Genetics Exam 1

Front 1

Allele

Back 1

One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome

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Allele series

Back 2

the different mutant alleles of a gene that case a range of phenotypes

Front 3

Ascus

Back 3

the sack that forms after meiosis in yeast that contains all 4 haploid spores produced

Front 4

Asexual reproduction

Back 4

When a single organism reproduces and the offspring inherits genes from only that parent

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Autosomal

Back 5

A chromosome whose number does not differ between sexes

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Auxotroph

Back 6

A living that requires additional nutrients to grow due to at least one faulty pathway

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Blended Inheritance

Back 7

An offspring expresses a phenotype that is in between the 2 homozygous traits of its parents

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Breeding True

Back 8

Self fertilization produces only offspring with the same trait

Front 9

centiMorgan

Back 9

unit used in genetic mapping derived from probability

Front 10

Chi-Squared Analysis

Back 10

a statistical method for testing the probability that the null hypothesis is true

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Chiasmata

Back 11

a point at which paired chromosomes remain in contact and crossing over occurs

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chromatid

Back 12

one identical half of a chromosome

Front 13

chromosome

Back 13

the part of the cell that holds the genetic transcript of the organism

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codominance

Back 14

expressing characteristics equally of both parents for a single trait

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coefficient of coincidence

Back 15

the measure of interference in the formation of chromosomal crossover during meiosis

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Complementation Test

Back 16

a cross done to determine if two recessive mutations are allelic

Front 17

crossing over

Back 17

homologous chromosomes exchange segments of genetic material to form recombinant chromosomes

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dipolid

Back 18

having two sets of haploid homologous chromosomes

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dihybrid cross

Back 19

a genetic cross between parents that differ in two characteristics controlled by genes at different loci

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ditype

Back 20

a tetrad type containing two different genotypes, both of which are parental

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dominant

Back 21

property of an allele that completely controls the phenotype regardless of whether the individual is homozygous or heterozygous for that allele

Front 22

duplicate genes

Back 22

2 loci encode for the same funcion

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epistasis recessive

Back 23

the phenotype is controlled by B which masks A. Additionally, a homozygous recessive b will mask any dominant A allele.

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Epistasis dominant

Back 24

the phenotype is controlled by B which masks A where any dominant B allele masks any A, despite its dominance

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expressivity

Back 25

the extent or degree to which the phenotype is expressed in each individual

Front 26

incomplete dominance

Back 26

when the inherited phenotype of a heterozygote is intermediate between those of the two homozygotes

Front 27

interference

Back 27

a situation where the number of observed double crossover events is less that what is predicted by the frequencies of a single crossover event

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gamete

Back 28

a cell that joins together to begin making an organism

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gene

Back 29

a (hypothetical) unit or object of inheritance

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hypothesis

Back 30

a proposed explanation that is consistent with the known limited evidence, therefore is not simply accepted and must be tested

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genotype

Back 31

all or part of the genetic constitution of an individual

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haploid

Back 32

having a single set of unpaired chromosomes

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haploinsufficient

Back 33

when a diploid organism has only a single functional copy of a gene and can not produce enough gene product for a wild-type phenotype

Front 34

hemizygous

Back 34

having only 1 allele for a particular locus

Front 35

heterogametic sex

Back 35

forming two types of gametes which one produces male offspring and the other female offspring

Front 36

heterozygous

Back 36

when an organism possesses more than one distinct alleles for one trait

Front 37

homogametic sex

Back 37

forming gametes which all have the same type of sex chromosome

Front 38

homozygous

Back 38

when all of an organism's alleles for a trait are identical

Front 39

hypomorphic allele

Back 39

an allele that reduces but does not eliminate a product's functionality

Front 40

independent assortment

Back 40

during gamete formation, the segregation of one pair of genes is independent of other gene pairs

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linkage groups

Back 41

a set of genes at different loci on the same chromosome that, except for crossing over, tend to act as a single pair of genes in meiosis instead of undergoing independent assortment

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linked genes

Back 42

genes found on the same chromosome that do not assort independently of one another

Front 43

mapping function

Back 43

a visual representation of gene placement on a chromosome

Front 44

meiosis

Back 44

cell division that results in 4 daughter cells each with half the number of chromosomes as the parent cell

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mutation

Back 45

a permanent change in genetic code

Front 46

neomorphic allele

Back 46

an allele that produces an altered product with a completely different function than the wild type

Front 47

null allele

Back 47

an allele that makes a completely nonfunctional product

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mitosis

Back 48

cell division that results in two daughter cells that have the same number and kind of chromosomes as the parent cell

Front 49

null hypothesis

Back 49

a statement that says that the difference between observed and expected values is due to change alone

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partial dominance

Back 50

a phenotype of a heterozygote is intermediate between those of two homozygotes

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pedigree

Back 51

a diagramed representation used to follow heritable characteristics through bloodlines

Front 52

penetrance

Back 52

a binary case where a fraction of individuals with a given genotype show an associated phenotype

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phenotype

Back 53

the set of observable characteristics of an individual resulting from the interaction of its genotype with its environment

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poisson distribution

Back 54

the probability of independent events occurring within a fixed amount of time

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product law of probability

Back 55

probability of events occurring together is the product (multiply) of their individual probabilities

Front 56

prototroph

Back 56

an organism that has all of the metabolic pathways required to survive given initial nutrients

Front 57

punnett square

Back 57

a diagram that uses each gamete possibility to determine possible genotypic outcomes of offspring

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recessive

Back 58

property of an allele in which the trait is only seen in homozygous individuals and not heterozygous individuals

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reciprocal cross

Back 59

breeding experiment designed to test the role of parental sex on a given inheritance pattern using true breeding parents

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recombination

Back 60

the formation of nonparental combination of genes in a gamete or individual

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recombination frequency

Back 61

the probability of recombination occurring

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redundant genes

Back 62

the same function is encoded by two or more genes

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segregation of allele pair

Back 63

when chromosomes (or sister chromatids) move to opposite sides of the cell to divide into individual daughter cells

Front 64

sex linkage

Back 64

a gene that is on a sex chromosome and therefore linked to it

Front 65

sexual reproduction

Back 65

two separate individuals produce gametes in meiosis that come together to form a zygote

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sister chromatid

Back 66

one half of a chromosome that contains identical genetic information to its counterpart

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suppression

Back 67

gene B prevents the expression of gene A

Front 68

synthetic phenotype

Back 68

when a double mutant (involving 2 distant loci) has a phenotype distinct from either single mutant homozygote

Front 69

testcross

Back 69

a test cross is crossing an individual homozygous recessive for a trait with an individual of unknown genotype to determine the unknown genotype

Front 70

tetrad

Back 70

the sack that forms after meiosis in yeast that contains all 4 haploid spores produced

Front 71

tetratype

Back 71

tetrad containing 4 different genotypes, two parental and two recombinant

Front 72

wild-type allele

Back 72

the allele that occurs most commonly in nature for a given gene