Chapter 9 Patterns of Inheritance

Question 1

Allele

Answer 1

One of several alternative forms of a particular gene.

Question 2

Autosome

Answer 2

A chromosome that occurs in homologous pairs in both males and females and that does not bear the genes determining sex.

Question 3

Codominance

Answer 3

The relation between two alleles of a gene, such that both alleles are phenotypically expressed in heterozygous individuals.

Question 4

Cross-Fertilization

Answer 4

The union of sperm and egg from two individuals of the same species.

Question 5

Crossing Over

Answer 5

The exchange of corresponding segments of the chromatids of two homologous chromosomes during meiosis.

Question 6

Dominant

Answer 6

An allele that can determine the phenotype of heterozygotes completely, such that they are indistinguishable from individuals homozygous for the allele; in the heterozygotes, the expression of the other (recessive) allele is completely masked.

Question 7

Dystrophin

Answer 7

Muscle cells are firmly tired together by a gigantic protein called dystophin. The almost 3,700 amino acids of dystrophin from a supple yet strong rod that connects the cytoskeleton inside a muscle cell to proteins in its plasma membrane, which in turn attach to proteins that form a fibrous support surrounding each muscle.

Question 8

Gene

Answer 8

A unit of heredity that encodes the information needed to specify the amino acid sequence of protiens and hence particular traits; a functional segement of DNA located at a particular place on a chromosone.

Question 9

Genotype

Answer 9

The genetic composition of an organism; the actual alleles of each gene carried by the organism.

Question 10

Heterozygous

Answer 10

Carrying two different alleles of a given gene; also called hybrid.

Question 11

Homozygous

Answer 11

Carrying two copies of the same allele of a given gene; also called true-breeding.

Question 12

Incomplete Dominance

Answer 12

A pattern of inheritance in which the heterozygous phenotype is intermediate between the twe homozygous phenotypes.

Question 13

Inheritance

Answer 13

The genetic transmission of characteristics from parten to offspring.

Question 14

Law of Independant Assortment

Answer 14

The independant inheritance of two or more distince traits; states that the alleles for one trait may be distributed to the gametes independantly of the alleles for other traits.

Question 15

Law of Segregation

Answer 15

Gregor Mendel’s conclusion that each gamete recives only one of each parent’s pair of genes for each trait.

Question 16

Linkage

Answer 16

The inheritance of certain genes as a group because they are parts of the same chromosome. Linked genes do not show independant assortment.

Question 17

Locus(plural, loci)

Answer 17

The physical location of a gene on a chromosome.

Question 18

Muscular Dystophy

Answer 18

A group of inherited disorder that result in degeneration of muscle tissue.

Question 19

Nondisjunction

Answer 19

An error in meiosis in which chromosomes fail to segregate properly into the daughter cells.

Question 20

Pedigree

Answer 20

A diagram showing genetic relationships among a set of individuals, normally with respect to a specific genetic trait.

Question 21

Phenotype

Answer 21

The physical characteristics of an organism; can be defined as outward appearance (such as flower color), as behavior, or in molecular terms (such as glycoproteins on red blood cells.)

Question 22

Pleitropy

Answer 22

A situation in which a single gene influences more than one phenotypic characteristic.

Question 23

Polygenic Inheritance

Answer 23

A pattern of inheritance in which the interaction of two or more functionally similar genes determine phenotype.

Question 24

Punnett square method

Answer 24

An intiutive way to predict the genotypes and phenotypes of offspring in specific crosses.

Question 25

Recessive

Answer 25

An allele that is expressed only in homozygotes and is completely masked in heterozygotes.

Question 26

Self-fertilization

Answer 26

The union of sperm and egg from the same individual.

Question 27

Sex Chromosone

Answer 27

One of the pair of chromosomes that usually determines the sex of an organism; for example, the X and Y chromosomes in mammals.

Question 28

Sex-linked

Answer 28

Referring to a pattern of inheritance characteristic of genes located on one type of sex chromosone (for example, X) and not found on the other type (for example, Y); also called X-linked. In sex-linked inheritance, traits are homozygous recessive, whereas males express whichever allele is on their single X chromosome.