Chapter 5 - Extensions & Mods of Basic Principles Flashcards
An organism’s ____ is the result of how ___ are expressed and whether two or more ____ products interact.
phenotype; genes; gene
Recessive lethal alleles usually have a : ratio rather than 3:1 because 1/4 of the progeny die.
2:1
Dominance is ____ to the characteristic being examined.
relative
If organism YY dies, organism Yy is yellow, and yy are a color other than yellow, what is the dominance characteristic of Y? Are there any recessive characteristics?
Y is dominant with respect to coat color. It’s recessive with respect to lethality.
When a heterozygote has a phenotype that is ‘intermediate’ (on a spectrum) compared to the phenos of the homos, the alleles are said to have ______ dominance.
incomplete
When progeny of a homozygous dominant crossed to a homo recessive demonstrate the following phenotypes 1 homo dominant, 2 half way between homo dominant and homo recessive, and 1 homo recessive, the alleles are demonstrating ______ _______. What is the typical phenotypic ratio of progeny?
Incomplete dominance. 1:2:1
In ______ the heterozygote expresses the phenotype of both ________ (e.g. the MN blood group system).
codominance; homozygotes
Cystic fibrosis is an example of how determination of dominance depends on ____ at which the phenotype is being evaluated: _____ (outward appearance); ______ (function); or _______ (proteins, RNA, etc.)
level; anatomical; physiological; molecular
The gene responsible for cystic fibrosis is autosomal/allosomal, and is chromosome # ___. It is considered a recessive/dominant allele.
autosomal; 7; recessive.
CFTR stands for ? What does it regulate?
Cystic fibrosis transmembrane conductance regulator.
It regulates the movement of Cl- across the cell membrane.
Heterozygotes of the cystic fibrosis allele make what? What does this mean in terms of dominance on the molecular level? The clinical/physiological level?
Heterozygotes make functional and nonfunctional proteins.
Codominant at the molecular level; recessive at the physiological level.
Dominance is the result of ____ interactions; but the way genes are inherited is in accordance with ___ observations.
allelic; Mendel’s
The BRCA allele is an example of _____ _______ - the genotype doesn’t always produce the expected phenotype (it doesn’t always ‘penetrate’ through to the phenotype).
incomplete penetrance.
Polydactyly is an example of ____ ____ - some individuals are normal, but one or more of their offspring have the condition.
incomplete penetrance.
Penetrance is the _____ of individuals with a specific genotype who demonstrate the expected _____ . _____ is the degree to which the trait is expressed.
percentage; phenotype.
Expressivity
Explain variable expressivity using polydactyly as an example.
Some will have just a bit of extra skin while others will have fully-functioning digits - they both have the SAME allele.
Incomplete penetrance and variable expressivity may result from _____ between other genes and ____ factors.
interactions; environmental.
A gene that encodes for a temperature sensitive protein is an example of how _____ factors interact with genes to determine _____.
environmental; phenotype
Multiple _____ allow for greater variety of genotypes and phenotypes.
alleles
A phenotypic ratio of 2:1:1 (instead of 3:1) might be indicative of multiple ____. (e.g. ___ blood grouping and ____ feathers.
alleles; ABO; duck
Gene _____ result from non-______ genes who’s products lead to new phenotypes that were not expected based on the phenotype of each individual locus.
interactions; non-allelic;
A cross that looks monohybrid in F1 progeny, then looks dihybrid in F2 selfed progeny might be due to what phenomenon?
gene interactions.
A gene interaction in pepper colors involves ___ mutations that affect ___ biochemical pathway.
2; 1
Two enzymes (proteins) that contribute to the coloration of peppers in a biochemical pathway is an example of a?
gene interaction
When solving for gene interaction problems, it’s important to determine the ____ of single-locus genotypes, then multiply the _____ because the phenotypes can’t be determined without considering the effects of the genes at all contributing ______.
probability; probabilities; loci.
What’s the formula for determining the phenotypic ratios of progeny?
x = 16X/n x = phenotype; n = total progeny
A type of gene interaction where one gene hides (“masks”) the effect of another gene (separate locus) is called ____.
epistasis
Epistasis ____ the allele of a gene at different ____.
Dominance _____ the allele of a gene at the same ______.
masks; loci.
masks; loci
When considering genes at different loci, the ____ gene masks the ____ gene.
epistatic; hypostatic
The Bombay (hh) phenotype is an example of _______ _____ because 2 copies of the allele (homozygous) are needed in order to ____ the alleles at the ABO locus.
recessive epistasis; mask
Consider 2 genes: C and T. C_ codes for copper pigment; cc codes for purple pigment. T codes for transport of pigment to the leaf; tt lacks the transport protein and results in a green leaf.
