Nucleotides

Front 1

What is the mechanism of Actinomycin D and what organisms does it work against?

Back 1

Actinomycin D prevents transcription.

Actinomycin D works against both bacteria and eukaryotes.

Front 2

What is the mechanism of Puromycin and what organisms does it work against?

Back 2

Puromycin disrupts translation.

Puromycin D works against bacteria and eukaryotes.

Front 3

What is the mechanism of Tetracycline and what organisms does it work against?

Back 3

Tetracycline prevents blocks the binding of aminoacyl-tRNA to the ribosome.

Tetracycline works on bacteria.

Front 4

What is the mechanism of streptomycin and what organisms does it work against?

Back 4

Streptomycin inhibits translation.

Streptomycin works on bacteria.

Front 5

What is the mechanism of chloramphenicol and what organisms does it work against?

Back 5

Chloramphenicol inhibits translation.

Chloramphenicol works on bacteria.

Front 6

What is the mechanism of erythromycin and what organisms does it work against?

Back 6

Erythromycin inhibits translation.

Erythromycin works on bacteria.

Front 7

What is the mechanism of rifampicin and what organisms does it work against?

Back 7

Rifampicin blocks the initiation of RNA polymerase, inhibiting RNA synthesis.

Rifampicin works on bacteria.

Front 8

What is the mechanism of cycloheximide and what organisms does it work against?

Back 8

Cycloheximide blocks the translocation reaction the ribosome, inhibiting translation.

Cycloheximide works on eukaryotes.

Front 9

What is the mechanism of anisomycin and what organisms does it work against?

Back 9

Anisomycin blocks the peptidyl transferase reaction on the ribosomes, inhibiting translation.

Anisomycin works on eukaryotes.

Front 10

What is the mechanism of α-Amanitin and what organisms does it work against?

Back 10

α-Amanitin block mRNA synthesis by binding to RNA Polymerase II and III

α-Amanitin works on eukaryotes.

Front 11

Which properties are unique for RNA polymerase (compared to DNA polymerase)?

Back 11

- Creates a cap on the 5' end

- Does not need a primer

- Has no nuclease activity

- Copies only certain genes, not the whole DNA

Front 12

Which properties are similar between RNA polymerase and DNA polymerase?

Back 12

Both:

- synthesize in the 5' -> 3' direction

- have similar mechanism of elongation

- have similar processivity

- work by hydrolysis of pyrophosphate

Front 13

Name 3 proteins (not DNA polymerases) that can be found in the replication fork of E. coli.

Back 13

Helicase, ligase and primase

Front 14

Describe briefly the mechanism of the spliceosome.

Back 14

The spliceosome is comprised of several snRNPs (small nuclear ribonucleic proteins).

One snRNP binds to the 3' end of the intron while another binds to the 5' end. Other snRNPs lead these two snRNPs together, making the intron into a loop. The snRNPs then cut out the loop and ligate the exons together.

Front 15

Which transcription factor is the main regulator of TNF-α expression?

Back 15

NF-kB is the main transcription factor of all pro-inflammatory cytokines, including TNF-α, IL-1 and IL-6.

Front 16

Describe how the amino acid selenocysteine is be incorporated into proteins.

Back 16

There is no codon for selenocysteine. Instead, special tRNA(Ser) will recognize some UGA codons (which is usually a stop codon) and insert the amino acid serine.

Serine is then selenylated by an enzyme to become selenocysteine.

Front 17

Define the term "tumor suppressor".

Back 17

A tumor suppressor gene encodes for a protein involved in either DNA repair, promotion of apoptosis or inhibiting cell proliferation.

When this gene is mutated, the protein product can no longer execute its normal function and can allow the cell to proliferate uncontrolled.

Front 18

What is the role of Sirt1 in the regulation of FOXO transcription factor?

Back 18

Sirt1 activates FOXO by removing an acetyl-group from it.

Front 19

Define the term "proto-oncogene".

Back 19

A proto-oncogene is a gene that encodes for a protein involved in cell proliferation or inhibiting cell death.

When this gene is mutated it can become an oncogene, which encodes for a protein that causes uncontrolled activation of cell division or uncontrolled inactivation of apoptosis.

Front 20

Describe briefly processing of tRNA.

Back 20

tRNA is transcribed by RNA polymerase III, and is then cut at the 5' and 3'-ends by RNases. The sequence CCA is then added to the 3'-end.

Many of the tRNA bases are then modified by posttranslational modification (methylation, deamination and reduction).

Front 21

Which protein in the replication fork has no enzymatic activity?

Back 21

Single-strand binding protein (SSB)

Front 22

How does acetylation of histones regulate gene expression and why?

Back 22

Acetylation of histones activates genes while deacetylation deactivates genes.

Acetylation relaxes the DNA around the histone, making it easier to transcribe.

Front 23

How does methylation of DNA regulate gene expression?

Back 23

Methylation of DNA deactivates genes.

Front 24

What is the primer for reverse transcriptase?

Back 24

tRNA is the primer for reverse transcriptase.

In HIV the primer is tRNA(Lys)

Front 25

Name the enzymes involved in nucleotide excision repair.

Back 25

ABC excinuclease, DNA helicase, DNA polymerase I and DNA ligase are involved in nucleotide excision repair.

Front 26

Name the enzymes involved in base excision repair.

Back 26

DNA glycosylase, AP endonuclease, DNA polymerase I and DNA ligase are involved in base excision repair.

Front 27

Which enzymes are involved in direct repair?

Back 27

AlkB

O6-methylguanine-DNA methyltransferase.

DNA photolyase

Front 28

Which cofactors does AlkB need?

Back 28

AlkB requires α-ketoglutarate and Fe2+ to work.

Front 29

Which enzymes are involved in methyl-directed mismatch repair?

Back 29

Mut-complex

Exonucleases

Helicase

DNA polymerase III and Dam methylase

Front 30

What is the "secondary genetic code"?

Back 30

The interaction between aminoacyl-tRNA synthetase and the tRNAs is sometimes called the "secondary genetic code".

Front 31

What are the types of eukaryotic RNA polymerase?

Back 31

RNA polymerase I

RNA polymerase II

RNA polymerase III

Front 32

Which RNA polymerase transcribes tRNA?

Back 32

RNA polymerase III

Front 33

Which RNA polymerase transcribes mRNA?

Back 33

RNA polymerase II

Front 34

In what way can bacterial antibiotics be toxic to humans?

Back 34

The mitochondria in eukaryotic cells are similar to prokaryotes, so bacterial antibiotics can affect mitochondrial DNA transcription and translation.