Genetics 2038 test 1 ch 5-9 Flashcards Preview

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Flashcards in Genetics 2038 test 1 ch 5-9 Deck (83):
1

Level of Dominance can alter outcome name 3 types

Complete dominance, incomplete dominance, and codominance

2

Complete dominance, incomplete dominance, and codominance are ALL the result of the relationship between

two alleles at a particular locus, but with VERY different outcomes

3

incomplete dominance

Type of dominance in which the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes

4

complete dominance

Type of dominance in which the same phenotype is expressed in homozygotes (AA) and in heterozygotes (Aa); only the dominant allele is expressed in a heterozygote (

5

Codominance

in which the phenotype of the heterozygote is not intermediate between the phenotypes of the homozygotes; rather, the heterozygote simultaneously expresses the phenotypes of both homozygotes. An example of codominance is seen in the MN blood types of humans.

6

Penetrance is the percent of individuals with

a genotype that express the expected phenotype

7

Expressivity is the DEGREE to which

a trait is expressed in an individual (Polydactyly)

8

Long fingers as RECESSIVE TRAIT. If penetrance is 80%, and two people HETEROZYGOUS for the finger length trait have offspring, what is the probability that a child will have LONG fingers?

1/4 *8/10=8/40 or 1/5

9

test cross is between

heterozygote and homozygote

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Lethal Allele: causes

death at early development stage

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how do Lethal alleles affect both genotypic and phenotypic ratios of offspring

Yellow mice; Yy is genotype; YY offspring die, so ratio is Yy:yy, 2/3 to 1/3 now only 3 offspring not 4.

12

Multiple alleles means that you have

more than two choices of alleles at a particular locus (ABO blood group

13

The effect of genes at one locus depend on

the presence of genes at other loci

14

Gene Interactions can produce

novel phenotypes, or perhaps masking gene effects (epistasis) (Table 5.2)

15

epistasis

Type of gene interaction in which a gene at one locus masks or suppresses the effects of a gene at a different locus.

16

what is the bombay Phenotype

in a process referred to as epistasis - a gene for compound H is located at another locus on the gene. If that gene locus does not allow compound H to be produced than the AB antigens will not be expressed (added) to the surface of the RBC. hence the gene for A and B are masked even if present.

17

Production of yellow color in summer squash requires

two enzymes

18

if neither enzyme is produced in squash the squash is what color?

white

19

If only the first enzyme is produced the squash is what color?

green

20

Coat color in dogs is VERY complex because

FOUR loci

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Sex-influenced characteristics:

Inherited in Mendelian fashion, but express differently in males and females

22

Sex-limited characteristics

Inherited, encoded by autosomal genes, expressed in only ONE sex

23

Cytoplasmic inheritance typically refers to

mitochondrial DNA, typically maternally inherited; results in extensive phenotypic variation

24

Genetic maternal effect means that the

genotype of mother determines phenotype of offspring

25

Genomic imprinting causes

differential expression depending on parental inheritance

26

Epigenetics effects are due to

DNA changes which are not changes in base sequences, but expression

27

What are 4 different ways Inheritance of Continuous Characteristics work ?

discontinuous, continous, polygenic, Pleiotropy

28

how does Pleiotropy effect genes and charateristics?

one gene affects multiple characteristics

29

Polygenic charicteristics are

encoded by genes at many loci, but don’t interact

30

inheritence of CONTINUOUS characteristic would mean that a ----range of -----

WIDE RANGE of phenotypes, due to interactions between genes at MANY loci

31

Inheritance of Continuous Characteristics
Most are DISCONTINUOUS and

affect relatively FEW phenotypes ie round or wrinkled with few other options.

32

Study of Human Genetics is Difficult because

controlled mating not possible, long generation time, and small overall family size

33

A Pedigree is a pictorial representation of

family history, outlining inheritance of one of more characteristics

34

Twins studies help us understand what 3 things

Help determine concordance of a trait (percent that a trait is SHARED by both members of a twin pair)
Useful in studying genetic, AND environmental effects on traits

35

the Interpretation of Genetic Tests is complicated by what factors?

1. diseases that are caused by numerous mutations, not just single one
2. environmental factors and incomplete penetrance
3. the enforcement of the Genetic Information Non-Discrimination Act (2008)

36

Linked genes DO NOT

sort independently so they do not follow Mendelian rules

37

Linked gene alleles may or may not

separate during meiosis; they MAY or MAY NOT sort into new combinations

38

what causes recombination of linked genes?

“crossing over” during meiosis moves alleles that were once “linked” to possibly become “unlinked”. Anaphase 1

39

Formula for recombination frequency

(# recombinants / # total offspring) x 100%

40

wild type alleles on one chromosome, mutants on other chromosome of pair is callled________________and is in what conformation?

