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Flashcards in Mutations Deck (27)
1

mutations always change ________

genotype of organism

2

genotype

complement of genes organism possesses

3

phenotype

physical expression of genes
appearance, chemical and structural characteristics of individuals

4

effect of mutation on organism depends on

where it occurs and how much the protein changes

5

sickle cell anemia

1 DNA base change in gene for hemoglobin changes 1 amino acid
glutamate (GLU) is replaced by valine (VAL)

6

neutral mutations

do not affect survival
may occur in unexpressed regions of DNA

7

beneficial mutations

rare
antibiotics resistance in bacteria

8

2 forms of mutations

1. spontaneous
2. induced

9

spontaneous mutations

occur naturally during replication or form as misalignment deletions

10

induced mutations

caused by mutagens

11

3 types of mutagens

1. chemical
2. physical
3. biological

12

chemical mutagens

chemicals mimic DNA bases or alter normal bases
AZT- mimics thymine
acyclovir- mimics guanine
aminopurine- mimics adenine
bromouracil- mimics thymine; binds guanine not adenine
nitrous acid- alters adenine to bind cytosine not thymine

13

physical mutagens

uv light and ionizing radiation

14

uv light

non ionizing, non penetrating rays
cause thymine dimers in DNA of skin from sunburn

15

thymine dimers

adjacent thymines bind laterally
may cause melanoma

16

xeroderma pigmentosum

genetic disease
tumors in response to uv

17

ionizing radiation

penetrates barriers
damages DNA

18

biological mutagens

transposons
"jumping genes"
control own movement- move around genome
cause mutations when inserted into other genes

19

5 mutation patterns

1. base substitution
2. frameshift
3. inversions
4. duplications
5. translocation

20

base substitution

point mutation
1 DNA base changed to another
a. missense
b. silent
c. nonsense

21

missense mutation

changes codon at 1st or 2nd DNA base
alters codon meaning to change amino acid
alters amino acid sequence of protein- may change protein function
sickle cell anemia

22

silent mutation

changes 3rd base of codon
usually codes for same amino acid
usually no effect on protein function

23

nonsense mutation

base substitution forms stop codon
protein synthesis stops before correct termination point

24

frameshift

insertions and deletions
shift codon reading frame to change amino acid sequence

25

inversions

reverse DNA base sequence of gene

26

duplications

inserts additional copies of DNA sequence into genome

27

translocation

DNA moves from 1 chromosome to another
Down's syndrome