non-mendelian inheritence pt.2&3

Question 1

why does pleiotropy go agiants mendelian genetics

Answer 1

cuz mendel beleived one gene controlled one phenotype/characteristic. and pleitropy says that one gene controls many traits

Question 2

Genes affected in human genetic
disorders are often _________

Answer 2

Genes affected in human genetic
disorders are often pleiotropic – for
example, people with the hereditary
disorder Marfan syndrome may have a
constellation of seemingly unrelated
symptoms

Question 3

marfan syndrome

Answer 3

Marfan syndrome may have a
constellation of seemingly unrelated
symptoms
– Dislocation of the lens of the eye
– Heart problems (in which the aorta bulges
or ruptures)
-unusally long limmbs and fingers
result of mutation of one gene which results in fewer fibrils
(eye and aorta contain many fibrils that help maintain strcuture hence the problems in these organs. and fibrils serve as storag esheles for growth factors so marfan leads to excessive growth)

Question 4

why does marfan syndrome lead to excessive growth of limbs and fingers

Answer 4

Marfan syndrome may have a
constellation of seemingly unrelated
symptoms
– Dislocation of the lens of the eye
– Heart problems (in which the aorta bulges
or ruptures)

Question 5

polygenic inheritence

Answer 5

-a character/pheno trait is regulated by more than one gene. phenotypic expression of a trait
in an offspring is a mixture or additive of traits displayed in parents
=quantitative inheritence wherein two or more indepen dnet genes additively affect a single trait
-non mendelian cuz in mendielian a trait is monogeneic (one trait controlled by one gene)

Question 6

what are examples of polygenic inheritence

Answer 6

-height, skin color bc these cant be categorized as tall or short / light or dark
eg) although there are two major eye color genes, there are at least 14 additional genes that play roles in determining a person’s exact eye color
-these traits exhibit multipl and continous variatios of the phenotype

Question 7

is incomplete dom and co-dom mendelian?

Answer 7

no mendel only described complete dominance

Question 8

polygenic inheritence produces a ____ _____ of phenotypic traits

Answer 8

wide range

Question 9

_________ __________ is a form of incomplete dominance

Answer 9

polygenic inheritence

Question 10

types of gene interaction

Answer 10

-intragenic interaction: 2 alleles of a gene which are presen on the same gene locus on the two homologous chroms, react to produce modified phenotype that deviates from mendelian (eg. incomplete dom, co-dom, multiple alleles)
-intergenic interaction: two genes on diff loci interact of the same of diff chroms for the expression of a phenotypic hcarcater (eg. epistasis and polygenic inheritence)

Question 11

what is an example of multiple alleles?

Answer 11

blood type (its also co-dominance)

Question 12

intergenic vs intragenic interactions

Answer 12

-inter (think international so diff places) genes at diff places on either the same or diff chroms interact to produce a trait. eg)epistasis and polygenic inheritence

-intra sounds like “inside” or “internal,” which means within one place or thing. So, intragenic = within the same gene/locus. can occur between these two alleles at the same locus on the homologous chromosomes or on one gene on a single chrom eg) incomplete dom, co-dom, and multiple alleles

Question 13

pleitropy vs polygenic inheritence

Answer 13

Pleiotropy = one gene, many traits (like a multitasking gene). eg. marfan syndrome

Polygenic = many genes, one trait (like teamwork between genes). eg. height

Question 14

the interaction between genes is ______ in epistasis.

Answer 14

In epistasis, the interaction between genes is antagonistic, such that one gene masks or interferes with the expression of another

The epistatic gene does the masking while the hypostatic gene is masked.

The Labrador dog example in the first set of notes is a case of recessive epistasis-The E gene is responsible for developing fur pigmentation while the B gene determine the color of the pigmentatio

Question 15

in recessive epistasis E gene is epistatic whi;e the B gene is hypostatic (lab example)

Answer 15

-if the E gene is double rec (ee), then the lab dog will be yellow no matter the genotype expressed at the B gene. then if E_ then it depends on the B gene and it will be black if hetero or homo dom, brown if bb.

Question 16

dominant epistasis

Answer 16

-when the dom allele of one gene masks the expression of all alleles of another gene
- the epistatic gene masks the expression of the second gene even if it is in the heterozygous or homozygous dominant form (A_).

Question 17

dom vs rec epistatsis

Answer 17

-Recessive epistasis requires two recessive alleles (aa) to mask another gene’s effect.
-Dominant epistasis only requires one dominant allele (A) to mask another gene’s effect.

