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Flashcards in Exam 1 Deck (109):
1

Define acrocentric

Chromosome with the centromere located very close to one end. (human chromosomes 13, 14, 15, 21, 22)

2

Define allele

One of the possible alternative forms of a gene, often distinguished from other alleles by phenotypic effects

3

Define carrier

An individual heterozygous for a recessive trait

4

Define centromere

Specialized heterochromatic chromosomal region at which sister chromatids remain attached after replication, and the site to which spindle fibers attach to the chromosome during cell division. Location of the centromere determines the shape of the chromosome during the anaphase portion of cell division

5

Define chiasma

Crossed strands of nonsister chromatids seen in diplotene of the first meiotic division. Regarded as the cytological evidenc for exchange of chromosomal material (crossing over)

6

Define chi-square

Statistical test to determine whether or not an observed set of data is equivalent to a theoretical expectation.

7

Define chromosome

In prokaryotes, a DNA molecule containing an organism's genome; in eukaryotes, the DNA molecule complexed with proteins and RNA to form a threadlike structure containing genetic information that is visible during mitosis and meiosis

8

Define codominance

Condition in which the phentoypic effects of a gene's alleles are fully and simultaneously expressed in the heterozygote

9

Define epigenesis

Idea that an organism or organ arieses through the sequntial appearance and development of new structures

10

Define epistasis

Nonreciprocal interaction between nonallelic genes such that one gene influences or interferes with the expression of another gene (leads to a specific phenotype)

11

Define expressivity

The degree to which a phenotype for a given trait is expressed

12

Define consanguinity

Related by a common ancestor within the previous few generations

13

Explain crossing over/recombination

Exchange of chromosomal material (parts of chromosomal arms) between homologous chromosomes by breakage and reunion. The exchange of materila between nonsister chromatids during meiosis is the basis of genetic recombination

14

Define cytogenetics

Branch of biology in which the techniques of both cytology and genetics are used in genetic investigations

15

Explain a dihybrid cross

A genetic cross involving two characters in which the parents possess different forms of each character (yellow, round w/ green, wrinkled)

16

Define diploid

Condition in which each chromosome exists in pairs; having two of each chromosome

17

Define gamete

A specialized reproductive cell with a haploid number of crhomosomes

18

Define gene

A fundamental physical unit of heredity, whose existence can be confirmed by allelic variants and which occupies a specific chromosomal locus. A DNA sequence coding for a single polypeptide

19

Define genomic imprinting

Process by which the expression of an allele depends on whether it has been inherited from a male or a female parent (parental imprinting)

20

Define genotype

Allelic or genetic constitution of an organism; often, the allelic composition of one or a limited number of genes under investigation

21

Define haploid

Cell or an organism having one member of each pair of homologous chromosomes.

22

Define heterozygous

An individual with different alleles at one or more loci. Such individuals will produce unlike gametes and therefore will not breed true

23

Define homozygous

An individual with identical alleles for a gene or genes of interest. These individuals will produce identical gametes (with respect to the gene or genes in question) and will therefore breed true

24

Define homologous chromosomes

Chromosomes that synapse or pair during meiosis and that are identical with respect to their genetic loci and centromere placement

25

Define incomplete dominance

Expressing a heterozygous phenotype that is distint from the phenotype of either homozygous parent (partial dominance)

26

Explain G1 checkpoint

Point in G1 phase of the cell cycle when a cell either becomes commited to initiating DNA synthesis and continuing the cycle or withdraws into the G0 resting stage

27

Explain G0

A nondividing but metabolically active state that cells may enter from the G1 phase of the cell cycle

28

Define independent assortment

The independent behavior of each pair of homologous chromosomes during their segregation in meiosis I. The random distribution of maternal and paternal homologs into gametes

29

Define interphase

Interval between divisions, during the cell cycle

30

Define karyotype

Chromosome complement of a cell or an individual. Often used to refer to the arrangement of metaphase chromosomes in a sequence according to length and centromere position

31

Define lethal alleles

An allele whose expression results in premature death of the organism at some stage of its life cycle

32

Define locus (loci)

