IASM 02-07 Some Basics of Medicine

Question 1

Name the process causing RNA to become back DNA

Answer 1

Reverse Transcription

Question 2

For Deoxyribose molecule, what are connected to the following bases?
1'
2'
3'
5'

Answer 2

1’: Base
2’: OH
3’: Bond to the next nucleotide
5’: Bind to phosphate

Question 3

DNA has a ___________helix structure

Answer 3

Right handed helix

Question 4

Which bases are purines

Answer 4

A G

Question 5

Which bases are pyrimidines

Answer 5

C T (CT scan!)

Question 6

How many H bonds are there between A and T bases, C and G bases respectively?

Answer 6

A and T: 2

C and G: 3

Question 7

In transcription, the TEMPLATE strand is read from _____ to _____. In translation, the mRNA strand is read from _____ to _____.

Answer 7

Transcription template strand is read from 3’ to 5’
For the mRNA, the transcription direction is from 5’ to 3’ of that mRNA.

5’ to 3’ (Translation mRNA)

Question 8

Name the defective gene in Sickle cell Anaemia

Answer 8

HBB

Question 9

Name the amino acid change in Sickle Cell Anaemia, and then what’s the change in terms of hydrophobicity?

Answer 9

Glutamic Acid to Valine

From hydrophilic to hydrophobic

Question 10

Normal haemoglobin adopts a _________ structure.
Foetus haemoglobin adopts a _________ structure.
Foetus haemoglobin has a _______ affinity to oxygen

Answer 10

Normal haemoglobin adopts a Alpha 2 Beta 2 structure.
Foetus haemoglobin adopts a Alpha 2 Gamma 2 structure.
Foetus haemoglobin has a higher affinity to oxygen

Question 11

Name the amino acid deletion of Cystic Fibrosis

Answer 11

Delta F508

Absence of Phenylalanine

Question 12

In CRISPR-Cas9, there is Tracr RNA and Guide RNA. What are their functions respectively?

What do they form

Answer 12

Tracr RNA: Scaffolds to Cas9 protein
Guide RNA: Bind to the target DNA Sequence
They form sgRNA

Question 13

Process of the gene cutting:

sgRNA binds to \_\_\_\_\_
Cas9 binds to \_\_\_\_\_
DNA \_\_\_\_\_\_\_
\_\_\_\_\_\_\_ binds to the target sequence
\_\_\_\_\_\_\_ cuts the original DNA leading to modification

Answer 13

Process of the gene cutting:

sgRNA binds to Cas9 (Responsibility of Tracr RNA)
Cas9 binds to PAM
DNA unwinds
gRNA binds to the target sequence (responsibility of Guide RNA)
Cas9 cuts the original DNA leading to modification

Question 14

Transcription by RNA polymerase is a ______ dependent reaction

Answer 14

Magnesium

Question 15

Describe the 2 further processes after transcription

Answer 15

1. Addition of Poly A Tail at 3’

2. Splicing (by spliceosome) to remove introns to obtain the final mRNA

Question 16

Name a disease caused by splicing problems, and name the respective genes responsible for it?

Answer 16

Spinal Muscular ATROPHY

Genes: SMN1, SMN2

Question 17

Name a start codon

Answer 17

AUG

Question 18

Name the stop codons

Answer 18

UAG UGA UAA

Question 19

What is the function and significance of Aminoacyl tRNA synthase

Answer 19

Links amino acid with tRNA

Matches the amino acid with the anticodon

Question 20

Name the 4 histone proteins

Answer 20

H2A
H2B
H3
H4

Question 21

Name the enzyme required to convert mRNA to cDNA

Answer 21

Reverse Trnascriptase

Question 22

Microarray:
Isolate ______ from normal people
Convert to _____ using ________
________ label the cDNA of normal patient in red, and the diseased patient in green
In the microarray, there are multiple nucleotide sequences in _____, they are known sequences to some important genes in human genome
_____ binds to the probes, unbound cDNAs are ________.

Colour red > green: _____________

No colour: ___________

Answer 22

Microarray:
Isolate mRNA from normal people
Convert to cDNA using reverse transcriptase
Fluorescently label the cDNA of normal patient in red, and the diseased patient in green
In the microarray, there are multiple nucleotide sequences in probes, they are known sequences to some important genes in human genome
cDNA binds to the probes, unbound cDNAs are washed off.

Colour red > green: gene is more expressed in healthy people

No colour: gene is not expressed in both healthy and diseased people

Question 23

Humans use which type of amino acids

L type or D type

Answer 23

L-alpha amino acid

Question 24

How to distinguish L type from D type amino acid? Name the CORN rule

Answer 24

with H facing towards you, L type amino acids spell CORN in clockwise direction

Question 25

Which amino acid is the simplest and has no enantiomers

Answer 25

Glycine

Question 26

Which amino acid forms disulphide bonds?

Answer 26

Cysteine

Question 27

What is a primary structure of amino acids

Answer 27

Sequence of amino acid from N to C terminal

Question 28

Name 2 secondary structures for amino acids

Answer 28

Alpha Helix

Beta sheet

Question 29

Is alpha helix a left-handed helix or right–handed helix

Answer 29

Right-handed

Question 30

Name the structure of Beta Sheet

Answer 30

Pleated Structure

Question 31

For Tertiary Structure, it is still _____

Answer 31

only 1 polypeptide

Question 32

For Quaternary Structure, it has _____ (number) polypeptide chain

Answer 32

More than 1

Question 33

Name an example of Quaternary Structure

Answer 33

Haemoglobin

Question 34

Haemoglobin has 4 sub units, each sub-unit carries a ______

Answer 34

Haem