Molecular Biology - DNA & RNA

Question 1

What is DNA?

Answer 1

• Deoxyribonucleic acid
• Long nucleic acid chain with many genes
• Blueprint / Master copy of genetic information
• Provides instructions to make proteins

Question 2

What is RNA?

Answer 2

• Ribonucleic acid
• Short nucleic acid chain with few genes
• Used for transmission and is the bridge between DNA and protein

Question 3

What are nucleic acids and what are they used for?

Answer 3

• DNA and RNA = nucleic acids
• Carry genetic information and direct protein
• Polymers of repeating subunits called nucleotides

Question 4

What is the make up of a nucleotide?

Answer 4

• 5 Carbon sugar (either ribose or deoxyribose)
• A phosphate group
• Nitrogenous base

Question 5

What are the nitrogenous bases?

Answer 5

Adenine
Guanine
Cytosine
Thymine (DNA only)
Uracil (RNA only)

Question 6

What is the structure of DNA?

Answer 6

• Double helix
• Outside is a sugar-phosphate backbone
• Inside complementary base pairings of nucleic acids
• Outside is hydrophilic, inside is hydrophobic
• Complete turn every 10 base pairs

Question 7

What are the base pairings of nitrogenous bases?

Answer 7

• One purine (single loop) and one pyramidine (double loop)
• Adenine and Thymine
• Guanine and Cytosine

Question 8

What are chromsomes and genomes?

Answer 8

Chromosomes = long DNA molecule with part / all of the genetic material of an organism

Genome is stored in the chromosome

Genome = complete set of information for gene expression and protein synthesis (RNA)

Question 9

What is the importance of histones, chromatin, centomere, and telomere?

Answer 9

Structure of a chromsome
DNA is wrapped around proteins called histones
DNA + histones = chromatin
Chromatin is further wound up
Centromere is at the centre of a chromosome
Telomere is at the end of a chromosome

Question 10

What is central dogma?

Answer 10

Describes the flow of genetic information during cell growth and replication

DNA (double stranded) transcription into RNA (single stranded)
RNA translation into Protein (linked amino acids)

Information cannot flow backwards

Question 11

What is transcription?

Answer 11

The process of making an RNA copy of a DNA sequence

Question 12

What is translation?

Answer 12

The process by which a cell makes proteins using genetic info carried by RNA

Translation of a mRNA sequence into amino acids

Question 13

What is an amino acid and how many are there?

Answer 13

Basic structural units of proteins (molecules that combine to form proteins)

There are 20 different amino acids

Question 14

What is the genetic code?

Answer 14

Dictionary that links a sequence of RNA bases to an amino acid

Converts a codon (3x RNA bases) into one amino acid

4 possible RNA bases and 20 different amino acids, genetic code deciphers which acid is being formed

Question 15

What are the start and stop codons?

Answer 15

Start = AUG (methionine)

Stop = UAA, UAG, or UGA

Question 16

What mutations can occur in the genetic code?

Answer 16

Silent mutation = Different codon, but the same amino acid

Missense mutation = Different codon, different amino acid

Nonsense mutation = Different codon resulting in termination

Question 17

What are the components for translation?

Answer 17

mRNA
Amino acids
tRNA = adapter molecules (recognises both mRNA and amino acids)
Ribosomes = action stations
Enzymes and energy

Question 18

Describe ribosomes and how they function

Answer 18

Translation of mRNA into protein takes place inside ribosoems

Large complexes made up of three subunits (2 small, 1 large)

Small subunits bind to the mRNA and links the codons to the anti-codons in tRNA

The large subunit catalyses the formation of peptide bonds, linking amino acids to form protein