Chapter 14: Gentetics

Question 1

Gregor Mendel

Answer 1

Founder of modern genetics, as a monk documented inheritance in peas
– used experimental method
– used quantitative analysis
– excellent example of scientific method

Question 2

Self-Pollination

Answer 2

Pollen from the anther is transferred to the stigma of the same plant

Question 3

Cross-Pollination

Answer 3

when pollen from a plant is transferred to the stigma of another plant

Question 4

What exactly was Mendel’s process with observing the pea plants?

Answer 4

P=parental
f=Filal Generation

1st: Cross-Pollinate true breeding parents pea plants (Plants that are not heterozygous)

2nd: Raise seeds & then observe traits (F1)

3rd: Allowed offspring to self-pollinate & observed next generation (F2)

Question 5

What did Mendel discover?

Answer 5

He leaned that after breeding two pure pea plants that the dominant trait will only appear in the F1. However, If the F1 cross or self-pollinate the recessive trait will show up again about 25% of the time.

Question 6

Alleles

Answer 6

Traits come in alternative versions.

different alleles vary in sequence of nucleotides at the specific locus of a gene.

Ex: Purple-flower allele & white-flower allele are two DNA variations at the flower color locus.

Question 7

For each characteristic, an organisms inherit….

Answer 7

2 alleles , 1 from each parent

diploid organism
- inherits 2 sets of chromosomes, 1 from each parent
-homologous chromosomes

Question 8

What did Mendel’s findings of the purple and white flower traits of the pea plants mean?

Answer 8

some traits masks others

Question 9

Dominant allele

Answer 9

functional protein
masks other alleles

a.k.a: wild type

Question 10

Recessive allele

Answer 10

allele makes a malfunctioning protein.
- mutant

Question 11

Phenotype

Answer 11

description of an organism’s trait
the “physical”

Question 12

Genotype

Answer 12

description of an organism’s genetic makeup

Question 13

What are the proportion of genotypes?

Answer 13

1:2:1

Question 14

Wat are the proportions of phenotype?

Answer 14

3:1

Question 15

Homozygous

Answer 15

same alleles
Ex: PP, pp

Question 16

Heterozygous

Answer 16

different alleles Pp

Question 17

Is it possible for 2 organisms can have same phenotype but have different genotypes?

Answer 17

Yes

Question 18

Test Cross

Answer 18

breed the dominant phenotype– the unknown genotype– w/ a homozygous recessive(pp) to determine the identity of the unknown allele.

Question 19

What is Mendel’s 1st law of hereditary?

Answer 19

Law of Segregation
- during meiosis, alleles segregate
- homologous chromosomes separate
- each allele for a trait is packaged into a separate gamete

monohybrid cross
- single trait

Question 20

Which stage of meiosis creates the law of segregation?

Answer 20

Metaphase 1

Question 21

Monohybrid Cross

Answer 21

Following the inheritance of single characters

Ex: flower color, seed color

Question 22

Dihybrid Cross

Answer 22

Following the inheritance of 2 different characters

Ex: seed color & seed shape

Question 23

Mendel’s 2nd Law of Heredity

Answer 23

Law of independent assortment
- different loci (genes) separate into gametes independently
- non-homologous chromosomes algin independently
- classes of gametes produced in equal amounts
- YR= Yr=yR=yr
- only true for genes on separate chromosomes or on same chromosome but so far apart that crossing over happens frequently

dihybrid (or more) crosses

Question 24

Which stage of meiosis creates the law of independent assortment?

Answer 24

Metaphase 1

Question 25

Mendel’s law of segregation and independent assortment reflect what rules?

Answer 25

The rules of probability

Question 26

How is the rule of addition used in genetics?

Answer 26

Rules of Addition: The probability that any one of two or more exclusive event will occur is calculated by probabilities.

It can used to figure out the probability that an F2 plant from a monohybrid cross will be heterozygous rather than homozygous.

Question 27

How do you apply the multiplication and addition rules of probabilities to genetics?

Answer 27

These rules are used to predict the outcome pf crosses involving multiple characters.

A dihybrid or other multicharacter cross is equivalent to two or more independent monohybrid crosses occurring simultaneously.

In calculating the chances for various genotypes, each character is considered separately and then the individual probabilies are multiplied.

Question 28

Incomplete Dominance

Answer 28

Heterozygote shows an intermediate blended phenotype.

RR –> red flowers
rr –> white flowers
Rr –> pink flowers

P: true breeding red x true breeding white flower

F1: 100% pink flowers

F2: 25%: red 50%: Pink 25%: White

Question 29

Co-dominance

Answer 29

2 alleles affected the phenotype equally & separately

• not blended phenotype
• human ABO blood groups
  -3 alleles

Ia & Ib are codominant that explains why AB blood exists.

i is recessive which explains having 2 i make you O

+ is dominant
- is recessive

Question 30

Pleiotropy

Answer 30

one gene affects more than one phenotypic character.

1 gene affects more than one trait.

Ex: dwarfism

Question 31

Epistasis

Answer 31

One gene completely masks another gene

coat color in mice = 2 separate genes

C(pigment) c (no pigment)

more pigment (B=black) or less (b=brown)

cc = albino no matter B allele

same thing w/ Labradors

Question 32

Polygenic Inheritance

Answer 32

Some phenotypes determined by additive effects of 2 or more genes on a single character.
- phenotypes on a continuum
- human traits
- skin color
- weight
- height
- behaviors

Question 33

What controls phenotypes ?

Answer 33

Environment & genes