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Flashcards in Exam 1-Chs 2-7 Deck (105)
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1

Homologous pair

-A pair of chromosomes that are alike in structure and size
-Carry genetic info for the same set of hereditary characteristics
-1 Chromosome of a homologous pair is inherited from male parent, 1 from female parent

2

Diploid

-Possessing 2 sets of chromosomes (2 genomes)

3

Haploid

-Possessing a single set of chromosomes (1 genome)

4

Polyploid

-Possession of more than 2 sets of chromosomes

5

Centromere

-Constricted region on a chromosome that stains less strongly than rest of chromosome
-Serves as attachment point for spindle microtubules

6

Telomeres

-Stable end of a euaryotic chromosome

7

Sister Chromatids

-Two copies of a chromosome that are held together at the centromere
-Each chromatid consists of a single DNA molecule

8

Cell cycle

-Stages through which a cell passes through from one cell division to the next

9

Checkpoints

-A key transition point at which progression to the next stage in the cell cycle is regulated

10

Interphase

-Major phase of cell cycle btwn cell divisions
-Cell grows, develops, and prepares for cell division

11

M (mitotic) phase

-Major phase of cell cycle that encompases active cell divisions
-Includes mitosis (nuclear division) and cytokinesis (cytoplasmic division)

12

Mitosis

-Process by which the nucleus of a eukaryotic cell divides

13

Cytokinesis

-Process by which the cytoplasm of a cell divides

14

Prophase

-Stage of mitosis in which:
1. Chromosomes contract and become visible
2. Cytoskeleton breaks down
3. Mitotic spindles begin to form

15

Condensins

- A group of proteins that bind to chromosomes as a cell enters prophase, causing the chromosome to become more compact and visible under a light microscope

16

Prometaphase

-Stage of mitosis
-Nuclear membrane breaks down
-Spindle mictrotubules attach to chromosomes

17

Metaphase

-Stage of mitosis
-Chromosomes aligh in middle of cell (metaphase plate)

18

Anaphase

-Stage of mitosis
-chromatids separate and move toward spindle poles

19

Telophase

-Stage of mitosis
-chromosomes arrive at the spindle poles
-Nuclear membrane reforms
-Chromosomes relax and lengthen

20

Meiosis

-Process by which the chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells
-Meiosis 1 and 2

21

Fertilization

-Fusion of gametes (sex cells) to form zygote

22

Prophase I

-Stage in meiosis 1
-Chromosomes condense and pair
-Crossing over takes place
-Nuclear membrane breaks down
-Mitotic spindles form

23

Synapsis

-Close pairing of homologous chromosomes

24

Crossing Over

-Exchange of genetic material btwn homologous chromosomes but nonsister chromatids

25

Metaphase I

-Stage of meiosis I
-Homologous pairs of chromosomes align at metaphase plate (center of cell)

26

Anaphase I

-Stage of meiosis I
-Homologous chromosomes separate and move towards spindle poles

27

Telophase I

-Stage of meiosis I
-Chromosomes arrive at spindle poles

28

Interkinesis

-Between meiosis I and II

29

Prophase II

-Stage of meiosis after interkenesis
-Chromosomes condense
-Nuclear membrane breaks down
-Spindles form
**Some cells skip this stage

30

Metaphase II

-Stage of meiosis II
-Individual chromosomes align in the center of the cell

31

Anaphase II

-Stage of meiosis II
-Chromatids sepearate and move towards spindle poles

32

Telophase II

-Stage of meiosis II
-Chromosomes arrive at spindle poles

33

Recombination

-Process that produces new combinations of alleles of a chromatid

34

Cohesin

-Molecule that holds the two sister chromatids of a chromosome together
-Breakdown at centromeres enables chromatids to separate in anaphase of mitosis and anaphase II

35

Genotype

-Set of alleles possessed by an individual organism

36

Homozygous

-Having two identical alleles at a locus

37

Heterozygous

-Having 2 non-identical alleles at a locus

38

Phenotype

-Appearance or manifestation of a characteristic

39

Monohybrid crosses

-A cross btwn individuals that are homozygous for diff alleles at same locus
-Also refers to cross btwn two individuals that are heterozygous for 2 alleles at single locus
*Differ in one characteristic

