _____ gene(s)
heterozygous; 2
what is the phenotypic ratio of a dihybrid cross?
9:3:3:1
what is the label for the parental generation in a cross?
P = parental
what is the label for the first generation of offspring in a cross?
F1 = filial 1 hybrid = offspring of parental generation
what is the label for the second generation of offspring in a cross?
F2 = filial 2 hybrid = offspring of F1 generation
what are the 3 important single allele crosses?
homozygous x homozygous = 1/1 AA, Aa, or aa
homozygous x heterozygous = 1⁄2 AA (or aa) and 1⁄2 Aa
heterozygous x heterozygous = 1⁄4 AA; 1⁄2 Aa; 1⁄4 aa (1:2:1 monohybrid ratio)
what is the simplest way to calculate the probability of a specific dihybrid cross?
multiply the heterozygous x heterozygous single allele cross probabilities together

(ex: Aabb = 1/2 x 1/4 = 1/8)
in a dihybrid cross, gene loci must be on separate _____
chromosomes
_____ is the pattern of inheritance in which the expression of alleles is blended, producing a unique heterozygous phenotype
incomplete dominance
a heterozygote cross resulting in a 1:2:1 phenotype ratio of offspring is characteristic of _____ dominance
incomplete
_____ is the pattern of inheritance in which both alleles (for the same gene) are completely expressed at the same time
codominance
_____ is the pattern of inheritance in which more than 2 alleles exist for a given gene
multiple alleles
_____ is the pattern of inheritance in which 1 gene affects the phenotypic expression of a second, separate gene
epistasis
_____ is the pattern of inheritance in which a single gene has more than 1 phenotypic expression
pleiotropy
_____ is the pattern of inheritance in which the interaction of many genes shape a single phenotype with continuous variation
polygenic inheritance

(ex: height or skin color)
_____ genes are genes that reside on a sex chromosome
sex-linked

(ex: color blindness)
_____ genes can be affected by the sex of the individual carrying the trait
sex-influenced

(e.g. a Bb female is not bald, but Bb male is bald)
in _____, a specific allele is expressed (or not) depending on whether it is maternal or paternal
genomic imprinting
genomic imprinting is distinct from sex-linked genes because the effect also occurs on _____ chromosomes
autosomal
_____ is the probability that an organism with a specific genotype will express the corresponding phenotype
penetrance
_____ means that 100% of individuals will express a phenotype that corresponds to their genotype
complete penetrance
_____ means that less than 100% of individuals will express a phenotype that corresponds to their genotype
incomplete penetrance
_____ describes the variation of a phenotype for a specific genotype
expressivity

(ex: differences in hairiness despite the same genotype)
during embryonic development in female mammals, 1 of 2 X chromosomes does not uncoil - this is known as _____
X inactivation
the X chromosome that does not uncoild due to X inactivation in female mammals is known as a _____
Barr body
_____ genes are 2 or more genes that reside close together on the same chromosome
linked
linked genes are _____ likely to be separated by recombination during meiosis, and are _____ likely to be inherited together
less; more
the failure of chromosome/chromatid separation during mitosis or meiosis is known as _____
nondisjunction
_____ nondisjunction can result in gametes with missing or extra chromosomes, creating _____
meiotic; aneuploidies
an _____ is the presence of an abnormal number of chromosomes in a cell, but it does not include a difference of 1 or more _____ of chromosomes
aneuploidy; complete sets
a _____ is an aneuploidy created by meiotic nondisjunction, where there are 3 copies of a chromosome
trisomy

(ex: trisomy 21 = Downs syndrome)
_____ is a sex chromosome trisomy resulting in XXY and sterility
Klinefelter syndrome
a _____ is an aneuploidy created by meiotic nondisjunction, where there is 1 copy of a chromosome
monosomy

