Brainscape's Knowledge GenomeTM

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


See full index

BIOL-2301 Final Exam > Chapter 5 > Flashcards

Chapter 5 Flashcards

1
Q

in a notation such as a+b+/ab, what does the slash signify?

A

the presence of homologous pairs. in this case, there are two traits being analyzed, a and b, and you can see the two different homologous chromosomes. This individual is thus heterozygous for both traits.

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

in a notation such as a/a+;b/b, what does the semicolon signify?

A

the semi colon indicates that these genes are on separate chromosomes, and the dash indicates that we are looking at homologous chromosomes for each trait. therefore, we can say that this individual is heterozygous for the a trait, and homozygous for the b trait, and that the traits a and b are located on different chromosomes and thus unlinked.

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

in a dihybrid testcross, the phenotype of the offspring displays that genetic content of the _____ individual.

A

reflects the content of the gamete from the heterozygous parent. the other parents is recessive and thus will only reflect recessive traits.

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

If you were to dihybrid testcross an F1 generation, the expected gamete ratio is 1:1. If this deviates, this may indicate that:

A

the two genes are linked.

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

Are 2 genes on the same chromosome expected to assort independently?

A

no. 2 genes on the same chromosome are expected to NOT assort independently. 2 parts of a single chromosome can not segregate independently.

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

How do you determine which group of gametes are recombinant and non recom/parental?

A

progeny classes/allele combinations in greater numbers are the parental genotypes, and the progeny have the same genotypes as the parent. recombinant genotypes are the less populous allele combinations.

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

If normal independent assortment and segregation occured, the number of non recombinant and recombinant progeny are ____, and the % recombination frequency is ____%

A

equal, the recombination frequency is 50%.

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

genes with % recomb of < 50% are____

A

linked

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

genes with % Recomb= 50% are

A

unlinked

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

What are syntenic genes?

A

genes are syntenic if they are in the same chromosome, regardless of whether or not they show independent assortment (far away) or linkage (close together).

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

An individual with the geno type p+v+/pv has a ____ coupling allele configuration

A

cis.

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

What is trans-repulsion allele configuration?

A

the configuration where each chromosome has one mutant and one WT allele. ex: p+v/pv+

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

T/F Recombination between linked genes take place with the same frequency whether the alleles of the genes are in the trans(repulsion) or cis (coupling) configuration

A

true. recombination occurs the same no matter how the alleles are arranged.

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

Why do males show a smaller amount of recombination compared to females?

A

the Y chromosome does not have a homologue, it is paired with an nonidentical X chromosome.

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

T/F all syntenic genes on the Y chromosome show complete linkage in a male? why or why not?

A

recall : syntentic genes are on the same chromosome, in this case Y. They all transfer together ie/ show complete linkage because recombination cannot occur since Y does not have a homologue.

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

What is a linkage group?

A

all of the genes on a single chromosome (synentic genes). They are inherited as a group; that is, during cell division they act and move as a unit rather than independently.

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

The number of linkage groups is the same as the _____ # of chromosomes in a species

A

haploid

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

% recombination for genes that are far apart ____ the trus distance due to ____ that may have occurred

A

underestimates the true distance due to double cross overs that may have occurred.

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

T/F: When determining linkage and genetic recombination frequencies, double cross overs are counted

A

false. Double cross overs are not counted.

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

What is the maximum recombination frequency between linked genes?

A

50%, which indicates independent assortment.

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

Can a dihibrid test cross determine gene order?

A

no

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

How can you determine gene order and gene-gene distances?

A

using a triply heterozygous x homozygous recessive testcross.

23
Q

NCO?

A

no cross over. parental classes. 2 largest classes of allele groups.

24
Q

DCO?

A

double cross over gametes. 2 smallest classes.

25
Q

SCOx/SCOy

A

Single cross overs. 2 groups of intermediate size.

26
Q

How do you calculate the number of expected DCO’s if you know the single cross over ratios?

A

SCOx x SCOy= DCO frequency(total number of progeny)= expected portion of the population with DCO occurence.

27
Q

What is the coefficient of coincidence?

