AB biology: Mendel and Different forms of Inheritance

Question 1

Blending Hypothesis

Answer 1

The idea that genetic material contributed by 2 parents mixes in a manner analogous to the way blue and yellow plaints blend together to make green

Question 2

Particulate Hypothesis of inheritance

Answer 2

The Gene Idea

parents pass on discrete heritable units: genes

Question 3

Gregor Mendel studied and used peas for his work because:

Answer 3

They are available in many varieties

Could be strictly control which parents mated with which

Lots of offspring

Easily observable traits

Question 4

Reasoning as to why when Mendel crossed the F1 plants, they had a ratio of 3:1

Answer 4

In the F1, only the purple flower factor was affecting flower color in these hybrids.

Purple flower color was dominant, and white flower color was recessive

Question 5

Mendel’s model to explain the 3:1 ratio

Answer 5

1. alternative version of genes: account for variations in inherited characters (ALLELES)
2. For each character, an organism inherits 2 alleles: a gene locus represented twice
3. If 2 alleles at a lovus differ, the dominant allele determines the organisms appearance. The other allele, recessive allele has no noticeable effect on organisms appearance
4. Law of segregation

Question 6

Trait

Answer 6

a copy of a gene or an inherited characteristic

Question 7

Law of dominance

Answer 7

If one allele is present in a genotype, it will hide the other allele

Question 8

Law of Segregation

Answer 8

derived by following a single trait

The 2 alleles for a heritable character segregate during gamete formation and end up in different gametes

Question 9

Law of Independent assortment

Answer 9

Each pair of alleles segregates independently during gamete formation

Due to genes that are being followed are on separate chromosomes.

Question 10

Test Cross

Answer 10

allows one to determine the genotype of an organism with the dominant phenotype, but unknown genotype

Crosses an individual with the dominant phenotype with an individual that is homozygous recessive for a trait

Question 11

Characteristics of inheritance

Answer 11

inheritance patterns are often more complex than predicted by simple mendelian genetics

The relationship between the phenotupe and genotype is rarely simple.

Question 12

Complete Dominance

Answer 12

occurs when the phenotypes of the heterozygote and dominant homozygote are identical

Question 13

Codominance

Answer 13

2 dominant alleles are expressed at the same time

chickens and cows have multiple feathers and hair colors and the human blood group AB

Question 14

Multiple alleles

Answer 14

most genes exist in populations in more than 2 allelic forms

ie: blood types ABO in humans

Question 15

incomplete dominance

Answer 15

F1 is a mix of dominant and recessive

3 phenotypes

Question 16

Dominant inheritance

Answer 16

ie: Achandroplasia

a form of dwarfism that is lethal when homozygous for the dominant allele

Question 17

Huntingtons disease

Answer 17

A degenerative disease of the nervous system

has no obvious phenotypic effects until about 35 - 40 ys old.

Question 18

Multifactorial disorders

Answer 18

many human diseases have both genetic and environmental components

ie heart disease and cancer

Question 19

Gene Testing and counseling

Answer 19

genetic counselors can provide info to prospective patients concerned about a family history for a specific disease

Question 20

Pleiotropy

Answer 20

a gene has multiple phenotypic effects

ie: cystic fibrosis causes more than one symptom to occur (lungs, sodium channels, etc)

Question 21

polygenic traits

Answer 21

may be determined by 2+ traits

end up with a spectrum of phenotype possibilities

lots of traits follow this: eye color, hair color, height, skin color

Question 22

Quantitative variationusually indicates polygenic inheritance

Answer 22

an additive effect of 2 genes on a single phenotype

Question 23

Epistasis

Answer 23

a gene at one locus alters the phenotypic expression of a gene at a second locus

if one gene is fully recessive, it can prevent expressions of a dominant allele

Question 24

Nature and Nurture

Answer 24

The environmental impact on phenotype

another departure from simple mendelian genetics arises when the phenotype for a character depends on environment as well as on genotype

Question 25

The norm of reaction

Answer 25

The phenotypic range of a particular genotype that is influenced by the environment