Genetics of Living Systems

Question 1

Does the nucleus of every cell in the human body contain the same genes?

Answer 1

Yes

Question 2

Is every gene in every cell expressed?

Answer 2

No and not all of these genes are expressed all the time

Question 3

What are the mechanisms that make sure the correct genes are expressed in the correct cell at the correct time called?

Answer 3

regulatory mechanisms

Question 4

What are the three main types of regulatory mechanisms?

Answer 4

• regulation at the transcriptional level (i.e. regulatory mechanisms that occur during transcription)
• regulation at the post-transcriptional level (i.e. regulatory mechanisms that occur after transcription)
• regulation at the post-translational level (i.e. regulatory mechanisms that occur after translation)

Question 5

What are regulatory mechanisms controlled by?

Answer 5

many different regulatory genes

Question 6

What is a structural gene?

Answer 6

a structural gene codes for a protein that has a function within a cell (e.g. enzymes, membrane carriers, hormones etc.)

Question 7

What are regulatory genes?

Answer 7

regulatory genes code for proteins (or various forms of RNA) that control the expression of structural genes

Question 8

Do regulatory genes control structural genes or structural genes control regulatory genes?

Answer 8

regulatory genes control structural genes and their levels of protein production

Question 9

Can regulatory genes have control over several structural genes at once?

Answer 9

sometimes

Question 10

Give an example of a regulatory mechanism at the transcriptional level.

Answer 10

the lac operon

Question 11

What is a homeobox?

Answer 11

a DNA sequence that codes for a protein transcription factor