Question 18

epistasis controls the color of squash w/ the Y locus controlling colour (yellow is dom to green) and W locus determining expression of Y locus. case of dom epistatsis. what gene expression results in a yellow squash

Answer 18

wwYy & wwYY results in yellow squash.

cuz W is dom epi, we need ww for the other gene which shows color to be expressed, and since yellow is dom we need either Yy or YY

Question 19

complementary epistasis

Answer 19

-both genes need to work together to produce a phenotype
-either gene when homozygous is epistatic to the other gene

Question 20

eg) sweet pea flower

Answer 20

-complementary epistasis
-two genes that work in tandem to make the pigment anthocyanin that imparts color in the flower
-one produces precursor 1 (allele C) and the other makes precursor 2 (allele P)-need both precursors to produce anthocyanin
-gene C is responsible for producing chromogen (colorless chemical whcih gives white flower)-this chem substance is a precuror to a biochemical pigment (anthocyanin)
-gene P is responsible for producing an enzyme that converts chromogen into a pigment called anthocyanin (purple flower)

in short: flower is white when homo rec, ccpp (no chromogen or anthocyanin synthesis takes place). but flower is purple when its either homo dominant or hetero.

Question 21

hypostatic gene

Answer 21

a gene whose effect is masked or suppressed by another gene, which is known as the epistatic gene.

Question 22

duplicate dominant epistasis

Answer 22

aka duplicate dominant gene interaction.
-the dom alleles at the two loci produce the same phenotype but there is no additive/cumulative effect

Question 23

genes in a redundant system…

Answer 23

two different genes can perform the same function, and either one is enough to produce a dominant trait. In this case, the dominant allele of either gene can mask the effect of the other gene, resulting in the same phenotype. Essentially, both genes are redundant in terms of their function.

The only way for the recessive phenotype to appear is if both genes are homozygous recessive (aa and bb).

Question 24

give an example of duplicate dominant epistasis

Answer 24

fruit shape of capsella bursa pastoris (shepard’s purse) plant
-two shapes the fruit can be, dominant of either allele results in a triangular shaped fruit. if both are homo recessive (aabb) then fruit shape is oval

gives 15 triangular : 1 oval phenotypic ratio

Question 25

polymeric gene interacion epistasis

Answer 25

-additive gene interaction
-each dominant allele contributes equally to the trait, and the more dominant alleles present, the stronger or more pronounced the trait becomes. This results in a range of phenotypes rather than a simple dominant-recessive relationship
- so basically theres 2 or more genes that determine the phenotype, and the more dom alleles there are the stronger the trait (colour, size etc.)
-so when both genes are either homo dom, or hetero then the phenotypic effect is enhanced. but if one is hetero/homo dom and other is homo rec then a specififc pheno generated.

Question 26

what ratio is the polymeric gene interacction

Answer 26

9:6:1

Question 26

whats the diff between polygenic inheritence ans polymeric gene interaction?

Answer 26

-polygenic: Many genes, often more than two, contribute additively to a trait, Results in a continuous range of phenotypes (a spectrum of possibilities).
-polymeric gene interaction: type of epistasis, where the presence of dominant alleles from two or more genes affects the expression of the trait, but in a more limited or defined number of phenotypes (like a specific ratio such as 9:6:1).

Question 27

what are variants or mutants

Answer 27

all other phenotypes compared to the wild type (wild type is the most common phenotype among wild animals; norm) the variant may be rec or dom to the wild-type allele

Question 28

age dependent gene expression

Answer 28

-human male pattern baldness (androgenetic alopecia)
-dominant mutation of grey gene in horses causes hair depigmentation
-dom allele of the huntington (HTT) gene auses adult-onset huntington’s disease and isnt expressed until 30-50yrs of age (breakdown of nerve cells in the brain)

Question 29

sex-dependent gene expressiom

Answer 29

-expression of sex-dependent traits varies with the sex of the individual, due to the influence of sex hromones on gene expression.
-3 types of inheritence: sex-limited, sex-linked, and sex-influenced

Question 30

sex-linked are generally influenced by genes on which chrom

Answer 30

-X chrom bc this is bc the X chrom is large and contains many more genes than the smaller y chroms

Question 31

in sex linked genes which sex is more affected and why

Answer 31

-Males have one X chromosome (inherited from their mother) and one Y chromosome (inherited from their father). Since they only have one X chromosome, they do not have a second X chromosome to “back up” or compensate for a mutation.
-Many X-linked diseases are caused by recessive mutations. For a female to be affected by the disease, she must inherit two copies of the mutated gene
eg) color blindness

Question 32

sex-influenced traits

Answer 32

-influenced by genes on autosomes hence genes are present in both sexes but their expression varies in diff sexes
eg)male pattern baldness B is allele for bald. in women Bb=non-bald and men Bb=bald

Question 33

explain temp-dependent gene expression in himalayan bunnies

Answer 33

-they carry the C gene (mainly ch allele which colours nose, paws and ears only-himilayan) which is required for the development of pigments
-but colour is only present in optimal temps bc thenenzyme is nonfunctional in 35C or warmer so the bunnies are albino (enzyme=tyrosinase which produces melanin)
-the temp regulation of gene expressioin produces rabbits with the warm central parts of the body having no colour but nose and stuff is coloured