4

Question 1

haplosufficient

Answer 1

Dominant wild-type alleles are identified as haplosufficient since only one copy is sufficient to produce the wild-type phenotype.

Question 2

haploinsufficient

Answer 2

a single copy of the Allele is not sufficient to produce the wild-type phenotype

Question 3

loss of function mutation

Answer 3

a mutation that results in a significant decrease or in the complete loss of the functional activity of a gene product.
Usually recessive, but some times dominant

Question 4

gain of function mutation

Answer 4

identify alleles that have acquired a new function or are altered to express substantially more activity than the wild-type allele.

• almost always dominant
• some are lethal in a homozygous state

Question 5

null mutation

amorphic mutation

Answer 5

a loss of function mutation that results in a complete loss of gene function in comparison to the wild-type allele

Question 6

leak mutation

hypomorphic mutation

Answer 6

a mutation resulting in the partial loss of gene function.

-can lead to dominant loss of function mutations

Question 7

Hypermorphic mutations

Answer 7

produce more gene acivity per allele than the wild type

• usually dominant
• usually resulting from mutations that lead to more of the protein with increased function resulting from the mutation. as opposed to a mutation changing the amino acid configuration on the protein itself

Question 8

neomorphic mutations

Answer 8

mutations that acquire novel gene activities not found in the wild type and are usually dominant. The gene products of neomorphic mutants are functional, but have structures that differ from the wild-type gene product, leading to a mutant protein that functions differently than the wild-type protein.

Question 9

specific taxonomic genetic nomenclature

Answer 9

see back of book cover page

Question 10

Inomplete dominance
(partial dominance)

Answer 10

identifies circumstances when dominance of one allele over another is incomplete.

• more common than complete dominance
• the phenotype of the heterozygous organism is distinctive, falling between the categories of homozygous mutant and homozygous wild-type.

Question 11

Codominance

Answer 11

leads to a heterozygous phenotype different from the phenotype of either homozygous parent.

differs from incomplete dominance in how it is characterized by the detectable expression of both alleles in heterozygotes.

most clearly identified when the protein products of both alleles are detectable in heterozygous organisms, typically by means of some sort of molecular analysis such as gel electrophoresis or a biochemical assay that can distinguish between the different proteins.

Question 12

allelic series

Answer 12

in populations with multiple alleles, an order of dominance emerges among the alleles, based on the activity of each allele’s protein product, forming a sequential series known as an allelic series.

Question 13

temperature-sensitive allele

Answer 13

an allele producing a protein that is temperature sensitive, usually meaning that it denatures at high levels of heat

c^h is an example of this because it creates a pigment making enzyme that is temperature sensitive, so it only works in areas of the organism farther away from its core, where it is the hottest. thus, the phenotypic expression of this gene is characterized by the presence of pigment in the extremities and with no pigment in the areas seperate from the extremities

Question 14

lethal mutation

Answer 14

a single-gene mutation thats so messed up that they cause death early in life or terminate gestational development.
-often recessive, because natural selection kills off any dominant lethal mutations pretty quickly

Question 15

sex-limited gene expression

Answer 15

the limitation of gene expression to one sex but not the other

Question 16

sex limited traits

Answer 16

traits only evident in a particular sex. they are result of sex-limited gene expression

Question 17

sex-influenced traits

Answer 17

traits in which the phenotype corresponding to a particular genotype differs depending on the sex of the organism carrying the genotype
Hormones are thought to influence the differential expression of genotypes in the sexes

Question 18

delayed age of onset

Answer 18

abnormalities produced by a particular gene disfunction do not appear until after the affected organisms have had an opportunity to reproduce and transmit the mutation to the next generation

ex: huntingtons

Question 19

penetrant

Answer 19

when the phenotype of an organism is consistent with the organisms genotype, the organism is said to be penetrant for the trait. In such a case, if the organism carries a dominant allele for the trait in question, the dominant phenotype is displayed.

Question 20

nonpenetrant

Answer 20

an organism with a particular genotype that fails to produce the corresponding phenotype is nonpenetrant for the trait

Question 21

incomplete penetrance

Answer 21

traits for which nonpenetrant individuals occasionally or routinely occur are identified as displaying incomplete penetrance.

Question 22

variable expressivity

Answer 22

in this phenomenon, the same genotype produces phenotypes that vary in the degree or magnitude of expression of the allele of interest

Question 23

what are the three kinds of interactions that may be responsible for incomplete penetrance or variable expressivity

Answer 23

1) other genes that act in ways that modify the expression of the mutant allele
2) environmental or developmental (i.e., nongenetic) factors that interact with the mutant allele to modify its expression
3) some combination of other genes and environmental factors interacting to modify expression of the mutation

Question 24

pleiotropy

Answer 24

the alteration of multiple, distinct traits of an organism by a mutation in a single gene.

Most mutations displaying pleiotropy do so by either altering the development of phenotypic features through the direct action of the mutant protein or as a secondary result of a cascade of problems stemming from the mutation

Question 25

gene interaction

Answer 25

the collaboration of multiple genes in the production of a single phenotypic character or a group of related characteristics

Question 26

biosynthetic pathway

Answer 26

networks of interacting genes that produce a molecule or compound as their end product.

Question 27

one gene - one enzyme hypothesis

Answer 27

says that each gene produces an enzyme, and each enzyme has a specific functional role in the biosynthetic pathway that produces a phenotype.

Question 28

genetic dissection

for biosynthetic pathways

Answer 28

an experimental approach that tests the ability of a mutant to execute each step of a biosynthetic pathway and assembles the steps of a pathway by determining the point at which the pathway is blocked in each mutant.

Question 29

epistasis

Answer 29

the name given to gene interactions - called epistatic interactions - in which an allele of one gene modifies or prevents the expression of alleles at another gene. The genes that interact by epistasis are involved in producing a particular phenotypic characteristic, and they usually participate in the same pathway.

Epistasis is most readily detected among progeny of dihybrid crosses where bot genes carry dominant and recessive alleles.

Question 30

epistatic ratios

Answer 30

look into them further. page 127

Question 31

complementary gene interaction

Answer 31

results in a 9:7 phenotypic ratio

requires genes to work in tandem to produce a single product

Question 32

genetic complementation

Answer 32

the ability of two mutants with the same mutant phenotype to produce progeny with the wild-type phenotype is called genetic complementation

indicates that more than one gene is involved in determining the phenotype

Question 33

duplicate gene action

Answer 33

the genes in a redundant system have this.

they either encode the same gene product, or they encode gene products that have the same effect in a single pathway or compensatory pathways

Question 34

dominant interaction

Answer 34

characterized by a 9:6:1 ratio of phenotypes in the progeny of a dihybrid cross

Question 35

recessive epistasis

Answer 35

homozygosity for a recessive allele at one locus can mask the phenotypic expression of a second gene

has a characteristic 9:3:4 ratiof

Question 36

examples from this chapter

Answer 36

go over them and create seperate set of slides

Question 37

dominant epistasis

Answer 37

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

has a characteristic 12:3:1 ratio

Question 38

dominant suppression

Answer 38

similar to dominant epistasis but occurs when a dominant allele of one gene completely suppresses the phenotypic expression of alleles of another gene

Question 39

genetic heterogeneity

Answer 39

when mutations of different genes can produce the same, or very similar, abnormal phenotypes

Question 40

complementation group

Answer 40

mutations that mutually fail to complement one another are identified as this. Consisting of one or more mutant alleles of a single gene.

consists of mutants whose phenotypes consistently fail to complement one another and that complement in other complementation groups.