Prokaryotes

Question 1

What are prokaryotes?

Answer 1

Single-celled bacteria with no nucleus or membrane-bound organelles

Question 2

How does the structure of prokaryotic cells differ from eukaryotic cells?

Answer 2

Prokaryotes:
- Single circular chromosome free in the cytoplasm
- No membrane-bound organelles
- 70S ribosomes

Eukaryotes:
- DNA inside a nucleus wrapped around histones
- Have membrane bound organelles
- 80S ribosomes

Question 3

What are the key structures of a prokaryotic cell?

Answer 3

• Cell wall made of peptidoglycan
• Plasma membrane
• Cytoplasmibosomes (70S), plasmids, slime capsule, mesosomes, flagella, and pili.

Question 4

How do prokaryotes reproduce?

Answer 4

Asexual reproduction by binary fission

Question 5

What are the steps of binary fission?

Answer 5

Step 1:
- DNA replicates
- Attaches to the mesosome
- Cell elongates

Step 2:
- Septum develops across the middle of the cell

Step 3:
- Septum grows
- Divides the cell into 2

Step 4:
- Two genetically identical daughter cells are formed

Question 6

How can you calculate the number of cells produced in binary fission?

Answer 6

Formula: 2ⁿ
n = number of divisions.

Question 7

What are the similarities and differences between binary fission and mitosis?

Answer 7

Similarities:
- DNA replicates before division
- Produces genetically identical daughter cells

Differences:
- Chromosomes do not condense in binary fission but they do in mitosis
- Spindle fibres in mitosis but none in binary fission
- Chromosomes do not separate into chromatids in binary fission but they do in mitosis

Question 8

Why do prokaryotes not need a spindle for division?

Answer 8

• Prokaryotes have only one circular chromosome
• Do not have multiple chromosomes that require precise separation
• Mitosis is nuclear division but bacteria lack a nucleus.