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57 Cards in this Set

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Genes located close together on the same chromosome are referred to as ___ genes and generally ___.
linked, do not sort independently during meiosis
When is Mendel's principle of independent assortment not followed?
when genes are linked
How can new combinations of alleles be created when genes are linked?
crossing over during meiosis
When crossing over recombines linked genes into assortments of alleles not found in parents, they are called:
recombinant genes
In a cross of a purple-flowered, short-stemmed plant with a yellow flowered, long-stemmed plant, the expected phenotypic ratio is 1 purple short : 1 purple-long : 1 yellow-short : 1 yellow-long. When you do the actual cross you observe a 5 purple-short : 1 purple-long : 1 yellow-short : 5 yellow long phenotypic ratio. Which of the following explains these results?
both A and C are correct
A. the genes are linked
C. purple-long and yellow-short individuals are recombinants
The percentage of offspring that show a recombination of alleles of linked genes is called the
recombination frequency
The smaller the number of map units between linked alleles, the:
smaller the recombination frequency
Which of the following kinds of data could be used to map the relative position of three genes on a chromosome?
the frequencies with which the corresponding traits occur together in offspring
What is the normal complement of sex chromosomes in a human male?
one X chromosome and one Y chromosome
What is the normal complement of sex chromosomes in a human female
two X chromosomes
How many sex chromosomes are in a human gamete?
1
The sex of human offspring is determined by:
whether the egg is fertilized by a sperm carrying an X or Y chromosome
In ants and bees, there are no sex chromosomes. Females are ___, and males are ___.
diploid, haploid
What is meant by the statement that “male bees are fatherless”?
male bees develop from unfertilized eggs
A plant species in which individual plants produce both sperm and eggs is called:
monoecious
An animal species in which an individual produces both sperm and eggs is called:
hermaphroditic
A gene located on a sex chromosome is called a:
sex-linked gene
On what human chromosome are sex-linked genes unrelated to sex determination usually found?
X chromosome
Recessive sex-linked human conditions include which of the following?
all of the above
A. red-green color blindness
B. hemophilia
C. Duchenne muscular dystrophy
Why are X-linked recessive disorders more common in males than in females?
both B and C are correct
B. males need to inherit only one copy of the recessive allele for the condition to be fully expressed
C. females must inherit two copies of the recessive gene for the condition to be fully expressed
Suppose that in ladybugs, the genes for color and spot size are very closely linked. A heterozygous beetle with the dominant orange color and dominant big spots is crossed with a homozygous beetle with the recessive yellow color and small spots. All four possible phenotypes are produced: orange big spots, yellow small spots, orange small spots, and yellow big spots. If these genes are closely linked, what ratio (in the order of the phenotypes listed) would you expect to see in the offspring?
10:10:1:1
In a dihybrid cross involving linked genes, a heterozygous individual and a homozygous recessive individual produce offspring of four different phenotypes. 90 out of 100 offspring have the same combination of traits as a parent, but 10 out of 100 offspring exhibit a recombination of traits. What is the recombination frequency?
10%
In a dihybrid cross involving linked genes, there is a recombination frequency of 20%. What is the map distance between the two genes?
20 map units
Hemophilia is an X-linked recessive disease. If a hemophiliac male and a normal (non-carrier) female have a son, what are the chances that the son will have hemophilia?
0%
Hemophilia is an X-linked recessive disease. If a hemophiliac male and a normal (non-carrier) female have a daughter, what are the chances that the daughter will have hemophilia?
0%
Hemophilia is an X-linked recessive disease. If a hemophiliac male and a normal (non-carrier) female have a daughter, what are the chances that the daughter will be a carrier?
100%
Hemophilia is an X-linked recessive disease. If a carrier female and a normal male have a son, what are the chances that the son will have hemophilia?
50%
Hemophilia is an X-linked recessive disease. If a carrier female and a normal male have a daughter, what are the chances that the daughter will have hemophilia?
0%
Hemophilia is an X-linked recessive disease. If a carrier female and a normal male have a daughter, what are the chances that the daughter will be a carrier?
50%
Red-green colorblindness is an X-linked recessive disease. If a color blind female and a normal male have a daughter, what are the chances that the daughter will be colorblind?
0%
Red-green colorblindness is an X-linked recessive disease. If a color blind female and a normal male have a daughter, what are the chances that the daughter will be a carrier?
100%
Red-green colorblindness is an X-linked recessive disease. If a color blind female and a normal male have a son, what are the chances that the son will be colorblind?
100%
In a cross between a white-eyed female fruit fly and red-eyed male, what percent of the female offspring will have white eyes? (White eyes are X-linked, recessive)
0%
A female Drosophila of unknown genotype was crossed with a white-eyed male fly, of genotype (w = white eye allele is recessive, w+= red-eye allele is dominant.) Half of the male and half of the female offspring were red-eyed, and half of the male and half of the female offspring were white-eyed. What was the genotype of the female fly?
Xw+Xw
In a cross between a pure bred, red-eyed female fruit fly and a white-eyed male, what percent of the male offspring will have white eyes? (white eyes are X-linked, recessive)
0%
What is the genotype of a red-eyed, yellow-bodied female fruit fly who is homozygous for the eye color allele?
Red eyes (w+) and tan bodies (y+) are the dominant alleles. (Both traits are X chromosome linked).
Xw+yXw+y
A white-eyed female fruit fly is crossed with a red-eyed male. Red eyes are dominant, and X-linked. What are the expected phenotypes of the offspring?
All of the females will have red eyes; all of the males will have white eyes.
Hemophilia in humans is due to an X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophilac male?
all sons are normal and all daughters are carriers.
A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness (or alternatively, hemophilia), marries a normal male. What proportion of their male progeny will have red-green color blindness (or alternatively, will be hemophiliac)?
50%
Women have sex chromosomes of XX, and men have sex chromosomes of XY.

