Nucleotides and Nucleic Acids

Question 1

What are examples of polynucleotides?

Answer 1

DNA and RNA

Question 2

What do nucleotides consist of?

Answer 2

5 carbon sugar, organic base and a phosphate group

Question 3

How many strands does DNA have?

Answer 3

2 anti-parallel strands

Question 4

Describe the length of DNA

Answer 4

Very long

Question 5

What pentose sugar does DNA have?

Answer 5

Deoxyribose

Question 6

What are DNA’s nitrogenous bases?

Answer 6

Adenine, Cytosine, Guanine and Thymine

Question 7

What is the function of DNA?

Answer 7

Store genetic information

Question 8

How many strands does RNA have?

Answer 8

1 strand

Question 9

Describe the length of RNA

Answer 9

Relatively short

Question 10

What pentose sugar does RNA have?

Answer 10

Ribose

Question 11

What are RNA’s nitrogenous bases?

Answer 11

Adenine, Cytosine, Guanine and Uracil

Question 12

What are the functions of RNA?

Answer 12

Store genetic information and form ribsomes with protein

Question 13

What bonds and which reaction joins nucleotides?

Answer 13

Phosphodiester bonds and condensation reactions

Question 14

What are the characteristics of a DNA molecule?

Answer 14

Double helix and are composed of 2 polynucleotides

Question 15

What is the actual name for ATP?

Answer 15

Adenine triphosphate

Question 16

What are the characteristics of ATP?

Answer 16

A nucleotide derivative, ribose, base and three phosphate groups

Question 17

What happens before ADP and a phosphate molecule is formed and what is it catalysed by?

Answer 17

Energy is released when ATP is hydrolysed and it is catalysed by ATP hydrolase

Question 18

What can be used to phosphorylate other compounds?

Answer 18

The inorganic phosphate

Question 19

What happens before ATP is produced during respiration and photosynthesis and what is it catalsyed by?

Answer 19

Condensation of ADP and an inorganic phosphate. It is catalsyed by ATP synthase

Question 20

What does the semi-conservative replication of DNA ensure?

Answer 20

It ensures genetic continuity between generations of cells meaning that genetic information is passed from one generation to the next

Question 21

Explain thoroughly the steps of semi-conservative replication of DNA

Answer 21

The double helix unwinds. Hydrogen bonds between the complementary bases break using DNA helicase thus separating the 2 strands. Both strands are then used as templates. Complementary base pairing then occurs between the template strand and the free nucleotides. Adjacent nucleotides are joined by phosphodiester bonds formed in condensation reactions using DNA polymerase

Question 22

What are the characteristics of Genetic code?

Answer 22

It’s the order of bases. Consists of triplet bases

Question 23

What does each triplet base code for and what is it’s alternative name?

Answer 23

A particular amino acid and it’s alternative name is a codon

Question 24

What are amino acids joined by and what do they form?

Answer 24

Joined by peptide bonds and they form a polypeptide chain

Question 25

Do all genomes code for protein?

Answer 25

No

Question 26

Describe an Intron

Answer 26

Non-coding sections of DNA

Question 27

Describe an Exon

Answer 27

Coding sections of DNA

Question 28

What are the features of the genetic code?

Answer 28

Non-overlapping, regenerate and contains stop and start codons

Question 29

What is meant by non-overlapping?

Answer 29

Each triplet is read only once

Question 30

What is meant by regenerate and what is the importance of this?

Answer 30

More than one triplet codes for the same amino acid. The importance of it is that it reduces the phenotypic effect of mutations which are mistakes in the base sequences (base deletion, insertion or substitution). A change in the base of DNA may alter the amino acid sequence and the protein can therefore have various effects

Question 31

What is meant by stop and start codons?

Answer 31

Codons that stop or start protein synethesis

Question 32

What are the 2 stages of protein synthesis?

Answer 32

Translation and transcription

Question 33

Where does transcription occur and what does it involve?

Answer 33

In the nucleus and involves DNA and RNA

Question 34

Where does translation occur and what does it involve?

Answer 34

In the ribosomes and involves mRNA, tRNA and ribsomes

Question 35

Vaguely, what happens during transcription?

Answer 35

DNA strand is transcribed into mRNA

Question 36

Vaguely, what happens during translation?

Answer 36

Amino acids are assembled together to form a polypeptide chain/protein

Question 37

Explain, in detail, what happens during transcription?

Answer 37

Hydrogen bonds between complementary bases break. DNA uncoils thus separating the 2 strands. 1 strand is then used as a template by RNA polymerase to make the mRNA molecule. Free nucleotides line up by complementary base pairing. Adjacent nucleotides are joined by phosphodiester bonds made by RNA polyermase thus forming a single stranded molecule of mRNA. mRNA then moves out of the nucleus through a pore. It then attaches to a ribsome in the cytoplasm

Question 38

Explain, in detail, what happens during translation?

Answer 38

mRNA attaches to a ribosome and transfers RNA to collect amino acids from the cytoplasm and carries them to the ribosome. tRNA is a single stranded molecule with a binding site at one end meaning it can only carry one type of amino acid and a triplet of bases at the other. tRNA attaches itself to mRNA by complementary base pairing. The amino acid attached to the 2 tRNA molecules is joined by a peptide bond. tRNA molecules detach themselves from the amino acids, leaving them behind. The process is then repeated leading to the formation of a polypeptide chain until a stop codon is reached on mRNA and ends the process of protein synthesis