SNPS, STRS, and Indels

Question 1

Define SNPS’s

Answer 1

single nucleotide polymorphisms

Question 2

Over how many mutations in the gene _____ have been associated with cystic fibrosis?

Answer 2

gene CFTR, 1500

Question 3

What does the gene CFTR do> why do mutations cause cystic fibrosis?

Answer 3

Gene CFTR encodes protein that maintains correct balance of salt and water on lungs, mutations cause buildup of mucus on lungs

Question 4

What results from changes in the dna sequence?

Answer 4

Common polymorphisms and rare mutations

Question 5

What are indels?

Answer 5

insertions-deletions

Question 6

What are STRs?

Answer 6

short tandem repeats

Question 7

What is the most common type of genetic variation among humans?

Answer 7

SNPS, single base pair differences between dna sequences

Question 8

What’s a transition SNP?

Answer 8

purine is replace with purine
pyrimadine is replaced with pyrimadine

Question 9

What’s a transversion SNP

Answer 9

purine replaces with a pyrimidine or vice versa

Question 10

What are the three causes of SNPS?

Answer 10

Spontaneous DNA replication error (as dna is synthesizing a mistake is made, ex: can be due to tautomerization
Chemical changes to a nucleotides (due to the fact that cell has water and free radicals that’ll react with dna ex: depurination, deamination
Induced mutations (exposure to chemicals mutagens ex: replacing or altering a base)

Question 11

What are tautomers?

Answer 11

bases which exist in different chemical isoforms with diff stabilities

Question 12

What is the keto tautomer?

Answer 12

The most common form in DNA, keto form of A bonds to T as expected

Question 13

What is tautomerization?

Answer 13

Changes in the positions of bases atoms and bonds between atoms, these changes occur rapidly and transition between on another and are in equilibrium

Question 14

What does the enol form of thymine do?

Answer 14

Bonds to guanine, making three H bonds

Question 15

How does DNA polymerase prevent msimatching?

Answer 15

they have proofreading ability, where they remove mismatched bases by working backwards in 3’ to 5’ direction and removing it.
they then extend and add the correct base

Question 16

Mistakes that escape proof reading by dna polymerase are usually corrected by what?

Answer 16

additional dna repair mechanisms

Question 17

Is DNA polymerase an effective repair mechanism? why?

Answer 17

yes, less than 1 error in every 10^10 nucleotides doesnt get repaired

Question 18

What is depurination?

Answer 18

is when bond between the base and sugar gets broken by hydrolysis, during replication sometimes no base is added or paired with another base resulting in mutations

Question 19

What is an apurinic cite?

Answer 19

no purine on the nucleotide

Question 20

How often does depurination happen?

Answer 20

200-1000 times a day in each human cell

Question 21

Depurination is so common, how does it get corrected?

Answer 21

Through DNA repair mechanisms

Question 22

What is deamination?

Answer 22

hydrolytic removal of an amino (NH2) group

Question 23

What three bases contain amino groups?

Answer 23

cytosine, adenine, and guanine

Question 24

What does deamination or depurination result in?

Answer 24

transitions and transversions

Question 25

What do indels include?

Answer 25

nonrepetivie indels (includes point mutations)
STRs (short tandem repeats (repeats of 2-9 nucleotides)
VNTRs (variable tandem repeats of 10-100 nucelotides)

Question 26

What is a point mutation?

Answer 26

singe base pair is added, deleted, or changed

Question 27

What is an insertion mutation that in non repetivie? What abut a deletion?

Answer 27

for example adding a g-c pair or deleting a gc pair

Question 28

What do the single insertion/deletion mutations result in?

Answer 28

frameshift mutations

Question 29

Say you remove nucleotides in a multiple of 3? Does this result in a frameshift?

Answer 29

NOPE

Question 30

Say you repeat 2 nucleotides 100 times, what is classified as?

Answer 30

STRs

Question 31

STRs are also known as ______

Answer 31

microsatellites

Question 32

There are over how many STR regions in the human genome?

Answer 32

1 million

Question 33

What are STRs present in?

Answer 33

exon, introns, regulatory regions, and non functional dna sequences, can influence protein and non proteins coding regions

Question 34

STRs have a high or low mutation rate?

Answer 34

high

Question 35

The number of alleles at a str region (locus) is how large?

Answer 35

usually 20+

Question 36

What is mre useful in pinpointing suspects, SNPS or STRs?

Answer 36

STRs, usually have more than 20+ so if they all match can be really sure

Question 37

What are trinucleotide repeats?

Answer 37

are when 3 same nucelotides repeated again and again ex: CAGCAGCAG

Question 38

If you repeat CAG in the HTT gene what happens?

Answer 38

might get huntingtons if theres more than 35 repeats

Question 39

What is the cause of STR alleles?

Answer 39

slippage in the daughter strand (can be due to GC binding making a semi stable structure) which causes template to be repeated twice.

Question 40

What causes deletion- the removal of repeats?

Answer 40

slippage of the template strand, so it doesnt get made created in daughter strand, causes deletion

Question 41

What can stop slippage?

Answer 41

repair mechanisms