Chapter 3

Question 1

transmission genetics

Answer 1

field of genetics concerned with heredity and the mechanisms by which genes are transferred from parent to offspring

Question 2

The seven pea plant traits

Answer 2

Height, seed color, seed shape, pod color, pod shape, flower color, position of flowers

Question 3

selfing

Answer 3

in plant genetics, the fertilization of a plant’s ovules by pollen produced by the same plant (self-fertilization)

Question 4

P1

Answer 4

parental generation

Question 5

F1

Answer 5

first filial generation

Question 6

F2

Answer 6

second filial generation

Question 7

reciprocal crosses

Answer 7

a pair of crosses in which the genotype of the female in one is present as the genotype of the male in the other

Question 8

particulate unit factors

Answer 8

the factors that serve as the basic units of heredity and are passed unchanged from generation to generation, determining various traits expressed by each individual plant

Question 9

Mendel’s First Three Postulates

Answer 9

1. UNIT FACTORS IN PAIRS
2. DOMINANCE/RECESSIVENESS
3. SEGREGATION

Question 10

UNIT FACTORS IN PAIRS

Answer 10

a specific unit factor exists for each trait

each diploid individual receives one factor from each parent.

Question 11

DOMINANCE/RECESSIVENESS

Answer 11

When two unlike unit factors responsible for a single character are present in a single individual, one unit factor is dominant to the other, which is said to be recessive.

the trait expressed in the generation is controlled by the dominant unit factor.

The trait not expressed is controlled by the recessive unit factor.

Question 12

SEGREGATION

Answer 12

During the formation of gametes, the paired unit factors separate, or segregate, randomly so that each gamete receives one or the other with equal likelihood.

Question 13

phenotype

Answer 13

the overt appearance of a genetically controlled trait

Question 14

genes

Answer 14

the fundamental physical unit of heredity, whose exist can be confirmed by allelic variants and which occupy a specific chromosomal locus

Question 15

alleles

Answer 15

one of the possible alternative forms of a gene, often distinguished from other alleles by phenotypic effects

Question 16

genotype

Answer 16

The allelic or genetic constitution of an organism; often, the allelic composition of one or a limited number of genes under investigation.

Question 17

homozygote

Answer 17

An individual with identical alleles for a gene or genes of interest. These individuals will produce identical gametes (with respect to the gene or genes in question) and will therefore breed true.

Question 18

heterozygote

Answer 18

An individual with different alleles at one or more loci. Such individuals will produce unlike gametes and therefore will not breed true

Question 19

testcross

Answer 19

A cross between an individual whose genotype at one or more loci may be unknown and an individual who is homozygous recessive for the gene or genes in question

Question 20

dihybrid cross

Answer 20

A genetic cross involving two characters in which the parents possess different forms of each character (e.g., yellow, wrinkled peas).

Question 21

Mendel’s Fourth Postulate:

Answer 21

Independent Assortment

a genetic principle that describes how different genes separate independently during the development of reproductive cells

Question 22

product law

Answer 22

In statistics, the law holding that the probability of two independent events occurring simultaneously is equal to the product of their independent probabilities.

Question 23

trihybrid cross

Answer 23

three-factor cross

Question 24

chromosomal theory of inheritance

Answer 24

The idea put forward independently by Walter Sutton and Theodor Boveri that chromosomes are the carriers of genes and the basis for the Mendelian mechanisms of segregation and independent assortment.

Question 25

diploid

Answer 25

(2n) The condition when cells contain homologous pairs of each chromosome, one derived from the paternal parent and one from the maternal parent.

Question 26

haploid

Answer 26

(n) The number of homologous chromosome pairs characteristic of an organism or species.

Question 27

sum law

Answer 27

The law that holds that the probability of one of two mutually exclusive outcomes occurring, where that outcome can be achieved by two or more events, is equal to the sum of their individual probabilities.

Question 28

mutant type starch-branching enzyme (SBEI)

Answer 28

wrinkled genes for wrinkled pea too many type of sugar (sucrose - not starch) that brings in water causing pea to burst

Question 29

Tay–Sachs disease (TSD)

Answer 29

a devastating recessive disorder involving unalterable destruction of the central nervous system. Infants with TSD are unaffected at birth and appear to develop normally until they are about 6 months old. blindness, deafness, mental retardation, paralyzation by age 5 results from the loss of activity of a single enzyme hexosaminidase A (Hex-A)

Question 30

recessive mutations

Answer 30

a change in a gene that only causes a health condition when both copies of the gene are mutated

Question 31

The Particle Theory of Inheritance

Answer 31

which states that hereditary traits act like particles, units, or factors as they are passed from generation to generation

Question 32

Law of Segregation

Answer 32

which states that his hereditary factors do not blend but remain distinct during breeding—thus, disproving the blending theory

Question 33

Law of Independent Assortment

Answer 33

which states that character traits are not connected but are inherited independent of one another. This law was soon to be modified