M4

Question 1

Describe the basic structure of DNA

Answer 1

• Double helix stranded, H-bonds between bases
• Sugar backbone (deoxyribose)
• Phosphate group
• Nitrogenous base: adenine, guanine, cytosine, thymine

Question 2

Describe the basic structure of RNA

Answer 2

• Sugar backbone (ribose)
• Phosphate group
• Nitrogenous base: adenine, guanine, cytosine, uracil
• Single helix strand

Question 3

Describe the basic structure of proteins

Answer 3

• Amino acid subunits: amino group, carboxyl group, functional group
• Amino acids joined by peptide bonds

Question 4

Define transcription

Answer 4

Process where information in DNA is copied into mRNA for protein production

Question 5

Define translation

Answer 5

• Conversion of genetic material in mRNA into protein using ribosomes and tRNA.
• Sequence of nucleotides in mRNA transcripts and determines the exact sequence of amino acids in proteins

Question 6

Describe a typical bacterial chromosome

Answer 6

• One circular, double-stranded chromosome
• DNA
• Millions of base pairs
• No nuclear membranes
• Haploid

Question 7

What are the different types of mutations?

Answer 7

substitution, insertion, deletion

Question 8

What is substitution?

Answer 8

When the incorrect nucleotide is transcribed (A instead of C)

Question 9

What is insertion?

Answer 9

When a nucleotide is inserted (becomes longer)

Question 10

What is deletion?

Answer 10

When a nucleotide is taken away (becomes shorter)

Question 11

What are the consequences of mutations?

Answer 11

• silent (doesn’t affect or change amino acid)
• missense (structure/function changed)
• nonsense (Result in stop codon - premature
  truncation of proteins)

Question 12

What are mobile genetic elements?

Answer 12

• Pieces of DNA which can be transferred between bacterial cells
• Contribute to genetic diversity by: introduction of new genes into genome OR by altering gene expression downstream of insertion site
• Altering genetic environment leads to resistance or increased pathogenicity and virulence

Question 13

What are the transposable elements?

Answer 13

Insertion sequences (jumping gene), integrons and transposons

Question 14

How do insertion sequences work?

Answer 14

• Move from one position on a chromosome to another, when it moves it can be retained or lost at original position
• If inserted in gene, can inactivate expression
• Contains: transpose gene (enables to move), regulatory gene (induces or inhibits transpose gene), and inverted terminals (repeats &enables recombination)

Question 15

How do transposons work?

Answer 15

• Contains genetic materials often including virulence and antibiotic resistance genes, bracketed by IS
• Transported between bacteria on conjugate plasmids

Question 16

How do integrons work?

Answer 16

• Capture and carry genes
• Allows bacteria to adapt and evolve rapidly
• Integrase gene allows site specific recombination and integration of integron at a recombination site

Question 17

What are characteristics of plasmids?

Answer 17

• Extra-chromosomal circular double stranded DNA
• Smaller than chromosome
• Exists and replicates independent of chromosomes
• Multiple plasmids per cell
• Non-essential but improve survival under stress

Question 18

How do plasmids work?

Answer 18

• Can spread via conjugation to other bacteria
• Can encode variety of genes, including antibiotic
  resistance and virulence genes