ch 7 review

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

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

he genome of Homo sapiens. It is made up of 23 chromosome pairs with a total of about 3 billion DNA base pairs. There are 24 distinct human chromosomes: 22 autosomal chromosomes, plus the sex-determining X and Y chromosomes. Chromosomes 1-22 are numbered roughly in order of decreasing size.

Question 4

basis or nucleotides

Answer 4

a compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.

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

prismidines

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

the principle, originated by Gregor Mendel, stating that 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

Linked genes are genes that are likely to be inherited together because they are physically close to one another on the same chromosome. During meiosis, chromosomes are recombined, resulting in gene swaps between homologous chromosomes.

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. These not only carry the genes that determine male and female traits but also those for some other characteristics as well. Genes that are carried by either sex chromosome are said to be sex linked.

Question 21

sex-limited traits

Answer 21

are those characters that are expressed physically in one sex of a species. These traits are controlled by sex limited genes or autosomal genes that are expressed only in one sex. … Despite having the same genotype, both the sexes show different traits or phenotypes for these genes.

Question 22

sex-influenced traits

Answer 22

are autosomal traits that are influenced by sex. If a male has one recessive allele, he will show that trait, but it will take two recessive for the female to show that same trait. One such gene is baldness. A lot of sex-limtied traits can determine parental carriers by using a pedigree.

Question 23

genome

Answer 23

the haploid set of chromosomes in a gamete or microorganism, or in each cell of a multicellular 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.

Question 26

monosomy

Answer 26

is a form of aneuploidy with the presence of only one chromosome from a pair. Partial monosomy occurs when only a portion of the chromosome has one copy, while the rest has two copies.

Question 27

trisomy

Answer 27

is when a diploid organism has three copies of one of its chromosomes instead of two.

Question 28

polyploidy

Answer 28

Polyploidy is the state of a cell or organism having more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent.