Mutations

Question 1

What is the central dogma

Answer 1

DRAW IT

Question 2

What do the different stages in the Central dogma represent

Answer 2

1. DNA can replicate
2. Information coded in the sequence of bases in DNA is passed to molecules of RNA
3. Information in RNA is passed to proteins. It never passes from proteins to nucleic acids.

Question 3

What do genes code for

Answer 3

Polypeptides to be produced

Question 4

What are structural genes

Answer 4

Genes that are expressed in the phenotype of organisms

Question 5

What does expressed mean

Answer 5

Genes that are transcribed and translated

Question 6

What is the purpose of regulatory genes

Answer 6

They regulate the expression of the structural genes

Question 7

What do almost all cells have

Answer 7

The complete genome but different genes are expressed in specialised cells

Question 8

What is a feature of some genes

Answer 8

They are expressed all the time however some require a stimulus e.g. a hormone/enzyme

Question 9

What are inductive genes

Answer 9

Genes that require a stimulus to be expressed

Question 10

What is an Exon

Answer 10

Part of a eukaryotic gene that codes for part of a polypeptide

Question 11

What is an intron

Answer 11

Part of a eukaryotic gene that separates exons and does not code for any part of a polypeptide

Question 12

What is primary mRNA

Answer 12

It is mRNA that is produced by transcription and includes introns and exons

Question 13

What is mature mRNA

Answer 13

The mRNA right after introns are removed and the exons are spliced together

Question 14

What are codons

Answer 14

Triplet of bases that code for an amino acid

Question 15

What is the domain

Answer 15

Part of a globular protein that serves a particular function

Question 16

What are features of the genetic code

Answer 16

.Universal
.Punctuated
.Linear
.Degenerate

Question 17

What do mutations do

Answer 17

They change the sequence of bases

Question 18

What can mutations be caused by

Answer 18

Gene mutations and chromosome mutations

Question 19

What are the different gene mutations

Answer 19

Substitution (of one or more base pairs by others)
Addition of one or more base pairs (insertion)
Deletion of one or more base pairs

Question 20

What are the different chromosomal mutations

Answer 20

Translocation (transfer of a portion of one chromosome to another non homologous chromosome)
Non-disjunction
Deletion (section breaks off)
Inversion - section breaks off, is reversed and rejoins

Question 21

What is a feature of most mutations

Answer 21

They are harmful

Question 22

What are silent mutations

Answer 22

Mutations that don’’t cause a change in the amino acid sequence

Question 23

What is a feature of mutations to do with inheritance

Answer 23

Only changes in gametic cells are inherited

Question 24

How are chimera’s formed

Answer 24

When a change occurs in a somatic cell after the zygote stage

Question 25

What is a feature of mutations

Answer 25

They occur spontaneously in DNA replication and cell division, but can also be induced to mutate by ionising radiation, viruses and chemicals.

Question 26

What is a mutagen

Answer 26

A mutagen is a chemical, physical or biological agent that causes a mutation

Question 27

What is an example of a physical mutagens and what does it do

Answer 27

Ionising radiations such as X-rays, which break one or both DNA strands which can be repaired by mutations can occur in the process

Question 28

What is an example of a chemical mutagen and what does it do

Answer 28

Chemically alter bases in DNA such as converting cytosine to uracil in DNA, changing the base sequence

Question 29

What are examples of a biological mutagens and what does it do

Answer 29

Alkylating agents: methyl or ethyl groups are attached to bases resulting in the incorrect pairing of bases during replication Base analogs: incorporated into DNA instead of the usual base during replication, changing the base sequence Viral DNA may insert itself into a. Genome changing the base sequence Viral

Question 30

What does insertion or deletion of nucleotides do

Answer 30

It leads to frameshift mutations - where the reading frame of the sequence of bases is shifted, this will change every successive codon from the point of mutation

Question 31

What are the possible of effects of mutations (1)

Answer 31

No effect - no effect on the phenotype of an organism because the normally functioning proteins are still synthesised

Question 32

What are the possible of effects of mutations (2)

Answer 32

Damaging - the phenotype of an organism is affected in a negative way because proteins are no longer synthesised or proteins synthesised are non-functional. Interfering with one or more essential processes.

Question 33

What are the possible of effects of mutations (3)

Answer 33

Beneficial - rarely a protein is synthesised resulting in a new and useful characteristic in the phenotype

Question 34

What do silent mutations do

Answer 34

They do not change any proteins, or the activity of the proteins synthesised. Therefore they don’t affect the phenotype of the organism .

Question 35

How can silken mutations occur

Answer 35

Caused by a change in an intron Or the primary structure but not changing the overall structure

Question 36

What are nonsense mutations

Answer 36

They result in a codon becoming a stop codon instead of coding for an amino acid, resulting in a shortened protein