Lec 12. Eukaryotic gene mapping Flashcards Preview

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Flashcards in Lec 12. Eukaryotic gene mapping Deck (40)
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1
Q

What are the three mapping techniques?

A

Physical mapping, mapping with molecular markers and genome wide association studies

2
Q

What are the two type of Mapping with molecular markers?

A

Haplotype and linkage disequilibrium

3
Q

What do genome wide association studies deal with?

A

Associations within populations

4
Q

What is a haplotype?

A

Set of DNA variation or polymorphisms that tend to be inherited together

5
Q

Loci are said to be in linkage disequilibrium when

A

the frequency of association of their different alleles is higher or lower than what would be expected if the loci were independent and associated randomly

6
Q

What haplotypes contribute to differences in huntington disease?

A

HTT haplotypes

7
Q

What is another example of haplotypes when different can cause milder or more severe forms of the disease?

A

Sick cell anemia haplotypes.

8
Q

Using crossover events to map gene location, what test can be used to map three linked genes?

A

Three-point testcross

9
Q

What is coefficient of coincidence?

A

Number of observed double crossovers/number of expected double crossovers

10
Q

What is interference?

A

1 - coefficient of coincidence

11
Q

What are the 4 physical mapping methods used to determine the physical positions of genes on particular chromosomes?

A
  1. Physical and genetic maps differ. 2. Somatic-cell hybridization. 3. Deletion mapping. 4. physical mapping through molecular analysis (in situ hybridization).
12
Q

What do both genetic and physical maps do?

A

Illustrate the arrangement of genes and DNA markers on a chromosome.

13
Q

What is the difference between physical and genetic maps?**

A

Genetic map is based on crossing over, how many crossing over events can occur between 2 genes. Physical map is the actual nucleotide position of the genes.

14
Q

What is a centimorgan?

A

Map unit measuring genetic linkage.

15
Q

What does it mean when theres more centimorgans between two genes?

A

Further the distance between them and more crossing over between them.

16
Q

Pertaining to physical mapping, what test can be used to determine which chromosome contains a gene of interest?

A

Somatic-cell hybridization

17
Q

How would you do somatic-cell hybridization?

A

Get mouse and human cells together and they can fuse. Fairly stable and they realized that mouse chromosomes are telocentric and apparently mouse chromosomes are more dominant than human chromosomes and humans get kicked out. We have a cell that have mouse chromosomes and human chromosomes so if we have a marker and can extract it, then if we can identify the chromosome then we can identify that chromosome. Could establish a collection of lines, varies components of the human chromosomes.

18
Q

What can deletion mapping be used to determine?

A

To determine the chromosomal location of a gene

19
Q

What is the idea of deletion mapping?

A

The idea is that a gene happens to occur in a deleted region, if we can connect the phenotype to that deleted region we can say this is what happens

20
Q

What is one ex of a disease that was found with deletion mapping?

A

Duchenne muscular dystrophy. By looking at g banding on the boys with ducheenes they noticed some of them had deletions and that all deletions happened in the same spot on the X chromosome.

21
Q

What is in situ hybridization used for?

A

Another technique used for determining the chromosomal location of a gene

22
Q

What is an example of situ hybridization?

A

FISH.

23
Q

How is the test FISH done?

A

DNA probe containing gene is dyed with fluorescent dye and then hybridized to interphase or metaphase cells.

24
Q

What does FISH detect?

A

Small regions of deletions or duplication

25
Q

In what specific regions does FISH examine?

A

non-dividing tissues

26
Q

What three diseases can be found via FISH?

A

Prader-willi syndrome (PWS), Angelman syndrome (AS), and DiGeorge syndrome

27
Q

What is PWS caused by?

A

PART Deletion of chromosome 15, passed down from dad.

28
Q

What are some symptoms of PWS?

A

Behavior probs, intellectual disability, short height, delayed puberty, constant hunger.

29
Q

What is AS caused by?

A

Deletion of inactivation of genes on chromosome 15, passed down from mom.

30
Q

What are some symptoms of AS?

A

Severe intellectual and developmental disability

31
Q

What is DiGeorge Syndrome (deletion syndrome) caused by?

A

Most common microdeletion syndrome. Deletion near centromere on chromosome 22.

32
Q

What are some symptoms in DiGeorge Syndrome (deletion syndrome)?

A

Heart defects, poor immune system function, cleft palate, behavioral issues, low calcium.

33
Q

Genetic mapping must account for what?

A

Recombination rates that exhibit extensive variation

34
Q

In what three ways do levels of recombination vary widely?

A

Among species, among chromosomes of a single species(called hotspots) , and between M and F.

35
Q

What is MLH1?

A

Mismatch repair protein that is associated with crossover events

36
Q

What is a double edge sword for humans? How?

A

High recombination events per chromosomes. Good for genome evolution but more potential for rearrangements and breaks.

37
Q

What do (GWAS) genome wide association studies examine?

A

Genetic (sequence) variants across the entire genome to find those that are associated with a trait or disease

38
Q

How do people use GWAS?

A

Compare the genome of those with disease versus those who dont and seeing what they share.

39
Q

What are some weakness to GWAS?

A

The results are hard to interpret. Variants associated with a trait often occur in noncoding parts of the genome.

40
Q

What is Ambry genetics?

A

Company that does sequencing, that puts all the pts templates open to all to access and do GWAS.