Genetics

Question 1

Horizontal and vertical gene transfer

Answer 1

Horizontal: With a generation(HPV)

Vertical: parent to offspring

Question 2

Law of independent assortment

Answer 2

Each pair of alleles segregates independently of any other pair of alleles during gamete formation. This law applies only to genes location on different chromosomes(not homologous).

Question 3

What does each letter in the punnet square represent?

Answer 3

A haploid cell

Question 4

Why did Mendel choose to experiment with garden peas?

Answer 4

They can cross pollinate, theyre big enough to manipulate, and theyre true breeding

Question 5

What is the ultimate source of genetic variation? proximate sources?

Answer 5

Ultimate source: Mutation

Proximate:

1. Horizontal Gene transfer
2. Independent assortment
3. Crossover
4. Random fertilization
5. Mate choice

Question 6

What types of reproduction are the different sources of genetic variation limited to?

Answer 6

All: Mutation, horizontal gene transfer

Sexual reproduction only: Independent assortment, crossover, random fertilization, mate choice

Question 7

What were the important conclusions of Mendel’s experiment?

Answer 7

1. Inheritance is not due to blending of traits, traits are distinct(genes)
2. Traits can be dominant or recessive(alleles)
3. Traits segregate independently. Each parent carries 2 copies of the gene that separate from each other during meiosis

Question 8

Which law and phase of meiosis do monohybrid crosses correspond with?

Answer 8

Law of segregation, metaphase/anaphase 1

Question 9

Which law and phase of meiosis do dihybrid crosses correspond to?

Answer 9

Law of independent assort, metaphases 1 and 2

Question 10

Law of Segregation

Answer 10

Alleles for a heritable trait segregate from each other during gamete formation. Therefore, an egg or sperm only gets one of the two alleles present in the somatic cell making the gamete. This corresponds to separation of homologous pairs in meiosis

Question 11

Autosomes

Answer 11

non-sex chromosomes

Question 12

X-0 system

Answer 12

sex-determining system where the dosage of x chromosome determines the sex. Male=X0,Female=XX

Question 13

haplo-diploid system

Answer 13

Diploid=female, haploid=male. Common among colonial insects, often results in big size difference between genders

Question 14

ZW system

Answer 14

Female=ZW(hemizygous), Male=ZZ

Question 15

Incomplete dominance

Answer 15

Heterozygote presents an intermediate phenotype. no recessive alleles are present

Question 16

Codominance

Answer 16

More than 2 alleles are present, including one or more recessive alleles

Question 17

Pleiotropy

Answer 17

Multiple phenotypic effects result from one gene

Question 18

Norm of reaction

Answer 18

Individuals with same genotype exhibit different phenotypes depending on conditions

Question 19

Epistasis

Answer 19

Alleles of one gene impact phenotypic expression of another gene

Question 20

Polygenic

Answer 20

Trait is due to contributions of multiple genes, resulting in a spectrum of phenotypes

Question 21

Testcross

Answer 21

A testcross is performed to see if an individual with a dominant trait is homozygous or heterozygous. This is done by mating it with an individual expressing a recessive trait. If half the offspring express the recessive trait, the individual is heterozygous

Question 22

Which forms of inheritance are of a molecular basis

Answer 22

1. Incomplete dominance
2. Codominance
3. Pleitropy
4. Norm of reaction

Question 22

Which shape represents male and female in pedigrees?

Answer 22

Circle= Female
Square= Male

Question 23

PKU

Answer 23

(example of pleiotropy) A condition where there is a shortage of an enzyme that breaks down chemicals. The buildup of chemicals results in multiple phenotypic effects

Question 24

Which forms of inheritance are complex

Answer 24

1. Epistasis

2. Polygenic

Question 25

Linked Genes

Answer 25

Genes on the same chromosome, sometimes inherited as a set

Question 26

How are new combination of linked genes made?

Answer 26

crossing over