chapter 7

Question 1

chromosomes

Answer 1

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Question 2

genes

Answer 2

(in informal use) a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Question 3

human genome

Answer 3

made up of 23 chromosome pairs with a total of about 3 billion DNA base pairs.

Question 4

bases or nucleotides

Answer 4

can be A C T or G

Question 5

purines

Answer 5

a substituted derivative of purine, especially the bases adenine and guanine present in DNA.

Question 6

guanine

Answer 6

a compound that occurs in guano and fish scales, and is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with cytosine in double-stranded DNA.

Question 7

adenine

Answer 7

a compound which is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with thymine in double-stranded DNA.

Question 8

pyrimidines

Answer 8

a substituted derivative of pyrimidine, especially the bases thymine and cytosine present in DNA

Question 9

cytosine

Answer 9

a compound found in living tissue as a constituent base of nucleic acids. It is paired with guanine in double-stranded DNA.

Question 10

thymine

Answer 10

a compound which is one of the four constituent bases of nucleic acids. A pyrimidine derivative, it is paired with adenine in double-stranded DNA.

Question 11

double helix

Answer 11

a pair of parallel helices intertwined about a common axis, especially that in the structure of the DNA molecule.

Question 12

replication

Answer 12

the action of copying or reproducing something

Question 13

law of independent assortment

Answer 13

when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.

Question 14

linked genes

Answer 14

genes that are likely to be inherited together because they are physically close to one another on the same chromosome.

Question 15

recombination

Answer 15

the rearrangement of genetic material, especially by crossing over in chromosomes or by the artificial joining of segments of DNA from different organisms.

Question 16

crossing over

Answer 16

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

Question 17

genetic engineering

Answer 17

the deliberate modification of the characteristics of an organism by manipulating its genetic material.

Question 18

sex chromosomes

Answer 18

a chromosome involved with determining the sex of an organism, typically one of two kinds.

Question 19

autosomes

Answer 19

any chromosome that is not a sex chromosome.

Question 20

sex-linked traits

Answer 20

A particularly important category of genetic linkage has to do with the X and Y sex chromosomes

Question 21

sex-limited traits

Answer 21

Sex limited traits are those characters that are expressed physically in one sex of a species

Question 22

sex-influenced traits

Answer 22

Sex-influenced traits are autosomal traits that are influenced by sex

Question 23

genome

Answer 23

he complete set of genes or genetic material present in a cell or organism.

Question 24

karyotype

Answer 24

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

Question 25

nondisjunction

Answer 25

the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.