DNA & RNA (2.6)

Question 1

What does DNA and RNA stand for?

Answer 1

Deoxyribonucleic acid and Ribonucleic Acid

Question 2

What is the main characteristic shared by DNA and RNA?

Answer 2

Both are a polymer of nucleotides that form a strand.

Question 3

Structurally, what is the difference between DNA and RNA?

Answer 3

DNA is a double-stranded nucleic acid, while RNA is made up of a single strand.

Question 4

What are strands and what are their composition?

Answer 4

A DNA strand is a long, thin molecule—averaging only about two nanometers. The strand consists of a backbone of sugar molecules and phosphate groups, with bases attached to the sugars.

Question 5

What are DNA strands composed of? What are Nucleotides composed of?

Answer 5

They are all composed of building blocks called nucleotides that are linked together in a row. Nucleotides themselves are comprised of three joined parts: a pentose sugar, a phosphate group, and a nitrogenous base.

Question 6

What are the basis of DNA and RNA?

Answer 6

guanine (G), adenine (A), thymine (T) and cytosine (C). RNA has the same bases except for thymine, which is replaced by uracil (U).

Question 7

How can bases be classified? Name the classification and classify Guanine, Adenine, Thymine, Cytosine, and Uracil.

Answer 7

Bases can be classified based on the number of rings present in their structure. Purines are bases that have two rings in their structure, while pyrimidines contain only one ring. Thymine, cytosine, and uracil are examples of pyrimidines, while adenine and guanine are classified as purines.

Question 8

State differences between DNA and RNA:

Answer 8

DNA:
Contains the sugar deoxyribose.
Bases involved are adenine, thymine, guanine, and cytosine.
Is a double-stranded molecule.

RNA:
Contains sugar ribose.
Bases involved are adenine, uracil, guanine, and cytosine (thymine has been replaced by uracil).
Is a single-stranded molecule.

Question 9

What bond do the nucleotides use to be linked together?

Answer 9

Phosphodiester bond (a covalent bond).

Question 10

After the phosphodiester bond, what is formed?

Answer 10

A single strand, a polynucleotide

Question 11

How are phosphodiester bonds formed?

Answer 11

The phosphodiester bond is always formed between the phosphate group attached to the 5’-C of one sugar and the hydroxyl (OH) group attached to the 3’-C of another sugar.

https://youtu.be/o_-6JXLYS-k

Question 12

How do you count the carbons in a sugar?

Answer 12

3’ and 5’ refer to the carbon position of the sugar in DNA. Carbon 1 is attached to the base and from there on carbon atoms are counted in a clockwise direction

https://youtu.be/o_-6JXLYS-k

Question 13

How is the DNA structure usually described?

Answer 13

double helix
alpha helix
double stranded helix
double-stranded helix
double-helix
desoxyribonicleic acid

Question 14

What is the name of the pentose present in DNA molecules?

Answer 14

Deoxyribose

Question 15

What basis pair up with each other? And what is this known as?

Answer 15

Guanine always pairs with cytosine.
Adenine always pairs with thymine.

This rule is known as the complementary base pairing rule.

Question 16

What holds together the bonds between basis?

Answer 16

The two strands are held together by hydrogen bonds between G and C (3 hydrogen bonds) and between A and T (2 hydrogen bonds).

Question 17

What is required for the basis to face each other?

Answer 17

In order for bases to be facing each other, the two strands must run in opposite directions (i.e. they are antiparallel ) to each other. Thus, one strand of DNA runs from 5’ to 3’, and the opposite strand runs from 3’ to 5’.

Question 18

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?

Answer 18

40%

Question 19

Draw simple diagrams of the structure of single nucleotides of DNA and RNA using circles, pentagons and rectangles to represent phosphates, pentoses and bases.

Answer 19

Question 20

Who deduced the structure of DNA and what technique was used to determine it?

Answer 20

Crick and Watson, DNA X-ray diffraction patterns

Question 21

What tells us that A will always equal T and G will always equal C?

Answer 21

Chargaff’s base ratio