Chap 4- Alleles

Question 1

What are alleles?

Answer 1

alternative forms of the same gene

Question 2

What is wild-type allele?

Answer 2

Allele that occurs more frequently in a population

mostly dominant, not always

Question 3

What is mutation?

Answer 3

the source of alleles

contains modified genetic information and often specifies an altered gene product

Question 4

What may mutation cause to an enzyme?

Answer 4

change shape and thus reduce/eliminate affinity for substrate

Question 5

Loss of function mutation

Answer 5

Mutation may cause a complete loss of function

Question 6

Null allele

Answer 6

Some mutations may enhance allelic function ; usually increases quantity of gene product by affecting regulation of transcription of gene

Question 7

Gain of function mutation

Answer 7

Some mutations do not show any change in function

Question 8

What may a cross between parents with contrasting traits generate?

Answer 8

Offspring with an intermediate phenotype in the heterozygote; incomplete or partial dominance ; phenotypic ratio identical to genotypic ratio

Question 9

What is used if no dominance exist?

Answer 9

Italic uppercase and superscripts used to denote alternative alleles

Question 10

How is incomplete dominance in humans revealed?

Answer 10

examining the gene product or proteins

Question 11

What is Tay-sachs disease?

Answer 11

Lysosomal storage disease

Question 12

What is codominane?

Answer 12

The joint expression of both alleles in a heterozygote

Example: MN blood group in humans

Question 13

What do mutations modify?

Answer 13

the information stored in any gene by producing different alleles
-for any specific gene, there can be more than two alleles within members of a population

Question 14

What do multiple alleles refer to?

Answer 14

three or more alleles of the gene

Question 15

Where can multiple alleles be studied?

Answer 15

in populations, not individuals

Question 16

What provides an example of multiple alleles in a population?

Answer 16

Human ABO blood groups

Question 17

What does the ABO system exhibit?

Answer 17

the codominant mode of inheritance

Question 18

Antisera?

Answer 18

Antisera contain antibodies against A or B antigen and reveal four phenotypes

Question 19

The three alleles for ABO blood type?

Answer 19

Ia- A blood
Ib- B blood
I allele- O blood

Question 20

What alleles produce their respective antigens?

Answer 20

IA and IB

Question 21

Which allele does not produce antigen?

Answer 21

I allele; O

Question 22

What IA and IB dominant and codominant to?

Answer 22

Dominant to i and codominant to each other

Question 23

In Drosophila, what are phenotypes controlled by?

Answer 23

Multiple allelic inheritance

Question 24

What are essential genes?

Answer 24

genes that are required for survival

Question 25

What is huntington disease?

Answer 25

an autosomal dominant allele

Question 26

Gene Interaction

Answer 26

the cellular function of numerous gene products contribute to the development of a common phenotype

Question 27

Epigenesis

Answer 27

development concept where each step of development increases the complexity of the sensory organ and is under the control and influence of one or more genes

Question 28

Hereditary deafness

Answer 28

mutations that interrupt the many steps of development

Question 29

What is the hereditary deafness trait?

Answer 29

a heterogenous trait

Question 30

What is epitasis?

Answer 30

the expression of a gene or gene pairs masks or modifies the expression of another gene or gene pair

Question 31

Locus in first and second gene of epistasis

Answer 31

The first locus influences expression or alleles at a second gene locus; one dominant allele is required at each locus for phenotype expression

Question 32

Dominant epistasis

Answer 32

when a dominant allele at one genetic locus masks the expression of the alleles in the second locus