Lecture 13

Question 1

what is the unit of transmission in meiosis?

Answer 1

chromosomes

not genes

Question 1

linked genes can not undergo…

Answer 1

independent assortment

Question 2

frequency of crossing over on a single chromosome is proportional to…

Answer 2

distance between them

Question 3

crossing over results in

Answer 3

recombination

Question 4

chromosome maps indicate

Answer 4

relative location of genes on chromosome

Question 5

three consequences of linkage in meiosis

Answer 5

independent assortment
linkage without crossing over
linkage with crossing over

Question 6

linkage without crossing over is called

Answer 6

complete linkage

Question 7

is linkage exhibited in independent assortment

Answer 7

no

Question 8

linkage with crossing over

Answer 8

generates recombinant gametes

Question 9

what does complete linkage produce

Answer 9

parental (noncrossover) gametes

Question 10

crossing over occurs between

Answer 10

non-sister chromatids

Question 11

crossing over produces what

Answer 11

both parental and recombinant gametes

Question 12

the number of linkage groups corresponds to

Answer 12

haploid number of chromosomes

Question 13

linkage ratio refers to

Answer 13

phenotypes

Question 14

chiasmata are

Answer 14

synapsed chromosomes in meiosis that wrap around each other

Question 15

what shape are chiasmatas

Answer 15

x-shaped intersection with points of overlap
(points of genetic exchange)

Question 16

percentage of offspring resulting from recombinant gametes depends on?

Answer 16

distance between two genes on same chromosome

Question 17

what is less likely to have a chiasma

Answer 17

two genes located close to each other along a chromosome

Question 18

the frequency of crossing over is…

Answer 18

proportional to distance between any two loci on single chromosome

Question 19

one cM corresponds to about how many base pairs in humans on average

Answer 19

1 million

Question 20

relative distance between two loci influences amount of…

Answer 20

recombination and crossing over

Question 21

the closer the loci reside the …..

Answer 21

less likely of single-crossover event

Question 22

the farther apart the loci…

Answer 22

the more random crossover

Question 23

single crossovers are when..

Answer 23

two linked genes are greater than 50 map units apart

Question 24

double crossovers result from

Answer 24

double exchanges of genetic material

Question 25

three-point mapping criteria

Answer 25

• genotype of organism producing crossover gametes must be heterozygous at all loci
• cross must be constructed to determine genotype of all gametes by observing phenotypes of offspring.
  -Sufficient number of offspring must be produced for representative sample crossover.