Human Genetics Chapter 4

Front 1

A severe disease that is inherited as an autosomal recessive trait is more likely to skip generations in a pedigree than an autosomal recessive trait that causes a harmless phenotypic variant because

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a person with an autosomal recessive disease is less likely to be well enough to reproduce than a person with a harmless trait variant.

Front 2

Gregor Mendel is known for

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breeding plants to demonstrate the logic behind inherited trait transmission.

Front 3

One reason that dominant diseases remain in populations is that

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they often do not produce symptoms until a person has already had children.

Front 4

A Punnett square displays

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the probabilities of how alleles combine in offspring.

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***Ian and Bryony are both carriers for two autosomal recessive disorders, PKU (chromosome 12) and cystic fibrosis (chromosome 7). They are expecting a daughter. What is the probability that she will have PKU but not CF?

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3/16

Front 6

A person who has two identical alleles for a particular gene is _______ for that gene.

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homozygous

Front 7

The probability of giving birth to 5 girls in a row is

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1/32

Front 8

Autosomal dominant traits

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never skip generations

Front 9

In pea plants, the allele for tall (T) is dominant to the allele for short (t). The genotype for a short pea plant is __.

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tt

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An autosomal dominant trait

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can affect either sex.

Front 11

Mode of inheritance reflects

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whether the gene is on an autosome or sex chromosome and whether the allele is recessive or dominant.

Front 12

The difference in mode of inheritance between Huntington disease and cystic fibrosis is that

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Huntington disease does not skip generations but cystic fibrosis can.

Front 13

***If a child is born with an autosomal dominant trait***

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At least one parent will have the trait as well

Front 14

***In the Foofnagle family, the trait of being able to yodel affects members of both sexes in every generation. This trait could be

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autosomal recessive or autosomal dominant.

Front 15

Using the product rule, the probability that parents heterozygous for two traits (AaBb) produce an offspring homozygous recessive for the same two traits (aabb) is

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1/16

Front 16

***Which of the following represents a monohybrid cross?

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Bb x Bb

Front 17

The wild type eye color for humans is

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brown

Front 18

Sickle cell disease is inherited as an autosomal recessive trait. The genotype of an individual with sickle cell disease is

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homozygous recessive.

Front 19

In a human pedigree that traces the inheritance of albinism, a filled square represents a

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male with albinism.

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In a family that starts with you, your grandchildren would be the _______ generation.

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F2

Front 21

Genotype refers to

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the combination of alleles for a particular gene.

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Alleles are

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alternate forms of a gene.

Front 23

Eric and Janelle are carriers of the recessive allele causing Tay-Sachs disease, which is lethal in early childhood. If they have a healthy child, what is the probability that this child would NOT be a carrier of Tay-Sachs disease?

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1/3

Front 24

The chances of giving birth to a son, on a Tuesday, in the month of March is

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1/168

Front 25

Jermaine and Shikia are healthy parents of three young children. The oldest two, Bethany and Amber, are healthy, and they are six and four, respectively. Their youngest child was born with Peeling Skin Syndrome, an autosomal recessive disorder, two years ago. Roscoe's skin constantly peels, and is red and itchy. If Jermaine and Shikia have another child, the probability that he or she will inherit the skin condition is

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1/4

Front 26

If a child is born with an autosomal recessive trait that is not displayed in either parent

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both parents must be carriers

Front 27

For two traits A and B with two alleles each, the genotypes of the gametes that a heterozygote would produce are

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AB, Ab, aB, ab.

Front 28

When Mendel crossed pure breeding peas having yellow seed color (YY) with pure breeding peas having green seed color (yy), all of the offspring had yellow seed color. These results mean that yellow seed color is the

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dominant phenotype.

Front 29

***Mendel called physical units responsible for the inheritance of traits "characters." The basis for his first law is that characters

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are carried on separate chromosomes.

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A very narrow pedigree, such as that for Egypt's Ptolemy dynasty, reflects

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families with many relatives having children with blood relatives.

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Mendel followed the transmission of traits through several generations in

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peas.

Front 32

***Destiny has distal symphalangism - her fingers and toes are stiff, with tiny nails. She looks it up and finds it is an autosomal dominant trait. Since her parents do not have it, she reasons that she is a new mutation. However, if she has children, each of them, assuming her partner does not have the condition, has a(n) ___ probability of inheriting the condition.***

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1/2

Front 33

The phenotypic ratio expected from a dihybrid cross involving complete dominance is

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9:3:3:1

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In a human pedigree that traces the inheritance of sickle cell disease, a half-filled circle represents a

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heterozygous female.

Front 35

Hillary is 8 years old and has neuronal ceroid lipofuscinosis, also known as Batten disease. It is autosomal recessive. She was fine until age five, when she began to lose her vision and stumble. She had learning difficulties in school and was diagnosed at age six. Hillary may only live into her twenties, experiencing dementia and seizures. Her younger brother Jaden, age seven, is healthy, as are her parents. The probability that Jaden is a heterozygote is

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2/3

Front 36

Black mice may be either BB or Bb. To determine the genotype of a black mouse you plan to work with you mate the mouse to a white (bb) mouse. The is an example of a __________ cross.

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test

Front 37

Which of the following genotypes is homozygous?

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RRYY

Front 38

Cystic fibrosis is autosomal recessive. This means that

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both sexes can be affected and affected individuals and carriers pass the mutation.

Front 39

***The second generation resulting from a genetic cross is the _______ generation.

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F2

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A(n) ______ cross yields a genotypic ratio of 1:2:1 and a phenotypic ratio of 3:1.

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monohybrid

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A heterozygote has

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two different alleles for a gene.