Genetic Markers Flashcards Preview

BIOL 2320 - Genetics > Genetic Markers > Flashcards

Flashcards in Genetic Markers Deck (25)
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1
Q

T or F: phenotypic variation based on alleles of a gene is the only type of variation between individuals

A

false! it’s just one type of variation

2
Q

T or F: much of the sequence variation in the human genome does not affect our phenotype

A

true

3
Q

What can be used as a marker to map the location of a gene?

A

sequence variation

4
Q

Describe genetic (molecular) markers

A

polymorphic DNA sequences used to map the location of a gene

5
Q

Where do genetic markers typically exist in the genome? Where else are they sometimes found?

A

typically in noncoding regions

sometimes within a gene

6
Q

What do genetic markers involve?

A

single nucleotide polymorphisms (SNPs)

restriction fragment length polymorphisms (RFLPs)

7
Q

Which type of genetic marker is more commonly used?

A

SNPs

8
Q

When do SNPs occur?

A

When one base pair is substituted by another base pair

ex.
A T C C G A C
T A G G C T G

A T C C G G C
T A G G C C G

9
Q

Approximately how many SNPs exist in the human genome?

A

~3.3 million

10
Q

Where are some SNPs located?

A

within a restriction enzyme recognition sequence

11
Q

What is a consequence of an SNP in a restriction enzyme recognition sequence?

A

a single nucleotide change within a restriction enzyme recognition sequence destroys the restriction site and causes a RFLP

12
Q

Describe RFLPs

A

Restriction Fragment Length Polymorphisms form when an SNP causes a single nucleotide change within a restriction enzyme recognition sequence and destroys the restriction site

ie., they are changes in DNA sequence

13
Q

How are RFLPs detected?

A

by DNA-cutting enzymes (restriction enzymes, specifically restriction endonucleases)

14
Q

What are the pieces of DNA that result from restriction enzymes cutting?

A

restriction fragments

15
Q

How do you know if there’s a restriction site present?

A

2 smaller fragments are created when the region is cut with a restriction enzyme

16
Q

How do you know if there’s no restriction site present?

A

one larger fragment is created when the region is cut with a restriction enzyme

17
Q

Why are DNA (restriction) fragments different lengths?

A

because of the single nucleotide difference in the DNA sequence (SNP)

18
Q

On an agarose gel, how would DNA (restriction) fragments differ?

A

they would have different band sizes

19
Q

What purpose do genetic markers serve?

A

they can be used to trace the inheritance of disease-causing alleles

20
Q

What can be determined by a genetic marker being within a gene?

A

the presence of the marker will indicate which allele a person has

21
Q

What is there risk of if a genetic marker is near a gene?

A

misdiagnosis due to crossovers

22
Q

How can the probability of misdiagnosis be determined?

A

knowing how far the genetic marker is from the gene

23
Q

What must first be determined before using a genetic marker to trace the inheritance of a disease-causing allele?

A

the arrangement of the genetic marker and disease-causing allele

ie., which version of the genetic marker is linked to the disease-causing allele

24
Q

What does it mean if an SNP disrupts a restriction enzyme site on the same chromosome as the recessive allele?

A

the presence of the restriction enzyme site can be used as a genetic marker for the presence of the dominant allele

25
Q

What can cause a misdiagnosis if the disease-causing gene and the genetic marker are on the same chromosome?

A

if crossover occurs during meiosis