Inheritance

Question 1

how was inheritance believed to behave before Mendel

Answer 1

a range of blending from mother and father (equal contributions)

Question 2

what was predicted to happen if the blending hypothesis was correct

Answer 2

a freely mating population would make way to genetically uniform individuals (all the same)

Question 3

what does blending hypothesis fail to explain

Answer 3

how traits reappear fully developed after skipping a generation

Question 4

what is an allele

Answer 4

contrasting alternatives of a gene which can be dominant or recessive

Question 5

what is a phenotype

Answer 5

the observable properties of an individual

Question 6

what is a genotype

Answer 6

the genetic makeup of an individual gamete usually with reference to a specific characteristic

Question 7

difference between genotype and genome

Answer 7

genome- an organisms complete set of DNA with all its genes and noncoding DNA

Question 8

what is the location on a chromosome that holds the allele called

Answer 8

the gene locus, indicated by placing a line on a chromsome

Question 9

what is the P generation

Answer 9

the parental generation (homozygous)

Question 10

what is the F1 generation

Answer 10

the offspring of the P generation (most often heterozygous)

Question 11

why does each gamete only have one gene

Answer 11

because gametes are haploid
(at fertilization you get the same gene but not always the same allele)

Question 12

what does particulate inheritance mean

Answer 12

that alleles are discrete unchanging traits that can be passed down

Question 13

what is Mendel’s first law of inheritance

Answer 13

alleles of a gene segregate independently of each other during gamete formation
(the law of independent segregation)

Question 14

what is the principle of independent assortment

Answer 14

the alleles of one has nothing to do with the allele of the other (in dihybrid crosses RRYY)

Question 15

what is incomplete dominance

Answer 15

genes have different degrees of dominance and recessiveness in relation to each other

Question 16

how do we show incomplete dominance in the genotype

Answer 16

use superscripts to show there is no implication that one is dominant over the other (often times are blended)

Question 17

example of multiple alleles

Answer 17

blood type
different types are denoted I with superscripted A or B, and lowercase i for type O

Question 18

what is codominance

Answer 18

when they express both alleles simultaneously without any blending (blood type AB)

Question 19

what is epistasis

Answer 19

when the activity of one gene influences the activity of another
(one gene can mask the expression the alleles in another gene ex: if pigment cannot be deposited into skin despite whatever allele it ahs for colour none will show)

Question 20

what is polygenetic inheritance

Answer 20

when two or more genes affect the outcome of a single trait
(typically phenotypes show in a bell curve, ex: height, weight, skin colour, etc)

Question 21

what is pleiotropy

Answer 21

when a single gene affects more than one characteristic of an organism

Question 22

what is probability

Answer 22

the extent to which an event is likely to occur (ranges from 0-1)

Question 23

what is the product rule

Answer 23

when two or more events are independent the probability that they will both occur is calculated by multiplying their individual probabilities together

Question 24

what is the sum rule

Answer 24

when two or more events are mutually exclusive (cannot both happen) the probability that either will occur is calculated by adding their individual properties

Question 25

which is the heterogametic sex

Answer 25

males, XY

Question 26

which is the homogametic sex

Answer 26

females, XX

Question 27

which chromosome has a larger number of genes on it

Answer 27

the X chromosome

Question 28

what is it called when something i linked to the X-chromosome

Answer 28

x-linked

Question 29

what are other unlinked chromosome called

Answer 29

autosomes

Question 30

what is a Barr body

Answer 30

an inactivated X-chromosome only found in females (because they have two)

Question 31

what is it called when an x chromosome is inactivated

Answer 31

lyonization

Question 32

what can lyonization lead to

Answer 32

few whole body effects due to selective inactivation of the X-chromosome throughout the body (patchy placement of things like colour or sweat glands)

Question 33

what is the SRY gene

Answer 33

a gene linked to the Y- chromosome

Question 34

what is the SRY gene responsible for

Answer 34

it is the switch that directs the development towards maleness at an early stage in embryo development (if inactivated will continue to female)

Question 35

what are carriers

Answer 35

women that are heterozygous for a certain disease they don't express the disease due to a dominant allele suppressing it but they can pass the disease

Question 36

why is it only/almost always male offspring that inherit an x-linked disease

Answer 36

they will always get an x from their mother (if it is the recessive/disease carrying allele there is nothing to suppress it)

Question 37

why do we use pedigree charts

Answer 37

to determine if a human trait is dominant or recessive and autosomal or x-linked (we can't experiment on humans so we look at family trees)

Question 38

how to determine if a trait is autosomal

Answer 38

affects males and females equally

Question 39

when is a trait autosomal dominant

Answer 39

when there are no carriers (everyone who has it displays it), and no skipping of generations

Question 40

how to determine if it is x-linked

Answer 40

shown predominantly in the male population