40

P (Parental) Generation

-1st set of parents in a genetic cross

41

F1 (First filial) Generation

-Offspring of the initial parents (P) in a genetic cross

42

Reciprocal crosses

-Pair of crosses in which the phenotype of the male and female parents are reversed
-Ex: cross w/ tall male and short female, another cross with short male and tall female

43

F2 (2nd filial) generation

-Offspring of F1 gen. in a genetic cross
-3rd gen. of genetic cross

44

Principle of segregation

-Principle of heredity discovered by Mendel
-Each diploid individual possesses 2 alleles at locus
-2 alleles separate when gametes are formed, one allele goes to each gamete

45

Back cross

-Crosses btwn 1 F1 individual and 1 P individual

46

Probability

-Liklihood of the occurence of a particular event
-# of times a particular event occurs/ # of possible outcomes
-Ranges 0-1

47

Multiplication Rule

-Rule stating that the probability of 2 or more independent events occuring together is calculated by multiplying the probability of each of the individual events

48

Addition rule

-Ruel stating the probability of any 2 or more mutually exclusive events occuring is calculated by adding probabilities of the individual events

49

Conditional Probability

-Probability that is modified by additional info that another event has occured

50

Testcross

-Cross btwn an individual w/ an unknown genotype and an individual w/ the homozygous recessive genotype

51

Wild type

-The trait or allele that is most commonly found in natural populations

52

Dihybrid crosses

-Crosses btwn 2 individuals that differ in 2 characteristics
-Ex: cross btwn individuals that are homozygous for diff alleles at 2 loci OR cross btwn 2 individuals that are heterozygous at 2 loci

53

Principles of Independent Assortment

-Principle of heredity discovered by Mendel
-Genes encoding diff characteristics (genes at diff loci) separate independently
-Applies only to genes located on diff chromosomes or genes far apart on same chromosome

54

Chi^2

x^2= sum [(observed-expected)^2/expected]
Independent assortment: DF= n-1
Crossover-
--Df= (# of rows-1)x (#of columns-1)
-Expected= (row totalx column total)/ grand total

55

Hemizygous

-Possession of a single allele at a locus
-Males of X-X/X-Y determination are hemizygous for x-linked loci bcuz only have 1 X chromosome

56

Nondisjunction

-Failure of homologous chromosomes or sister chromatids to separate in meiosis or mitosis

57

Dosage Compensation

-Equalization in males and females of the amount of protein produced by X-linked genes
-In placental mammals, accomplished by random inactivation of one x-chromsome in cells of females

58

Barr bodies

-Inactive X chromosome that appears as a condensed, darkly stained structure in most cells of female placental mammals

59

Pedigree

-Pictorial representation of a family history outlining the inheritance of one or more traits or diseases

60

Proband

-A person having a trait or disease who a pedigree is constructed

61

Consanguinity

-Mating btwn relatives

62

Genetic mosaics

-Condition in which regions of tissue w/in single individual have diff chromosome constitutions

63

Complete Dominance

-Type of dominance
-Same phenotype is expressed in homozygous and heterozygotes
-Only dom allele is expressed

64

Incomplete dominance

-Type of dom
-Phenotype of heterozygote is intermediate btwn phenotype of 2 homozygotes

65

Codominance

-Type of allelic interaxction in which the heterozygote simultaneously expresses traits of both homozygotes

66

Incomplete penetrance

-A case in which some individuals possess the genotype for a trait but do not express the expected phenotype

67

Penetrance

-% of individuals w a particular genotype that express the phenotype expected of that genotype

68

Lethal Allele

-Allele that causes death of an individual organism
-Early in development
-Organism does not appear in progeny of genetic cross
-Recessive lethal allele kills homozygous recessive, dom lethal allele kills heterozygotes and homozygotes

69

Compound Heterozygote

-An individual w/ two diff recessive alleles at locus that result in a recessive phenotype

70

Gene Interaction

-Interaction btwn genes at diff loci that affect the same characteristics

71

Epistasis

-Type of gene in which gene at one locus masks or supresses the effects of a gene at a diff locus

