D1.3 (Mutations and gene editing)

Question 1

What is a gene mutation?

Answer 1

A gene mutation is a structural change in the sequence of base pairs in a DNA molecule, potentially resulting in a new allele.

Question 2

Define substitution mutation.

Answer 2

A substitution mutation occurs when a nucleotide base in the DNA sequence is randomly swapped for a different base.

Question 3

What is an insertion mutation?

Answer 3

An insertion mutation occurs when a nucleotide with a new base is randomly inserted into the DNA sequence, causing a frameshift.

Question 4

Define a deletion mutation.

Answer 4

A deletion mutation is when a nucleotide is randomly deleted from the DNA sequence.

Question 5

True or False? Deletion mutations can cause a frameshift in the DNA sequence.

Answer 5

True.

Question 6

True or False? A substitution mutation can have a knock-on effect on the rest of the DNA sequence.

Answer 6

False.

A substitution mutation will only change the amino acid for the triplet in which the mutation occurs; it will not have a knock-on effect on the rest of the sequence.

Question 7

What are single nucleotide polymorphisms (SNPs)?

Answer 7

SNPs are differences in a single DNA nucleotide, such as replacing cytosine (C) with thymine (T) in a certain stretch of DNA.

Question 8

True or False? SNPs are only found in the coding regions of DNA.

Answer 8

False.

SNPs are commonly found in the non-coding regions of DNA between genes.

Question 9

What are the three forms of substitution mutations?

Answer 9

The three forms of substitution mutations are silent mutations, missense mutations, and nonsense mutations.

Question 10

True or False? Insertions and deletions only affect the amino acid coded for by the mutated triplet.

Answer 10

False.

Insertions and deletions can cause a frameshift, altering the triplet grouping and affecting the entire amino acid sequence downstream.

Question 11

Define frameshift mutation.

Answer 11

A frameshift mutation is caused by insertions or deletions of nucleotides that shift the reading frame of the mRNA, altering the entire amino acid sequence after the mutation site.

Question 12

How do insertions and deletions lead to frameshift mutations?

Answer 12

Insertions and deletions add or remove nucleotides, disrupting the triplet grouping of codons and shifting the reading frame.

Question 13

What is the effect of a frameshift mutation on a polypeptide?

Answer 13

A frameshift mutation can dramatically change the amino acid sequence, potentially causing the polypeptide to cease functioning.

Question 14

Why are insertions and deletions often more harmful than substitution mutations?

Answer 14

Insertions and deletions are often more harmful than substitution mutations as they can cause frameshift mutations, altering the entire amino acid sequence downstream.

Question 15

How does a frameshift mutation alter the amino acid sequence?

Answer 15

A frameshift mutation alters the amino acid sequence because it shifts the reading frame, causing the ribosome to read different codons.

Question 16

True or False? Frameshift mutations have catastrophic effects on the resulting protein.

Answer 16

True.

Question 17

What is meant by the degenerate genetic code?

Answer 17

Degeneracy in the genetic code is where a single amino acid is coded for by multiple triplet codes.

Question 18

What can cause gene mutation?

Answer 18

Gene mutations can be caused by mutagens and by errors in DNA replication or repair.

Question 19

True or False? There are specific regions of DNA where mutations only occur.

Answer 19

False.

Question 20

What are the natural mechanisms for making a deliberate change to a particular base with the purpose of changing a trait?

Answer 20

No natural mechanism is known for making a deliberate change to a particular base with the purpose of changing a trait.

Question 21

What is variation in a species?

Answer 21

Variation refers to the differences that exist between organisms of the same species.

Question 22

What causes variation within a population?

Answer 22

Variation results from small differences in DNA base sequences between individual organisms within a population.

Question 23

Name the three main sources of genetic variation.

Answer 23

Three main sources of genetic variation are mutation, meiosis, and random fertilisation during sexual reproduction.

Question 24

What is the original source of genetic variation?

Answer 24

Mutation is the original source of genetic variation, leading to the generation of new alleles.

Question 25

How do mutations contribute to evolution?

