Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics > Tutorials for Midterm > Flashcards

Tutorials for Midterm Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is the C-value? What is it measured in?

A

the mass of a haploid genome

measured in picograms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In the equation 2n=4 what does each of these things stand for?

A

2 is the ploidy (diploid)
n is the number of different chromosomes
4 is the total number of chromosomes in the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

During what phase is DNA replicated?

A

S (synthesis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What joins sister chromatids?

A

centromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Do homologous chromosomes have the same alleles?

A

no they are different

one from each parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens during prophase of meiosis?

A

chromosomes condense

crossovers occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens during metaphase I?

A

independent assortment, align at the metaphase plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens during anaphase I?

A

homologous chromosomes separate and move towards opposite poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens during telophase I and cytokinesis?

A

the cytoplasm splits creating two daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens during prophase II? How long is it? Do all organisms have it?

A

nothing really because the chromosomes are already condensed and there is no crossover
it is very short
it only occurs in some eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens during metaphase II?

A

sister chromatids line up at the metaphase plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens during anaphase II?

A

sister chromatids are pulled to opposite poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens during telophase II and cytokinesis?

A

the cytoplasm splits and two daughter cells are created

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When during meiosis is there 4C? 2C? C?

A

4C, during G2 after S
2C, after the first round of division
C, after the second round of division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If two genes are unlinked what is the chance of a specific allele occurring?

A

25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is cis configuration in reference to two linked alleles?

A

both dominant alleles on one chromosome and both recessive on the other (in a heterozygote)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is trans configuration in reference to twi linked alleles?

A

a dominant and recessive allele on each chromosome (in a heterozygote)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a chiasma?

A

the place where two homologous chromosomes crossover

it is the only physical evidence that crossover has occurred

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When does a chiasma form?

A

during early prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

If two genes are not linked how often does recombination occur?

A

50% of the time

i.e. there are 4 possibilities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do you observe if a crossover took place between two homologous chromosomes?

A

you need to observe the phenotypes associated with the genotypes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why do you use a homozygous recessive parent as the tester when crossing with a heterozygote?

A

the recessive alleles won’t “mask” the alleles contributed by the heterozygote parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Is it possible to get more than 50% recombination?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the % of recombinant offspring equal to?

A

1/2 the % crossing over
i.e. if 20% cross over 10% will be recombinant (5% of each recombinant)

also equal to the map distance in map units or centiMorgans
ie in there are 10% recombinant offspring the loci are 10 map units apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

If two genes are linked what is their map distance?

A

less than 50 map units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How do you identify if 3 genes are in cis or trans configuration?

A

go in terms of the dominant alleles, can do it for each pair
all dominant together = cis
other than that there are combinations of cis and trans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

When you do a three-point test cross how many progeny phenotypes are possible? How do you know which are the parent configurations? The double CO configurations?

A

8
2 parental, 4 single CO and 2 double CO
parental are the most abundant
double CO are the least abundant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How do you figure out which gene is in the middle when you perform a three-point test cross?

A

compare the parental phenotypes with the double crossover phenotypes and look for the “odd man out”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How do you calculate the distance between 2 genes?

A 
# of progeny with a crossover between the two genes (both double and single COs, should be 4 numbers) 
/
the total # of progeny 
x100 
(gives the mu or % RO)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is interference?

A

crossovers have a limited amount of time and space to occur and thus crossovers in one area can interfere with crossovers in another area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How do you calculate the expected DCO?

A

multiply the probability of an AB CO by the probability of a BC CO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How do you calculate the coefficient of coincidence? Interference?

A 
CoC= observed DCO/ expected DCO
Interference= 1-CoC
33
Q

What does it mean if interference is positive? Negative?

A

positive means one crossover is affecting another

negative means that one crossover is facilitating another

34
Q

What is a forward mutation?

A

changes a WT allele to a different allele

35
Q

What is a reverse mutation?

A

changes a mutant allele back to a WT allele

36
Q

What are the 2 subtypes of substitutions?

A

transitions and transversions

37
Q

What is a transition?

A

purine to purine or pyrimidine to pyrimidine

38
Q

What is a transversion?

A

purine to pyrimidine or vice versa

39
Q

What is an inversion?

A

a 180 degree rotation of a piece of DNA

40
Q

What is a translocation?

A

the movement of DNA between non-homologous chromosomes

41
Q

What occurs more frequently, loss or gain of function mutations?

A

loss of function

42
Q

What are the 2 possibilities for a loss of function mutation?

A

the function can either be reduced or eliminated

43
Q

What are the 2 possibilities for a gain of function mutation?

A

enhanced function or an alternate (new) function

44
Q

What is a silent mutation? Do they have phenotypic changes? What kind of mutations do they include?

A

silent means the protein itself doesn’t change
there can still be phenotypic changes though i.e. codon usage, regulatory changes
this includes synonymous mutations

45
Q

What is a synonymous mutation?

A

changes the codon but not the amino acid coded for

46
Q

What are two types of non-synonmous mutations?

A

Missense mutations

Nonsense mutations

47
Q

What are the 2 types of missense mutations?

