DNA REPAIR

Question 1

WHAT IS THE FUNCTION OF EXONUCLEASES

Answer 1

‘PROOF READ’ DNA TO CORRECT ERRORS MADE IN REPLICATION

Question 2

WHAT TYPES OF DAMAGE CAN DNA BE EXPOSED TO

Answer 2

1. THERMAL DEGRADATION
2. METABOLIC BYPRODUCTS
3. ENVIRONMENTAL SUBSTANCES
4. RADIATION

Question 3

WHY IS IT IMPORTANT THAT DNA CAN BE REPAIRED COMPARED TO OTHER MOLECULES

Answer 3

DNA HAS TWO MOLECULES ONLY AND HARBOURS MOST INFORMATION

Question 4

WHICH BASES ARE CONSIDERED PURINES

Answer 4

ADENINE AND GUANINE

Question 5

WHAT STRUCTURALLY MAKES PURINES DIFFERENT TO PYRAMIDINES

Answer 5

TWO CARBON NITROGEN RING BASES

Question 6

WHICH BASES ARE CONSIDERED PYRIMADINES

Answer 6

CYTOSINE, THYMINE AND URACIL

Question 7

WHY IS THE CYTOSINE GUANINE PAIR A MORE STABLE MOLECULE

Answer 7

BECAUSE IT CAN FORM 3 H BONDS

Question 8

WHAT STRUCTURALLY STOPS THYMINE FORMING 3 H BONDS

Answer 8

CH3 GROUP

Question 9

DEAMINATION (ADDITION OF H2O AND REMOVAL OF NH3) OF CYTOSINE RESULTS IN WHAT

Answer 9

CONVERSION TO URACIL

Question 10

THERE ARE SITES ON ALL BASES THAT ARE VULNERABLE TO WHAT

Answer 10

1. HYDROLYTIC ATTACK

2. OXIDATIVE DAMAGE

Question 11

URACIL IS ALMOST CHEMICALLY IDENTICAL TO WHICH BASE

Answer 11

THYMINE

Question 12

WHAT IS THE DIFFERENCE BETWEEN URACIL AND THYMINE

Answer 12

ONE METHYL GROUP

Question 13

FAILURE TO UNDERTAKE DNA REPAIR RESULTS IN

Answer 13

MUTATION

Question 14

IF REPAIR IS NOT UNDERTAKEN BEFORE REPLICATION WHAT OCCURS

Answer 14

ONE OF THE NEW DAUGHTER STRANDS WOULD CARRY THE MUTATION

Question 15

WHAT ARE THE TWO CATEGORIES OF MUTATION

Answer 15

TRANSVERSION

TRANSITION

Question 16

WHAT IS TRANSVERSION

Answer 16

MUTATION OF A PURINE FOR A PYRIMIDINE OR VICE VERSA

Question 17

WHAT IS A TRANSITION

Answer 17

MUTATION OF A PURINE FOR A DIFFERENT PURINE OR PYRIMIDINE FOR ANOTHER PYRMIDINE

Question 18

HOW MANY TYPES OF TRANSVERSION IS THERE

Answer 18

4 TYPES

Question 19

HOW MANY TYPES OF TRANSITION IS THERE

Answer 19

2 TYPES

Question 20

IS TRANSVERSION OR TRANSITION MORE COMMON

Answer 20

TRANSITION MUTATIONS ARE MORE COMMON

Question 21

TRANSITION MUTATIONS ARE ……….. LIKELY TO RESULT IN AMINO ACID SUBSTITUTIONS

Answer 21

LESS

Question 22

MULTIPLE POTENTIAL …………… ALLOW FOR THE ………… AMINO ACID

Answer 22

CODONS

SAME

Question 23

MOST OF THE TIME MUTATION IN THE FIRST OR SECOND BASE WILL RESULT IN WHAT

Answer 23

AMINO ACID SUBSTITUTION

Question 24

MUTATIONS IN THE THIRD BASE OF A CODON, MOST ARE …………………….. ALTERNATIVES

Answer 24

TRANSITIONAL

Question 25

WHAT OCCURS AS A RESULT OF UV LIGHT

Answer 25

PHOTOLYTIC CONVERSION

Question 26

WHAT DOES PHOTOLYTIC CONVERSION CAUSE

Answer 26

PYRMIDINE DIMERS

Question 27

WHAT IS A PYRIMIDINE DIMER

Answer 27

THE DOUBLE BONDS IN PYRIMIDINES ARE HIGHLY REACTIVE AND WHEN UV LIGHT BREAKS THE BONDS, THEY FORM BOND WITH THEMSELVES INSTEAD OF THE COMPLIMENTARY PURINE

Question 28

HOW CAN PHOTOLYTIC CONVERSION BE REPAIRED

Answer 28

NUCLEOTIDE EXCISION REPAIR (NER/LONG PATCH) USES AN EXCISION NUCLEASE TO CLEAVE A 12 NUCLEOTIDE LONG SSDNA AROUND THE DIMER. DNA HELICASE UNWINDS IT FROM THE STRAND SO IT CAN BE EXPOSE TO DNA POLYMERASE AND SEALED BACK WITH DNA LIGASE.

