Biology Module 6 - Genetic Change

Question 1

What is a Mutation

Answer 1

Any change that occurs in the sequence of bases in DNA - small and large impacts.

Question 2

What are Point Mutations

Answer 2

Alterations to one or a few bases or have them inserted/deleted at a single point on the strand - substitution, insertion, deletion and inversion. E.g. cytosine substitutes for adenine.

Question 3

What are Chromosomal Mutations

Answer 3

Significant changes to the chromosome, can be added, deleted, inverted, duplicated or translocated. E.g. Trisomy causes Down syndrome, which uses an extra copy of chromosome 21.

Question 4

What is the cause of Mutations

Answer 4

When DNA fails to copy accurately, or the chromosome/tid fails to seperate in cell division.

Question 5

How often do errors occur in replicating DNA? How many base pairs are in DNA?

Answer 5

Errors occur around 1/100,000 bases - 10,000 mutations every DNA replication - repair mechanisms ‘proof read’ and correct mutations.
There are 3 billion base pairs in DNA.

Question 6

What is it called when a mistake is made when copying DNA?

Answer 6

Typos

Question 7

External causes of Mutations

Answer 7

Chemicals: Nicotine
Radiation: Electromagnetic, UV.
Virus’s can cause mutagens too: Human Papillomarvirus (HPV) causes mutations associated to cervical cancer.

Question 8

Effects of Mutations

Answer 8

If in coding-gene, it can alter produced protien positively or to not function. In non-coding it has little effect but can affect regulatory regions outside the gene, increasing or decreasing protein production.

Question 9

What happens if a Mutation infects a Gamete?

Answer 9

It can be inherited to the offspring - Germ-line mutations, which create variation.

Question 10

How are somatic mutations compensated?

Answer 10

Some mutations are compensated by surrounding healthy cells, other times the cell with it dies and is replaced in mitosis of healthy cells, can cause uncontrolled cell replication - cancerous tumours.

Question 11

Are all Mutations harmful?

Answer 11

No, some are beneficial and most do nothing, it creates variation to allow natural selection to favour specific characteristics.

Question 12

How does radiation cause mutations? Examples?

Answer 12

Any radiation with a shorter wavelength then light can be mutagenic.

Ionising radiation: Radioactive material from nuclear reactions which remove electrons from atoms.
Ultraviolet: Sunlight.

Question 13

How are chemical mutagens caused? Examples?

Answer 13

‘Free radicals’ are chemically unstable substances in the body that have lost an electron, they try to become stable by capturing electrons in the body.
Examples: Ingested chemicals, fatty foods, preservatives, irritants and poisons.

Question 14

How do Biological mutagens occur?

Answer 14

Viruses and microorganisms cause them.viruses from transduction, disturbing DNA, repair mechanisms to create mutation. HIV can influence genetically material to change gene functions and make cancer, aging leads to mistakes in mitosis or free radicals from the body, fungi mycotoxins too.

Question 15

What do radiation, biological and chemical mutations have in common?

Answer 15

They are naturally occurring mutagens

Question 16

What are somatic mutations? Example and effect on DNA repair cells?

Answer 16

Mutations that occur in the body besides gametes. Can have effect on DNA spontaneously and randomly or induced from mutagens. Can’t be passed to offspring. If the gene is involved in DNA repair and mutated it can cause cancer quickly.
Example: Change in skin cell can cause melanoma and other skin cancers.

Question 17

What are germ-line mutations? Example?

Answer 17

Mutations on the gamete from the gonads, passes variation to offspring.
Example: Queen Elizabeth passed haemophilia to descendants as recessive mutation.

Question 18

What are coding DNA mutations

Answer 18

Mutations occurring on exon’s/coding region of DNA for mRNA and protein production. Mutation can change activity if protein/cell and could become inactive.

Question 19

What are non-coding DNA mutations?

Answer 19

Non-coding DNA is not involved with gene-expression. It’s the introns that turn genes on/off. Mutation has little effect besides switching genes on-off or if introns becomes exon to cause effect.

Question 20

What is the effect of Electromagnetic radiation?

Answer 20

Radiation breaks bonds in DNA and mutations can occur from errors that rebind the DNA strands, they can also cause molecules to loose electrons.

Question 21

What is the effect of chemicals as a mutation?

Answer 21

Some are mistaken for substrates and bind into DNA strands when synthesising, creating a replication fork, this causes structural changes creating further miscopies of the template strand DNA when replicating.

Question 22

Founder effect

Answer 22

When a new population is formed from a small number of individuals, from existing parent population. E.g. beetles dumped on new island after cyclone.

Question 23

Why can’t founder effect organisms represent the original populations genetic makeup?

Answer 23

Inhabiting a new area will produce varying results who maybe heterozygous but doesn’t show the original populations on dominant and recessive genes there.

Question 24

What can cause the founder effect and bottleneck?

Answer 24

Genetic drift

Question 25

Missense mutations

Answer 25

Wrong amino acid is substituted in, changing the result amino acid & protein.

Question 26

Nonsense - what does non & sense mean?

Answer 26

Creates premature STOP codon.
Non - absent
Sense - sequence of amino acids in polypeptide.

Question 27

Silent mutation

Answer 27

Point mutation in coding region that doesn’t affect resulting amino acid.

Question 28

How do fertilisation, meiosis and mutation cause genetic variation.

Answer 28

Fertilisation: combines maternal and paternal material through independent assortment & random segregation.
Meiosis: Crossing Over
Mutation: increase alleles for traits.

Question 29

Histones

Answer 29

Protien that binds DNA to give chromosomes their shape and control gene activity.

Question 30

Insulators

Answer 30

DNA sequence element that protects genes from inappropriate signals from environment.

Question 31

Silencer

Answer 31

DNA element to reduce transcription from target promoters

Question 32

Enhancers

Answer 32

Cis-acting DNA sequences that increase transcription. Function independent of orientation and distance from promoters.

Question 33

Promoter

Answer 33

Region of DNA upstream of gene where proteins bind to imitate transcription of gene.

Question 34

UTR

Answer 34

Untranslated region, at end of 5’ of protein-coding genes that transcribe into mRNA but not translated into protien.

Question 35

What is CRISPR

Answer 35

(Clustered Regularly Interspaced Short Palindromic Repeats): gene editing tech made from bacteria’s immune system. Modify DNA from specific sequences to introduce changes, delete or insert.

Question 36

CRISPR Applications

Answer 36

Gene therapy (correct genetic mutations), agriculture (better crops.

Question 37

CRISPR Ethical issues

Answer 37

Unintended mutations/ecological damage.

Question 38

Change to earths biodiversity from genetic techniques

Answer 38

Reduces genetic variation, increased susceptibility (others gain resistance).

Question 39

Whole organism cloning examples

Answer 39

Grafting, tissue culture /micropropagation, artificial embryo twinning, SCNT.

Question 40

Examples of gene cloning

Answer 40

PCR