6A - Types of mutations and mutagens

Question 1

Missense

Answer 1

A substitution mutation which codes for a new amino acid - this can change the type of protein created and create new alleles

Question 2

Nonsense

Answer 2

A substitution mutation that creates an early stop codon (UUA, UAG, UGA). The proteins created from this are usually non-functional

Question 3

Silent

Answer 3

A substitution mutation that makes no difference in the type of amino acid produced (as multiple codons can code for the same gene)

Question 4

What is a substitution mutation?

Answer 4

A mutation where one nucleotide is replaced by another type of nucleotide.

Question 5

What are the three kinds of substitution mutations?

Answer 5

Silent, nonsense and missense

Question 6

What is a point insertion mutation?

Answer 6

When a base is inserted into the gene sequence (causes frameshift mutation)

Question 7

What is point base deletion mutation?

Answer 7

The deletion of bases in a DNA strand (causes frameshift mutation)

Question 8

What is a frameshift mutation?

Answer 8

When a base is inserted into the gene sequence and changes the ribosome reading order of all the codons (creates different amino acids)

Question 9

What is a point mutation?

Answer 9

A mutation that alters, adds or removes ONE OR FEW nucleotides from a sequence of DNA or RNA. Often occurs during DNA replication

Question 10

Somatic mutation?

Answer 10

A mutation that occurs in a body cell and cannot be inherited by offspring

Question 11

Germ-line mutation?

Answer 11

A mutation that occurs in a gamete (egg or sperm cell) and can be inherited by offspring. Does not affect the individual in which they occur and can create new alleles

Question 12

Chromosomal Mutations?

Answer 12

Involves alteration to part of or an entire chromosome. Often occurs during mitosis or meiosis

Question 13

What are the four kinds of chromosomal mutations?

Answer 13

Deletion, inversion, translocation and duplication

Question 14

What is translocation?

Answer 14

A type of chromosomal mutation:

When a broken chromosome joins with a non-homologous chromosome - unbalanced

Question 15

What is a mutagen

Answer 15

A change in DNA from a physical or chemical source

Question 16

Examples of physical mutagens:

Answer 16

Electromagnetic radiation (Such as UV light, X rays, gamma rays), alpha and beta particles

Question 17

What is ionising radiation and why is it dangerous for DNA?

Answer 17

Ionising radiation is high frequency radiation that can create ions and break the chemical bonds of DNA and cause adjacent nucleotides to bond

Question 18

What are chemical mutagens:

Answer 18

Chemicals that become incorporated into the DNA through prolonged presence and cause mismatched base pairs.

Question 19

What are some examples of chemical mutagens?

Answer 19

Alkylating agents, Base analogues and Intercalating agents

Question 20

Define aneuploidy:

Answer 20

When the overall chromosome number of the offspring is different to the parent organisms

Question 21

Define polyploidy:

Answer 21

When an organism contains more than two sets of homologous chromosomes

Question 22

What is non-disjunction?

Answer 22

Chromosomal mutation in which the homologous chromosomes (meiosis I) or sister chromatids (meiosis II) fail to separate

Disproportionate amounts of chromosomes in resulting gametes (E.g one has an extra copy)

Question 23

What is gene cloning and what are the two techniques of gene cloning?

Answer 23

Allows scientists to produce many exact copies of a gene, for multiple purposes, such as extracting proteins

INVITRO “outside the organism”

INVIVO “within the organism”

Question 24

What is recombinant DNA?

Answer 24

Recombinant DNA that results from moving a section of DNA from its normal location and inserting it into another DNA site in a different organism.

Recombinant DNA uses enzymes to cut and paste together the DNA sequences of interest. The recombined DNA sequences can be placed into vehicles called vectors that ferry the DNA into a suitable host cell where it can be copied or expressed.

Question 25

What is the aim of recombinant DNA technology?

Answer 25

The aim of recombinant DNA technology is to insert a gene from one organism or species into the genome of another (such as transgenics)

Question 26

In terms of recombinant DNA, what are sticky and blunt ends?

Answer 26

Types of cut out DNA fragments.
Sticky ends have exposed OVERHANGING nucleotide bases at the end of the fragment
Blunt ends do not have over hanging nucleotides