Nucleic acids, DNA, RNA

Question 1

What are the two types of nucleic acids?

Answer 1

RNA and DNA

Question 2

What is the monomer of a nucleic acid (polymer)?

Answer 2

Nucleotide

Question 3

What are the 3 components of a nucleotide?

Answer 3

a phosphate
a pentose sugar (monosaccharide with 5 carbons)
a nitrogenous organic base - 1 of 5 different bases (ACTGU)

Question 4

Structure of RNA

Answer 4

● Single stranded polynucleotide chain that is relatively short
● Pentose sugar - ALWAYS Ribose (hence the name)
● Bases - either A, G, C or U

Question 5

Structure of DNA

Answer 5

● A double helix structure - made up of two polynucleotide strands
● DNA molecules are extremely long
● Pentose sugar - ALWAYS deoxyribose
(hence the name)
● Bases - either A, T, C or G

Question 6

What are the base pairings?

Answer 6

C-G, A-U/T

Question 7

How many hydrogen bonds are there between A and T/U?

Answer 7

2

Question 8

How many hydrogen bonds are there between C and G?

Answer 8

3

Question 9

How many hydrogen bonds are there between C and G?

Answer 9

3

Question 10

How is DNA adapted for its function?

Answer 10

It has a very stable structure allowing it to pass from generation to generation without changing - only rarely does it mutate
● Its two strands are held together by weak hydrogen bonds, allowing the strands to be separated during DNA replication and protein synthesis for the genes to be read (by the breaking of the hydrogen bonds)
● Extremely large molecule - can carry a huge amount genetic information
● The function of the gene/protein made from that gene depends on the base
sequence
● Complementary base pairs means the DNA is replicated ACCURATELY

Question 11

Why is DNA a stable molecule?

Answer 11

● The sugar phosphate backbone (held together by phosphodiester bonds) protects the bases (the genetic code) inside the double helix (which carries the genetic code)
● Many hydrogen bonds are strong together

Question 12

Define nucleus

Answer 12

the large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes.

Question 13

Define chromosome

Answer 13

a structure found in the nucleus that consists of a single molecule of DNA bonded to proteins called histones (together these make chromatin). Chromosomes carry the genetic information in the form of genes.

Question 14

Define DNA

Answer 14

Carries the genetic information. The hereditary material responsible for passing genetic information from cell to cell and therefore, generation to generation

Question 15

Define gene

Answer 15

a section of DNA with a specific sequence of bases/nucleotides that encodes for a specific protein with a particular function. Genes can be inherited

Question 16

What is the step-by-step process of semi-conservative DNA replication?

Answer 16

1. The enzyme, DNA helicase, causes the DNA double helix to unwind and separate into two strands by breaking the hydrogen bonds between complementary base pairs, exposing the bases.
2. Both separate strands then act as a template for DNA replication to occur.
3. Free activated DNA nucleotides (in the nucleoplasm) are attracted to and hydrogen bond to their complementary bases on the exposed template strands by complementary base pairing.
4. The newly added nucleotides are then joined together by the enzyme DNA polymerase, which catalyses the formation of phosphodiester bonds, between adjacent nucleotides.
5. This results in two identical DNA molecules being produced, each of which contains one of the original DNA strands and one newly synthesised DNA strand (semi-conservative).

Question 17

What enzyme is involved in separating and unwinding DNA strands?

Answer 17

DNA helicase

Question 18

What enzyme catalysed the formation of phosphodiester bonds between nucleotides?

Answer 18

DNA polymerase