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Intro to Molecular and Cellular Biology > Molec and Cell 4 > Flashcards

Molec and Cell 4 Flashcards

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1
Q

Homunculus

A

sperm contained fully formed “little
people

Like begets like: offspring are like their parents

Everything from the egg: females controlled all traits

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2
Q

Paternal heredity

A

males control all traits

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3
Q

Blending inheritance

A

offspring were the average
between both parents

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4
Q

Inheritance of acquired characters

A

changes happening to parents could be passed on to offspring

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5
Q

Pangenesis

A

the idea that particles called “gemmules”
carry the traits we inherit.

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6
Q

Gregor Johann Mendel

A

Considered the father of
genetics

Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments

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7
Q

character

A

A heritable feature that varies among individuals (such as flower color)

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8
Q

trait

A

Each variant for a character, such as purple or white color for flowers

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9
Q

truebreeding

A

plants that produce offspring of the same variety when they self-pollinate

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10
Q

hybridization

A

a process of mating two contrasting, true-breeding varieties

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11
Q

P generation

A

true-breeding parents

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12
Q

F1 generation

A

The hybrid offspring of the P generation

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13
Q

F2 generation

A

When F1 individuals self-pollinate or cross-pollinate with other F1 hybrids

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14
Q

Phenotype

A

the characteristic version of a trait we actually see. Example: purple flower or blue eyes

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15
Q

Alleles

A

specific versions of a “hereditary particle” (today= versions of a gene)

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16
Q

Laws of Probability first concept

A

alternative versions of genes account for variations in inherited characters

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17
Q

Laws of Probability second concept

A

that for each character an organism inherits two alleles, one from each parent

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18
Q

Probability basics multiplication rule

A

For independent events A and B, the probability (P) of both occurring (A and B) is (PA x PB)

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19
Q

Probability basics sum rule

A

For mutually exclusive events A and B, the probability (P) that at least one occurs (A or B) is (PA + PB)

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20
Q

Laws of Probability third concept

A

if the two alleles at a locus differ, then one (the dominant allele) determines the organism’s appearance, and the other (the recessive allele) has no noticeable effect on appearance

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21
Q

Laws of Probability four concept

A

known as the Law of Segregation, states that the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

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22
Q

monohybrids

A

individuals that are heterozygous for one character

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23
Q

monohybrid cross

A

A cross between such heterozygotes

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24
Q

dihybrids

A

Crossing two true-breeding parents differing in two characters, heterozygous for both characters

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25
Q

Mendelian Ratios 3:1

A

3 Dominant Phenotype
1 Recessive Phenotype

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26
Q

Mendelian Ratios 9:3:3:1

A

9 Double Dominant Phenotypes
3 Dominant/Recessive Phenotypes
3 Recessive/Dominant Phenotypes
1 Double Recessive Phenotypes

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27
Q

Complete dominance

A

phenotypes of the heterozygote and dominant homozygote are identical

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28
Q

incomplete dominance

A

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties (snapdragon colors)

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29
Q

codominance

A

two dominant alleles affect the phenotype in separate, distinguishable ways (blood type)

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30
Q

The alleles for ABO blood groups

A

I^A, I^B, i

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31
Q

Phenotype A blood type

A

I^A I^A, I^A i

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32
Q

Phenotype B blood type

A

I^B I^B, I^B i

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33
Q

Phenotype O blood type

A

ii

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34
Q

Phenotype AB blood type

A

I^A I^B

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35
Q

Homeotic mutants

A

affect development and potentially many characters

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36
Q

Sex Linked Traits

A

Traits located on X, Y chromosomes or sex chromosomes

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37
Q

Human Sex Linked Traits two types

A

Recessive lethal

Dominant lethal

38
Q

Carriers

A

heterozygous individuals who carry the recessive allele but are phenotypically normal

39
Q

Risks of incest

A

If a recessive allele that causes a disease is rare, it is unlikely that two carriers will meet and mate

Consanguineous matings (that is, between close relatives) increase the chance that both parents of a child carry the same rare allele

40
Q

Cystic fibrosis

A

most common lethal genetic disease in the United States, striking one out of every 2,500 people of European descent

allele results in defective or absent chloride transport channels in plasma membranes, leading to a buildup of chloride ions outside the cell

Symptoms include mucus buildup in some internal organs and abnormal absorption of nutrients in the small intestine

41
Q

Sickle-cell disease

A

affects one out of 400 African-Americans

caused by the substitution of a single amino acid in the hemoglobin protein in red blood cells

In homozygous individuals, all hemoglobin is abnormal (sickle-cell)

Symptoms include physical weakness, pain, organ damage, and even paralysis

42
Q

Heterozygotes for sickle cell trait

A

usually healthy but may suffer some symptoms
About one out of ten African-Americans has sickle-cell trait, an unusually high frequency
Heterozygotes are less susceptible to the malaria parasite, so there is an advantage to being heterozygous in regions where malaria is common

43
Q

Dominantly Inherited Disorders

A

causes a lethal disease are rare and arise by mutation

44
Q

Huntington’s disease

A

a degenerative disease of the nervous system

The disease has no obvious phenotypic effects until the individual is about 35 to 40 years of age

Once the deterioration of the nervous system begins, the condition is irreversible and fatal

45
Q

Pairs of Unit Factors, or Genes

A

The first concept is that alternative versions of genes account for variations in inherited characters

46
Q

Law of Dominance

A

The third concept is that if the two alleles at a locus differ, then one (the dominant allele) determines the organism’s appearance, and the other (the recessive allele) has no noticeable effect on appearance

