chapter 14: genetics

Question 1

what are transmission genetics?

Answer 1

deals with the way genetic differences among individuals are passed from generation to generation

Question 2

what is a trait (characteristic)?

Answer 2

one or two or more detectable variants in a genetic character

Question 3

what is a genotype?

Answer 3

the genetic makeup, or set of alleles, of an organism

Question 4

what is a phenotype?

Answer 4

an organisms physical appearance, which is determined by its genetic makeup

Question 5

what is hybridization (“basic cross”)

Answer 5

the mating, or crossing, of two true-breeding varieties

Question 6

what does the term true-breeding mean?

Answer 6

referring to organisms that produce offspring of the same variety over many generations of self-pollination

Question 7

why are garden peas a good organism for genetic study?

Answer 7

they have easily identifiable traits (ex. tall or short)

Question 8

what is a character?

Answer 8

character: an observable heritable feature that may vary among individuals

Question 9

what is a dominant allele? what is a recessive allele?

Answer 9

dominant allele: is always expressed (it’s either in a homozygous or heterozygous pair)
recessive allele: is only expressed when in a homozygous pair (ex. bb)

Question 10

what does it mean to be heterozygous?

Answer 10

having two different alleles (ex. Pp)

Question 11

are true-breeding plants heterozygous or homozygous?

Answer 11

homozygous

Question 12

what does it mean to be homozygous?

Answer 12

having two identical alleles (ex. PP or pp)

Question 13

what is a locus?

Answer 13

the location of a gene on a chromosome

Question 14

what is the P generation? what is F1 and F2?

Answer 14

P generation: parental plants that were crossed
F1: the first filial hybrid (heterozygous) offspring, arising from a P generation cross
F2: second filial and offspring of F1

Question 15

how did Mendel show that “blending” is not taking place?

Answer 15

when Mendel cross-pollinated one variety of purebred plant with another, the crosses yielded offspring that looked like either one of the parent plants, not a blend of the two

Question 16

what is the law of segregation?

Answer 16

Mendel’s first law, stating that the two alleles in a pair segregate into different gametes during gamete formation

Question 17

how do you test cross? what type of information does this give you?

Answer 17

cross an individual with a dominant phenotype to a homozygous recessive individual. this test can determine whether a dominant phenotype is homozygous or heterozygous for a specific allele.

Question 18

what is the law of independent assortment?

Answer 18

Mendel’s second law, stating that each pair of alleles segregates independently of each other pair during gamete formation (this law only applies to genes/allele pairs located on different chromosomes or to genes that are very far apart on the same chromosome)

Question 19

what is epistasis?

Answer 19

a gene at one locus affects the expression of a gene at another locus

Question 20

what is pleiotropy?

Answer 20

the ability of a single gene to have multiple effects

Question 21

what is polygenic inheritance?

Answer 21

two or more genes influence a phenotype (ex. height and eye color)

Question 22

does the environment have an impact on phenotype?

Answer 22

yes, things such as temperature, oxygen levels, diet, and humidity can all affect phenotypes

Question 23

what happens in recessive disorders?

Answer 23

recessive: in recessive disorders heterozygous individuals are carriers

Question 24

who is Gregor Mendel? what organism did he use in his work?

Answer 24

was a biologist, who through his work with pea plants, discovered the fundamental laws of inheritance