Gene interactions

Question 1

What are gene interactions?

Answer 1

Interactions between allelic and non-allelic genes of the same genotype in the production of phenotypic characteristics

Question 2

What is the wild type gene?

Answer 2

the gene that encodes for the phenotype most common in particular natural population

Question 3

what is the mutant gene?

Answer 3

any form of that allele other than the wild type

Question 4

What is Haplosufficiency?

Answer 4

When an individual who is homozygous or heterozygous dominant and sufficient to produce wild-type phenotypes

Question 5

What is haploinsufficiency?

Answer 5

When an individual who is heterozygous or hemizygous is incapable of producing the wild-type phenotype

Question 6

Which is the functional allele?

Answer 6

The dominant

Question 7

What does it mean if an organism is haploinsufficient?

Answer 7

when a single copy of the standard (so-called wild-type) allele at a locus in heterozygous form is insufficient to produce the standard phenotype

Question 8

Name the 5 types of gene interactions

Answer 8

• Dominant/recessive
• Co-dominant
• Incomplete dominance
• Sex-linked
• Multiple alleles

Question 9

What is the type of interaction called between alleles at different loci?

Answer 9

epistasis

Question 10

What is epistasis?

Answer 10

Interactions between alleles at different loci

“the masking of the phenotypic effects of alleles at one gene loci by alleles of another gene loci “

Question 11

What is co-dominance?

Answer 11

When neither allele is recessive so both alleles are expressed in the phenotype equally

i.e: blood groups A and B in humans to create ABO

Question 12

What are lethal genes?

Answer 12

Genes that can cause the death of the organisms that carry them.

Sometimes, death is not immediate; it may even take years, depending on the gene

Question 13

Give an example of lethal genes

Answer 13

Cystic fibrosis
Sickle-cell anemia
Huntington's disease
Yellow mice
Tail-lessness in manx cats

Question 14

What are sub-lethal genes

Answer 14

when genes have the potential to be lethal in certain situations - not all individuals with the genes will die as a consequence

i.e: Haemophilia

Question 15

What are dominant and recessive lethal genes?

Answer 15

Dominant - when just one dominant copy of the gene is fatal

Recessive - when two copies are needed to be fatal

Question 16

what are sex-linked genes

Answer 16

traits are genetic characteristics determined by genes located on sex chromosomes

Question 17

Give an example of a sex-linked gene

Answer 17

Haemophilia A in thorougbred horses is transmitted by X chromosome

The gene for tabby cats are only found in female cats

Question 18

What are multiple alleles?

Answer 18

When there are three or more possible alleles for one individual trait

i.e: coat colour

Question 19

what is polygenetic inheritance?

Answer 19

occurs when one characteristic is controlled by two or more genes – often genes are large in quantity but with small effect

Question 20

what is incomplete dominance?

Answer 20

where a heterozygote phenotype intermediates between two homozygote phenotypes - neither allele is completely expressed so the phenotype is a mixture of the two

example: black and white chickens = a blue chicken

Question 21

What is pleiotrophy?

Answer 21

when one gene influences two or more seemingly unrelated phenotypic traits

Question 22

give an example of pleiotrophy?

Answer 22

40% of white furred cats with blue eyes are also deaf (Hartl & Jones, 2005)

Question 23

what is the masking of the phenotypic effects of alleles at one gene loci by alleles of another gene loci known as?

Answer 23

Epistasis

Question 24

What is the epistatic allele?

Answer 24

The allele that does the masking

Question 25

what is the hypostatic allele?

Answer 25

The allele that is being masked

Question 26

what is the MASKED allele known as?

Answer 26

the hypostatic allele

Question 27

what is the allele that does the masking known as

Answer 27

the epistatic allele

Question 28

what is dominant epistasis?

Answer 28

When the dominant allele of one gene masks the expression of ALL alleles of another gene

Question 29

what is recessive epistasis?

Answer 29

when the recessive allele of one gene masks the effects of either allele of the second gene when present in homozygous form