The tt gene is an example of ___ ____ because it masks the effect of C.
recessive epistasis.
When dealing with recessive epistasis, progeny have more of the epistatic/hypostatic phenotype; for dominant epistasis, progeny will have more of the epistatic/hypostatic phenotype.
recessive = hypostatic dominant = epistatic
In ____ epistasis, one copy of the epistatic gene is sufficient to mask the second gene at a different ____.
dominant; locus
In ______ _____, the F1 progeny look like Mendel’s monohybrid cross, but the F2 progeny have a phenotypic ratio of 3:1 (dominating phenotype):(other phenotypes) simplified from a 12:4 ratio.
Dominant epistasis
Epistasis is often seen affecting the sequential steps of a ______ ______.
biochemical pathway
In ____ _____ epistasis, 2 copies of a ____ allele at either loci are able to mask genes at different loci.
duplicate recessive
Individuals heterozygous for two loci are crossed and yield 9:7 phenotypic ratio instead of 9:3:3:1. What might this be evidence of?
duplicate recessive epistasis
Consider the following:
Albino snails were mated (aaBB x AAbb) and produced F1 heterozygous pigmented snails. F1 was selfed and produced: 9/16 A_B_ pigmented; 3/16 aaB_ albino; 3/16 A_bb albino; and 1/16 aabb albino. What might cause this phenomenon?
duplicate recessive epistasis (9:7 ratio pigmented to albino).
In a given biochemical pathway, failure to make wither enzyme I due to homozygosity of allele (aa) and/or failure to make enzyme II due to homozygosity of a second allele (bb) yields a failure to produce a specific protein. What is this phenomenon?
duplicate recessive epistasis
In order to determine whether mutations are at the same locus or at different loci, you can run a genetic _____ test by crossing two homozygous, each with one of the two mutations. If the mutations are allelic, the progeny will have the ___ phenotype. If they’re at different loci, the progeny will have the ___ phenotype because each parent contributes its complimentary allele at the differing loci.
complementation; mutant; wild-type
Consider the following:
Strains 1, 2, and 3 can’t synthesize “C”. Cross:
Strain 1 x strain 2 = C+ producing progeny
Strain 1 x strain 3 = C+ producing progeny
Strain 3 x strain 2 = no synthesis.
What test is this? How is it possible that 2 progeny can produce C, and one can’t?
This is a complementation test.
2 of the progeny are able to produce C because the mutated alleles are at 2 different loci; and the each parent had the WT allele at complementary loci.
The progeny that couldn’t produce C have parents who’s mutations are on the same allele.
A sex ____ characteristic is when a trait has higher penetrance in one of the sexes; a sex ____ characteristic is when a trait is limited to just one of the sexes.
influenced; limited
In males, a single allele is sufficient to produce compound A. In order for females to produce compound A, they must be homozygous. The gene is located on an autosomal chromosome, not a sex chromosome. What is the likeliest cause of this phenomenon.
sex-influenced characteristics.
An extreme case of sex-influenced characteristics is a ___-______ characteristic wherein penetrance in the other sex is zero. Examples include cock feathering and precocious puberty in human males.
Sex-limited.
_____ inheritance describes the inheritance of genetic material from organelles rather than the nucleus. Reciprocal crosses will give _____ results.
In fact, different progeny from the same parents might yield ____ results (if there’s a mutation) because the _____ containing the genetic materials do not segregate _____ during meiosis (when the gametes were created). Even individual ____ within a person can show this variability.
Cytoplasmic; different; different; organelles; equally.
cells
Progeny from the same mother can show considerable _____ variability if, and only IF, her mitochondrial genes have mutations. This is known as _____ inheritance.
phenotypic; cytoplasmic
_____ ______ is easy to confuse with cytoplasmic inheritance; but in this phenomenon, the progeny inherit genes from both parents, but the progeny’s phenotype is determined by the genotype of the ______.
Maternal effect; mother
In some species of snails, the shells will be sinistral or dextral depending on the ____ of the female - NOT on the genotype of the offspring. This phenomenon is due to ____ ____.
genotype; maternal effect
In maternal effect, a self-fertilizing snail who’s genotype is s+s and is sinistral will give birth to progeny who’s shells are _______ due to the parents _____ - not their _____, and not the progeny’s ______.
dextral; genotype; phenotype; genotype
Differential expression of genetic material depending on whether it’s inherited from the mother or father is known as _____ ______. The mechanism responsible isn’t fully understood, but it has something to do with ____ of DNA after synthesis.
genomic imprinting.
methylation
Children who inherit a deletion on chromosome ___ from their fathers will develop Prader-Willi syndrome; if they inherit the exact same deletion from their mothers they’ll inherit Angelman syndrome. This is known as ____ _____.
