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Question 1

What is bee promelittin? What may it be used for?

Answer 1

Melittein is the active component of bee venom, a small peptide (26aa)

Melittin is highly toxic to cells, and has anti microbial activity

Researchers are trying to use this to fight HIV and cancer

Question 2

what is RNAi?

Answer 2

dsRNA interference

Question 3

What is miRNA?

Answer 3

microRNA

Question 4

How long are RNAi and microRNA about? Also to whom are they specific to?

Answer 4

They’re 20 to 25 bp long

Specific to eukaryotes

Question 5

What does UTRs stand for?

Answer 5

untranslated regions

Question 6

What are UTRs like in prokaryotes?

Answer 6

5’ and 3 ‘ UTRs are usually short

Question 7

What are UTRs like in eukaryotes?

Answer 7

They’re usually longer, and fit between the TATA box and Exon 1

Question 8

What kind of enzymes are along the genes? For eukaryotes. 6

Answer 8

1. upstream enhancers
2. promoter
3. TATA box
4. 5’ UTR
5. Exon 1
6. Intron 1
   etc

Question 9

What is co suppression?

Answer 9

When extra genes are suppressing the original genes and themselves.

Question 10

What are two mechanisms that may explain the gene silencing in plants?

Answer 10

1. transcriptional silencing - mRNA isn’t made

2. Post transcriptional silencing - mRNA is made but then degraded

Question 11

At what step is RNAi working?

Answer 11

degradation at mRNA, protein and function

Question 12

What is hnRNA?

Answer 12

heterogeneous nuclear RNA

i.e pre mRNA

Question 13

RNAi blocks the accumulation of what?

Answer 13

mRNA

Question 14

What are the RNAi effects on target RNAs?

Answer 14

mRNA is absent

hnRNA is greatly decreased but not absent

Question 15

What is more effective in RNA interference?

Answer 15

dsRNA is more effective than antisense or sense

Question 16

How is RNAi a useful tool?

Answer 16

1. RNAi can be used experimentally to silence genes and test their function
2. possible therapeutic uses to silence genes that causes diseases

Question 17

Why would an organism have RNAi?

Answer 17

to be able to fight against double stranded viruses . molecular arms race.

Question 18

what is siRNA?

Answer 18

short interfering RNA

Question 19

What does the dicer during the mechanism of RNAi?

Answer 19

dicer cleaves dsRNA into siRNA

Question 20

What does RISC stand for?

Answer 20

RNA induced silencing complex

Question 21

What does RISC do during mechanism of RNAi?

Answer 21

RISC binds to siRNA and separates its strands

Question 22

what are mRNAs?

Answer 22

MicroRNAs are a class of post-transcriptional regulators. They are short ~22 nucleotide RNA sequences that bind to complementary sequences in the 3’ UTR of multiple target mRNAs, usually resulting in their silencing.

Question 23

How are miRNA and siRNA molecules usually produced?

Answer 23

dicer enzyme

Question 24

how are miRNAs and siRNAs presented?

Answer 24

by argonaute proteins

Question 25

how does miRNA and siRNA usually work in gene expression?

Answer 25

They're regulators to silence gene expression. They usually prevent translation or degrading specific mRNA transcript

Question 26

What exactly is the dicer enzyme?

Answer 26

an endonuclease that cleaves RNA duplexes. It acts as a moelcular ruler that cuts at about 20-25 nt

Question 27

What can the substrate for the dicer be?

Answer 27

substrate can either be dsRNA duplex or single stranded hairpin

Question 28

Since dicers does not recognize specific sequences, it binds to what?

Answer 28

the duplex's sugar phosphate backbone

Question 29

Dicer enzymes have two RNAse III domains, one for each strand and each binds to what?

Answer 29

each one binds to two metal ions

Question 30

How does RISC complex block translation?

Answer 30

RISC complex binding to 3' region of mRNAs blocks translation