block A - DNA replication + gene expression

Question 1

which bases are pyrimidines?

Answer 1

cytosine, thymine and uracil

Question 2

which bases are purines?

Answer 2

adenine and guanine

Question 3

what is the central dogma of molecular biology?

Answer 3

DNA -> RNA -> protein

Question 4

what is a nucleoside?

Answer 4

a base conjugated to a sugar

Question 5

what are the names of the four nucleosides?

Answer 5

(deoxy) adenosine, guanosine, cytosine and thymidine

Question 6

what is a nucleotide?

Answer 6

a nucleoside conjugated to one or more phosphate groups

Question 7

what are chargaff’s rules?

Answer 7

DNA has equal numbers of adenine and thymine + equal numbers of guanine and cytosine

Question 8

which direction does synthesis occur (prime to prime)?

Answer 8

5’ to 3’

Question 9

how many prokaryotic DNA polymerases are there?

Answer 9

three

Question 10

how many eukaryotic DNA polymerases are there?

Answer 10

five

Question 11

what are the names of the prokaryotic DNA polymerases?

Answer 11

DNA Pol I, DNA Pol II and DNA Pol III

Question 12

what are the names of the eukaryotic DNA polymerases?

Answer 12

DNA Pol α, DNA Pol β, DNA Pol γ, DNA Pol δ and DNA Pol ε

Question 13

which polymerase is involved in mRNA synthesis?

Answer 13

RNA Pol II

Question 14

what are the stages of mRNA synthesis?

Answer 14

initiation -> elongation -> termination

Question 15

what happens during initiation of mRNA synthesis?

Answer 15

RNA Pol II and transcription factors assemble at promoter sites and the RNA chain is modified with a 5’ cap

Question 16

why is the RNA chain modified with a 5’ cap?

Answer 16

to protect mRNA from degradation and to facilitate efficient translation

Question 17

what happens during elongation of mRNA synthesis?

Answer 17

RNA Pol II moves along the DNA template to synthesise mRNA growing in a 5’ -> 3’ direction

Question 18

what happens during termination of mRNA synthesis?

Answer 18

RNA Pol II ceases transcription at a defined site and the mRNA transcript is stabilised by modifications

Question 19

which specific DNA sequences recruit RNA Pol II and define the point of transcription initiation?

Answer 19

CAAT boxes and TATA boxes

Question 20

what does a poly A tail at the 3’ end do?

Answer 20

enhances translation efficiency and RNA stability

Question 21

what is the definition of epigenetics?

Answer 21

modifications of the genome that affect gene expression but do not alter the DNA sequence

Question 22

what is DNA methylation?

Answer 22

the addition of methyl groups to nitrogen bases of nucleotides modulating DNA structure and regulating gene expression (mainly gene silencing)

Question 23

what is chromatin?

Answer 23

the overall DNA-histone complex

Question 24

what is a nucleosome?

Answer 24

a DNA-histone octamer complex

Question 25

what assemble to make up an octamer?

Answer 25

four histone subunits

Question 26

what is altered when a CpG island undergoes chemical modification?

Answer 26

the binding of transcription factors

Question 27

70% of CpG islands are methylated in which type of genome?

Answer 27

mammalian genomes

Question 28

what is prevented by methyl-binding proteins binding to methylated DNA?

Answer 28

the binding of transcription factors

Question 29

which enzyme acetylates a histone?

Answer 29

HATs - histone acetyltransferases

Question 30

which enzyme deacetylates a histone?

Answer 30

HDACs - histone deacetylases

Question 31

what does histone methylation correlate with?

Answer 31

transcriptional activity or transcriptional inactivity

Question 32

how is euchromatin different to heterochromatin?

Answer 32

euchromatin is loosely packed, enriched in genes and under active transcript

Question 33

how is heterochromatin different to euchromatin?

Answer 33

heterochromatin is tightly packed, inaccessible to RNA polymerase and generally genetically inactive

Question 34

what does acetylation correlate with universally?

Answer 34

gene activity

Question 35

how many introns does the average human gene have?

Answer 35

eight

Question 36

which base code do all introns begin with?

Answer 36

GU - guanine, uracil

Question 37

which base code do all introns end with?

Answer 37

AG - adenine, guanine

Question 38

what increases the number and length of introns?

Answer 38

the complexity of the organism

Question 39

what is a rough range of nucleotides for intron size variation?

Answer 39

50 to 10000

Question 40

what is generated by alternate splicing?

Answer 40

proteins with different functions

Question 41

what does cell communication failure and impairment lead to?

Answer 41

disorder, disease and death

Question 42

why do cells signal?

Answer 42

to regulate physiological activities

Question 43

what is the result of cell signalling?

Answer 43

changes to gene expression

Question 44

what is intercellular signalling?

Answer 44

communication between cells

Question 45

what is intracellular signalling?

Answer 45

signalling within a cell

Question 46

is synaptic transmission an example of intercellular or intracellular signalling?

Answer 46

intercellular signalling

Question 47

are second messengers an example of intercellular or intracellular signalling?

Answer 47

intracellular signalling

Question 48

what is impacted by bias existing in extracellular signal and intracellular signal location?

Answer 48

the kinetics of the response

Question 49

what is a signalosome?

Answer 49

a large supramolecular complex

Question 50

what are the names of the four major types of cell signalling receptors?

Answer 50

ligand-gated ion channel receptors, G-protein coupled receptors, kinase-linked receptors and nuclear receptors

Question 51

what is the timescale of ligand-gated ion channel receptors

Answer 51

millisecond timescales

Question 52

what is the timescale of G-protein coupled receptors?

Answer 52

second timescales

Question 53

what is the timescale of kinase-linked receptors?

Answer 53

hour timescales

Question 54

what is the timescale of nuclear receptors?

Answer 54

hour/day timescales

Question 55

what is the timescale of cell-matrix adhesion receptors?

Answer 55

minute timescales