Chapter 6 & 7

Question 1

What is a pedigree?

Answer 1

a chart that tracks which members of a family have a particular trait

Question 2

What four different patterns will a pedigree reveal?

Answer 2

• autosomal recessive
• autosomal dominant
• X-linked recessive
• X-linked dominant

Question 3

What is X-linked recessive?
How can you tell if a pedigree shows this?

Answer 3

• A gene located on the X-chromosome

signs:
- more affected males
- affected males only pass trait to their daughters
- unaffected carrier mothers produce affected sons

Question 4

What is X-linked dominant?
How can you tell if a pedigree shows this?

Answer 4

• Much more severe effects in males

signs:
- affect father passed trait to all of his daughter
- no sons are affected unless mother is

Question 5

How can you tell if a pedigree shows autosomal recessive?

Answer 5

signs:
- trait skips generations (affected individuals with carrier parents)
- equal male-female ratio

Question 6

How can you tell if a pedigree shows autosomal dominance?

Answer 6

signs:
- trait doesn’t skip generations
- equal male-female ratio

Question 7

What are the two types of twins?

Answer 7

• monozygotic
• dizygotic

Question 8

What are monozygotic twins?

Answer 8

• identical twins
• a zygote splits into two separate masses of cells, and develops into a separate embryo
• share genes, not environment

Question 9

What are dizygotic twins?

Answer 9

• non-identical twins
• 2 ovum at the same time
• different genes, same environment

Question 10

What is concordance?

Answer 10

the occurrence of the same clinical condition in both members of a twin pair

Question 11

What is genetic counseling?

Answer 11

• process that identifies potential genetic risks
• use of family pedigree
• helpful in the family planning process

Question 12

What is linkage?

Answer 12

the tendency for loci to be inherited together

Question 13

Why would loci be inherited together?

Answer 13

they are physically close on the same chromosome

Question 14

What is no linkage’s ratio?

Answer 14

9:3:3:1

Question 15

What is a two-point test cross?

Answer 15

heterozygous crossed with homozygous recessive

Question 16

What is coupling?
What is it called?
What is the ratio?

Answer 16

• when 2 dominant alleles are on a chromosome and 2 recessive alleles are on another
• cis configuration
• 4:1:1:4

Question 17

What are parental genes (non-recombinant?

Answer 17

chromosomes that carry similar genes from two different parents

Question 18

What are recombinant chromosomes?

Answer 18

a chromosome that carry genes derived from two different parents

Question 19

What is repulsion?
What is it called?

Answer 19

• when A and b are on one chromosome and a and B are on another
• trans configuration

Question 20

Repulsion:
What are(is) the percentage(s) for:
Independent assortment
- AaBb
- aabb
- Aabb
- aaBb

Complete linkage
-AaBb
- aabb

Linkage with cross-over
- AaBb
- aabb
- Aabb
- aaBb

Answer 20

Independent assortment
- all 25%

Complete linkage
- all 50%

Linkage with cross over
- all 25%

Question 21

What is complete linkage?

Answer 21

2 loci are so close together in the same chromosome that there is no crossing over

Question 22

With complete linkage, is there recombination?

Answer 22

no

Question 23

How might there be recombination with complete linkage?

Answer 23

if 2 loci have just enough spacing inbetween

Question 24

What is genetic mapping?

Answer 24

The process of determining the location and chemical sequence of specific genes on specific chromosomes.

Question 25

Morgan and his students hypothesized that the probability of crossing over between linked loci should be proportional to the actual ___ ___

Answer 25

physical distance

Question 26

How do you calculate the frequency of recombination?

Answer 26

the total recombination divided by the total offspring

Question 27

If two crossing over events occur between two loci, they will cancel each other out, and there is no ___

Answer 27

recombination

Question 28

Shorter distance is ___ than longer distance for mapping

Answer 28

better

Question 29

What are the advantages of the three-point test cross?

Answer 29

• fewer crosses are needed
• some double cross overs are detected

Question 30

What are genome-wide association studies?

Answer 30

A large-scale analysis of the genomes of many people having a certain phenotype or disease
- aim to find genetic markers that correlate with that phenotype or disease.

Question 31

What is a haplotype?

Answer 31

A group of gene or DNA variations that exist on the same chromosome and are likely to be inherited together.

Question 32

What does crossing over disrupt?
What does it cause?

Answer 32

• length of mutant haplotype region get shorter
• different lengths in different families

Question 33

What are genetic markers?

Answer 33

Genetic abnormalities found in some people that predict the odds of having certain types of cancers.

Question 34

What is Single Nucleotide Polymorphism (SNP)?

Answer 34

It is a common single base substitution between individuals. Rare single base substitutions are called mutations.

Question 35

What is deletion mapping?

Answer 35

• to find where transcription factors bind
• make a series of different deletions and see where activation stops.

Question 36

The bigger of a deletion the ___ loci disappear

Answer 36

more

Question 37

What is somatic cell hybridization?
What is it called?

Answer 37

-type of physical gene mapping
-fuses two cells. The chromosomes begin to degrade throughout cell lines and can be used to determine which chromosome contains a gene of interest

• heterokaryons

Question 38

What are recombination hotspots?

Answer 38

Small regions of the genome that are particularly prone to serving as locations of crossover.