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BIOL-2301 Final Exam > Chapter 5 > Flashcards

Flashcards in Chapter 5 Deck (54)
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1

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

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.

2

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

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.

3

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

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

4

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

the two genes are linked.

5

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

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

6

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

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.

7

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

equal, the recombination frequency is 50%.

8

genes with % recomb of < 50% are____

linked

9

genes with % Recomb= 50% are

unlinked

10

What are syntenic genes?

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).

11

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

cis.

12

What is trans-repulsion allele configuration?

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

13

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

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

14

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

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

15

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

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.

16

What is a linkage group?

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.

17

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

haploid

18

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

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

19

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

false. Double cross overs are not counted.

20

What is the maximum recombination frequency between linked genes?

50%, which indicates independent assortment.

21

Can a dihibrid test cross determine gene order?

no

22

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

using a triply heterozygous x homozygous recessive testcross.

23

NCO?

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

24

DCO?

double cross over gametes. 2 smallest classes.

25

SCOx/SCOy

Single cross overs. 2 groups of intermediate size.

26

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

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

27

What is the coefficient of coincidence?

Observed DCO/ Expected DCO

28

What is interference?

1-COC

29

If interference is positive, there is _____ than expected DCOs

less than expected DCO

30

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

more than expected DCO.