Question 29

HOW IS DEPURINATION REPAIRED

Answer 29

VIA THE BASE EXCISION REPAIR PATHWAY (BER/SHORT PATCH)

Question 30

WHAT IS THE BER PATHWAY

Answer 30

REPAIR ENZYMES(GLYCOSYLASES) FIND AN INAPPROPRIATE BASE, IT IS CLEAVED AN ENDONUCLEASE AND PHOSPHODIESTERASE REMOVE THE BACKBONE DNA POLYMERASE ADDS THE NEW NUCLEOTIDE DNA LIGASE SEALS IT IN

Question 31

WHAT METHOD DO GLYCOSYLASES USE TO FIND ERRORS

Answer 31

BASE FLIPPING

Question 32

WHAT HAPPENS WHEN DNA POLYMERASE REACHES ABNORMAL DNA THAT HAS NOT BEEN REPAIRED

Answer 32

IT RELEASES FROM THE STRAND AND TRANS-LESIONAL DNA POLYMERASE BINDS VIA ASSEMBLY FACTORS

Question 33

WHAT IS THE DISADVANTAGE OF TRANS LESIONAL DNA POLYMERASE

Answer 33

THEY LACK PRECISION AND ARE MORE LIKELY TO MAKE ERRORS WHEN CROSSING THE POINT OF DAMAGE

Question 34

WHAT IS THE MAIN CAUSE OF BASE SUBSTITUTION AND SINGLE NUCLEOTIDE DELETION MUTATIONS

Answer 34

TRANS LESIONAL DNA POLYMERASE

Question 35

WHAT ARE THE ADVANTAGES OF TRANS LESIONAL DNA POLYMERASE

Answer 35

1. ITS MISTAKES ARE A DRIVER OF EVOLUTION | 2. IT IS THE BEST CASE SCENARIO IN TERMS OF REPAIR THAT HAS NOT HAPPENED PRIOR TO REPLICATION

Question 36

WHY ARE DOULE STRANDED BREAKS HAZARDOUS

Answer 36

THERE IS NO TEMPLATE FOR REPAIR

Question 37

WHAT ARE THE CAUSES OF DS BREAKS

Answer 37

IONISING RADIATION REPLICATION ERRORS OXYGEN RADICALS

Question 38

WHAT ARE THE TWO MECHANISMS THAT EXIST TO REPAIR DS BREAKS

Answer 38

1. NON HOMOLOGOUS END JOINING | 2. HOMOLOGOUS RECOMBINATION

Question 39

WHAT HAPPENS IN NON HOMOLOGOUS END JOINING

Answer 39

THE ENDS OF THE BROKEN DNA MOLECULES ARE JOINED TOGETHER AFTER EACH END IS PROCESSES

Question 40

WHAT ARE THE DISADVANTAGES OF NON HOMOLOGOUS END JOINING

Answer 40

THERE IS A CHANCE OF LOSS OF NUCLEOTIDES | THERE IS A CHANCE THAT THERE IS JOINING OF THE WRONG STRANDS

Question 41

WHAT IS HOMOLOGOUS RECOMBINATION

Answer 41

NUCLEASE DIGESTS THE ENDS OF BROKEN STRANDS | THE STRAND INVADES THE HOMOLOGOUS STRAND ALLOWING TEMPLATED REPLICATION IN ORDER TO GET AN ACCURATE COPY

Question 42

WHAT IS THE ADVANTAGE OF HOMOLOGOUS RECOMBINATION

Answer 42

IT IS MORE ACCURATE

Question 43

WHAT IS THE DISADVANTAGE OF HOMOLOGOUS RECOMBINATION

Answer 43

YOU GET LOSS OF HETEROZYGOSITY AS THE LOST ALLELE MAY HAVE BEEN DIFFERENT FROM WHAT IS BEING COPIED

Question 44

GIVE AN EXAMPLE OF A DISEASE THAT ARISES FROM LACK OF DNA REPAIR ENZYMES

Answer 44

XERODERMA PIGMENTOSUM

Question 45

FAILURES IN DNA REPAIR SYSTEMS HAVE STRONG LINKS TO WHAT

Answer 45

CANCERS