Coupling (cis Configuration)

41

when the wild type allele and the mutant type of allele are on the same chromosome it is callled ___________ and is in ______configuration

Repulsion (TRANS)

42

what type of test is done to determine the amount of linkage between genes.

test cross of heterozygous with recessive homozygous (AaBb*aabb)

43

independent assortment of a test cross for AaBb with an aabb would result in

25% in each group

44

completely linked genes in a test cross would result in how many outcomes

only 2 of the possible 4 outcomes.

45

why would a test cross produce any results other than 2 or 4?

difference from those ratios would indicate linkage with SOME crossing over

46

A GENE LINKAGE MAP can be constructed using

recombination frequencies; test crosses help determine order

47

in a gene linkage map with 3 genes involved you are looking for

double crossovers (least numerous) and the nonrecombinants (most numerous). different phenotype between the two is the gene between them

48

what are 2 ways of Determining gene locations:

1. Somatic cell hybridization
2. Deletion mapping

49

Somatic cell hybridization is used to determine

which chromosome a gene is on

50

Deletion mapping is used to determine the

location on a particular chromosome (can also use in situ hybridization)

51

Chromosome mutations include

rearrangements, aneuploids, and polyploids

52

Rearrangement mutations include which 4 categories

duplication, deletion, inversion, translocation

53

Duplication effects

gene product imbalances (gene dosage

54

Deletion effects:

gene product imbalances, expression of recessive gene (pseudodominance

55

Inversions: can be

paracentric or pericentric (centromere location important)

56

Paracentric inversions

do not include the centromere; more detrimental

57

Pericentric inversions

include the centromere; some viable gametes

58

translocations can be classified in which 3 types

Non-reciprocal, reciprocal, or Robertsonian

59

Robertsonian: translocation trades?

Two long arms of chromosomes recombine, as do the short arms;

60

which chromosome is viable after a Robertsonian translocation

one chromosome becomes very large, the other too small and non-viable

61

In a non-reciprocal translocation, one chromosome transfers genes

to another chromosome (uni-directional)

62

In reciprocal translocation, two non-homologous chromosomes

transfer genes to each other

63

Aneuploid is Caused by

non-disjunction in meiosis and mitosis

64

examples of aneuploid include

Robertsonian translocations; deletion of centromere during mitosis and meiosis. This is the loss or gain of certain chromosomes or homologous pairs of chromosomes. (Remember Turner syndrome and Kleinfelter syndrome?) Also – Down Syndrome (trisomy 21)

65

Polyploidy: can arise from

non-disjunction in mitosis or meiosis, or hybridization between two species followed by chromosome doubling. It is the presence of more than two complete sets of chromosomes

66

what is autopoyploidy

presence of 2 complete sets of chromosomes from single species

67

what is allopolyploidy

2 complete sets of chromosomes from two species. Confers some advantages – increased cell size and larger attributes in plants.

68

why is it advantagous to study Bacterial and Viral Genetic Systems

rapid reproduction and many progeny; haploid genome allows direct mutation expression; growth in lab requires little space; medically important; techniques exist to manipulate genes.

69

what type of bacteria are wild type and require minimal media to grow

prototrophic

70

what type of bacteria are mutant and require complete media? What does complete media mean?

auxotrophic, complete media contains all substances/additives the bacteria needs to grow.

71

how are auxotrophic media selected for?

with media that includes nutrients that favor one species or is missing for a different species

72

why does genetic analysis of bacteria require special techniques

due to circular DNA and presence of plasmids; some plasmids are freely replicating on their own (F factor – fertility factor is one example)

73

some plasmids are freely replicating on their own (F factor – fertility factor is one example) These extra circular segments are called

EPISOMES.

74

episomes are extra circular segements that can be transfered via

Conjugation for sure (possibly includs- transformation, transduction)

75

transfer of DNA from one bacterium to another (F factor experiments; Lederberg and Tatum); is called

conjugation

76

we now use Hfr (High frequency strains with F factor incorporated into the bacterial chromosome directly) for many experiments; F’ (F prime) is the standard bacterial cell with F factor in a plasmid with some bacterial gene. what type of transfer is this?

Conjugation

77

bacteria taking up free DNA is called a__________

transformation

78

for dna transfer via _______ the cells must be competant to take up free DNA

transformation

79

Co-transformed cells are those transformed by

2 or more genes

80

bacterial viruses take DNA from one bacterium to another

Transduction

81

provide three facts about transduction

1. Useful because of viral incorporation into host bacterial DNA
2. Usually occurs between bacteria of same or closely related
3. Viruses can also affect many OTHER species (humans, for example – HIV and influenza, Zika virus)

82

R factor plasmids are those

conferring antibiotic resistance

83

R factor plasmids are those conferring antibiotic resistance? how could this be a problem?

bacterial transfer can be to bacterial species DIFFERENT from the host (this is a BIG problem!)