Chapter 29 1110/1120

Question 1

is the study of heredity—that is, the characteristics children inherit from their parents.

Answer 1

Genetics

Question 2

the study of how genetic traits are passed from parent to offspring. Mendelian genetics allows us to make predictions about the patterns of how traits are passed from one generation to the next.

Answer 2

Mendelian genetics

Question 3

e genetic approach to the diagnosis and management of disease, has indeed come a long way since its early beginnings.

Answer 3

genomic medicine

Question 4

or sex cells, each gamete receives one of these factors. Then two gametes combine to produce the next generation, so that each member of the next generation of pea plants has two heritable factors for each characteristic.

Answer 4

gametes

Question 5

is the genes an organism has for a given trait. The actual genetic constitution of an individual is its

Answer 5

genotype

Question 6

is the expression of the genes as a trait.

Answer 6

phenotype

Question 7

Mendel stated that genes occur in dominant and recessive forms. Alternate forms of genes

Answer 7

alleles

Question 8

for a trait if the two alleles for the trait are identical.

Answer 8

homozygous

Question 9

for a trait if the two alleles for the trait are different.

Answer 9

heterozygous

Question 10

results in a lack of normal coloring of the skin, hair, and eyes. Several human genes produce the enzymes that are necessary for the synthesis of melanin, the pigment responsible for skin, hair, and eye color

Answer 10

albinism

Question 11

has extra fingers or toes. One allele for polydactyly is dominant over the recessive, normal allele that results in the normal number of fingers or toes.

Answer 11

polydactyly

Question 12

are all the cells of the body except the gametes. Examples of somatic cells are epithelial cells, muscle cells, neurons, fibroblasts, lymphocytes, and macrophages

Answer 12

Somatic cells

Question 13

The somatic cells have a normal number of chromosomes

Answer 13

diploid

Question 14

The normal number of chromosomes in a gamete

Answer 14

haploid

Question 15

Humans have 22 pairs of this. which are all the chromosomes except the sex chromosomes, and 1 pair of sex chromosomes, which determines the sex of the individual. Sex chromosomes are denoted as X or Y chromosomes.

Answer 15

autosomal chromosomes

Question 16

is a display of the chromosomes of a somatic cell during metaphase of mitosis. It is produced by photographing the cell’s stained chromosomes through a microscope and arranging the photographed chromosomes in pairs

Answer 16

karyotype

Question 17

An individual has only two alleles for a given gene, one on each homologous chromosome. At the population level, however, many forms of an allele may exist.

Answer 17

multiple alleles

Question 18

is an autosomal recessive trait with multiple alleles. A gene on chromosome 12 encodes for an enzyme that converts the amino acid phenylalanine to the amino acid tyrosine

Answer 18

phenylketonuria

Question 19

his type of inheritance pattern in which the dominant allele is fully expressed over the recessive allele

Answer 19

complete dominance

Question 20

two alleles at the same locus are expressed, so that separate, distinguishable phenotypes occur at the same time.

Answer 20

codominance

Question 21

the dominant allele does not completely mask the effects of the recessive allele in the heterozygote. The heterozygote produces less of the protein product than the homozygous dominant and has phenotypic characteristics intermediate between the homozygous dominant and the homozygous recessive.

Answer 21

incomplete dominance

Question 22

is a disorder of a gene on chromosome 11. It affects the synthesis of β-globulin polypeptide chains, which are part of the hemoglobin in red blood cells.

Answer 22

beta thalassemia

Question 23

two abnormal alleles are present, and much lower-than-normal amounts of β-globulin polypeptide chains are synthesized.

Answer 23

major thalassemia

Question 24

which is a deficiency of hemoglobin in the blood. Symptoms include pallor, weakness, fatigue, and spleen enlargement. Blood transfusions are necessary to maintain hemoglobin levels. In the heterozygous condition

Answer 24

anemia

Question 25

one normal allele and one abnormal allele are present. The production of hemoglobin is intermediate between the normal phenotype and major thalassemia, and mild anemia results.

Answer 25

minor thalassemia

Question 26

result from the interactions of many genes. Although all the genes contribute to the phenotype without being dominant or recessive to each other, each gene has its own characteristics, such as multiple alleles or incomplete dominance.

Answer 26

polygenic trait

Question 27

haploid gametes are produced that have one chromosome from each of the homologous pairs of chromosomes. Therefore, gametes have one-half the number of chromosomes and one-half as many alleles as the original diploid cells.

Answer 27

meiosis

Question 28

is a failure of structure, function, or both as a result of abnormalities in a person’s genetic makeup—that is, his or her DNA. Humans may have a variety of genetic disorders

Answer 28

genetic disorder

Question 29

In most cases, the specific cause of a mutation cannot be determined. Once a mutation has occurred, however, the abnormal trait can be passed from one generation to the next.

Answer 29

mutagen

Question 30

The failure of chromosomes to separate during meiosis

Answer 30

nondisjunction

Question 31

When the gametes are fertilized, the resulting zygote has either 47 chromosomes or 45 chromosomes, rather than the normal 46

Answer 31

aneuploidy

Question 32

trisomy 21, is a type of aneuploidy in which three chromosomes 21 are present

Answer 32

Down syndrome

Question 33

is a set of signs and symptoms occurring together as the result of a single cause, such as a single mutation or one extra chromosome (a trisomy).

Answer 33

syndrome

Question 34

One hypothesis of aging suggests the existence of this, after a certain passage of time or a certain number of cell divisions, results in the death of a given cell line.

Answer 34

Cellular clock

Question 35

Another hypothesis suggests that there are “death genes,” which turn on late in life, or sometimes prematurely, causing cells to deteriorate and die.

Answer 35

Death genes

Question 36

Other hypotheses suggest that, through time, DNA is damaged, resulting in cell degeneration and death.

Answer 36

DNA damage

Question 37

which are atoms or molecules with an unpaired electron.

Answer 37

free radicals

Question 38

are traits affected by genes on the sex chromosomes

Answer 38

Sex-linked traits

Question 39

re affected by genes on the X chromosome

Answer 39

X-linked traits

Question 40

are affected by genes on the Y chromosome. In humans, the X chromosome is much larger than the Y chromosome.

Answer 40

Y-linked traits

Question 41

The specific location of a gene on a chromosome is its

Answer 41

Locus

Question 42

If an albino (aa) mates with a person homozygous for normal pigment (AA)

Answer 42

All the offspring are normal but carriers.

Question 43

In humans, somatic cells have ____ chromosomes, while reproductive cells (gametes) have ____.

Answer 43

46; 23

Question 44

A mutation involving a single nucleotide change is

Answer 44

point mutation