Chapter 9: Mendelian Genetics And Mutation Flashcards

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1
Q

theory of blending inheritance

A

proposed that traits present on the parents mixed together like paint to produce a new combination in the offspring

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2
Q

horticulture

A

the artificial selection of plants

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3
Q

hybridizing

A

the process of crossing two different types of plants

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4
Q

true breeding

A

strains of plants that contain only one form of a trait

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5
Q

reciprocal cross

A

an experimental cross in which 2 different forms of a trait are interchanged between male and female plants

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6
Q

monohybrid cross

A

an experiment that uses parent varieties (or strains) differing in a single trait

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7
Q

self-crossing/self-fertilization

A

a plant is pollinated with its own pollen as opposed to pollen from another plant

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8
Q

genes

A

heritable factors; discrete unit of hereditary information

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9
Q

alleles

A

alternate forms of a gene

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10
Q

homozygous

A

has two identical alleles for a given trait

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11
Q

heterozygous/hybrid

A

has two different alleles for a given trait

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12
Q

genotype

A

an allelic combination

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13
Q

phenotypes

A

the physical expression of genes

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14
Q

recombination

A

the occurrence of an offspring whose phenotype differs from that of the parent

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15
Q

test-cross

A

crossing an organism of an unknown genotype with a homozygous recessive individual to determine the unknown genotype; the ratio of phenotypes in the offspring determines the unknown genotype

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16
Q

inheritance

A

the way traits are passed on from generation to generation

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17
Q

back cross

A

a test cross with the homozygous recessive parent (a reverse test cross)

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18
Q

Punnett square

A

invented by Reginald Punnett in 1905. It is a grid that shows all the possible gametes formed by each of the parents and all of the possible genotypes and phenotypes in the offspring.

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19
Q

dihybrid

A

a breeding experiment that uses parental varieties differing in two traits

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20
Q

independent assortment

A

the alleles for the two different traits must assort independently with respect to one another

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21
Q

meiosis

A

a type of cell division in sexually reproducing organisms which results in gametes with half of the chromosome number of the original cell

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22
Q

recombination

A

a process in meiosis that results from homologous chromosomes segregating into different gametes, resulting in multiple possible allele combinations

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23
Q

the multiplicative law of probability

A

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

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24
Q

trihybrid

A

a breeding experiment that uses parental varieties differing in three traits

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25
Q

sickle cell anemia

A

caused by a defective hemoglobin protein in red blood cells which causes the cells to deform to a sickle shape and triggers blood clotting and other symptoms

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26
Q

the additive rule

A

the probability of one or another of two mutually exclusive (or separate) events occurring equals the sum of their individual probabilities

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27
Q

intermediate inheritance

A

the heterozygote genotype has a unique phenotype which is intermediate to the two parental phenotypes; neither allele dominates

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28
Q

codominance

A

both alleles of a heterozygote are distinctly expressed

29
Q

antigen

A

a foreign substance that does not belong to a particular host organism and elicits an immune response

30
Q

antibody

A

an immunoglobulin produced by B cells which binds to antigens, and in doing so function in immune response

31
Q

pedigree

A

information categorized into a family tree which traces the inheritance of various traits (including disorders) throughout generations

32
Q

Mendel’s 3:1 ratio

A

describes that in the F2 generation, dominant and recessive traits will occur 3-to-1

33
Q

Mendel’s 9:3:3:1 ratio

A

the result of a dihybrid cross, where out of 16 individuals, 9 represent both dominant traits, 3 represent one dominant trait, 3 represent another dominant trait, and 1 represents the recessive traits.

34
Q

epistasis

A

one gene’s expression modifies or suppresses another gene

35
Q

albino

A

characterized by a complete lack of pigment

36
Q

quantitative characters

A

traits that vary in population along a continuum, because there is more than one existing phenotype

37
Q

polygenic inheritance

A

two or more genes have an additive affect on one phenotypic character

38
Q

locus

A

the location of a gene

39
Q

pleiotropy

A

one gene can affect many traits

40
Q

lethal recessive

A

a condition that is lethal in the homozygous condition

41
Q

dominant allele

A

in the heterozygote, the allele that is fully expressed

42
Q

recessive allel

A

in the heterozygote, the allele that is completely masked

43
Q

mutation

A

a recessive allele results in a defective enzyme

44
Q

structural disorder

A

one defective, dominant allele results in a phenotypic effect

45
Q

over-dominance

A

a population level phenomenon where the heterozygote has a selective advantage over either homozygote (ex: those will sickle-cell anemia are resistant to malaria)

46
Q

linked genes

A

genes that stay on the same chromosomes

47
Q

parental phenotypes

A

the offspring have an appearance which is identical to one of the parents

48
Q

recombinant phenotypes

A

the offspring have an appearance which differs from either of the parents

49
Q

map unit

A

a way of calculating the relative distance between genes, calculated by dividing the number of recombinants by the total number of offspring times 100

50
Q

sex chromosomes

A

the pair of chromosomes that determine the sex of an organism

51
Q

sex-linked gene

A

a gene located on a sex chromosome

52
Q

chromosome theory

A

the theory that Mendel’s heritable factors are located on chromosomes

53
Q

hemizygous

A

having a total of one allele for a given trait; a condition that is associated with genes located on sex chromosomes

54
Q

Barr bodies

A

the inactive X chromosome present in each cell of the female which has been condensed into a compact object

55
Q

mosaic

A

in art, the term is used to describe a pattern; in biology, it is used to describe patchiness in a characteristic

56
Q

autosome

A

a chromosome that is not directly involved in sex determination; in humans there are 22 of these chromosomes

57
Q

sex chromosomes

A

the chromosomes that are responsible for sex determination; in humans there is only one pair of these chromosomes

58
Q

aneuploidy

A

a deviation in the chromosome number such that certain chromosomes are present in extra copies or are absent

59
Q

polyploidy

A

a deviation in the chromosome number such that the organism has more than two complete sets of chromosomes

60
Q

nondisjunction

A

a pair of homologous chromosomes or sister chromatids fail to separate properly during meiosis or mitosis

61
Q

karyotype

A

a technique in which an individual’s metaphase I chromosomes are examined in order to determine their number and characteristics

62
Q

deletion

A

the loss of a piece of chromosome during cell division, resulting in a fragment which lacks a centromere

63
Q

syndrome

A

having a number of phenotypic effects

64
Q

point mutation

A

a mutation that affects a single nucleotide of the DNA strand

65
Q

silent mutation

A

the base pair substitution has no phenotypic effect

66
Q

missense

A

the base pair substitution causes one amino acid to be substituted for another amino acid

67
Q

nonsense

A

the base pair substitution causes an amino acid-specifying codon to be changed to a stop codon; the prematurely shortened protein is usually not functional

68
Q

frameshift

A

if the number of nucleotides, inserted or deleted, is not a multiple of three, this can occur. The result is an improper grouping of codons leading to a changed protein product.