biol2153 exam 1

crosses of F1 dihybrids produces a ________ phenotype ratio

9:3:3:1

each F1 dihybrid produces four possible gametes in ________ ratio

1:1:1:1

an F1 dihybrid (Yy Rr) produces four gametes in what ratio

¼ YR, ¼ Yr, ¼ yR, ¼ yr

testcrosses on dihybrids should be with individuals that are __________ ________ for both traits.

homozygous recessive

the probability of two independent events occurring together is the product of their individual probabilities

product rule

probability of either of two mutually exclusive events occurring is the sum of their individual probabilities

sum rule

probability of either of two mutually exclusive events occurring is the ____ of their individual probabilities

sum

the probability of two independent events occurring together is the _______ of their individual probabilities

product

the number of different gametes = _______________ x ___________ …

number of different alleles for gene 1 x number of different alleles for gene 2

Aa Bb Cc Dd would produce ____ kinds of gametes

2×2×2×2 = 16

Aa BB Cc DD would produce _____ kinds of gametes

2×1×2×1 = 4

two alleles of a gene will segregate independently of each other during gamete formation, such that each gamete will have only one allele

Mendel’s 1st law (law of segregation)

genes for different traits will segregate independently of each other during gamete formation

Mendel’s 2nd law (law of independent assortment)

the phenotype of a recessive allele is always masked by the dominant allele

Mendel’s 3rd law (law of dominance)

ratio of progeny phenotypes in a cross between monohybrids

3:1

ratio of progeny genotypes in a cross between monohybrids

1:2:1

ratio of progeny genotypes in a cross between a heterozygote and a recessive homozygote

1:1 (Aa & aa —> 1 Aa: 1aa)

all progeny are the same phenotype- can result from either of two cases

AA & A- or aa & aa

ratio when all progeny are the same phenotype

1:0

progeny phenotypes in a dihybrid cross (Aa Bb)

9 A- B- : 3 A- bb : 3 aa B- : 1 aa bb

in human pedigrees a square represents a

male

in human pedigrees a circle represents a

female

in human pedigrees a diamond represents a

unspecified sex

in human pedigrees an unfilled shape means the individual is

unaffected

in human pedigrees a filled shape means the indiviudal is

diseased

in human pedigrees a direct horizontal line represents a

mating line

in human pedigrees a vertical line represents the

line of descent

in human pedigrees a vertical line sometimes connects to a horizontal line connecting many split vertical lines, this represents

sibship line (siblings)

in human pedigrees a line through a shape indicates the individual is

deceased

in human pedigrees a vertical pattern of inheritance indicates a rare _____ trait disease

dominant

a dominant trait disease means every affected person has at least one ________ parent

affected

one example of a dominant trait disease is

Huntington disease

the dominant Huntington disease allele produces abnormal ___ ______

Htt protein

the abnormal Htt protein, produced by the dominant Huntington disease allele, damages _____ _____, even when the normal protein is also present.

nerve cells

in human pedigrees a ______ pattern of inheritance indicates a rare recessive trait

horizontal

in human pedigrees parents of affected individuals (recessive trait diseases) are unaffected but are ___________ for the recessive allele

heterozygous (carriers)

one gene may contribute to several characteristics

pleiotrophy

extensions to Mendel for single-gene inheritance

dominance is not always complete, a gene may have >2 alleles, pleiotropy (one gene may contribute to several characteristics)

hybrid resembles one of the type parents

complete dominance

hybrid resembles neither parent

incomplete dominance

hybrid shows traits from both parents

codominance

example of incomplete dominance

flower color in snapdragons (pure-breeding red with pure-breeding white results in all pink F1 progeny)

F2 progeny ratios from snapdragon example

1 red (A1A1), 2 pink (A1A2), 1 white (A2A2)

in codominance, the F1 hybrids display traits of

both parents

an incomplete dominance cross of spotted (C^SC^S) x dotted (C^DC^D) results in

all F1 progeny are spotted and dotted

F2 progeny ratios from spotted and dotted example

1 spotted (C^SC^S), 2 spotted and dotted (C^SC^D), and 1 dotted (C^DC^D)

a gene can have more than two alleles, but each individual

can only carry two alleles

ABO blood type in humans are determined by ___ alleles of one gene

three

in human blood types I^A and I^B are _______ and I^A & I^B are _____ to i.

codominant, dominant

in human blood types an I^A allele =

A type sugar

in human blood types an I^B allele =

B type sugar

in human blood types an i allele =

no sugar

the percentage of the total number of copies for one allele in a population

allele frequency

most common allele is usually the _______ allele

wild-type (+)

rare allele is considered a _____ allele

mutant

gene with only one common wild-type allele is

monomorphic

gene with more than one common allele is

polymorphic

high-frequency alleles of polymorphic genes are

common variants (ex human blood types)

two misleading theories of inheritance at the time of Mendel’s studies: inherited feature of offspring are contributed mainly by only one parent; many microscopists thought they saw a fully formed, miniature fetus in the sperm head

the homunculus

two misleading theories of inheritance at the time of Mendel’s studies: parental traits become mixed and changed in the offspring

blended inheritance

visibly different traits (white vs purple flowers) rather than continuous traits (height, skin color, etc.)

antagonistic pairs

three major benefits of using pea plants in Mendel’s experiment

generation time short, large number of offspring in each generation, antagonistic pairs

Mendel’s experiment had two major results: each hybrid only resembled one parent and when reciprocal crosses were performed (switching traits of male and female parents) and observed the same results. these disproved the two major misconceptions/theories

blended inheritance and the theory that traits were transmitted via a single parent

latin for “son”

filial

this term means that the plant will always make more offspring identical to itself when self-fertilized over many generations

pure-breeding

____ progeny have only one of the parental traits

F1

both parental traits reappear in F2 progeny in a _____ ratio

3:1

trait that appears in F1 progeny is the ______ form

dominant

trait that is hidden in the F1 progeny is the ______ form

recessive

units of inheritance are now known as

genes

alternate forms of a single gene are

alleles

most cells in every organism have two copies of each gene except

gametes (egg and sperm cells)

gametes have ___ copy/copies of each gene

one

an observable characteristics (e.g. yellow or green pea seeds)

phenotype

a pair of alleles in an individual

genotype

an individual that has two identical alleles

homozygote

an individual that has two different alleles

heterozygote

this represents an unknown genotype

a dominant allele with a dash

orderly diagrams of a family’s relevant genetic features

pedigrees

three key aspects of pedigrees with dominant traits: affected children have _______ parent, a [vertical/horizontal] pattern of inheritance, and two [unaffected/affected] parents can produce [unaffected/affected] children if both are _________

at least one affected parent, vertical, affected, unaffected, heterozygotes

four key aspects of pedigrees with recessive traits: affected individuals can be the children of __________, all the children of two affected parents should be [unaffected/affected], rare recessive traits show a [vertical/horizontal] pattern of inheritance, recessive traits may show a [vertical/horizontal] pattern of inheritance if the trait is extremely common in the population

two unaffected carries, affected, horizontal, vertical

dominance relations are relative to a ______ ______

second allele

in regards to blood types, __________ are made against type A and type B sugars.

antibodies

successful blood transfusions occur only with

matching blood types

type __ are universal blood recipients while type __ are universal donors.

AB, O