6.1.1

Question 1

What is mutation

Answer 1

Changes to the base sequence of DNA

Question 2

What types of mutation are they

Answer 2

Substitution - one or more bases are swapped for another e.g ATGCCT becomes ATTCT
Deletion - one or more bases are removed e.g ATGCCT becomes ATCT
Insertion - one or more bases are added

Question 3

Define chromosome mutation

Answer 3

Mutation that affect the whole chromosome or number of chromosomes within the cell.
Caused by mutagens and normally occur during meiosis

Question 4

Define mutagens

Answer 4

Mutagen is a chemical,physical or biological agent that causes mutation

Question 5

What are the 4 stages that control/regulate gene expression

Answer 5

Transcriptional control
Post-transcriptional control
Translational control
Post translational control

Question 6

Define promoter and operator

Answer 6

Promoter = DNA sequence located before the structural genes that RNA polymerase binds to 
Operator = DNA sequence that transcription factors bind to

Question 7

Define an operon

Answer 7

Group of genes that are controlled by the same promoter

Question 8

What is a heterochromatin

Answer 8

Methylation makes histones more hydrophobic, tighter packaging, less transcription

Question 9

What is a euchromatin

Answer 9

Acetylation and phosphorylation reduces the charge on histones, looser packing, more transcription

Question 10

How are chromatins formed

Answer 10

DNA associated with histone proteins

DNA wraps twice around a bundle of 8 histones from chromatin subunit structure called nucleosome

Question 11

What is transcription factor in eukaryotes

Answer 11

Factors that bind to specific DNA sequences
Right complex of transcription factors is required for transcription to begin
Increasing or decreasing the production of specific transcription factors, transcription of other genes can be controlled

Question 12

How can be genes be regulated (detailed)

Answer 12

Transcriptional - genes can be turned on or off
Post transcriptional - mRNA can be modified which regulates translation and types of proteins produced
Translational - translation can be stopped or started
Post translational - proteins can be modified after synthesis which changes their function

Question 13

What are the post transcription control factors

Answer 13

Product of transcription =pre-mRNA, modified forming mature mRNA
Cap and tail is added- stabilise mRNA and delay degradation
Splicing occurs - introns (non coding DNA) are removed and exons (coding DNA) joined together

Question 14

Where and explain where RNA editing occur

Answer 14

Post transcriptional
Nucleotide sequence of some mRNA molecules can also be changed via addition,substitution and deletion.
Increases the range of proteins

Question 15

What are translational control

Answer 15

Degradation of mRNA- more resistant the molecule, longer it will last in the cytoplasm
Binding of inhibitory proteins to mRNA prevents it binding to ribosomes and the synthesis of proteins

Question 16

What are the post translational control

Answer 16

Addition of non protein groups such as carbohydrate chains
Modifying AA and the formation of bonds such as disulfied bridges
Folding or shortening of proteins
Modification by cAMP

Question 17

What is the lac operon

Answer 17

Group of three genes involved in the metabolism of lactose. Structural genes as they code for three enzymes

Question 18

What is the term used to describe the regulation of the pattern of anatomical development

Answer 18

Morphogenesis

Question 19

Define home box genes

Answer 19

Ancient, highly conversed regions of DNA found in animals, plants and fungi
Code for homeodomains- protein segment that act as a transcription factor

Question 20

Define hox genes

Answer 20

Specific group of home box genes, only found in animals

Question 21

Describe the events that occur within E.Colin when lactose is the only respiratory substrate available

Answer 21

When lactose is present, it binds to the repressor, changing the repressors, changing the repressors shape so that it can no longer bind to the operators site
RNA polymerase can now begin transcription of the structural genes

Question 22

Explain why beta galactosidase and lactose permease are not produced when lactose is absent

Answer 22

The regulatory gene (lacl) produces the lac repressor, transcription factor that binds to the operator site when there’s no lactose present
Blocks transcription because RNA polymerase can not bind to the promoter.

Question 23

Outline why the majority of mutation do not have an influence phenotype

Answer 23

Mutation is random and the majority of DNA is non coding, mutations in non coding regions do not affect phenotype

Question 24

Discuss why beneficial mutations are rare and suggest a process that beneficial mutation underpins

Answer 24

Majority of mutations are silent, beneficial mutation increases chances of survival if environment,surviving organisms reproduce and pass new alleles to offspring