Chapter 4.6 Types of Mutations ✓

Question 1

Define point mutation

Answer 1

A mutation that affects a single base-pair within a gene

Question 2

How is a DNA sequence affected by point mutation?

Answer 2

It affected by a substitution, deletion or addition

Question 3

Define substitution mutation

Answer 3

A mutation in which a single nucleotide is swapped for another in the original gene sequence

Question 4

Define single nucleotide polymorphism

Answer 4

SNP is a single nucleotide difference that occurs at a given position in the genome of two or more individuals (or simply, differences between sequences of just one nucleotide)

Question 5

Define synonymous mutation (or silent mutation)

Answer 5

A mutation in which the DNA codon for one amino acid becomes another DNA codon for the same amino acid

Question 6

Define missense mutation

Answer 6

A gene mutation that results in one amino acid being replaced by another amino acid in the encoded protein

Question 7

Define nonsense mutation

Answer 7

A mutation in which a codon for an amino acid is changed to one that codes for a stop codon, terminating translation.

Question 8

Define insertion mutation

Answer 8

A mutation in which one or more nucleotide pairs have been added to a segment of DNA

Question 9

Define deletion mutation

Answer 9

A mutation in which one or more nucleotide pairs have been lost from a segment of DNA

Question 10

Define frameshift mutation

Answer 10

A mutation that changes the reading frame used in translation, during polypeptide synthesis

Question 11

What three mutations can be classify as substitution mutations?

Answer 11

-Synonymous
-Missense
-Nonsense

Question 12

What two mutations are considered frameshift mutations?

Answer 12

-Substitution
-Deletion

Question 13

Define neutral mutations

Answer 13

A mutation that has no effect on an organism’s chances of survival and reproduction

Question 14

Define deleterious mutations

Answer 14

A mutation that decreases an organism’s chances of survival and reproduction

Question 15

Define beneficial mutations

Answer 15

A mutation that increases an organism’s chances of survival and reproduction

Question 16

What mutation is an example of a neutral mutation and why?

Answer 16

Missense mutations can be neutral because it changes a single amino acid in a protein and this change can be neutral if the substituted amino acid is similar in properties of the original.

Question 17

What mutation is an example of a deleterious mutation and why?

Answer 17

Nonsense mutations can be deleterious because they introduce a premature stop codon into the mRNA sequence. This early termination leads to the production of an incomplete protein that if often nonfunctional or unstable.

Question 18

What mutations is an example of beneficial mutations and why?

Answer 18

Both nonsense and missense can be considered beneficial because
-Nonsense could eliminate a protein that may have been harmful to the organism
-Missense could change the function of the original protein that could of been harmful

Question 19

What three things can mutations be categorised as?

Answer 19

-Neutral
-Deleterious
-Beneficial

Question 20

Describe the effect of the following mutations on a coded protein:
a) synonymous mutation
b) missense mutation
c) nonsense mutation
d) frameshift mutation

Answer 20

Synonymous mutation
-No change in the amino acid sequence of the protein. It changes a single nucleotide but still codes for the same amino acid.

Missense mutation
-Changes one amino acid in the protein. A single nucleotide change results in a codon that codes for a different amino acid, why may or may not affect protein function depending on the role of the altered amino acid.

Nonsense mutation
-Produces a premature stop codon. The mutation changes a codon into a stop codon, causing the protein to be shortened, which often makes it non-functional

Frameshift mutation
-Changes the entire amino acid sequence after the mutation site. Insertion or deletion of nucleotides shifts the reading frame, drastically altering the downstream amino acid sequence and usually resulting in a non functional protein

Question 21

Define karyotype

Answer 21

A display that presents the number and appearance of the chromosomes of an organism or cell as observed at metaphase

Question 22

How are chromosomes ordered?

Answer 22

By length going from largest to smallest

Question 23

Define monoploid

Answer 23

Describes a cell or organism that has a functional genome consisting of one copy of each chromosome, represented as 1n.

Question 24

What animals are monoploid?

Answer 24

Colonial male insects such as ants, bees and wasps

Question 25

Define parthenogenisis

Answer 25

A process in which an entire organism is regenerated from a single egg cell, without the need for fertilisation.

Question 26

What is the advantage of diploid organisms compared to monoploid organisms?

Answer 26

-When diploid organisms have any defective alleles that arise can be compensated for by a functioning allele on the corresponding chromosome. -If monoploid organisms have a defective allele, it is the only allele available for a particular gene and the consequences are likely to be deleterious.

Question 27

Define polyploid

Answer 27

A cell or organism with a genome comprising three or more copies of each chromosome, represented as 3n, 4n, 5n, 6n etc.

Question 28

What organism is polyploidy common in?

Answer 28

Flowering plants, ferns and green algae

Question 29

What are some advantages of polyploidy?

Answer 29

-Commercial applications; increases fruit size, hardiness and infertility which lead to increases profits for farmers and businesses

Question 30

Define aneuploid

Answer 30

Describes a genome that varies from the conventional genome through the loss or addition of one or a few chromosomes (e.g. 2n + 1 or 2n -1)

Question 31

Define non-disjunction

Answer 31

The failure of sister chromatids in mitosis or homologous chromosomes in meiosis to separate and go to opposite poles

Question 32

Define trisomy

Answer 32

A condition in which somatic cells contain three copies of a particular chromosomes (a normal pair plus an extra one)

Question 33

Define monosomy

Answer 33

The condition in which somatic cells of an organism are missing one copy of a particular chromosome

Question 34

What are the 4 types of structural mutations to chromosome?

Answer 34

-Deletion -Inversion -Translocation -Duplication

Question 35

Define deletion in terms of chromosome mutation.

Answer 35

A region of a chromosome lost , resulting in the absence of all the gene in that area

Question 36

Define translocation in terms of chromosome mutation

Answer 36

A region from one chromosome is aberrantly attached to another chromosome

Question 37

Define duplication in terms of chromosome mutation

Answer 37

A region of a chromosome is repeated, resulting in an increase in copies of the genes in that region.

Question 38

Describe the difference between haploid and diploid

Answer 38

Haploid (n) refers to a cell that has one complete set of chromosomes Diploid (2n) refers to a cell that has two complete sets of chromosomes; one from each parent

Question 39

Describe the differences between monoploid and haploid

Answer 39

Monoploid refers to the basic set of chromosomes (one complete set of non-repeated chromosomes, represented as n) Haploid refers to a cell having half the total number of chromosomes found in somatic (diploid) cells.

Question 40

Describe the difference between monoploid, diploid and polyploid.

Answer 40

-Monoploid: A cell or organism with one basic set of chromosomes (symbolised as n) -Diploid: A cell with two sets of chromosomes (symbolised as 2n) -Polyploid: A cell or organisms with more than two sets of chromosomes (e.g. 3n, 4n, 4n etc)

Question 41

Draw a chromosome mutation of deletion

Answer 41

check page 105

Question 42

Draw a chromosome mutation of inversion

Answer 42

check page 105

Question 43

Draw a chromosome mutation of translocation

Answer 43

check page 105

Question 44

Draw a chromosome mutation of duplication

Answer 44

check page 105