2.12 DNA Mutagenesis, Repair and Relevant Diseases Flashcards Preview

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Flashcards in 2.12 DNA Mutagenesis, Repair and Relevant Diseases Deck (46)
1

Any permanent heritable change in the DNA base sequence of an organism

Mutation

2

Has the potential to change the base sequence of mRNA and the amino acid sequence of proteins

Mutation

3

Organisms that are the exact same compy

Clone

4

DNA molecules are cleaved and the fragments are rejoined to give a new combination

Recombination

5

Recombination results to

Generation of new gene/allele combinations
Generating new genes
Integration of a specific DNA or virus
DNA repair

6

Purpose of recombination

For mapping of genes on chromosomes
For making transgenic cells and organisms

7

3 types of mutation

Point Mutation
Frame shift Mutation
Large segment deletion

8

Replacement of a single base with another single base nucleotide

Point mutation

9

2 types of point mutation on the level of the DNA

Type I: Transition
Type 2: Transversion

10

Name the type of point mutation. Cytosine -> Thymine

Transition

11

Name the type of point mutation. Thymine-> Adenine

Transversion

12

Point mutations lead to the following effects in proteins

Silent mutation
Missense mutation
Nonsense mutation

13

New codon codes for the same amino acid
Covered by buffering systems

Silent mutation

14

In silent mutation, there is usually a base change in ____

third position

15

True or false
Silent mutation has no effect on protein.

True

16

New codon codes for a different amino acid
Has variable effects of protein

Missense mutation

17

Missense mutation is called ____ if the new amino acid is similar to the old in terms of chemical structure

Conservative

18

On the other hand, missense mutation is considered ___ when the mutation results in a different amino acid with different properties.

Non-conservative

19

In sicke cell anemia, __ is produced instead of glutamic acid

Valine

20

New codon is stop codon

Nonsense mutation

21

Nonsense mutation results in a ___ and __ protein product

Truncated
Non-functional

22

Deletion or addition of a number of bases not divisible by three

Frame shift mutation

23

Frame shift mutation results in a truncated and usually non-functional protein product, just like in ___ mutation

Nonsense

24

Loss of large areas of chromosomes during unequal crossover in meiosis
Leads to loss of function

Large segment deletion

25

Characterized by intellectual disability, delayed development, small head size, low birth weight and weak muscle tone during infancy
Affected individuals ave distinctive facial features, including widely set eyes, low-set ears, small jaw, and a rounded face

Cri-du-chat

26

Cri-du-chat is caused by a deletion of the end of the short arm of chromosome __

5

27

DNA damage is caused by ___ that escaped proofreading.

Mismatched strands

28

DNA repair occurs in ___ of cell cycle

G2

29

Nicks the mismatched strand and the mismatched base is removed

Endonuclease

30

Enzymes that complete the repair after endonuclease nicked the mismatched strand

DNA polymerase I
DNA ligase

31

Also known as Lynch syndrome

Hereditary Non-polyposis colorectal cancer (HNPCC)

32

Familial clustering of cancers at several sites

Hereditary non-polyposis colorectal cancer

33

Hereditary non-polyposis colorectal cancer is due to ___ and ___

Mismatch repair deficiency
Microsatellite instability

34

Caused by gene mutations and epigenetic alterations (activation of oncogenic pathways and inactivation of tumor suppressor genes)

Colorectal cancer

35

Thymine dimers exposed to UV light prevents DNA from replicating the DNA strand beyond the dimers

Xeroderma pigmentosum

36

Damaged DNA due to exposure of UV light by thymine dimers are removed by ___ and the resulting gap is filled by ____

UV-specific endonuclease
DNA polymerase I

37

Remove abnormal nitrogenous bases by hydrolytically cleaving N-glycosidic bond from the deoxyribose-phosphate backbone

Glycosylases

38

Makes a nick at the 5'-site of the AP site

AP endonucleases

39

Types of recombination

Homologous
Site specific
Transposition

40

Occurs between sequences that are nearly identical

Homologous

41

Occurs between sequences with a limited stretch of similarity

Site specific

42

DNA element moves from one site to another

Transposition

43

Mismatched base pairs that escape the proofreading step are repaired by Mut proteins
Mutation to proteins involved in this is associated with Lynch syndrome

Methyl-directed mismatch repair

44

Repair mechanism
UV light exposure causes covalent binding of two adjacent pyrimidies

UV light damage repair

45

Repair mechanism
DNA nitrogen bases altered spontaneously or through deaminating/alkylating compounds

Base excision repair

46

Repair mechanism
Double-strand breaks caused by high-energy radiation or oxidative free radicals

Double strand break repairs