cell genetic material damage and repair

Question 1

what is xeroderma pigmentosum

Answer 1

sensitivity to sunlight

risk to multiple skin cancers after exposure to UV in sunlight

1/250,000

Question 2

what are mutations

Answer 2

permanent changes in DNA sequence

Question 3

where can mutations could be in?

Answer 3

somatic cells or in germline

Question 4

what can mutations be

Answer 4

chromosomal rearrangements (can alter large sequences of DNA)

Question 5

4 types of chromosomal rearrangements

Answer 5

deletions, duplications, inversions, and translocations

Question 6

what are point mutations

Answer 6

mutations affecting a single or few DNA base pair

Question 7

mutations on normal allele

Answer 7

codes for a functional protein

Question 8

mutations with no phenotypic effect

Answer 8

codes for a functional protein

Question 9

loss-of-function mutation

Answer 9

codes for nonfunctional protein

Question 10

gain-of-function mutation

Answer 10

codes for a protein with a new function

Question 11

silent mutation

Answer 11

no affect on amino acid sequence

Question 12

missense mutation

Answer 12

produces an amino acid that is different from the usual amino acid at that position

Question 13

nonsense mutation

Answer 13

causes the premature termination of a protein

Question 14

loss-of-stop mutation

Answer 14

original termination codon (a stop was lost), resulting in abnormal extension of a protein’s carboxyl terminus

Question 15

frameshift mutation

Answer 15

insertion or deletion of nucleotide bases in numbers that are not multiples of three

Question 16

DNA polymerase makes ______ mistake per ______ nucleotides copied

Answer 16

1 per 100,000

Question 17

mutations can occur?

Answer 17

spontaneously

Question 18

what are the most frequent chemical reactions known to create serious DNA damage in cells

Answer 18

deprivation and deamination

Question 19

what does deamination lead to

Answer 19

transition mutations (GC to AT)

Question 20

depurination leads to?

Answer 20

base pair deletion

Question 21

what are chemical mutagens

Answer 21

alkylating agents
base analogs
acridines
deaminating agents
hydroxylating agents

Question 22

mutations can be _______ by chemical reagents

Answer 22

induced

Question 23

what does alkylating agents induce

Answer 23

transitions, transversions, frameshift and chromosome aberrations

Question 24

acridine dyes (like _____) induce _______

Answer 24

like proflavine induce frameshift mutations

Question 25

nitrous acid induces

Answer 25

transition

Question 26

mutations can also be induced by

Answer 26

radiation

Question 27

UV radiation induces

Answer 27

thymine dimers

Question 28

x-rays and y-rays cause ??

Answer 28

single and double stranded breaks in DNA

Question 29

what kind of activity foes DNA polymerase have

Answer 29

proofreading

Question 30

DNA polymerase with a proofreading activity makes _____ mistake per _____ nucleotides copied

Answer 30

1 per 10,000,000

Question 31

mismatch repair mechanism repairs ______

Answer 31

mispaired bases

Question 32

mismatch repair (MMR) mechanism restores the ______ ?

Answer 32

original sequence

Question 33

what do mismatch repair proteins recognize and repair?

Answer 33

DNA

Question 34

what removes modified bases

Answer 34

base excision repair mechamism BER

Question 35

what repairs thymine dimers

Answer 35

nucleotide excision NER

Question 36

what repairs mechanisms

Answer 36

point mutations

Question 37

how can double-strand DNA breaks be repaired?

Answer 37

non homologous end joining and homologous recombination

Question 38

a single nucleotide change causes the disease

Answer 38

sickle-cell anemia

Question 39

failure to repair _________ in xeroderma pigmentosum disease

Answer 39

thymine dimer

Question 40

many human diseases are caused by ????

Answer 40

defects in DNA repair