Genetics - Mutations

Question 1

What are the three types of chromosomal abnormalities?

Answer 1

Numerical

Structural

Mutational

Question 2

What are numerical chromosomal abnormalities?

Answer 2

They are disorders in which whole chromosomes are missing or extra to the normal pair

Question 3

What are structural chromosomal abnormalities?

Answer 3

They are disorders in which a part of an individual chromosome is missing, added or switched to another chromosome

Question 4

What are the four subtypes of structural abnormalities?

Answer 4

Translocations

Deletions

Insertions

Inversions

Question 5

What are the two types of chromosomal translocations?

Answer 5

Reciprocal

Robertsonian

Question 6

What are reciprocal translocations?

Answer 6

It involve breaks in two chromosomes with formation of two new derivative chromosomes

Question 7

What are the two types of reciprocal translocations?

Answer 7

Balanced

Unbalanced

Question 8

What are balanced reciprocal translocations?

Answer 8

They are when the exchange of genetic material between the two chromosomes is equal, with no genetic information extra or missing

This means that full functionality is still achieved, and the individual is simply a carrier

Question 9

What are unbalanced reciprocal translocations?

Answer 9

They are when the exchange of genetic material between the two chromosomes is uneven, with extra or missing genes resulting

This means that one chromosome will have partial trisomy (extra information) and another will have partial monosomy (missing information)

Question 10

What are Robertsonian translocations?

Answer 10

It is a form of chromosomal rearrangement where the participating chromosomes break at their centromeres and the long arms fuse to form a single, large chromosome with a single centromere.

Question 11

Is genetic material lost in Robertsonian translocations?

Answer 11

No

Question 12

What are deletion chromosomal abnormalities?

Answer 12

This is the deletion of one or more nucleotide base pairs in a DNA sequence

Question 13

What are the two types of chromosomal deletions?

Answer 13

Terminal

Interstitial

Question 14

What is a terminal chromosomal deletion?

Answer 14

This is the loss of the end of a chromosome

Question 15

What is an interstitial chromosome deletion?

Answer 15

This is the loss of the middle of a chromosome

Question 16

What is an insertion chromosomal abnormality?

Answer 16

This is when a one or more nucleotide base pairs is added into a DNA sequence

Question 17

What is an inversion chromosomal abnormality?

Answer 17

This is when a segment of chromosome is reversed end to end

This occurs when a single chromosome undergoes breakage and rearrangement within itself

Question 18

What are the two types of chromosomal inversions?

Answer 18

Paracentric

Pericentric

Question 19

What are paracentric chromosomal inversions?

Answer 19

They do not include the centromere and both breaks occur in one arm of the chromosome

Question 20

What are pericentric chromosomal inversions?

Answer 20

They include the centromere and there is a break point in each arm

It results in balanced rearrangements as no genetic material is added or lost

Question 21

What is the mechanism of chromosomal abnormalities?

Answer 21

Non-disjunction

Question 22

What is nondisjunction?

Answer 22

It is the failure of homologous chromosomes or sister chromatids to separate properly during cell division (meiosis)

Question 23

What occurs when nondisjunction occurs during anaphase I of meiosis I?

Answer 23

This means that at least one pair of the homologous chromosomes did not separate

This results in two cells that have an extra copy of one chromosome and two cells that are missing the chromosome

Question 24

What occurs when nondisjunction occurs during anaphase II of meiosis II?

Answer 24

This means that at least one pair of sister chromatids did not separate

This results in two cells that have the normal haploid number of chromosomes

However, one cell will have an extra chromosome and one will be missing a chromosome.

Question 25

What are autosomal aneuploidy syndromes?

Answer 25

They refer to all abnormalities that do not involve the sex chromosomes

Question 26

Name three autosomal aneuploidy syndromes

Answer 26

Down's syndrome Patau syndrome Edward's syndrome

Question 27

What are sex chromosome aneuploidy syndromes?

Answer 27

They refer to all abnormalities that involve the sex chromosomes

Question 28

Name two sex chromosome aneuploidy syndromes

Answer 28

Turner's syndrome Klinfleter's syndrome

Question 29

What are germline gene mutations?

Answer 29

A gene mutation affecting germ cells

Question 30

Can gremline gene mutations be passed onto offspring?

Answer 30

Yes

Question 31

What are somatic gene mutations?

Answer 31

A gene mutations affecting somatic cells

Question 32

Can somatic gene mutations be passed onto offspring?

Answer 32

No

Question 33

What are non-coding gene mutations?

Answer 33

These are mutations that arise in non-coding DNA sequences These are components of an organism’s DNA that do not encode protein sequences

Question 34

What are coding mutations?

Answer 34

These are mutations that arise in coding DNA sequences, which are components of an organism’s DNA that encode protein sequences

Question 35

What are the four types of coding mutations?

Answer 35

Silent Missense Nonsense Frameshift

Question 36

What are silent gene mutations? Give an example

Answer 36

They are mutations in DNA that do not have an observable effect on the organism’s phenotype For example, CGA (Arg) to CGC (Arg)

Question 37

What are missense gene mutations? Give an example

Answer 37

They are mutations in DNA that change a single nucleotide base This causes the substitution of a different amino acid in the resulting protein For example, CGA (Arg) to GGA (Gly)

Question 38

What are the three potential affects of missense gene mutations?

Answer 38

No effect It may cause the protein to have a different function It may cause the protein to have no function at all

Question 39

What are nonsense gene mutations? Give an example

Answer 39

They are mutations in DNA that cause substitution of a nucleotide with a stop codon - where previously there was a codon that coded for an amino acid For example, CGA (Arg) to TGA (stop codon)

Question 40

What is the effect of nonsense gene mutations?

Answer 40

The production of a shortened, likely non-functional protein

Question 41

What are frameshift gene mutations? Give an example

Answer 41

This is a mutation caused by insertions or deletions of a number of nucleotides in a DNA sequence .For example, CGA (Arg) to CCG A… (Pro)

Question 42

What is the effect of frameshift gene mutations?

Answer 42

These insertions and deletions will affect the whole DNA sequence after the mutation, as it will result in the sequence shifting to forward or backwards so that each codon is read differently