DNA, RNA And Genes

Question 1

Common diseases associated with gene malfunction

Answer 1

Cystic fibrosis;
Alzheimer’s disease;
Parkinson’s disease;
Diabetes;
Heart disease;
Cancer;
Sickle cell anaemia;

Question 2

Nuclei acids contain inorganic phosphate in two forms, which are?

Answer 2

Phosphate (Pi);

Pyrophosphate (PPi);

Question 3

Phosphodiester bond properties

Answer 3

Polar;

Assymetric;

Question 4

Directionality

Answer 4

5’ to 3’

Question 5

Any polynucleotide has polarity because?

Answer 5

It’s ends are not chemically identical

Question 6

Which end of a polynucleotide is not defined by the presence of a phosphate?

Answer 6

5’ end

Question 7

By convention, nuclei acid sequences are written in which direction?

Answer 7

5’ to 3’;

Left to right;

Question 8

All nucleic acid polymerisation reactions proceed in which direction?

Answer 8

5’ to 3’

Question 9

Describe DNA double helix

Answer 9

2 polynucleotide chains coiled around common axis;
Anti-parallel - 5’ to 3’ in opposite directions;
Bases on inside and sugars, phosphate on outside;
Base plane 90 degrees to helix axis;
Chains held together by - H bonds, hydrophobic stacking forces;
Right-handed helix;

Question 10

A chemical that inserts between stacking bases

Answer 10

Benzo[a]pyrene

Question 11

Genetic information

Answer 11

Sequences of bases on one strand carries genetic information;
Species specific; slight variations within species;
Inherited from one cell to Daughter cells or one organism to progeny;
Expressed in each cell/organism to control shape, form, function;

Question 12

Sequence of bases is called

Answer 12

Genetic code

Question 13

Genotype

Answer 13

DNA - store of genetic info

Question 14

Phenotype

Answer 14

Expressed info

Question 15

Unit of DNA function

Answer 15

Gene

Question 16

DNA is packaged into

Answer 16

Chromosomes

Question 17

Two possibilities of DNA replication

Answer 17

Conservative replication - all of parental DNA conserved in one Daughter molecule;

Semi-conservative replication - half of parental DNA in each Daughter molecule;

Question 18

DNA synthesis needs

Answer 18

All 4 deoxynucleotide triphosphates (dTTP; dATP, dGTP, dCTP) ;
Requires an RNA primer;

Question 19

DNA gyrase inhibitors used as anti-bacterial therapy for bacterial infections because

Answer 19

Eukaryotic DNA does not require DNA gyrase;
Nalidixic acid - DNA gyrase A inhibitor;
Novobiocin - DNA gyrase B inhibitor;
Ciprofloxacin - targets DNA gyrase enzymes;

Question 20

Etoposide is a topoisomerase II inhibitor and is used as. An anti-cancer chemotherapeutic because

Answer 20

Eukaryotic DNA replication requires topoisomerase enzymes

Question 21

Sulphonamide drugs specifically inhibit folic acid synthesis as

Answer 21

Bacteria makes folic acid

Question 22

RNA species in eukaryotic cells

Answer 22

MRNA;
RRNA;
TRNA;
HNRNA;
7S RNA;
RRNA comprises vast majority of cell’s RNA;

Question 23

MRNA is initially produced as a precursor

Answer 23

MRNA first produced as hnRNA;
HNRNA contains non-coding intron sequences;
HNRNA is processed after transcription to yield mature mRNA;
Introns within hnRNA are removed by splicing;

Question 24

Important features of mRNA

Answer 24

RBS/kozak sequence;
5’ cap;
Start codon;
Stop codon;
Coding sequence/open reading frame
Poly(A)tail;
3’ UTR;

Question 25

5’ cap of eukaryotic mRNA

Answer 25

Added post transcriptionally;
5’ to 5’ triphosphate linkage;
Important fo translation;

Question 26

Eukaryotic mRNAs have UTRs

Answer 26

Untranslated region;
Has both 5’ and 3’ UTRs;
UTRs carry important information affecting translation and mRNA stability;
UTR mutation causes human disease;

Question 27

MRNAs carry specific translation initiation points - includes 2 main elements

Answer 27

Start/initiation codon -AUG;
Ribosome binding site/Kozak sequence;

RBS (Shine Dalgarno sequence) -
Spacing with respect to AUG critical;
Specific to bacterial mRNAs only;

Kozak sequence:
Positions -3 and +4 critical

Question 28

Coding region

Answer 28

Open reading frame (ORF)

Question 29

Correct reading frame is defined by

Answer 29

AUG start codon

Question 30

Termination required specific signal

Answer 30

Web termination/stop codon is reached;
3 stop codons:
UGA (Opal);
UAG (amber);
UAA (ochre);

Question 31

Most eukaryotic mRNAs carry a 3’ tail

Answer 31

Tail added post transciptionally;
Tail is a non-template directed polymer of A residues now as a poly(A) tail;
Tail addition requires consensus sequence;
Tail aids in efficient nucleocytoplasmic transport, regulates mRNA stability and translation;