47
Q

Equal Segregation of Alleles

A

the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

48
Q

Independent Assortment

A

How one Allele segregates has no affect on how another Allele segregates

Linked Genes Violate the Law of Independent Assortment

49
Q

Epistasis

A

One gene controls the expression of another

Dog color, One gene determines the pigment color (with alleles B for black and b for brown)

The other gene (with alleles E for color and e for no color) determines whether the pigment will be deposited in the hair

modified versions of 9:3:3:1

50
Q

Polygenic Inheritance

A

Quantitative characters are those that vary in the population along a continuum

Quantitative variation usually indicates polygenic inheritance

51
Q

polygenic inheritance

A

an additive effect of two or more genes on a single phenotype (skin color)

52
Q

chromosome theory of inheritance

A

Mendelian genes have specific loci (positions) on chromosomes
Chromosomes undergo segregation and independent assortment

53
Q

first solid evidence associating a specific gene with a specific chromosome

A

Thomas Hunt Morgan, an embryologist

Morgan’s experiments with fruit flies provided convincing evidence that chromosomes are the location of Mendel’s heritable factors

54
Q

wild type

A

normal, phenotypes that were common in the fly populations

55
Q

mutant phenotypes

A

Traits alternative to the wild type

56
Q

chromosomal basis of sex determination

A

two varieties of sex chromosomes: a larger X chromosome and a smaller Y chromosome
Only the ends of the Y chromosome have regions that are homologous with the X chromosome

57
Q

SRY gene on the Y chromosome

A

Codes for the development of testes through increase of testosterone

58
Q

sex-linked gene

A

A gene located on either sex chromosome

In humans, sex-linked usually refers to a gene on the larger X chromosome

59
Q

For a recessive sex-linked trait to be expressed

A

A female needs two copies of the allele
A male needs only one copy of the allele

Sex-linked recessive disorders are much more common in males than in females

60
Q

Some disorders caused by recessive alleles on the X chromosome in humans

A

Color blindness
Duchenne muscular dystrophy
Hemophilia

61
Q

inactive X in mammalian females

A

one of the two X chromosomes in each cell is randomly inactivated during embryonic development and condenses into a Barr body

62
Q

How many genes are on a chromosome

A

hundreds or thousands of genes

63
Q

linked genes

A

Genes located on the same chromosome that tend to be inherited together

64
Q

genetic recombination

A

the production of offspring with combinations of traits differing from either parent

65
Q

parental types

A

Offspring with a phenotype matching one of the parental phenotypes

66
Q

recombinant types, or recombinants

A

Offspring with nonparental phenotypes (new combinations of traits)

67
Q

Chiasmata

A

crossing over of homologous chromosomes

some process must sometimes break the physical connection between genes on the same chromosome

68
Q

genetic map

A

an ordered list of the genetic loci along a particular chromosome

69
Q

A crossover event and loci of gene on chromosome relation

A

the farther apart two genes are, the higher the probability that a crossover will occur between them and therefore the higher the recombination frequency

70
Q

linkage map

A

a genetic map of a chromosome based on recombination frequencies

71
Q

one map unit, or centimorgan

A

Distances between genes can be expressed as map units, represents a 1% recombination frequency

Map units indicate relative distance and order, not precise locations of genes

Genes that are far apart on the same chromosome can have a recombination frequency near 50%

72
Q

Cytogenetic maps

A

the positions of genes with respect to chromosomal features

73
Q

Large-scale chromosomal alterations

A

often lead to spontaneous abortions (miscarriages) or cause a variety of developmental disorders

74
Q

nondisjunction

A

pairs of homologous chromosomes do not separate normally during meiosis

one gamete receives two of the same type of chromosome, and another gamete receives no copy

75
Q

Aneuploidy

A

the fertilization of gametes in which nondisjunction occurred

Offspring with this condition have an abnormal number of a particular chromosome

76
Q

Two types of Aneuploidy

A

monosomic zygote

trisomic zygote

77
Q

monosomic

A

zygote has only one copy of a particular chromosome

78
Q

trisomic

A

three copies of a particular chromosome

79
Q

Polyploidy

A

a condition in which an organism has more than two complete sets of chromosomes

80
Q

Triploidy

A

(3n) is three sets of chromosomes

81
Q

Tetraploidy

A

(4n) is four sets of chromosomes

Polyploidy is common in plants, but not animals

Polyploids are more normal in appearance than aneuploids

82
Q

four types of changes in chromosome structure

A

Deletion
Duplication
Inversion
Translocation

83
Q

Deletion

A

removes a chromosomal segment

84
Q

Duplication

A

repeats a segment

85
Q

Inversion

A

reverses a segment within a chromosome

86
Q

Translocation

A

moves a segment from one chromosome to another

87
Q

Down syndrome

A

an aneuploid condition that results from three copies of chromosome 21
It affects about one out of every 700 children born in the United States

88
Q

Klinefelter syndrome

A

the result of an extra chromosome in a male, producing XXY individuals

89
Q

Monosomy X
Turner syndrome

A

produces X0 females, who are sterile; it is the only known viable monosomy in humans

90
Q

syndrome cri du chat (“cry of the cat”)

A

results from a specific deletion in chromosome 5
A child born with this syndrome is mentally retarded and has a catlike cry; individuals usually die in infancy or early childhood

91
Q

Certain cancers, including chronic myelogenous leukemia (CML)

A

caused by translocations of chromosomes

92
Q

genomic imprinting

A

involves the silencing of certain genes that are “stamped” with an imprint during gamete production

the result of the methylation (addition of –CH3) of DNA

Intro to Molecular and Cellular Biology (5 decks)

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