Chapter 5 - Extensions & Mods of Basic Principles

Question 1

An organism’s ____ is the result of how ___ are expressed and whether two or more ____ products interact.

Answer 1

phenotype; genes; gene

Question 2

Recessive lethal alleles usually have a : ratio rather than 3:1 because 1/4 of the progeny die.

Answer 2

2:1

Question 3

Dominance is ____ to the characteristic being examined.

Answer 3

relative

Question 4

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?

Answer 4

Y is dominant with respect to coat color. It’s recessive with respect to lethality.

Question 5

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.

Answer 5

incomplete

Question 6

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?

Answer 6

Incomplete dominance. 1:2:1

Question 7

In ______ the heterozygote expresses the phenotype of both ________ (e.g. the MN blood group system).

Answer 7

codominance; homozygotes

Question 8

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.)

Answer 8

level; anatomical; physiological; molecular

Question 9

The gene responsible for cystic fibrosis is autosomal/allosomal, and is chromosome # ___. It is considered a recessive/dominant allele.

Answer 9

autosomal; 7; recessive.

Question 10

CFTR stands for ? What does it regulate?

Answer 10

Cystic fibrosis transmembrane conductance regulator.

It regulates the movement of Cl- across the cell membrane.

Question 11

Heterozygotes of the cystic fibrosis allele make what? What does this mean in terms of dominance on the molecular level? The clinical/physiological level?

Answer 11

Heterozygotes make functional and nonfunctional proteins.

Codominant at the molecular level; recessive at the physiological level.

Question 12

Dominance is the result of ____ interactions; but the way genes are inherited is in accordance with ___ observations.

Answer 12

allelic; Mendel’s

Question 13

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).

Answer 13

incomplete penetrance.

Question 14

Polydactyly is an example of ____ ____ - some individuals are normal, but one or more of their offspring have the condition.

Answer 14

incomplete penetrance.

Question 15

Penetrance is the _____ of individuals with a specific genotype who demonstrate the expected _____ . _____ is the degree to which the trait is expressed.

Answer 15

percentage; phenotype.

Expressivity

Question 16

Explain variable expressivity using polydactyly as an example.

Answer 16

Some will have just a bit of extra skin while others will have fully-functioning digits - they both have the SAME allele.

Question 17

Incomplete penetrance and variable expressivity may result from _____ between other genes and ____ factors.

Answer 17

interactions; environmental.

Question 18

A gene that encodes for a temperature sensitive protein is an example of how _____ factors interact with genes to determine _____.

Answer 18

environmental; phenotype

Question 19

Multiple _____ allow for greater variety of genotypes and phenotypes.

Answer 19

alleles

Question 20

A phenotypic ratio of 2:1:1 (instead of 3:1) might be indicative of multiple ____. (e.g. ___ blood grouping and ____ feathers.

Answer 20

alleles; ABO; duck

Question 21

Gene _____ result from non-______ genes who’s products lead to new phenotypes that were not expected based on the phenotype of each individual locus.

Answer 21

interactions; non-allelic;

Question 22

A cross that looks monohybrid in F1 progeny, then looks dihybrid in F2 selfed progeny might be due to what phenomenon?

Answer 22

gene interactions.

Question 23

A gene interaction in pepper colors involves ___ mutations that affect ___ biochemical pathway.

Answer 23

2; 1

Question 24

Two enzymes (proteins) that contribute to the coloration of peppers in a biochemical pathway is an example of a?

Answer 24

gene interaction

Question 25

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 ______.

Answer 25

probability; probabilities; loci.

Question 26

What’s the formula for determining the phenotypic ratios of progeny?

Answer 26

x = 16X/n 
x = phenotype; n = total progeny

Question 27

A type of gene interaction where one gene hides (“masks”) the effect of another gene (separate locus) is called ____.

Answer 27

epistasis

Question 28

Epistasis ____ the allele of a gene at different ____.

Dominance _____ the allele of a gene at the same ______.

Answer 28

masks; loci.

masks; loci

Question 29

When considering genes at different loci, the ____ gene masks the ____ gene.

Answer 29

epistatic; hypostatic

Question 30

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.

Answer 30

recessive epistasis; mask

Question 31

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.

Answer 31

recessive epistasis.

Question 32

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.

Answer 32

recessive = hypostatic
dominant = epistatic

Question 33

In ____ epistasis, one copy of the epistatic gene is sufficient to mask the second gene at a different ____.

Answer 33

dominant; locus

Question 34

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.

Answer 34

Dominant epistasis

Question 35

Epistasis is often seen affecting the sequential steps of a ______ ______.

Answer 35

biochemical pathway

Question 36

In ____ _____ epistasis, 2 copies of a ____ allele at either loci are able to mask genes at different loci.

Answer 36

duplicate recessive

Question 37

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?

Answer 37

duplicate recessive epistasis

Question 38

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?

Answer 38

duplicate recessive epistasis (9:7 ratio pigmented to albino).

Question 39

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?

Answer 39

duplicate recessive epistasis

Question 40

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.

Answer 40

complementation; mutant; wild-type

Question 41

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?

Answer 41

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.

Question 42

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.

Answer 42

influenced; limited

Question 43

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.

Answer 43

sex-influenced characteristics.

Question 44

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.

Answer 44

Sex-limited.

Question 45

_____ 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.

Answer 45

Cytoplasmic; different; different; organelles; equally.

cells

Question 46

Progeny from the same mother can show considerable _____ variability if, and only IF, her mitochondrial genes have mutations. This is known as _____ inheritance.

Answer 46

phenotypic; cytoplasmic

Question 47

_____ ______ 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 ______.

Answer 47

Maternal effect; mother

Question 48

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 ____ ____.

Answer 48

genotype; maternal effect

Question 49

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 ______.

Answer 49

dextral; genotype; phenotype; genotype

Question 50

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.

Answer 50

genomic imprinting.

methylation

Question 51

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 ____ _____.

Answer 51

15; genomic imprinting

Question 52

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.)

Answer 52

anticipation; unstable; unstable; 1900s

Question 53

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?

Answer 53

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%

Question 54

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.

Answer 54

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

Question 55

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

Answer 55

C. Epistasis masks genes at different loci.

Question 56

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

Answer 56

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

Question 57

The effect of sex on the expression of genes that are on autosomes is said to be ____-____ (e.g. goat beards and male pattern _____).

Answer 57

Sex-limited

Question 58

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.

Answer 58

cytoplasmic inheritance; variability; random

Question 59

Situations where ONLY the genotype of the mother determines the phenotype of the progeny is called ____ ____ (e.g. dextral vs. sinistral snail coiling).

Answer 59

maternal effect

Question 60

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 (____).

Answer 60

imprinting; 15; Angelman; Prader-Willi

Question 61

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.

Answer 61

phenocopy; drosophila

Question 62

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.

Answer 62

quantitative traits; polygenic

Question 63

What is the formula to determine the possible genotypes when there are only 2 alleles per gene?

Answer 63

3^n where n = the number of genes/loci being considered.

Question 64

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.

Answer 64

pleiotropic.

one; multiple; one; environmental

Question 65

______ characteristics usually include multiple genes (aka ____) and environmental factors.

Answer 65

Multifactorial; polygenic

Question 66

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?

Answer 66

recessive epistasis

Question 67

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?

Answer 67

The interaction is dominant epistasis.

The phenotype can be viewed as (dominant epistatic trait):(some color), which would be 12:4, or 3:1!!!

Question 68

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?

Answer 68

duplicate recessive epistasis