genetics

Question 1

What are mutations (germ line vs somatic)

Answer 1

mutation - change in DNA sequence
mutations in non coding regions can still have effect
germline - hertiable
somatic - non heritable
can be in coding - affects proteins
non coding regions - can affect gene regulatory regions

Question 2

What are the scales of mutation

Answer 2

DNA lvl - single nucl, few base pairs
- insert, del, sub
chromosomal rearrangments - hundreds or throusand bp
changes in chromosome numb - aneuploidy, polyploidy

Question 3

what are alleles

Answer 3

Varients of genes are called alleles
Humans have 2 copies of all of our genetic content
Each parent can have diff allele
Alleles that are more abundant are wildtype

Question 4

What is spont vs induced mutation`

Answer 4

Spontaneous - no known cause, can be from replication errors infrequent (can be casued by replication error, transposons)
Induced- there is agent that causes disruption. Like x rays
Ultra violet radiation, when you step outside

Question 5

Effects of mutation

2 types + 5 subtypes

Answer 5

Loss of functions - reduces or abolishes protein funct
- null (amorphic) - complete loss
- hypomorphic - incomplete, reduced activity
Gain of function -increase activity or new funct, almost always dominant
-Hypermorphic -increase protein efficiency, not necessarily good
-Neomorphic- allwos it to do new things
-Dominant neg - it creates a new allele with a new protien function but it is to antagonize the normal protein

Question 6

What are haplo insufficient genes`

Answer 6

Haplo insufficient - when the dominant gene is not able to carry the function of the gene
If there is a mutation with the recessive allele in a heterozygous organism and the single proper dominant allele is not enough to carry the whole function
results in recessive acting like dominant?

Question 7

Dominant neg vs loss of funciton mutation

Answer 7

Dominant neg is when one of the dominant alleles gains the new function to antagonize the normal protein funciton, looks like loss of function
Loss of function - the mutation causes loss of function of protein

Question 8

example of loss of funct and gain of funct in cancer

Answer 8

P53 is important tumor suppressor/transcription factor
will stop cell growth in G1 or G2 if finds problems
when loss of funct - if the DNA binding domain(DBD) of the protein is mutated and can’t bind to DNA it can’t detect issues with the cell DNA. P53 does not work, only happens if both alleles messed up
when gain of funct - mutant p53 that suppresses normal P53. Does the opposite of normal P53. deccreases apoptosis and DNA repair gene expression. increases cell cycle. looks liek loss of funct mut

Question 9

How do point mutations happen

tautomer

Answer 9

through transient isomeric nucleotide
GC usually has 3 bonds
TA has 2
When the tautomeric thymine comes in it might be able to bind with guanine during DNA replication
On the second round of DNA replication A will bind with the tautomeric T
But that’s not the usual base pair in that location
The tautomer will reverse to normal thymine and will continue to act as thymine for the rest of the replications
ex sickle cell anemia

Question 10

What are framshift mutations

Answer 10

insertions or deletions that cause the reading frame, changes the polypep seq
called indels

Question 11

How do indels happen

Answer 11

small indels - replication slippage, insertion or deletion when replicating over repeating sequence.
large indels - transposons, unequal crossing over of chromosmes, Expanded trinucleotide repeats

Question 12

what are Expanded trinucleotide repeats

Answer 12

type of large frameshift mutationj
when 3 nucl repeat a lot in sucession
Expanded trinucleotide repeats - type of insertion that arises due to slippage in regios withtrinucleotide repeats
ex huntingtons

Question 13

how is huntingtons and example of Expanded trinucleotide repeats

Answer 13

expanded CAG
if a person has too many CAG repeats then they get huntingtons
ppl are supposed to have less than 28
Expanded trinucleotide repeats incrases with each generation, called ANTICIPATION

Question 14

What are the key steps in the central Dogma

Answer 14

transcription
splicing
translation

Question 15

Nucleoside vs nucleotide

Answer 15

Nucleoside is like nucleodite but without the phosphorous group on the C5

Question 16

Deoxyribonucleic acid vs ribonucleic acid

Answer 16

DNA - has one less OH group
RNA - has extra OH group on carbon 2
both of them contain a ribose (5 carbon) sugar, have Phosphate group on c5
both of them can have a nitrogenous base on c1

Question 17

What are phosphodiester bonds and where do they form

Answer 17

formed between the phosphate group on C5 and the OH group in C3 of the next nucleotide

Question 18

why are single stranded DNA rare

Answer 18

ssDNA is very fragile
mRNA is single stranded and it is fragile
some non coding RNA is actually very strong though bc it can fold in on itself

Question 19

What are Histones

Answer 19

proteins that help hold DNA together,
Histones+ DNA = chromatin
provide structure and prevents degredation of DNA

Question 20

What is the core promoter

Answer 20

the segment of DNA that is aroudn 20-50 bp wthin the transcription start site, required to start transcription, ex Taataa box.

Question 21

What is proximal and distal promoter sequenct

Answer 21

proximal - upstream of core promoter, 100-200 bp from start, recognized by specific transcription factors, ex Kaiso
distal - found far upstream or downstream, can be enhancers or silencers depending on how it interacts with RNA polii, DNA can fold it over and meet proximal or core promoter

Question 22

What does terminator seq do

Answer 22

terminates transcriptoin

Ex the poly A tail in mRNA. Once it is read it causes confomational change which destabalizes it and ends transcription

Question 23

C value paradox vs G value paradox

Answer 23

c paradox - The size of the genome does not correlate with the complexity with the organism, amoebas have more bp than humans
G paradox -the discrepancy between the complexity of the protein coding genes and the amount of base pairs. This is because Some proteins are codes by the same locus. Multiple proteins can come form 1 gene

Question 24

What is splicing + how does it work

Answer 24

Process by which introns are removed from a primary transcript(pre-mRNA) to make the mature transcript(mRNA)
mediated by spliceosome
all introns have branchpoint in the middle (A)
the A binds to the beginning of the intron
disconnects the beginning of the intron with the end of the last exon
makes lariat intermediate
end of last exon binds to start of next exon and lariat is removed

Question 25

What is alternative splicing + types (5, CMEAI)

Answer 25

the same sequence of DNA can have multiple mRNAs made from it constitutive splicing - take out all introns mutually exclusive splicing - 1 exon is kept at the expense of another exon skipping- skip an exon alternate 3'/5' - an exon can be split up and one part excluded intron retention - keep an intron, not common

Question 26

What happens in translation

Answer 26

mature mRNA is read by ribo to make polypep chain from amino acids uses tRNAs which hold amino acids

Question 27

Steps in translation, 3

Answer 27

initiation eleongation termination

Question 28

key step in expression of protein coding genes