Which of a man's grandparents could not be the source of any of the genes on his Y-chromosome?
Mother's Mother, Mother's Father, and Father's Mother.
Women have sex chromosomes of XX, and men have sex chromosomes of XY.

Which of a women's grandparents could not be the source of any of the genes on either of her X-chromosomes
Father's Father.
A human female "carrier" who is heterozygous for the recessive, sex-linked trait red color blindness, marries a normal male.

What proportion of their female progeny will show the trait?
0
The alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+) is dominant to yellow body color (y).

What is the genotype of a yellow-bodied, red-eyed female who is homozygous for eye color?
Xw+yXw+y
The alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+ ) is dominant to yellow body color (y).
What is the genotype of a tan-bodied, white-eyed male?
Xwy+y
What offspring would you expect from a cross between the female Drosophila described in problem 1 (red eyes and a yellow body, homozygous recessive for the yellow body color allele and homozygous dominant for the eye color allele) and the male described in problem 2 (hemizygous for both the recessive (white) eye color allele and dominant (tan) body color allele?)
A reminder that the alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+) is dominant to yellow body color (y)
Daughters would be tan-bodied, red-eyed; the sons would be yellow-bodied, red-eyed
If we mated the F1 female and male flies from the cross obtained in problem 3, what male phenotype in the F2 generation would be evidence that crossing over had occured during gamete formation?

Daughters were tan-bodied, red-eyed, heterozygous for both eye and body color. The sons were yellow-bodied, red-eyed hemizygous.
white eyes and yellow bodies and red eyes and tan bodies
Audrei is the family member who contacted us. She and her father Sydney are color blind, but her mother, Barbara, has normal vision. What is Audrei's genotype?
homozygous recessive for the red-green color blind allele
Now that we determined that Audrei is homozygous recessive for the red-green color blind allele. What is her father's genotype?
hemizygous with a recessive allele
We have determined that Audrei is homozygous recessive for the red-green color blind allele and that her father is hemizygous with a recessive allele. What is the mother's genotype? Remember that Audrei's mother does not have a color perception defect.
heterozygous carrier of the red-green color blind allele
What is the genotype of Audrei's sister Caroline, who has normal vision?
heterozygous carrier of the red-green color blind allele
In her message, Audrei also tells us that her sister Liz and brother Paul are also color blind, but that her brother David has normal vision. How will Liz be represented on the family pedigree?
affected
Paul, like Liz, is color blind. How will he be represented in the family pedigree?
male affected
Andrew and Jason have not been tested. What is the possibility that they will have the color perception defect?
50%
We don't know if any of Audrei's grandparents were red-green color blind, but we can make some educated guesses. Is it possible that all of Audrei's grandparents have normal vision?
yes
Would we predict that Stephen's father is color blind?
no
What is the probability that Audrei's sons will be color blind?
100%
What is the probability that Audrei's daughters will be color blind?
O% if the father has normal vision, and
100% if the father is red-green color blind