Site or place on a chromosome where a particular gene is located

33

Explain maternal effects

Phenotypic effecs in offspring attributable to genetic information transmitted through the oocyte derived from the maternal genome

34

Define maternal inheritance

Transmission of traits strictly through the maternal parent, usually due to DNA found in the cytoplasmic organeeles, the mitochondria, or chloroplasts

35

Explain meoisis

Process of cell division in gametogenesis or sporogenesis during which the diploid number of chromosomes is reduced to the haploid number

36

Explain mitosis

Form of cell division producing two progeny cells identical genetically to the parental cell- that is, the production of two cells from one, each having the same chromosome complement as the parent cell

37

Define metacentric

Chromosome that has a centrally located centromere and therefoe chromosome arms of equal lengths

38

Explain monohybrid cross

A genetic cross involving only one character

39

Define multiple alleles

Presence of three or more alleles of the same gene in a population of organisms

40

Define mutagen

Any agent that causes an increase in the spontaneous rate of mutation

41

Explain null hypothesis

Used in statistical tests, the hypothesis that there is no real difference between the observed and expected datasets. Statistical methods such as chi-squared analysis are used to test the probabiltiy associated with this hypothesis

42

Explain pedigree (kindred, family tree)

In human genetics, a diagram showing the ancestral relationships and transmission of genetic traits over several generations in a family

43

Define penetrance

The frequency, expressed as a percentage, with which individuals of a given genotype manifest at least some degree of a specific mutant phenotype associated with a trait

44

Define phenotype

Overt appearance of a genetically controlled trait

45

Define pleiotoropy

Condition in which a single mutation causes multiple phenotypic effects

46

Define population genetics

Branch of science that deals with the statistical anaylsis of the inheritance and prevalence of genes in populations and genetic divergence between populations.

47

Define preformation

Theory that the sperm or the fertilized egg contains a complete miniature adult

48

Define primary constriction

A cytologically defined chromosomal constriction associated with and determined by the centromeric region

49

Define probability

Study of the likelihood of the occurrence of a particular event or offspring

50

Define synapsis

The pairing of homologous chromosomes at meiosis

51

Define prokaryote

Microscopiic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles

52

Explain a Punnett square

Gid used to show the gamets of each parent and their possible offspring

53

Define quantatitive genetics

Branch of population genetics that deals with phenotypes that vary continuously, as opposed to discretely identifiable phenotypes and gene-products

54

Explain random chance

Genes are entirely based on chance

55

Define wild-type

The most commonly observed phenotype or genotype, designated as the norm or standard

56

Define reciprocal crosses

A pair of crosses between a male of one strain and a female of another, vice versa

57

Explain relative frequency

Value representing a proportion of the entire population under study

58

Explain Rh blood group system

System that classifies blood groups based on the presence or absence of the Rh antigen (Rh factor) on the cell membranes of the RBCs

59

Define RhoGAM

An injectable drug that is used to protect an Rh+ fetus from antibodies in an Rh- mother's blood and to prevent Rh allergy in the mother

60

Define antibody

A blood protein produced in response to and counteracting a specific antigen. Antibodies combine chemically with substances that the body recognizes as alien, such as bacteria, viruses, and foreign substances in the blood

61

Define selfing

Union of male and female gamets from the same organism

62

Explain sickle cell anemia

Abnormal hemoglobin that can cause blockages that damage vital organs and tissues, recessive autosomal disorder, found on chromosome 11

63

Define sister chromatids

Two identical strands joined by a common centromere as a result of a chromosome that duplicated during the S phase of the cell cycle

64

Define spindle fibers

Protein structure that divides the genetic material in a cell, equally divides the chromosomes in a parental cell into two daughter cells during mitosis & meiosis

65

Define dihybrid cross

A cross between two parents that differ by two pairs of alleles (AABB x aabb)

66

Define daughter cells

Identical cells formed by mitosis

67

Explain cystic fibrosis

Buildup of mucus that damages the body's organs, autosomal recessive pattern

68

Define degrees of freedom

df=n-1, n is # of classes

69

Who is Darwin

Did not provide an adequat account of inheritance, so it was logically incomplete. He was not able to interpret his own data. Later, Mendel did

70

Define epigenesis

The idea that an organism or organ arises through the sequential appearance and development of new structures already present in the egg

71

Define true-breeding

When parents pass down a specific phenotypic trait to their offspring. Pure genotpe with only one phenotype

72

Define dominant

An allele or a gene that is expressed in an organism's phenotype, masking the effect of the recessive allele or gene when present.

