Cellular Control

Question 1

Where is mRNA made?

Answer 1

mRNA is made in the nucleus

Question 2

What bases does mRNA contain?

Answer 2

Adenine, guanine, uracil and cytosine

Question 3

What does universal mean when referring to properties of the genetic code?

Answer 3

The same codons code for the same amino acids in all organisms

Question 4

What does degenerate mean when referring to the properties of the genetic code?

Answer 4

Most amino acids have more than one codon that code for them

Question 5

What does non-overlapping mean when referring to properties of the genetic code?

Answer 5

Each base is only read once

Question 6

What are the 4 types of genes?

Answer 6

Structural genes
Regulatory genes
Housekeeping genes
Tissue specific genes

Question 7

What are structural genes?

Answer 7

Genes that code for a protein that has a function within a cell.

Eg. Genes coding for enzymes, membrane carriers, hormones etc.

Question 8

What are regulatory genes?

Answer 8

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

Eg. Genes coding for transcription factors

Question 9

What are housekeeping genes?

Answer 9

Genes that code for proteins that are constantly required

Eg. Genes that code for enzymes necessary for reactions in respiration

Question 10

What are tissue specific genes?

Answer 10

Genes that code for proteins that are only required at certain times to carry out a short-lived response

Eg. Genes coding for hormones used for growth and repair

Question 11

What are the 4 different ways genes can be regulated?

Answer 11

Transcriptional
Post-transcriptional
Translation
Post-translational

Question 12

How are genes regulated at transcriptional level?

Answer 12

Genes are able to be turned on/off

Question 13

How are genes regulated at post-transcriptional level?

Answer 13

mRNA can be modified, which regulates translation and the types of proteins produced

Question 14

How can genes be regulated at translational level?

Answer 14

Translation can be stopped or started

Question 15

How can genes be regulated at post-translational level?

Answer 15

Protein can be modified after synthesis, which changes their function

Question 16

What are heterochromatin?

Answer 16

Tightly wound DNA —> Chromosomes are visible under a microscope

Question 17

What are Euchromatin?

Answer 17

Loosely wound DNA —> Not visible under a microscope

Question 18

Transcription isn’t possible when DNA is tightly wound (heterochromatin). Why?

Answer 18

Because RNA polymerase can’t attach and move along the DNA

Question 19

During what part of the cell cycle does protein synthesis take place?

Answer 19

During the interphase because there is euchromatin, making genes more accessible to RNA polymerase

Question 20

What charge does DNA have?

Answer 20

DNA has a negative charge

Question 21

What charge do histone proteins have?

Answer 21

A positive charge

Question 22

What happens at acetylation and phosphorylation?

Answer 22

•Reduce charge on histone
•Histones now become more negative
•Causing DNA to coil less tightly
•Genes are now more accessible

Question 23

What happens during methylation of histone proteins?

Answer 23

• Involved adding a hydrocarbon
• Histones now more hydrophobic
• The histone bind tighter together
• DNA coils tighter as a result
• This prevents transcription of genes