Nucleic Acids and DNA

Question 1

What are some of the cellular activities performed by proteins?

Answer 1

Catalyze metabolic reactions, build cellular structures, and send/receive signals.

Question 2

What is the function of the building blocks of DNA?

Answer 2

Storage of genetic information

Question 3

What is the function of the building blocks of RNA?

Answer 3

carrier of genetic information + structural components of tRNA, ribosomes, spliceosomes, etc.

Question 4

What are the functions of energy metabolism?

Answer 4

ATP, GTP, and perform biochemical work

Question 5

What is the function of cellular signalling?

Answer 5

second messengers in the form of cAMP etc

Question 6

What is the linear polymer of deoxyribonucleotides?

Answer 6

DNA

Question 7

What is the linear polymer of ribonucleotides?

Answer 7

RNA

Question 8

What are nucleotides composed of?

Answer 8

phosphate, pentose sugar (5 carbon) and nitrogenous base

Question 9

What is the difference between nucleotides and nucleoside?

Answer 9

Nucleotides consist of phosphates, sugar, and base while nucleoside only has sugar and base (i.e. no phosphate group).

Question 10

What makes up an adenosine?

Answer 10

Ribose and adenine

Question 11

What are some differences between pyrimidine and purine?

Answer 11

Pyrimidines have single ring and smaller structure. Purines have double ring and larger structure.

Question 12

What are the five types of nitrogenous bases? What are considered pyrimidines and purines?

Answer 12

Thymine, cytosine and uracil are types of pyrimidines. Adenine and guanine are types of purines.

Question 13

What are two types of pentose sugars? Differentiate between the two.

Answer 13

Ribose has OH group at #2 carbon and is a building block of Ribonucleic acid. While 2-deoxyribose lacks OH group at the #2 carbon (only has H) and is a building block of deoxyribonucleic acid.

Question 14

What is the difference between pyrimidines and purines in terms of the connection between nitrogen and carbon of ribose sugar.

Answer 14

In pyrimidines, nitrogen 1 is connected to the 1’ carbon of the ribose sugar. In purines, nitrogen 9 is connected to the 1’ carbon of the ribose sugar.

Question 15

What forms when a sugar phosphate is added to a base such as guanine?

Answer 15

Nucleotide

Question 16

Where does nucleotides attach on the structure of the ribose (sugar)?

Answer 16

Through 5’ and 3’ carbons

Question 17

How does polymerization occur?

Answer 17

Polymerization occurs via formation of 3’ to 5’ phosphodiester bonds.

Question 18

In what direction does DNA get synthesized?

Answer 18

In the 5’ -> 3’ direction

Question 19

What is an enzyme catalyzed condensation reaction?

Answer 19

When 3’ carbon of the first nucleotide attacks the 5’ carbon of the second nucelotide.

Question 20

How does nucleotides polymerize?

Answer 20

Nucleotide1 is about to polymerize nucleotide 2. Then 3’ OH of the nucleotide 1 attacks the 5’ phosphates of nucleotide 2. Afterwards, 3’-5’ phosphodiester bond connects nucleotide 1 and 2. Then when Nucleotide 3 is about to polymerize, 3’ OH of the nucleotide 2 attacks the phosphates of nucleotide 3. Therefore, nucleotide 3 is now incorporated into the polymerize nucleotides.

Question 21

Where does incoming nucleotides get added?

Answer 21

Incoming nucleotides always gets added to the 3’ end of the already existing poly-nucleotide.

Question 22

What is the alternating chains of sugar and phosphate called?

Answer 22

Sugar-phosphate backbone.

Question 23

What is true about the 5’ end of the linear polynucleotide?

Answer 23

They will always have 3 phosphates attached.

Question 24

How are nitrogenous bases forms a pair?

Answer 24

Bia hydrogen bonds

Question 25

What are the Watson Crick base pairing?

Answer 25

Adenine pairs with thymine (or uracil), guanine pairs with a cytosine, and purine pairs with pyrimidines.

Question 26

What holds the two strands of DNA together,i.e., what makes double stranded DNA?

Answer 26

Base-pairing of nitrogenous bases between two strands of DNA holds the strands together.

Question 27

How are the two strands of DNA held and why is that?

Answer 27

Two strands of DNA are held antiparallel to each other with respect to their 5'-3' polarity.

Question 28

What is on the outside and inside of a double stranded DNA?

Answer 28

Sugar-phosphate backbone on the outside and nitrogenous bases inside.

Question 29

What is the distance between the two C1' carbons in a base-pair?

Answer 29

10.85 A or 1.085 nm

Question 30

What hold DNA strands together?

Answer 30

Hydrogen bonds

Question 31

What is the difference between C-G pair and A-T pair?

Answer 31

C-G pair has one more hydrogen bond compared to A-T pair, therefore, it takes more energy to break apart a CG pair.

Question 32

What is denaturation?

Answer 32

It is when hydrogen bonds break with heat

Question 33

What is true about the species living in extremely high temperatures in terms of % GC of genome?

Answer 33

They may have higher % GC

Question 34

An organism's genome is 15% Adenine. What is the % Guanine fro this organism?

Answer 34

15% A = 15% T, so AT = 30% 100% - 30% AT = 70% GC 70% GC / 2 = 35% G, 35% C

Question 35

What is used as a template to 'copy' DNA?

Answer 35

A single strand of parental DNA

Question 36

In what direction should the nucleotide sequence be written?

Answer 36

5' to 3'

Question 37

What did Levene deciphered about the DNA structure?

Answer 37

DNA contains equal proportions of deoxyribose, nitrogenous bases, and phosphates

Question 38

What did Chargaff decipher about the DNA structure?

Answer 38

number of adenine = number of thymine, number of guanine = number of cytosine

Question 39

What did Franklin and Wilkins decipher about the DNA strcuture?

Answer 39

X-ray diffraction shows DNA structure is double helix

Question 40

What did Watson and Crick decipher about the DNA structure?

Answer 40

Deduced the double helical structure of DNA

Question 41

What is the distance per one turn of double helix? What is the distance between adjacent base-pairs? How many bases are there per turn?

Answer 41

3.4 nm is the distance per one turn, 0.34 nm is the distance between adjacent pairs, therefore, there are 10 bases per turn of double helix.

Question 42

What are the 3 structural variants of double stranded DNA?

Answer 42

A, B, and Z

Question 43

Describe the structure of A-DNA

Answer 43

* right handed * short and broad * <75% humidity

Question 44

Describe the structure of B-DNA

Answer 44

* right handed * longer and thinner * physiological conditions

Question 45

Describe the structure of Z-DNA

Answer 45

* left handed * elongated and slim * function unknown

Question 46

What angle does a major groove have? How about minor groove?

Answer 46

257, 103

Question 47

At what angle does DNA rotate while the next base pair gets attached on top?

Answer 47

36 degrees

Question 48

Where are the different 'shapes' of nucleotides exposed?

Answer 48

On the minor and major grooves

Question 49

What is the purpose of the major and minor grooves for proteins?

Answer 49

They become binding points for proteins

Question 50

How is the chemical composition of RNA similar to DNA?

Answer 50

Sugar-phosphate backbone with nitrogenous bases attached to sugars

Question 51

What are the differences of RNA compared to DNA?

Answer 51

* Pyrimidine uracil instead of thymine * Sugar is ribose, not deoxyribose; the sugar has a OH group on the 2' carbon * Exists as a single stranded molecule with extensive secondary structures * Not for storage * Some RNA has catalytic activity

Question 52

How are secondary structures formed using RNA?

Answer 52

When bases within the same molecule of single stranded RNA base-pair with one another