A

Conservative- similar amino acid

Nonconservative- non-similar amino acid

48
Q

What is the average mutation rate per gene affecting phenotype? (spontaneous)

A

2-12 x 10^-6

49
Q

Name 4 factors affecting mutation rate

A

gene size
gene sequence
tissue type (i.e. skin will get damaged a lot)
number of cell divisions prior to gamete production (for gametes)

50
Q

What is an endogenous mutation? Exogenous?

A

endogenous is spontaneous

exogenous is induced

51
Q

Name 3 endogenous mutational events

A

oxidation
depurination
deamination

52
Q

What causes oxidation to DNA? Where do these species come from?

A

cause by reactive oxygen species (ROS)

produced by natural cellular processes, but environmental stress i.e. heat, UV can increase the amount of them

53
Q

What are 2 mechanisms used to combat ROS?

A

enzymes- superoxide dismutase, catalases

antioxidant molecules- vitamins (ascorbic acid, tocopherol)

54
Q

What does oxidation do to DNA?

A

affects how guanine base pairs, makes it pair with A

get a GC to TA transversion

55
Q

How often does hydrolysis of purines occur in human cells? (depurination)
What is the result?

A

about 1000 times per hour

use lose an A or G base and put a random one back in

56
Q

What does deamination do to DNA?

A

it removes the amino group off of C making it U
U pairs with A
causes a CG to TA transition

57
Q

Name 8 types of exogenous mutational events

A 
X-ray radiation
UV light
Base analogs
Hydroxylating agents
Alkylating agents
Deaminating agents
Intercalating agents
58
Q

What does X-ray radiation do to DNA? What does it cause?

A

breaks the sugar-phosphate backbone

can cause a huge deletion

59
Q

What does UV light do to DNA? How can this be fixed?

A

causes pyrimidine dimers (thymine usually)

SOS repair system that uses error-prone polymerases can be used to fix it

60
Q

Explain how 5-bromouracil works as a base analog

A

the keto form pairs with A
the enrol (rare ionized) form pairs with G
can bind with an A, tautomerize and then have G put in during replication
this results in a TA to CG transition

61
Q

What do hydroxylating agents do? What happens as a result?

A

they add a hydroxyl group (OH)
hydroxylate C, now it base pairs with A
results in a CG to TA transition

62
Q

What do alkylating agents do? What happens as a result?

A

they add ethyl or methyl groups
can add to G or T
mispaired G pairs with T (and vice versa)
causes a GC to AT transition (or TA to GC)

63
Q

What do deaminating agents do? What happens as a result?

A 
they remove an amino group 
Nitrous acid (HNO2)
Changes C to U (mispairs with A)
Changes A to hypoxanthine (mispairs with C)
cause CG to TA transition (or AT GC)
64
Q

What are intercalating agents? Give some examples

A

flat, planar molecules that insert between bases

ie proflavin, acridine orange and ICR-191

65
Q

What happens as a result of intercalating agents?

A

insertions and deletions (when you are trying to remove them)

66
Q

What test is used to test for mutagenicity? What bacteria are used? What is special about them?

A

Ames test
Salmonella typhimurium
they are his- (can’t produce histidine)

67
Q

Explain the Ames test

A

put the bacteria in a tube with a suspected carcinogen/mutagen and rat liver enzymes (some need catalytic activity)
grow on his- media and see if there are any revertant mutations (his- gone back to WT)

68
Q

What is retinoblastoma? What hypothesis does it follow?

A

a rare cancer of the retina
40% of cases result from the inheritance of one Rb- allele
two-hit hypothesis

69
Q

What is the two-hit hypothesis?

A

need to lose both alleles (or be born without one and lose one, or be born without either) in order to get the disease

70
Q

What is an oncogene?

A

one abnormal gene is enough to cause phenotype

gain of function

71
Q

What is a tumour-supressor gene?

A

haplosufficient
loss of function
need to non-functional alleles to have mutant phenotype

72
Q

What is the Law of Segregation?

A

two alleles separate while making gametes then one from each parent come together at fertilization

73
Q

What is the Stay-green gene (Sgr) in peas?

A

it is a nonsense mutation near the 5’ end of the coding sequence
if a pea has 2 it stays green instead of turning yellow
it is haplosufficient (need to non-functional copies for mutant phenotype)

74
Q

Describe the mutation to the human CCR5 gene (a chemokine receptor) and the resulting phenotypes

A

small 32 bp deletion on chromosome 3
affects T cell function
heterozygous have reduced susceptibility to HIV and delayed onset of AIDS
homozygous for the mutation are resistant to HIV

75
Q

What is a good way to track deletions?

A

using PCR and gel electrophoresis

76
Q

What is a haplotype?

A

haploid genotype…talking about one allele
a combination of two or more DNA marker alleles that are close together and therefore stay associated over many generations

77
Q

What is linkage disequilibrium?

A

the non-random association of alleles at two or more loci

78
Q

What do you do in a haplotype-based study?

A

look for linkage disequilibrium between sections of chromosomes and phenotypes

79
Q

Are most SNPs biallelic?

A

yes most only have 2 alleles

Genetics (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions