Unit 2, part 8

Question 1

What is a genetic mutation?

Answer 1

A permanent change in the DNA sequence that can be passed on to descendants.

Question 2

What is the difference between somatic and germline mutations?

Answer 2

Germline mutations occur in gametes and can be passed to offspring; somatic mutations occur in non-germ cells and are not passed to offspring.

Question 3

How are gene mutations categorized?

Answer 3

By types of gene mutations and their effects, including base substitutions, insertions, and deletions.

Question 4

What are the types of base substitutions?

Answer 4

• Silent * Missense * Nonsense * Read-through

Question 5

What is a frameshift mutation?

Answer 5

An insertion or deletion that alters the reading frame of a gene.

Question 6

What are the potential effects of mutations?

Answer 6

• Detrimental * Neutral * Beneficial

Question 7

What is a germline mutation?

Answer 7

A mutation in gametes that results in the entire organism carrying the mutation.

Question 8

What is a somatic mutation?

Answer 8

A mutation in non-germ cells that is passed to daughter cells through mitosis.

Question 9

What are the phenotypic effects of forward mutations?

Answer 9

Changes from wildtype (WT) to mutant (new novel mutation).

Question 10

What is a reverse mutation?

Answer 10

Changes a mutant phenotype back to the wild-type phenotype.

Question 11

What is a missense mutation?

Answer 11

Changes a sense codon into a different sense codon, resulting in the incorporation of a different amino acid in the protein.

Question 12

What is a nonsense mutation?

Answer 12

Changes a sense codon into a nonsense (stop) codon, causing premature termination of translation.

Question 13

What is a silent mutation?

Answer 13

Changes a sense codon into a synonymous codon, leaving the amino acid sequence of the protein unchanged.

Question 14

What is a loss-of-function mutation?

Answer 14

Causes a complete or partial loss of function of the protein.

Question 15

What is a gain-of-function mutation?

Answer 15

Produces a new trait or causes a trait to be exhibited in new places.

Question 16

What are the causes of spontaneous mutations?

Answer 16

Naturally occurring mutations that happen during replication due to wobble or strand slippage.

Question 17

What are mutagens?

Answer 17

Anything in the environment that increases the mutation rate.

Question 18

What is the role of DNA repair mechanisms?

Answer 18

To correct potential mutations through detection, excision, polymerization, and ligation.

Question 19

What is a neutral mutation?

Answer 19

Changes the amino acid sequence of a protein without altering its ability to function.

Question 20

True or False: Somatic mutations can be passed to offspring.

Answer 20

False

Question 21

Fill in the blank: A _______ mutation causes premature death.

Answer 21

lethal

Question 22

What are the three main types of DNA repair mechanisms?

Answer 22

Direct repair, Base-excision repair, Nucleotide-excision repair

These mechanisms are critical for maintaining genomic integrity.

Question 23

What is the difference between somatic cell mutations and germ line mutations?

Answer 23

Germ-line mutations impact the organism’s progeny and somatic mutations impact the organism itself, but are not passed on to progeny

Germ-line mutations can lead to hereditary diseases, while somatic mutations typically affect only the individual.

Question 24

True or False: DNA repair pathways have a lot of redundancy because they are so important.

Answer 24

True

Question 25

Loss of function and gain of function mutations are generally ______.

Answer 25

recessive

Question 26

True or False: Defects in DNA repair systems do not cause disease.

Answer 26

False

Question 27

What are the main types of chromosomal mutations?

Answer 27

* Rearrangements * Aneuploidy * Polyploidy ## Footnote These mutations can significantly impact genetic stability and organismal development.

Question 28

What are the types of rearrangements in chromosomal mutations?

Answer 28

* Duplications * Deletions * Inversions * Translocations

Question 29

What is aneuploidy?

Answer 29

Change in the number of individual chromosomes ## Footnote This condition can lead to various genetic disorders, including Down syndrome (Trisomy 21).

Question 30

What is polyploidy?

Answer 30

Change in the number of complete sets of chromosomes ## Footnote Common in plants but rare in animals.

Question 31

What are the types of duplications in chromosomal mutations?

Answer 31

* Tandem * Displaced * Reverse

Question 32

What are the types of deletions in chromosomal mutations?

Answer 32

* Interstitial * Terminal ## Footnote Terminal deletions can result in the loss of centromeres, leading to chromosomal loss during meiosis.

Question 33

What is an inversion in chromosomal mutations?

Answer 33

A chromosomal segment is inverted (turn 180°) ## Footnote Inversions can affect gene expression without losing any genes.

Question 34

What is a translocation in chromosomal mutations?

Answer 34

Movement of chromosomal segments between non-homologous chromosomes or within the same chromosome

Question 35

What is a reciprocal translocation?

Answer 35

A two-way exchange of segments between non-homologous chromosomes

Question 36

What is a non-reciprocal translocation?

Answer 36

A one-way exchange of segment(s) between chromosomes

Question 37

What is the 'Philadelphia chromosome'?

Answer 37

A gene called 'BCR-abl' formed on chromosome 22 due to a translocation, often found in chronic myelogenous leukemia

Question 38

What is a Robertsonian translocation?

Answer 38

Short arm of a chromosome is exchanged with the long arm of another chromosome, resulting in one large chromosome and one small fragment

Question 39

True or False: Sex chromosome aneuploidies are often lethal.

Answer 39

False

Question 40

What is the primary cause of aneuploidy?

Answer 40

Non-disjunction: failure of homologous chromosomes or sister chromatids to separate normally during mitosis or meiosis

Question 41

What is autopolyploidy?

Answer 41

Nondisjunction of entire sets of chromosomes from the same species ## Footnote This can be advantageous in agriculture.

Question 42

What is allopolyploidy?

Answer 42

Polyploidy where sets of chromosomes come from different, but typically related, species

Question 43

What can result in sterility?

Answer 43

Seedless plants ## Footnote Seedless plants often cannot reproduce naturally.

Question 44

What is allopolyploidy?

Answer 44

Sets of chromosomes come from different, but typically related, species ## Footnote Allopolyploidy is primarily used in plant cultivation.

Question 45

What percentage of flowering species are affected by allopolyploidy?

Answer 45

40% ## Footnote This indicates a significant role in the evolution of flowering plants.

Question 46

What percentage of grasses are affected by allopolyploidy?

Answer 46

80% ## Footnote Allopolyploidy is particularly common in grass species.

Question 47

What is a rare event in allopolyploidy?

Answer 47

Hybridization between species ## Footnote This involves gametes fusing and nondisjunction in mitosis.

Question 48

In allopolyploidy, what must happen for a full set of homologous chromosomes to be produced?

Answer 48

Gametes must fuse, then have nondisjunction in mitosis ## Footnote This allows for the reproduction of asexually derived plants.

Question 49

What is an example of an allopolyploid plant?

Answer 49

Wheat ## Footnote Wheat is an allohexaploid with 42 chromosomes from 3 distinct species.

Question 50

How many chromosomes does wheat have?

Answer 50

42 chromosomes ## Footnote It is derived from 3 distinct species, each with a diploid set of 14 chromosomes.

Question 51

True or False: Allopolyploidy is primarily a tool for animal cultivation.

Answer 51

False ## Footnote Allopolyploidy is primarily a tool for plant cultivation.