A

Observed DCO/ Expected DCO

28
Q

What is interference?

A

1-COC

29
Q

If interference is positive, there is _____ than expected DCOs

A

less than expected DCO

30
Q

If interference is negative, there is ____ than expected DCO’s

A

more than expected DCO.

31
Q

generally, the short the distance between genes, the ____ the interference

A

greater

32
Q

T/F: if I= 0, the expected number of DCO’s are observed

A

true

33
Q

What is a parental ditype tetrad?

A

a tetrad when only parental genotypes present.

34
Q

What is the non parental ditype tetrad?

A

only recombinant genotype spores present.

35
Q

Tetratype tetrad?

A

2 PD and 2NPD haploid spores present in the tetrad.

36
Q

What is heterochromatin? How does it influence genetic recombination?

A

heterochromatin is condensed chromatin near the centromere. it suppresses recombination because it is so tightly coiled.

37
Q

Because there is less crossing over occurring in heterochromatin, a given length of heterochromatin will appear ____ in the genetic map then an equal length of euchromatin

A

much shorter in length.

38
Q

if PD=NPD, the genes are:

A

not linked

39
Q

if PD>NPD, the genes are:

A

linked.

40
Q

% recombination for ordered tetrads

A

%Recombination= ((NPD+0.5TT)/Total tetrads x 100)

41
Q

What is special about meiosis in ordered tetrads

A

most meiosis 1 and 2 organisms divide perpendicularly, but in sordaria fimicola, the planes of division of parallel and the spindles do not overlap. this results in the linear arrangement of spores, which allows for gene centromere mapping.

42
Q

What kind of mapping do ordered tetrads allow us to perform?

A

gene centromere mapping

43
Q

% recombination frequency for ordered tetrads?

A

(0.5 SDS)/total octads x 100

44
Q

does crossing over occur in drosophila males

A

no

45
Q

What’re the characteristics of genes that show recombination frequency of 50%?

A

1) genes may be on different chromosomes
2) genes may be really far away on the same chromosome (distantly syntenic)
3) the genes undergo independent assortment
4) if the genes are syntenic, more than one cross over occurs between the genes in almost every meiosis.

46
Q

4% of the cells with 2 specific linked genes undergoing meiosis at a particular time have one cross over event. the rest 96% have no cross over. What is the percent recombination between genes?

A

2%. Recall that when a cross over occurs in a bivalent, two of he four chromatids do not participate in the cross over, so that only half of the gametes are recombinant. Therefore, the percent recombination is half of the proportion of cells undergoing meiosis that have a cross over in the interval.

47
Q

What is SDS?

A

in ordered tetrads. when 2 alleles did not segregate until M2, crossing over occurred.

48
Q

What is FDS?

A

in ordered tetrads, when 2 alleles segregated at M1- no cross over occurred.

49
Q

In ordered tetrads, the map distance (%) recombination is ____ the expected SDS frequency

A

half. % recombination is proportional to 1/2SDS

50
Q

In budding yeast, what type of tetrad results from a four strand double cross over?

A

a non parental ditype. All spores in the tetrad will be recombinant because all four chromatids were involved in cross over

51
Q

What would happen to the recombination frequency of two genes if a double cross over involving all four strands occurred in each meiotic cell? Is this possible

A

the % recombination would be 100% because if all four strands recombine with each other, when the strands separate into separate cells, all the cells would be recombinant. This is not possible in real life because only 50% of gametes can be recombinant because DCO’s only occur between four strands.

52
Q

For an unlinked gene pair, how is a TT Ascus formed?

A

TT is formed when there is a cross over between ONE of the genes and its centromere for unlinked gene pairs

53
Q

If a gene is unlinked, and there is no crossing over between the gene and its centromere, how many TT tetrads occur?

A

none. Only PD and NPD

54
Q

If there are no TT tetrads that occur between two genes, what does that mean in terms of their position to their centromere?

A

the genes are very close to their centromere. most likely located in the heterochromatin, where there is low amounts of crossing over/recombination occurring.

BIOL-2301 Final Exam (6 decks)

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