Topic 10-1

Question 1

independent assortment allows for:

Answer 1

new allelic combinations

Question 2

what is homologous recombination?

Answer 2

a cross over mechanism for mixing genes on the same chr

Question 3

the recombination frequency between two genes depends on:

Answer 3

how far away from each other they are along the chr

Question 4

a set of genes located close together on the same chr

Answer 4

linkage group

Question 5

how is linkage tested?

Answer 5

a testcross

Question 6

how is a testcross created?

Answer 6

cross a plant that is heterozygous for both characteristics with a plant that is homozygous recessive for both

Question 7

if alleles are completely unlinked, crossing over:

Answer 7

will occur! some gametes will be non-recombinant and recombinant

Question 8

are test crosses able to determine whether or not unlinked genes are far apart on the same chr or if they are on two different chr?

Answer 8

no

Question 9

if alleles are completely linked, crossing over:

Answer 9

will not occur between genes and so alleles for two genes stay together; all gametes will be non-recombinant

Question 10

over many gametes, the majority will be:

Answer 10

non-recombinant

Question 11

is it possible for genes to be partially linked?

Answer 11

yes

Question 12

counting percentage of recombinant and non-recombinants from a testcross tells us something about:

Answer 12

how close the genes are

Question 13

what is the maximum recombinant percentage?

Answer 13

50%

Question 14

can be measured by counting the recombinant vs. non-recombinant progeny from a test cross

Answer 14

recombination frequency

Question 15

what is the formula for recombination frequency?

Answer 15

Rf = (# recombinant progeny / # total progeny) x100%

Question 16

what does a recombination frequncy of 16% mean?

Answer 16

16 out of 100 gametes from the heterozygous parent will be recombinants

Question 17

genes can be ____ on the chr

Answer 17

mapped

Question 18

who came up with gene mapping?

Answer 18

Thomas Hunt Morgan

Question 19

the further apart two genes are, the more likely there will be a:

Answer 19

crossover event

Question 20

recombination frequency can also tell you the ____ between multiple genes

Answer 20

gene order (eg: B is b/w A and C)

Question 21

what are “genetic maps”?

Answer 21

chr maps calculated by using recombination

Question 22

1 map unit =

Answer 22

1% recombination rate

Question 23

true or false: we only know distances relative to each gene and not actual chr physical location

Answer 23

true

Question 24

what are physical maps?

Answer 24

actual physical locations measured in actual bases along the chr

Question 25

genetic mapping of genes far away from each other will give you:

Answer 25

an underestimate of the distance (double crossovers are more likely the farther apart)