Reading The Code

Question 1

How is DNA transcription regulated?

Answer 1

Histone modification or transcription factors

Question 2

How does histone modification work?

Answer 2

DNA is packaged around histone proteins as chromatin - acetylation of histones regulates access to DNA, increasing transcription.

Question 3

How do transcription factors work?

Answer 3

They are regulatory proteins which bind to specific sequences in the DNA, promoting transcription of the adjacent gene. They interact with RNA polymerase, setting it off to copy DNA into RNA.

Question 4

How is RNA processing controlled?

Answer 4

Alternative splicing

Question 5

How does alternative splicing work?

Answer 5

Some RNAs use different combinations of exons to form different proteins, regulated by the cell or conditions. Several mRNAs can be made from the same gene in this way.

Question 6

How is translation regulated?

Answer 6

microRNA

Question 7

What are miRNAs?

Answer 7

Short strands of nucleotides (less than 22 long) which regulate mRNA

Question 8

How do miRNAs work?

Answer 8

They cause mRNA to be degraded so they can’t be translated. They can partially complementarily bind to sites on mRNA to do this, causing mRNA cleavage.

Question 9

What does RISC stand for?

Answer 9

RNA induced silencing complex

Question 10

How can circulating miRNAs be detected?

Answer 10

Using biomarkers - these are stable in the blood and released from cells, indicative of tissue of origin and response to disease.

Question 11

What are the stages of PCR?

Answer 11

1. Denature - occurs at 95 degrees Celsius. Hydrogen bonds holding strand of DNA together are broken apart, unravelling DNA helix.
2. Anneal - occurs at 55 degrees Celsius. Two primers attach to complementary base pairing. Primers are 20 nucleotides long.
3. Extend - occurs at 72 degrees Celsius. Taq polymerase binds to each PCR primer and begins adding nucleotides so the chain extends.

Question 12

What are the components of PCR?

Answer 12

DNA of target, forward/reverse primers, PCR buffer, movoalent salts, MgCl2, Taq polymerase

Question 13

What are some uses of PCR?

Answer 13

Virology, detection of bacteria, forensic an paternity kits, any genetic test

Question 14

Which process is often used in conventional DNA sequencing?

Answer 14

Gel electrophoresis

Question 15

How is next generation sequencing different to conventional?

Answer 15

Processes hundreds of millions of sequences in parallel, often using a solid surface.

Question 16

What are some applications of next generation sequencing?

Answer 16

Mutation detection, pharmogenomics, metagenomics, gene expression in disease