(ex: monosomy X = Turner syndrome)
_____ occurs in cells that undergo mitotic nondisjunction during embryonic development; as a result, a fraction of body cells have extra or missing chromosomes
mosaicism
list the possible gametes of a meiosis I nondisjunction:
n+1, n+1, n-1, n-1
list the possible gametes of meiosis II nondisjunction:
n, n, n+1, n-1
a _____ is a mutation that causes a single nucleotide change
point mutation
what are the 3 general types of mutations that can result in a point mutation?
substitution; insertion; deletion
a _____ mutation is the change of 1 nucleotide to a different nucleotide
substitution
an _____ mutation is the addition of a nucleotide
insertion
a _____ mutation is the removal of a nucleotide
deletion
a _____ results in the 'reading frame' of an RNA transcript being shifted, causing different amino acids to be translated and resulting in impaired protein structure
frameshift mutation
the insertion/deletion of nucleotides in multiples of _____ will not lead to a frameshift mutation
3
both _____ and _____ of nucleotides can cause a frameshift mutation
insertion; deletion
a _____ is when a purine nucleotide is converted to another purine, or a pyrimidine is converted to another pyrimidine
transition mutation
a _____ is when a purine nucleotide is converted to a pyrimidine nucleotide or vice versa
transversion mutation
a _____ changes a wild type allele to a mutant allele
forward mutation
a _____ reverts a mutant allele to a wild type allele
backwards/reverse mutation
_____ involve changes to segments of DNA
chromosomal abberations
_____ occur when a chromosome segment is repeated on the same chromosome, and can occur from unequal crossing over
duplications
_____ occur when a chromosome segment is rearranged in the reverse of its original orientation
inversions
_____ occur when a chromosome segment is moved to another chromosome
translocations
2 non-homologous chromosomes swap segments in _____ translocations
reciprocal
a chromosome segment is transferred to a different chromosome in _____ translocatins
non-reciprocal
non-reciprocal translocations may also be called _____
insertions
a _____ translocation involves 2 different chromosomes breaking and rejoining near their centromeres
Robertsonian
a _____ can occur spontaneously or be induced as a result of mutagenic agents
chromosomal breakage

(the fragments can rejoin or may remain un-repaired)
_____ are physical or chemical agents that change the genetic material of an organism
mutagenic agents
what are some general examples of mutagenic agents?
cosmic rays, X-rays, UV rays, radioactivity, chemical compounds, etc.
_____ is a mutagenic agent that inhibits mitotic spindle formation and can induce polyploidy
colchicine
_____ cells and organisms are those containing more than 2 paired (homologous) sets of chromosomes
polyploid
_____ regulate normal cell growth/function (e.g. ras gene)
proto-oncogenes
if mutated, proto-oncogenes can become _____
oncogenes
oncogenes are mutated proto-oncogenes that can cause _____ due to dysregulated cell growth/function
cancer
proto-oncogenes turn into cancerous oncogenes after a _____ mutation following the _____ hit hypothesis
gain-of-function, one
_____ (e.g. p53) help prevent uncontrolled cell growth
tumor suppressor genes
if tumor suppressor genes are mutated in a way that _____ their activity, they can contribute to the onset of cancer
decreases
tumor-suppressor genes becomes cancerous after _____ mutations following the _____ hit hypothesis
loss-of-function, two
_____ traits follow a dominant inheritance pattern on an autosome
autosomal dominant
if an autosomal dominant allele is inherited from _____ parent(s), the offspring will be affected
either

(GG, Gg, Gg are all "affected" by the dominant trait)
_____ traits follow a recessive inheritance pattern on an autosome
autosomal recessive
if an autosomal recessive allele is inherited from _____ parent(s), the offspring will be affected
both
_____ genetic disorders are carried on either the X or Y chromosome
sex-linked
_____ disorders are _____ genetic disorders characterized by a dominant allele on the X chromosome
X linked dominant; sex-linked
if a X linked dominant allele is inherited from _____ parent(s), the offspring will be affected
either

(fathers must pass the Y chromosome to their son)
X linked dominant alleles cannot be passed from _____ to _____
father; son

(fathers must pass the Y chromosome to their son)
_____ disorders are _____ genetic disorders characterized by a recessive allele on the X chromosome
X linked recessive; sex-linked
if a X linked recessive allele is inherited from _____ parent(s), the offspring will be affected
both

(fathers must pass the Y chromosome to their son)
X linked recessive alleles cannot be passed from _____ to _____
father; son

(fathers must pass the Y chromosome to their son)
_____ disorders are _____ genetic disorders characterized by an affected allele on the Y chromosome
Y linked; sex-linked
the Y chromosome is only present in men (1 copy), so alleles that cause Y linked disorders can be _____ or _____
dominant; recessive
Y linked disorders can only be passed from _____ to _____
father; son
_____ describes inheritance patterns involving genetic material outside the nucleus
extranuclear inheritance
in eukaryotes, genes also exist outside the nucleus and can be found in _____ and _____
mitochondria; chloroplasts
all mitochondrial related diseases are _____ inherited
maternally
a _____ gene prevents survival of an organism
lethal
_____ result in a mutant phenotype in the offspring, regardless of the offspring's own genotype
maternal effect genes

(mutant child phenotypes only arise when the maternal effect gene is mutated in the mother)
_____ is a needle puncture of the amnionic sac to withdraw amniotic fluid for analysis
amniocentesis
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