Proakryotic Cells And Virises

Question 1

What is a capsid?

Answer 1

The protein coat that surrounds the core of genetic material in a virus.

Question 2

What is the role of viral attachment proteins?

Answer 2

They allow a virus to attach/cling to specific/suitable host cells, which have the complementary receptor proteins.

Question 3

Why is a capsule needed within a prokaryotic cell?

Answer 3

Made of secreted slime (dry out)

Helps protect bacteria from attack by cells of host immune system

Question 4

Name and describe the process by which prokaryotic cell reproduce

Answer 4

Binary fission. (Asexual reproduction)
1. The circular DNA and plasmids replicate.
The main DNA loop is only replicated once but the plasmids can be replicated several times.

2. The cell gets bigger and the DNA loops move to opposite poles of the cell. (Mb elongates which separates DNA)
3. The cytoplasm begins to divide and new cell walls begin to form. (Cross wall starts form causes mb invaqinates)
   Cell wall forms completely
4. The cytoplasm divides and two daughter cells are produced.
   Each daughter cell has one copy of the circular DNA but a variable number of copies of the plasmids.

Question 5

What is a prokaryotic cell wall made of?

Answer 5

Murein / peptidoglygon

Question 6

What do plasmids contain?

Answer 6

Genes - eg antibiotic resistant
Which is used between prokaryotics

Question 7

What does increasing the conc of phosphate and also nucleotides do?

Answer 7

Increase phosphate = increase atp/ dna/ rna

Increase nucleotides = increase dna synthesis

Question 8

What is a host cell?

Answer 8

Cells inside which viruses replicates once it has invaded cell

Question 9

Outline the stages of viral replication

Answer 9

1. Virus attached to host cell receptor proteins
2. Genetic material (DNA or RNA - nuclei acids) released into host cell
3. Genetic material and proteins are replicated used host cell own machinery (eg enzymes and ribosomes)
4. Viral components assembled
5. Replicated viruses released from host cell

Question 10

Suggest why the capsule and flagellum that make this bacterium
well adapted to living in the gut.

Answer 10

Feature B (capsule) is a layer of slime that can help protect the bacterium from attack by the host’s immune system.
Feature D (flagellum) allows the bacteria to move through the gut.

Question 11

Name two features of HIV particle that are not found in bacteria?

Don’t include attachment proteins

2 marks

Answer 11

1. Capsid;
   (Ignore protein coat)
2. Reverse transcriptase;
3. RNA genome;
   (Accept ‘genetic material’ OR ‘genes’ for ‘genome’)
4. Nuclear Envelope;

Question 12

All prokaryotic contain circular dna and some contain plasmids

Scientists have found that the rate of plasmid replication is faster in cells growing in a culture with a lower concentration of amino acids than
growing in a culture with a high concentration of amino acids concentration.

Suggest one explanation for the faster rate of plasmid replication in cells.
2 marks

Answer 12

1. Amino acids used in) protein synthesis;
   Accept for ‘protein synthesis’, translation
2. So) more enzymes (for DNA/plasmid replication)
   OR
   (So) more DNA polymerase;
3. (Amino acids used in) respiration;
4. (So) more energy/ATP (for DNA/plasmid replication);

Question 13

The human papilloma virus contains a double-stranded DNA genome.

Which components are found in a human papilloma virus?

A) capsid and attachment proteins

B) capsid, attachment proteins and reverse transcriptase

C) capsule and attachment proteins

D) cell surf mb and attachment proteins

1 mark

Answer 13

A) capsid and attachment proteins