MODULE 6 IQ1: Mutation

Question 1

mutagens definition

Answer 1

any agent which can cause a genetic mutation

Question 2

mutations definition

Answer 2

refers to any change in the DNA sequence

Question 3

mutagenesis definition

Answer 3

process by which the genetic material of an organism is changed, resulting in a mutation

Question 4

types of mutagens

Answer 4

physical (EMR) sources, chemical sources, naturally occuring

Question 5

physical sources description

Answer 5

• has high ionising radiation
• formation of covalent bonds between complementary nucleotides making them end prematurely

Question 6

chemical sources description

Answer 6

• substances that can give rise to mutations
• usually free radicals

Question 7

what are free radicals

Answer 7

odd unpaired electrons that try to bond with another electron to become stable

Question 8

naturally occurring description

Answer 8

present at natural levels but after long term exposure they can cause mutations

Question 9

biological mutagens

Answer 9

viruses, bacteria, fungi

Question 10

non-biological mutagens

Answer 10

mercury, cadmium, charred surface of fish or hamburger

Question 11

point mutation

Answer 11

alters, adds or removes one nucleotides from DNA or RNA sequence. only affects 1 gene

Question 12

cause of point mutation

Answer 12

• errors in DNA replication
• exposure to mutagens

Question 13

what is substitution mutation

Answer 13

1 nucleotide is replaced by another nucleotide

Question 14

what are the types of substitution mutation

Answer 14

silent, missense, nonsense

Question 15

silent mutation

Answer 15

new codon that still codes for same amino acid

Question 16

missense mutation

Answer 16

different amino acid but still produces a protein

Question 17

nonsense mutation

Answer 17

creation of stop codon

Question 18

what is frameshift mutation

Answer 18

addition or removal of 1 or 2 nucleotides causing whole DNA sequence to shift forwards or backwards

Question 19

what is the effect of a frameshift mutation

Answer 19

alters all codons due to production of different amino acids, causing significant effects on polypeptide produced

Question 20

what is chromosomal mutation

Answer 20

affects whole chromosomes and whole genes. also referred to as block mutations

Question 21

cause of chromosomal mutation

Answer 21

• errors in cell division (meiosis)
• exposure to mutagens

Question 22

what are the different types of chromosomal mutations

Answer 22

deletion, insertion, inversion, translocation, aneuploidy

Question 23

deletion

Answer 23

removes section of chromosome

Question 24

insertion

Answer 24

section of chromosome breaks off and attaches to different chromosome

Question 25

inversion

Answer 25

section of sequence breaking off chromosome, rotating 180 degrees and attaching to same chromosome

Question 26

translocation

Answer 26

whole chromosome or segment becomes attached or exchanged with another chromosome or segment

Question 27

aneuploidy

Answer 27

1 or more extra copies of an entire chromosome are made or entire chromosome is missing

Question 28

somatic mutations

Answer 28

• occurs in body cells
• affects individual but not hereditary
• when mutated somatic cell continues to divide by mitosis, error in DNA is replicated

Question 29

germ line mutations

Answer 29

• occurs in sex cells
• affects individual, chance of it being hereditary
• when germ line cell mutates, it is replicated in embryo and is hereditary

Question 30

exons

Answer 30

coding segment of DNA

Question 31

exons function

Answer 31

template to make polypeptides which later forms proteins

Question 32

exons importance

Answer 32

proteins are involved in coordinating bodily functions, maintenance and repair of body’s tissues and metabolic reactions

Question 33

significance of mutations in exons

Answer 33

• causes number of genetic diseases resulting in change of phenotype
• controls mitosis

Question 34

introns

Answer 34

non-coding segment of DNA

Question 35

introns function

Answer 35

regulatory functions
- gene expression & cell functioning for embyro development
- promoter regions (TATA box)
- terminators

Question 36

significance of mutations in introns

Answer 36

• protein expressed in wrong time or place
• disruptions in functions of regulatory elements (promoters/terminators)
• increased risk of some non-communicable diseases
• birth defects

Question 37

genetic variation in meiosis

Answer 37

produces 4 genetically unique haploid daughter cells
- crossing over (prophase I)
- independent assortment (metaphase I)
- random segregation of chromatids (anaphase II)

Question 38

genetic variation in fertilisation

Answer 38

random unison of male and a female gamete to produce an offspring
- one allele inherited from each parent

Question 39

genetic variation in mutations

Answer 39

• any change to DNA sequence