73

Explain Ehlers-Danlos syndrome

Affects the connective tissues, usually autosomal recessive pattern

74

Explain ABO blood group system

Classification of human blood based on the inherited properties of RBCs as determined by the presence or absence of antigens A and B

75

Explain albinism

Congenital, autosomal redessive disorder characterized by the complete or partial absence of pigment in skin, hair, and eyes.

76

Define antibody

Immunoglobins, proteins that help stop intruders from harming the body

77

Define antigen

Substance that enters the body and starts a process that can start a disease

78

Define autosomal genetic disorder

Disorders caused by genes

79

Define Bombay phenotype

Rare condition first spotted in Bombay, India, where there is no expression of the A, B, or H antigens on the RBCs

80

Define chloroplast

Plastid containing chloropyll that has its own DNA

81

Define dihybrid cross

A cross showing two organisms with opposite phenotypes (yellow round vs green wrinkled)

82

Define daughter cells

Cells formed due to mitosis, genetically identical to the parent cell

83

Explain cystic fibrosis

Buildup of thick, sticky mucus that can damage the body's organs, autosomal recessive

84

Define degrees of freedom

(df)=n-1, where n is the number of classes

85

Who is Darwin

English naturalist whose scientific theory of evolution by natural selection

86

Define epigenesis

The idea that an organism or organ arises through the sequential appearance and development of new structures, in contrast to preformationism, which holds that development is the result of the assembly of structures already present in the egg

87

Define diplonema

The doubled form of chromosomes strand visible at the diplotene stage of meiosis

88

Define dominant

Effect on phenotype of one allele masks the contibution of a second allele at the same locus

89

Explain Ehlers-Danlos syndrome

Affect connective tissues, usually autosomal dominant pattern

90

Define epistasis

Nonreciprical interaction between nonallelic genes such that one gene influences or interferes with the expression of another gene, leading to a specific phenotype

91

Define eukaryote

Organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus

92

Define experimental error

Erros that may occur in the execution of a statistical experiment design (human, systematic, or random error)

93

Define expressivity

Degree to wich a phenotype for a given trait is expressed

94

Explain extranuclear inheritance

Transmission of traits by genetic information contained in cytoplasmic organelles such as mitochonria or chlorplasts

95

Explain a genetic disorder

Genetic problem caused by one or more abnormalities in the genome

96

Define heredity

Passing on of traits from parents to their offspring, through asexual or sexual reproduction

97

Define homunculus

A supposed microscopic but fully formed human being from which a fetus was formerly believed to develop

98

Explain Hutington disease

Degeneration of neurons in the brain, autosomal dominant,

99

Define H substance

Polysaccharide precursor molecule used to make the antigens on the surface of human RBCs that are classified in the ABO system

100

Explain identical twins

Develop from one zygote

101

Explain fraternal twins

Develop from two different eggs

102

Who is Mendel

Father of genetics, discovered the fundamental laws of inheritance

103

Explain independent events

Event whose occurence or non-occurence is not in any way influenced by the occurrence or non-occurence of another event. The probability that both events will occur is equal to the product of their separate probabilities

104

Explain mutually exclusive events

Two events that are disjoint, meaning that they both cannot occur

105

Define mitochondria

Organelle in the cytoplasm of cells that functions in energy production, it has its own DNA

106

Explain modifier genes

Gene that influences the expression of another gene

107

Define phenocopy

An individual showing features characteristic of a genotype other that its own, but produced environmentally rather than genetically

108

Explain non-sister chromatids

Either of the two chromatids of the paired homolgous chromosomes, form the chiasma to exchange genetic material during meiosis

109

Explain phenylkenoturia (PKU)

Causes an amino acid to buildup in the body, autosomal recessive