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Flashcards in Test 2 Deck (80):
1

Prevalent alleles in a population are termed..

Wild-type alleles

2

___ ___ can produce more than one wild-type in large populations.

Genetic polymorphism

3

Alleles that have been altered by mutation are termed..

Mutant alleles

4

Gain-of-function

Protein encoded by the mutant gene is changed so it gains a new or abnormal function

5

Dominant-negative

Protein encoded by the mutant gene acts antagonistically to the normal protein

6

Haploinsufficiency

Loss of function
Heterozygote does not make enough product to give the wild type phenotype

7

Incomplete penetrance

In some instances, a dominant allele does not influence the outcome of a trait in a heterozygote individual

8

Expressivity

The degree to which a trait is expressed

9

Incomplete dominance

The heterozygote exhibits a phenotype that is intermediate between the corresponding homozygotes

10

Overdominance

Heterozygote is more vigorous than both of the corresponding homozygotes

Heterozygote advantage

11

At the molecular level, overdominance is due to..

Two alleles that produce slightly different proteins

12

Three possible explanations for overdominance at the molecular level

1. Disease resistance
2. Homodimer formation
3. Variation in functional activity

13

Type O blood people can only accept what type of blood?

Type O

14

Who can type O blood donate to?

Anyone

Universal donor

15

Sex-linked genes

Found on one of the two types of sex chromosomes, but not both

16

Pseudoautosomal inheritance

Very few genes found on both X and Y chromosomes

17

Sex-influenced traits

Involve an allele that is dominant in one sex but recessive in the opposite sex

18

Lethal allele

One that has the potential to cause of death of an organism

19

Essential genes

Those that are absolutely required for survival

20

Nonessential genes

Those not absolutely required for survival

21

Conditional lethal alleles

May kill an organism only when certain environmental conditions prevail

22

Semilethal alleles

Kill some individuals in a population, not all of them

23

Pleiotrophy

Multiple effects of a single gene on the phenotype of an organism

24

Gene interactions

Occur when two or more different genes influence the outcome of a single trait

25

Epistasis

When the alleles of one gene mask the phenotypic effects of the alleles of another

26

Gene knockout

Geneticists have developed techniques to directly generate loss-of-function alleles

27

Maternal effect

An inheritance pattern for certain nuclear genes in which the genotype of the mother directly determines the phenotype of her offspring

28

Maternal effect and epigenetic inheritance involves..

Genes in the nucleus

29

Extranuclear inheritance involves..

Genes in organelles other than the nucleus

30

The non-Mendelian inheritance pattern of maternal effect genes can be explained by the process of ___ in female animals.

Oogenesis

31

Epigenetic inheritance

A pattern in which a modification occurs to a nuclear gene or chromosome that alters gene expression

32

Lyon hypothesis

Mechanism of X inactivation

33

The process of X inactivation can be divided into 3 stages:

Initiation
Spreading
Maintenance

34

Initiation

One of the X chromosomes is targeted for inactivation

35

Spreading

The chosen X chromosome is inactivated

36

Maintenance

The inactivated X chromosome is maintained as such during future cell divisions

37

Genomic imprinting

A phenomenon in which a segment of DNA is marked and the effect is maintained throughout the life of the organism inheriting the marked DNA

38

Monoallelic expression

Depending on how the genes are marked, the offspring expressed either the maternally-inherited or the paternally-inherited allele

39

Three stages of imprinting

1. Establishment of the imprint during gametogenisis
2. Maintenance of the imprint during embryogenesis and in the adult somatic cells
3. Erasure and reestablishment of the imprint in the germ cells

40

Genomic imprinting must involve a ___ ___.

Marking process

41

Genomic imprinting is permanent in the somatic cells of an ___ animal.

Individual

42

Extranuclear inheritance

Inheritance patterns involving genetic material outside the nucleus

43

The genetic material of mitochondria and chloroplasts is located in a region called the ___.

Nucleoid

44

The genome is composed of a single chromosome containing..

Double-stranded DNA

45

The two most important examples are due to genetic material with what two organelles?

Mitochondria and chloroplasts

46

The main function of choroplasts is ___

Photosynthesis

47

Species with maternal inheritance may, on occasion, exhibit ___ ___.

Paternal leakage

48

Paternal leakage

The paternal parent occasionally provides mitochondria through the sperm

49

Heteroplasmy

Important factor in mitochondrial disease

50

Endosymbiosis theory

Describes the evolutionary origin of mitochondria and chloroplasts

51

Bacteria reproduce ___

Asexually

52

Genetic transfer

A segment of bacterial DNA is transferred from one bacterium to another

53

Bacteriophages

Viruses that infect bacteria

54

Transfer of genetic material from one bacterium to another can occur in 3 ways:

Conjugation
Transduction
Transformation

55

Conjugation

Involves direct physical contact

56

Transduction

Involves viruses

57

Transformation

Involves uptake of genes from the environment

58

Auxotrophs

Cannot synthesize a needed nutrient

59

Prototrophs

Make all their nutrients from basic components

60

Genetic transfer in bacteria was discovered by who?

Lederberg and Tatum

61

U-tube

Large enough to allow the passage of the genetic material but small enough to prevent the passage of bacterial cells

62

Fertility plasmids

Allow conjugation

63

Resistance plasmids

Contain genes conferring resistance to antibiotics

64

Degradative plasmids

Carry genes allowing digestion of unusual substances

65

Col-plasmids

Contain genes for colicins, proteins that kill other bacteria

66

Virulence plasmids

Carry genes that turn bacterium into pathogenic strains

67

The ___ of ___ of the integrated F factor determines the starting point and direction of the transfer process.

Origin of transfer

68

thr+

Able to synthesize the essential amino acid threonine

69

leu+

Able to synthesize the essential amino acid leucine

70

azi^s

Sensitive to killing by azide

71

ton^s

Sensitive to infection by T1

72

lac+

Able to metabolize lactose and use it for growth

73

gal+

Able to metabolize galactose and use it for growth

74

str^s

Sensitive to killing by streptomycin

75

Cotransduction

The packaging and transfer of two closely-linked genes

76

Cotransduction frequency

(1-d/L)^3

77

Natural transformation

DNA uptake occurs without outside help

78

Artificial transformation

DNA uptake occurs with the help of special techniques

79

Competent cells

Bacterial cells able to take up DNA

80

"Illegitimate" recombination

The DNA that enters the cell is not homologous to any genes on the host chromosome