Mutations

Question 1

What is a Mutation?

Answer 1

-Any change in the genetic composition of an organism.

Question 2

How do Mutations occur?

Answer 2

-Could occur by chance.
-Could occur as a result of a mutagen.

Question 3

What are Mutagens?

Answer 3

-Mutagens are physical or chemical agents that cause mutations.

Question 4

When can mutations be transferred to children?

Answer 4

-only mutations that occur in the sexual organs can be passed on.

Question 5

What are two types of mutations?

Answer 5

-Gene Mutations
-Chromosomal Mutations

Question 6

What are gene mutations?

Answer 6

-A change in the nucleotide sequence

Question 7

A change in the nucleotide sequence. As a result…

Answer 7

A change in the nucleotide sequence. As a result, the code for protein synthesis changes and forms a faulty protein or no protein at all.

Question 8

When can gene mutations occur?

Answer 8

They can occur during:
- crossing-over during meiosis.
- DNA replication
- Transcription of DNA

Question 9

What are the four types of gene mutations?

Answer 9

-substitution
-deletion
-insertion
-inversion

Question 10

What happens during substitution?

Answer 10

-One nitrogenous base is replaced by another.
-Point Mutation occurs
- meaning there is an alteration of one amino acid.

Question 11

What happens in deletion?

Answer 11

-One or more nitrogenous bases are lost.
-Frame shift occurs
-All base triplets are altered, and consequently, all amino acids are.

Question 12

What happens during insertion?

Answer 12

-One or more nitrogenous bases are inserted.
-Frame shift occurs
-All base triplets are altered, and consequently, also the amino acids

Question 13

What happens during inversion?

Answer 13

-One or more base triplets are inverted.
-Point mutation
-results in the alteration of one or more amino acids.

Question 14

What does a frame shift cause?

Answer 14

-It causes all subsequent codons to be read incorrectly.
-leads to a change in the amino acid sequence of the resulting protein.

Question 15

What does a point shift cause?

Answer 15

-A single amino acid to be altered.

Question 16

How does a chromosomal mutation occur?

Answer 16

-It occurs when Meiosis doesn’t proceed properly, which results in changes in one’s chromosome number or structure.

Question 17

Define Aneuploidy:

Answer 17

-extra or missing chromosomes in a cell

Question 18

Give examples of aneuploidy:

Answer 18

-Down syndrome - 47 chromosomes
-Turner syndrome - only one sex chromosome (X0)
-Klinefelter syndrome - extra sex chromosome (XXY)

Question 19

How does Down syndrome occur?

Answer 19

-Occurs during the production of eggs during meiosis when chromosome number 21 doesn’t separate during Anaphase 1.

Question 20

What are the characteristics of Down syndrome? (9)

Answer 20

-small almond-shaped eyes
-flat forehead
-ears situated lower down on the head
-large tongue
-flat nose bridge
-short, stubby toes
-poor muscle tone
-mental retardation
-pre disposed to heart disease

Question 21

What is another name for Down Syndrome?

Answer 21

Trisomy 21

Question 22

What is the maternal age effect?

Answer 22

-After the age of 35, the risk of complications like miscarriage, congenital disorders & high blood pressure rises.

Question 23

What gender does Turner syndrome affect, and what happens with the chromosomes?

Answer 23

• It affects the development of females.
  -Only one X chromosome (X0)

Question 24

What are the characteristics of Turner syndrome?

Answer 24

-abnormal growth
-lack of female secondary sexual characteristics.
-sterile
-slight mental retardation
-webbed neck
-heart defects
-low hairline

Question 25

What gender does Klinefelter syndrome affect, and what happens with the chromosomes?

Answer 25

-It affects males -They have 2 or more X chromosomes (XXY)

Question 26

What are the characteristics of Klinefelter syndrome?

Answer 26

-Abnormal development of testes -Infertile -Often tall -Produce small amounts of testosterone -Develop some female characteristics

Question 27

What may reduce Klinefelter syndrome's symptoms?

Answer 27

-Testosterone treatment may reduce symptoms.

Question 28

What are Somatic Mutations?

Answer 28

-Mutations that occur in the body cells. -They are not passed on to the next generation. -It can cause cells to become malignant (cancerous)

Question 29

What are Gametic mutations?

Answer 29

-Mutations that occur in the reproductive organs. -Produce a change in gametes. -They are transmitted to the next generation.

Question 30

What may Gametic mutations lead to?

Answer 30

Gametic mutations may lead to hereditary diseases.

Question 31

What are 3 different types of Gametic mutations?

Answer 31

-Neutral -Beneficial -Lethal/Harmful

Question 32

How does a beneficial mutation occur?

Answer 32

-If a mutation results in organisms adapting better to new or unfavourable conditions, the organism will survive to reproduce & the beneficial mutation will be transferred to offspring.

Question 33

Where do small mutations occur?

Answer 33

-Small mutations occur in the phenotype.

Question 34

What is "Nature Selects" ?

Answer 34

-Nature selects the better-adapted feature/ability. -Then it is passed on to the next generation till all individuals have it.

Question 35

What are examples of beneficial Mutations?

Answer 35

-Antibiotic-resistant bacteria -HIV resistance

Question 36

What are examples of Harmful Mutations?

Answer 36

-Albinism -Colour blindness

Question 37

What traits do Harmful Mutations usually have?

Answer 37

Harmful Mutations usually have autosomal recessive traits

Question 38

What are Neutral Mutations?

Answer 38

-Neutral Mutations are mutations that don't affect the phenotype of have any survival effect on the organism.

Question 39

What are some examples of neutral mutations?

Answer 39

-attached vs unattached earlobes -Heterochromia, a mutation that causes different coloured eyes.

Question 40

Give examples of reproductive organs:

Answer 40

-ovaries -testes