Chromosomes And Human Genetics

Front 1

abortion

Back 1

Expulsion of a pre-term embryo or fetus from the uterus.

Front 2

allele

Back 2

One of two or more molecular forms of a gene that arise by mutation and specify slightly different versions of the same trait.

Front 3

aneuploidy

Back 3

In cells, too many or too few chromosomes relative to the parental number.

Front 4

autosome

Back 4

Any chromosome of a type that is the same in males and females of a species

Front 5

crossing over

Back 5

At prophase I of meiosis, the reciprocal exchange of segments between two nonsister chromatids of a pair of homologous chromosomes; results in novel combinations of alleles.

Front 6

deletion

Back 6

Loss of a chromosome segment. Also, a mutation involving the loss of one or more bases of a DNA molecule.

Front 7

disease

Back 7

Illness caused by an infectious, dietary, or environmental factor.

Front 8

duplication

Back 8

DNA sequence repeated several to many hundreds or thousands of times.

Front 9

fetus

Back 9

Stage of animal development; in humans, the start of the ninth week to birth.

Front 10

gene

Back 10

Unit of information for a heritable trait in DNA, passed from parents to offspring.

Front 11

gene locus

Back 11

A gene’s chromosomal location.

Front 12

genetic disorder

Back 12

Heritable defect in one’s genetic material; causes mild to severe medical problems.

Front 13

in vitro fertilization

Back 13

IVF. Combining sperm and eggs outside the body, as in a petri dish.

Front 14

inversion

Back 14

Mutation in which a section of chromosome becomes oriented in reverse.

Front 15

linkage group

Back 15

All genes on a chromosome.

Front 16

nondisjunction

Back 16

Failure of sister chromatids or homologous chromosomes to separate during meiosis or mitosis. Daughter cells end up with too many or too few chromosomes.

Front 17

pedigree

Back 17

Chart of genetic connections.

Front 18

polyploidy

Back 18

Having three or more of each chromosome type characteristic of a species.

Front 19

sex chromosomes

Back 19

Chromosomes that, in certain combinations, determine a new individual’s sex.

Front 20

syndrome

Back 20

A set of symptoms that characterize an abnormality or a disorder.

Front 21

testosterone

Back 21

Male sex hormone produced in testes; functions in sperm formation and development of secondary sexual traits.

Front 22

translocation

Back 22

Of cells, a repositioning of a stretch of DNA to a new chromosomal location with no molecular loss. Of vascular plants, distribution of organic compounds through phloem.

Front 23

y-linked gene

Back 23

Gene on a Y chromosome.

Front 24

Crossing over during meiosis results in combinations of alleles not present in the parental cell. True or False?

Back 24

True

Front 25

A human sperm carrying a Y chromosome fertilizes an egg. Assuming the egg is normal, what sex will the offspring be?

a. female
b. either, depending on the temperature at fertilization
c. not enough information
d. male

Back 25

correct answer: d

Front 26

The probability that a crossover will disrupt the linkage between two genes is proportional to:

a. the number of alleles for the genes.

b. the distance between the genes.

c. none of the choices.

d. the time of _expression of the genes.

Back 26

correct: b

Front 27

The human X chromosome:
a. is much larger than the Y chromosome.
b. carries the master gene for male sex determination.
c. carries about 330 genes.
d. is an autosome.

Back 27

correct answer: A

Front 28

Genes that are closely linked:

a. are rarely separated by crossing over.
b. have never been found in humans or other mammals.
c. are on nonhomologous chromosomes.
d. usually govern the same trait.

Back 28

correct answer A

Front 29

6 What standardized symbols are used to represent males and females on a pedigree?

a. a star for males and a square for females
b. a square for females and a circle for males
c. a square for males and a circle for females
d. a question mark for both males and females

Back 29

Correct C

Front 30

Huntington disease is governed by autosomal dominant inheritance. What is the likelihood that a person who has one heterozygous affected parent and one normal parent will develop the disease?

Back 30

a. 50%
b. 0% (impossible)
c. 75%
d. 100% (certain)

Front 31

Galactosemia is governed by autosomal recessive inheritance. What is the likelihood that a person who has one affected parent and one homozygous normal parent has the disorder?

a. 0% (impossible)
b. 75%
c. 100% (certain)
d. 50%

Back 31

answer: A

Front 32

If a man has hemophilia (an X-linked recessive trait) and his wife is homozygous for the normal allele,

a. all sons will have hemophilia.
b. all daughters will have hemophilia.
c. all daughters will be carriers.
d. all offspring will have hemophilia.

Back 32

answer: C

Front 33

Cri-du-chat syndrome is a genetic disorder caused by:

a. trisomy of chromosome 17.
b. a deletion from chromosome 5.
c. an inversion on chromosome 12.
d. a translocation between chromosomes 9 and 22.

Back 33

answer: b

Front 34

Down syndrome:

a. occurs only in males.
b. is also known as trisomy 21.
c. affects only the central nervous system.
d. results from a deletion.

Back 34

answer: B

Front 35

A gene's most common form is called the:

a. wild-type allele.
b. mutant allele.
c. dominant allele.
d. homozygous form.

Back 35

answer: a