Module Two, Lecture Ten

Question 1

What is the “Central Dogma” of Molecular Biology?

Answer 1

Describes the flow of genetic information within a cell as a unidirectional process: from DNA to RNA ( transcription ), then from RNA to protein ( translation )

Question 2

What is Gene Expression?

Answer 2

The process by which information from a gene is used in the synthesis of a functional gene product: protein or non-coding RNA

Question 3

What is a Gene?

Answer 3

A defined region ( sequence ) of DNA that produces a type of RNA molecule that has some function

Question 4

What is Transcription?

Answer 4

Is the process of making an RNA copy of a gene’s DNA sequence. This copy, called messenger RNA, carried the genes protein information encoded in DNA

Question 5

What is Initiation?

Answer 5

RNA polymerase binds to the promoter region of the DNA and unwinds the DNA double helix, exposing the template strand

Question 6

What is Elongation?

Answer 6

RNA polymerase moves along the template strand, adding RNA nucleotides to the growing RNA molecule, creating a complementary RNA strand

Question 7

Describe the process of Elongation… ( 2 )

Answer 7

1. RNA pol II uses the template strand, which runs the 3’ - 5’ direction, as a templated, and inserts complementary RNA nucleotides in the 5’ - 3’ direction
2. Topoisomerase II is an enzyme that releases the tension ( supercoil ) that builds up ahead of RNA pol II

Question 8

What is Termination?

Answer 8

RNA polymerase reaches a termination signal in the DNA, causing the RNA polymerase to detach from the DNA, releasing the newly synthesised RNA molecule

Question 9

Describe the structure of Split Genes… ( 8 )

Answer 9

1. They contain both coding and non-coding regions
2. Exons are the coding regions that will be translated into a protein
3. Introns are the non-coding regions that are spliced out during the production of mature mRNA
4. In complex eukaryotes, introns can be longer than exons
5. Contains noncoding DNA regions upstream and downstream of the coding sequence as well as within the coding sequence
6. These non-coding DNA regions can be transcribed by are not translated
7. These non-coding DNA elements are involved in regulating gene expression
8. Changes ( mutations ) in these non-coding gene sequences may ‘disrupt’ normal gene expression