Molecular biochemistry W1

Question 1

Where is DNA found

Answer 1

Nucleus and mitochondria

Question 2

How does DNA store heritable information

Answer 2

Through its nucleotide sequence

Question 3

Name the purines

Answer 3

Adenine , Guanine

Question 4

Name the pyrimidines

Answer 4

Cytosine , Thymine

Question 5

What does each nucleotide consist of

Answer 5

• deoxyribose sugar.
  -Pentose sugar
  -Nitrogenous base

Question 6

What is the 5 end

Answer 6

Phosphate end

Question 7

What is the 3 end

Answer 7

Hydroxyl end

Question 8

What is the effect of Methylation in relation to DNA

Answer 8

It affects gene expression, without chnaging the DNA sequence

Question 9

What are the functions of methylation

Answer 9

-X chromosme inactivation in females
-Regulation of gene expression during development
-Silencing of transposons
-Imprinting

Question 10

How many hydrogen bonds are presen between Adenine and Thymine

Answer 10

2

Question 11

How many hydrogen bond present between Cytosine and guanine

Answer 11

3 hydrogen bonds

Question 12

Name the 2 hydrogen donors bases contain

Answer 12

• OH, NH2

Question 13

Name the 2 hydrogen acceptors bases contain

Answer 13

• O , N

Question 14

How many donors + acceptors does A+ T have

Answer 14

• 1 donor + 1 acceptor

Question 15

How many donors+ acceptors does guanine have

Answer 15

2 donors and 1 acceptor

Question 16

What is Chargaffs Rule

Answer 16

• That DNA contains equal amounts of A&T and C&G

Question 17

Explain the structure of DNA

Answer 17

-Double helical structure with 2 complementary strands running in opposite directions

Question 18

Where are hydrogen bonded bases located

Answer 18

Near the central axis

Question 19

What do unequal spaces in the DNA create

Answer 19

Major and minor groove

Question 20

Name the differnt types of DNA helices

Answer 20

• A-DNA , B-DNA, Z-DNA

Question 21

What type of DNA helices is the most common

Answer 21

• B-DNA

Question 22

What do transcription factors bind to and why

Answer 22

• Major or minor grooves, to recognise nucleotide sequences

Question 23

What happens to the hydrogen bonds between the bases during replication, repair and transcription

Answer 23

They break and reform

Question 24

How is DNA organised during DNA compaction

Answer 24

Into nucleosomes, then into chromatin fibers , then into chromatids during cell divison

Question 25

What does a nucleosme consits of

Answer 25

- Core particle -Linker DNA

Question 26

How is DNA found in eukaryotic cells

Answer 26

- It is found associated with various types of proteins known as nucleoprotein

Question 27

How is DNA found in prokaryotes

Answer 27

-Found in a non-membrane bound region, called nucleoid

Question 28

What is the difference between the Nucleoside and Nucleotide

Answer 28

Nucleoside contains: -Pentose sugar -Nitogenous bases Nucloetide contains: -Phosphoric Acid -Pentose -Nitrogenous base

Question 29

What is the structure of purines

Answer 29

-Double ring structures

Question 30

What is the structure of pyrimidines

Answer 30

-Single ring structures

Question 31

Name the amino acids necessary for purine synthesis

Answer 31

Glycine, Aspartate, Glutamate

Question 32

What is Deamination reactions

Answer 32

- Removal of an amine group

Question 33

What does the deamination of cytosine produce?

Answer 33

- Uracil

Question 34

What does the deamination of Adenine produce

Answer 34

Hypoxanthine

Question 35

What does the deamination of Guanine produce

Answer 35

Xanthine

Question 36

What does the deamination of 5-Methylcytosine produce

Answer 36

- Thymine

Question 37

What does the methylation of Uracil make

Answer 37

- Thymine

Question 38

What is the loss of the helical structure in DNA called ?

Answer 38

- Denaturation

Question 39

Name 2 ways the DNA structure can be altered

Answer 39

-PH -Heat

Question 40

What is renaturation

Answer 40

- When the DNA solution is cooled or titrated to a neutral pH, the complementary DNA strands can reform the double helix

Question 41

What is the structure of DNA in eukaryotes

Answer 41

-Closed,long, linear circular DNA

Question 42

What is the structure of DNA in prokaryotes

Answer 42

- Single, circular DNA

Question 43

Name the 5 classes of histones

Answer 43

- H1, H2A, H2B, H3 and H4

Question 44

What type of Bonds does histones form with negatively charged DNA

Answer 44

- Ionic bonds

Question 45

2 molecules of what type of Histoens form the octameric core of the nucleosomes

Answer 45

H2A, H2B, H3 and H4

Question 46

What can happen to the N-Terminal ends of the histones

Answer 46

They can be acetylated, methylated or phosphorylated

Question 47

What does acetylation,methylation and phosphorylation of the N terminal ends in histones influence

Answer 47

- They influence how tightly the histones bind to DNA

Question 48

What is drug induced Lupus caused by

Answer 48

- Use of certain drugs in ppl with anti-histone antibodies

Question 49

What are signs of Lupus(symptoms)

Answer 49

- Rashes -Muscle pain -Unintentional weight loss

Question 50

Which is more condensed heterochromatin or euchromatin

Answer 50

heterochromatin

Question 51

Explain which one of the chromatins are inactive and active

Answer 51

Euchromatin:Active Hetrochromatin: Inactive