72

Epistatic gene

-Genes that mask or supress the effect of a gene at diff locus

73

Hypostatic gene

-Gene that is masked by the action of a gene at a diff locus

74

Complementation test

-Test designed to determine whether 2 diff mutations at the same locus (allelic) or a diff locus (nonallelic)
-Two individuals who are homozygous for 2 diff mutations are crossed, producing F1 progeny that are heterozygous for the mutation
-If mutation at same locus= f1 mutant phenotype
-If at same locus= wildtype

75

Complementation

-Manifestation of 2 diff mutations in the heterozygous conditions as the wild-type phenotype; indicates that the mutations are at diff loci

76

Sex-influenced characteristics

-Characteristics encoded by autosomal genes that are more radically expressed in one sex
-Ex: autosomal dom gene may have higher penetrance in males than females, or gene is dom in males and recessive in females

77

Sex-limited characteristics

-Characteristics encoded by autosomal genes and expressed in only 1 sex
-Both males and females carry genes for sex-limited characteristics, but the characteristics appear in only one of the sexes

78

Cytoplasmic inheritance

-Inheritance of characteristics encoded by genes located in cytoplasm
-Most cytoplasmically inherited characteristics are inherited from 1 parent bcuz usually contributed by 1 parent
-Usually inherited from mother

79

Genetic maternal effect

-determination of the phenotype of an offspring not by its own genotype, but the nuclear genotype of its mother

80

genomic imprinting

-Differential expression of a gene that depends on the sex of the parent that transmitted the gene

81

Epigenetics

-Phenomena due to alterations in dna that do not include changes in the base sequence
-Often affect the way in which dna sequences are expressed
-Such alterations are often stable and heritable in the sense that they are passed to decendant cells or individuals

82

Temp-sensitive allele

-Allele that is expressed only at certain temps

83

Phenocopy

-Phenotype produced by environmental effects that is the same as the phenotype produced by a genotype

84

Discontinous characteristics

-Characteristics that exhibit only a few, easily distinguished phenotypes
-Ex: seeds being either round or wrinkled

85

Continuous characteristics

-Characterisitics that display large # of possible phenoytypes that are not easily distinguished
-Ex: human height
*or is encoded 4 multiple genetic factors
*Quantitative characteristics

86

Polygenetic characteristics

-Characteristics encoded by genes at many loci
-aka mutliple genes 4 one characteristic

87

Pleiotropy

-Single gene influences multiple genes/phenotypes

88

Multifactorial Characteristics

-Characteristic determined by multiple genes and environmental factors

89

Recombination frequency

-Portion of recombinant progeny produced in a cross
= # of recombo progeny/total # of progeny

90

Coupling

-Arrangement of linked genes
-wild type alleles of two or more genes are on one chromosome and their mutant alleles are on the homologous chromosome
-Also known as cis-configursation

91

Repulsion/trans configuration

-Arrangenment of 2 linked genes
-each of a homologous pair of chromosomes contain one wild type (dominant) and one mutant (recessive) allele

92

Genetic Map

-Map of relative distances btwn genetic loci, markers, or other chromosome regions
-Determined by rates of recombination
-Measured on recombination frequencies or map units

93

Physical maps

-Map of physical distances btwn loci, genetic markers, or other chromosome segments
-Measured in base pairs

94

Two-point testcross

-Cross btwn an individual heterozygous at 2 loci and an individual homozygous for recessive alleles at those loci

95

Three-point testcross

-cross btwn an individual heterozygous at 3 loci and an individual homozygous for recessive alleles at 3 loci

96

Interference

-Degree to which one crossover interferes w/ additional crossovers

97

Coefficient of coincidence

# observed double crossovers/ # expected doubel crossovers

98

Haplotype

-A specific set of linked genetic variants or alleles on a single chromosome or on part of a chromosome

99

Kinetochore

-Multiprotein comlex that assembles the centromere b4 cell division
-Spindle microtubules attach to it

100

Xist

-Activity of gene leads to a barr body being created

101

Allelic Series

-Multiple alleles at single gene that show a rank in order in their dominance relationships

102

Gene's w/ recombination of 50% or greater

-Tends to underestimate the true physical distance btwn them
-Doesn't take into account double crossovers that might take place--> restores original parental combo of alleles

103

Pangenesis

-Genetic information travels from different parts of the body to reproductive organs

104

Preformationism

-Minature organism resides in sex cell, all traits inherited from one parent

105

Blending inheritance

-Genes blend and mix