Genetics Chapter 5

Front 1

Genes located on the same chromosome are referred to what?

Back 1

syntenic genes

Front 2

Why are syntenic genes often referred to as linked genes?

Back 2

since they are so close together their alleles cannot assort independently

Front 3

Which of the following statements about genetic linkage is generally true?

A. Crossing over is more likely to occur between linked genes that are close to one another than between genes that are farther apart on a chromosome.
B. Individuals that are heterozygous for two linked genes (AaBb) will produce roughly equal numbers of recombinant and parental gametes.
C. Individuals that are heterozygous for two linked genes (AaBb) will produce genetically different gametes in a ratio of 1:1:1:1.
D. Genetic linkage results in the production of significantly more parental gametes, and significantly fewer nonparental (recombinant) gametes than expected by chance.

Back 3

D. Genetic linkage results in the production of significantly more parental gametes, and significantly fewer nonparental (recombinant) gametes than expected by chance.

Front 4

True or False: Crossing over during prophase I of meiosis occurs between alleles on sister chromatids

Back 4

False: Crossing over during meiosis occurs between alleles on NON-SISTER chromatids.

Front 5

Who is generally credited with creating the first genetic linkage map?

Back 5

Alfred Sturtevant

Front 6

What is the definition of a map unit?

Back 6

One percent recombination (or more precisely, one percent recombinant products of meiosis)

Front 7

How can genetic linkage be quantified?

Back 7

It can be quantified to map the positions of genes on chromosomes.

Front 8

Alleles of syntenic genes can be reshuffled when crossing over occurs between homologs to produce what?

Back 8

recombinant chromosomes

Front 9

Homologs that do not reshuffle alleles under study are called ___ or _____ chromosomes

Back 9

parental chromosomes or nonrecombinant chromosomes

Front 10

What does genetic linkage mapping accomplish?

Back 10

It plots the positions of genes on chromosomes

Front 11

True or False: Independent assortment of syntenic genes can occur if they are close together on a chromosome so that recombination occurs very frequently

Back 11

FALSE: if the are far apart on a chromosome so that recombination occurs very frequently

Front 12

TRUE OR FALSE: Incomplete genetic linkage is much more common than complete linkage

Back 12

True

Front 13

Does genetic linkage leads to the production of significantly more gametes with parental allele combinations or significantly more gametes with nonparental combinations?

Back 13

Genetic Linkage leads to significantly more gamete with PARENTAL alleles.

Front 14

genetic linkage can be recognized by comparing what?

Back 14

by comparing observed frequencies of gametes or progeny phenotypes with those expected under independent assortment.

Front 15

When does independent assortment of syntenic genes occur?

Back 15

if they are far apart on a chromosome so that recombination occurs very frequently

Front 16

Crossing over that prevents linked genes from segregating together occurs in what stage?

Back 16

during prophase I of meiosis

Front 17

TRUE OR FALSE: If genes are linked, parental allele combinations will be observed at higher frequency than predicted by chance

Back 17

TRUE

Front 18

When does complete genetic linkage occur?

Back 18

When NO CROSSING OVER occurs between linked genes; only parental gametes are formed?

Front 19

What organisms exhibit complete linkage?

Back 19

Male Drosophila (flys) -- means no crossing over.

Front 20

what is the biological basis for complete genetic linkage?

Back 20

unknown

Front 21

Morgan figured out what ____ and ____ had identified as genetic linkage

Back 21

Batsen and Punnett

Front 22

How did Morgan realize that linkage of autosomal genes in Dorosphila could be interpreted?

Back 22

Two-Point Test-Cross anaylsis

Front 23

TRUE OR FALSE: Genetic linkage is a not a physical relationship between genes located near one another on a chromosome

Back 23

FALSE: Genetic linkage is A PHYSICAL relationship between genes located near one another on a chromosome

Front 24

Genetic Linkage Mapping Is Based on what?

Back 24

Recombination Frequency Between Genes

Front 25

what is another name for a map unit?

Back 25

centiMorgan (cM)

Front 26

1% recombination = how many m.u or cM

Back 26

one

Front 27

Recombination frequency is likely a reflection what?

Back 27

physical distance between two genes

Front 28

how is recombination (r) frequency measured?

Back 28

r= number of recombinant gametes/ total number of meiosis