Answer 25

Mutations result in new alleles that can be advantageous, disadvantageous, or neutral, influencing natural selection and the evolution of a species.

Question 26

Why are mutations important for evolution by natural selection?

Answer 26

Mutations introduce new alleles that can be selected for or against, contributing to the adaptation and evolution of species.

Question 27

What is the only source of variation in asexually reproducing species?

Answer 27

Mutation is the only source of variation in asexually reproducing species.

Question 28

What happens to a disadvantageous mutation in a population?

Answer 28

A disadvantageous mutation is less likely to be passed on because it decreases the organism's chances of survival and reproduction.

Question 29

What are the two types of genetic testing available?

Answer 29

Two types of genetic testing are clinical/medical genetic testing and commercial genetic testing.

Question 30

Who typically performs clinical or medical genetic testing?

Answer 30

Healthcare providers such as doctors, nurse practitioners, or genetic counsellors perform clinical genetic testing.

Question 31

True or False? Commercial genetic testing always involves healthcare providers.

Answer 31

False.

Question 32

What are some potential problems with commercial genetic testing?

Answer 32

Potential issues with commercial genetic testing include inaccurate results, stress from unexpected information, and the risk of making important decisions based on misunderstood information.

Question 33

Why is genetic counselling important in genetic testing?

Answer 33

Genetic counseling ensures that individuals understand their test results and the implications for their health and family.

Question 34

What is gene knockout?

Answer 34

Gene knockout is a technique that removes or makes a gene unusable in an organism in order to study its function.

Question 35

What is a knockout organism?

Answer 35

A knockout organism is an organism that has had one or more of its genes knocked out or made unusable.

Question 36

Define gene editing.

Answer 36

Gene editing is the process of altering the DNA of an organism by inserting, deleting or replacing DNA at specific sites in the genome.

Question 37

How does gene editing differ from genetic engineering?

Answer 37

Gene editing differs from genetic engineering in that it involves modifying the existing DNA of an organism rather than inserting DNA from another organism.

Question 38

Name an example of a medical condition that has been studied using gene knockout techniques.

Answer 38

Conditions that have been studied using gene knockout techniques include obesity, diabetes, cancer likelihood, addiction, and cardiovascular disease.

Question 39

What is CRISPR?

Answer 39

CRISPR is a gene editing technique that uses a bacterial defence mechanism to cut DNA at a specific point determined by a guide RNA.

Question 40

What is the purpose of gene therapy?

Answer 40

The purpose of gene therapy is to treat genetic diseases by altering the person's genotype, or genetic makeup.

Question 41

True or False? The CRISPR-Cas system is used by prokaryotes for gene editing.

Answer 41

False.

Question 42

What is the role of ethics committees in genetic engineering?

Answer 42

Ethics committees must approve all experiments involving genetic engineering and provide guidance on the ethical issues involved.

Question 43

True or False? Scientists across the world are subject to the same regulatory systems.

Answer 43

False.

Question 44

Define the term conserved sequence?

Answer 44

A conserved sequence is a section of DNA or RNA that shows minimal mutations over time, often being identical or similar across a species or group of species.

Question 45

What is a highly conserved sequence?

Answer 45

A highly conserved sequence is a sequence that shows little to no mutations over long periods of evolution.

Question 46

Give examples of highly conserved sequences.

Answer 46

Examples of highly conserved sequences include those that lead to DNA replication, transcription, translation, and proteins involved in cellular respiration.

Question 47

What are two hypotheses for why conserved sequences exist?

Answer 47

One hypothesis is that conserved sequences exist within genes that code for proteins essential for survival. The other hypothesis is that certain sections of gene sequences are less prone to mutations.

Question 48

Define the term mutation rate?

Answer 48

Mutation rate is the measure of how many changes there are to the DNA sequence over time.

Question 49

Why are coding regions of the genome more conserved?

Answer 49

Coding regions of the genome are more conserved because DNA repair and proofreading mechanisms are very active in these regions.

Question 50

Why are non-coding regions of the genome less conserved?

Answer 50

Non-coding regions of the genome are less conserved because error correcting and proofreading mechanisms are less active in these areas.