Ubc Med 1 Week 3

Front 1

What are differences between rna and dna

Back 1

RNA = uracil, un methylated thymine
has OH at 2' C of ribose

What is the impact of these differences?

Hint 1

Un-methylated...

OH - much more likely to hydrolyse bw OH on 3' (also for DNA) and 2'

RNA much less stable

Front 2

What are the RNA pols and what do they do?

Back 2

RNA pol I = 28S, 18S and 5.8S subunits of rRNA
RNA pol II = mRNA
RNA pol III = tRNA + 5S rRNA

which is the most common?

Hint 2

RNA pol II

Front 3

what are common shapes of proteins?

Back 3

Globular - globin

Fibrous - keratin and collagen

Front 4

Give a detailed structure of hemoglobin

Back 4

2 alpha 2 beta
globin chains each binding to a heme.

What is heme?

Hint 4

Heme is produced in mitochondria and cytosol, and contains a porphyrin + iron
Iron binds O2 reversibly
Allosteric!!

Front 5

What does allosteric mean?

Back 5

Changing shape, applied to hemoglobin, the binding of one O2 to one heme group alters the conformation of the other three, making their affinity to O2 higher

Front 6

Define aliphatic

Back 6

small neutral hydrocarbons
hydrophobic

Front 7

give the general structure of an amino acid

Back 7

R
H2N--C--COOH
H

Label +ve and -ve sides, what is charge at physio conditions

Hint 7

COO-
NH3+
net charge neutral

Front 8

Why is the shape of a peptide bond flat?

Back 8

C-N peptide bond has partial double bond character due to shared electrons

means?

Hint 8

that the C-N bond cannot rotate and the only rotation occurs at alpha C... much more stable conformation of 3D structure

Front 9

Why is polycistronic RNA formed?

Back 9

Operon for bacteria is a promoter, operator and the gene cluster associated with a specific purpose

Front 10

Define aliphatic

Back 10

small neutral hydrocarbons
hydrophobic

Front 11

give the general structure of an amino acid

Back 11

R
H2N--C--COOH
H

Label +ve and -ve sides, what is charge at physio conditions

Hint 11

COO-
NH3+
net charge neutral

Front 12

Why is the shape of a peptide bond flat?

Back 12

C-N peptide bond has partial double bond character due to shared electrons

means?

Hint 12

that the C-N bond cannot rotate and the only rotation occurs at alpha C... much more stable conformation of 3D structure

Front 13

Why is polycistronic RNA formed?

Back 13

Operon for bacteria is a promoter, operator and the gene cluster associated with a specific purpose

Front 14

what is colinear dna?

Back 14

When teh DNA sequence is identical to the RNA sequence

where do you see this?

Hint 14

in bacteria, humans do not have colinear dna due to introns

Front 15

5' to 3' what are typical regions of human dna

Back 15

5' flanking
enhancer
adapter
uar
TATA
exon-intron
3' flanking sequence

Front 16

Define - enhancer

Back 16

increases rate of transcription in a tissue specific manner - located most 5'

Front 17

Define - adapter

Back 17

turns gene on in response to a stimulus (hormone)

Front 18

Define - UAR

Back 18

Upstream regulatory region
site of recruitment and binding of transcription factors culminating in the assemby of hte protein complex at tata

Front 19

define - PIC

Back 19

Preinitiation complex
- binding of RNA Pol II and transcription factors to tata box

Front 20

what is the looping out model of transcriptional activation

Back 20

transcription factors bind to UAR and interact with PIC at the tata box to up regulate the level of transcription

Front 21

what happens to primary transcript before leaving the nucleus

Back 21

5' flanking sequence cleaved and 7 MeG cap put on
Introns removed by spliceosome
3' poly A tail added (100-150 nt)

What does the poly A tail do?

Hint 21

Adds stability

Front 22

how are aa's attached to the tRNA

Back 22

the C of the COOH and the 3' OH of the tRNA ribosome

Front 23

which are the stop codons

Back 23

UGA
UAG
UAA

Front 24

Which bases are purines? Pyrimidines?

Back 24

A and G

C, T, U

What is the difference?

Hint 24

Purines = 2 rings
Pyrimidines = 1 ring

Front 25

Coding strand is 'read' in which direction by the RNA polymerase II

Back 25

Coding strand is not really read, but the template strand is. Template strand is read 3'--> 5' producing a complimentary mRNA identical to the coding strand

Front 26

which is the start codon?

Back 26

AUG = methionine

What is the anticodon for this?

Hint 26

codon = 5' AUG 3'
tRNA = 3' UAC 5'

mRNA is translated 5' to 3'

Front 27

which rRNA site sits on the start codon?

Back 27

P = AUG
A site is on the next codon - downstream - towards 3' end

what happens next?

Hint 27

P site methionine added
A site next codon added
P site moves to next codon site and A site moves down one
Releases meth tRNA, meth peptide bonded to next codon aa

Front 28

Is the free end of the methionine added N or C terminus?

Back 28

N!

C terminus of the meth is peptide bonded to the N of the next aa

Front 29

define mutation

Back 29

permanent inheritable change in the DNA sequence
<1% of population has this change
usually cause disease

Front 30

define polymorphism

Back 30

mutations which affect >1% of the population
usually benign/ silent

Front 31

what are 6 types of mutations

Back 31

1. gene deletion/ additions - trisomies
2. gene rearrangement - translocation, inversions
3. ins/del within a gene
4. nt substitution
5. splicing mutations
6. trinucleotide repeat expansions

Front 32

Alpha thalessemia is a result of what kind of mutation?

Back 32

deletion of an entire gene
alpha globin has 4 possible genes, two on each chromo, 2 genes from each parent

what are potential phenotypes?

Hint 32

4 deletions = hydrops fetalis
3 deletions = HbH disease, moderate hemolytic anemia, B tetramers formed
2 deletions = microcytic rbc
- can be 2 off one gene, or one off each
1 deletion = most common, minimal symptoms

Front 33

which chromosome has the alpha thalessemia gene?

Back 33

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