15; genomic imprinting
A genetic mutation that is expressed more strongly in successive generations is known as ______. The mutation are associated with an _____ regions of DNA, and the ____ regions change in the germline cells. (It was originally observed in the ____ but dismissed.)
anticipation; unstable; unstable; 1900s
Assume that attached earlobes are a recessive trait with 70% penetrance. One parent is heterozygous and the other homozygous recessive for the attached earlobe gene. What is the probability that their child will have attached earlobes?
Attached = ee
Ee x ee = 1/2 Ee; 1/2 ee - so 50% attached to normal
0.5 x 0.7 = 0.35, or 35%
A child who is blood type O has a mother who is blood type A. In a paternity suit a man is accused of being the father. He has blood type B. Is he the father?
A. Yes
B. No
C. He cannot be excluded as the father.
D. There is a 12.5% chance that he is the father.
C. He cannot be excluded as the father.
The type O blood of the child must be ii. The mother’s genotype must be IAi. The man could be the father if his genotype is IBi
The difference between dominance and epistasis is
A. Dominance masks genes at different loci.
B. Epistasis masks genes at the same loci.
C. Epistasis masks genes at different loci.
D. Dominance and epistasis are the same
C. Epistasis masks genes at different loci.
Female flies with cinnamon colored eyes were crossed to males with cyan colored eyes. All of the F1 progeny have dark red (wild type) eyes. Which of the following statements is (are) true?
A. Cinnamon and cyan eyes result from alleles of the same gene.
B. Cinnamon and cyan eyes involve two different genes.
C. This is an example of genetic complementation
D. Cinnamon eyes are the result of an environmental effect (such as temperature) that alters expression of the affected gene.
E. More than one of the above
E. More than one of the above:
Both are correct:
B. Cinnamon and cyan eyes involve two different genes.
C. This is an example of genetic complementation
The effect of sex on the expression of genes that are on autosomes is said to be ____-____ (e.g. goat beards and male pattern _____).
Sex-limited
The effect of genes in cytoplasmic organelles on the expression of characteristics is known as ______ ______ and, if there are any mutations, phenotypic _____ can be seen within progeny and even within cell lines due to the ____ distribution of the organelles.
cytoplasmic inheritance; variability; random
Situations where ONLY the genotype of the mother determines the phenotype of the progeny is called ____ ____ (e.g. dextral vs. sinistral snail coiling).
maternal effect
Prader-Willi syndrome and Angelman syndrome are examples of genomic _____ because the implicated genetic defect, a deletion on chromosome ____, can be present on the maternal chromosome (____ syndrome…mothers are angels) OR paternal chromosome (____).
imprinting; 15; Angelman; Prader-Willi
When an environmental factor causes a phenotype to mimic, or ‘copy’ the phenotype of another genotype, it is called ____ (e.g. eyeless ____ can occur due to mutation or feeding Na metaborate.
phenocopy; drosophila
Continuous traits, aka ______ traits, must use some kind of measurement to describe the phenotype. Additionally, these traits are often ____, meaning they involve more than one gene.
quantitative traits; polygenic
What is the formula to determine the possible genotypes when there are only 2 alleles per gene?
3^n where n = the number of genes/loci being considered.
The opposite of polygenic is ______. This is a situation where ____ gene(s) affect(s) _____ phenotypes (e.g. phenylketonuria involves only ___ gene, but impacts blue eyes, light skin, and mental retardation if ____ factors are not controlled.
pleiotropic.
one; multiple; one; environmental
______ characteristics usually include multiple genes (aka ____) and environmental factors.
Multifactorial; polygenic
Phenotypic ratios: a ratio of 9:3:4 is seen in coat color of Labradors where A_B_ is black (9/16); A_bb is brown (3/16), and both aaB_ (3/16) AND aabb (1/16) are yellow. What is the interaction?
recessive epistasis
Phenotypic ratios: a ratio of 12:3:1 is seen in the color of some squashes where A_B_ (9/16) AND A_bb (3/16) are white, aaB_ (3/16) are yellow, and aabb (1/16) are green. What is the interaction? What is another way to evaluate the phenotype, and what’s its ratio?
The interaction is dominant epistasis.
The phenotype can be viewed as (dominant epistatic trait):(some color), which would be 12:4, or 3:1!!!
Phenotypic ratios: a ratio of 9:7 is seen in snail albinism where A_B_ (9/16) have pigment, A_bb (3/16) AND aaB_ (3/16) AND aabb (1/16) are albinos. What is the interaction?
duplicate recessive epistasis
