1.2 Cell structure

Question 1

Prokaryotic cells

What are prokaryotic cells?

Answer 1

Prokaryotes are organisms whose cells lack a nucleus
* They belong to the kingdom Monera (i.e. bacteria)

Question 2

Procarytic cells

The structure of procarytic cells

Answer 2

Prokaryotic cells share the following structures:
* A single, circular DNA molecule (genophore)
* A peptidoglycan cell wall and 70S ribosomes
Prokaryotic cells may also contain the following:
* Pili (for attachment or bacterial conjugation)
* Flagella (a long whip-like tail for movement)
* Plasmids (autonomous DNA molecules)

Question 3

Prokaryotic versus Eukaryotic Cells

According to what do Prokaryotic and Eukaryotic Cells differ?

Answer 3

Prokaryotic and eukaryotic cells differ
according to a number of key features:
* DNA (composition and structure)
* Organelles (types present and sizes)
* Reproduction (mode of cell division)
* Average Size (exceptions may exist)

Question 4

Prokaryotic versus Eukaryotic Cells

Prokaryotic versus Eukaryotic Cells

Answer 4

DNA:
Prokaryotic- DNA is naked and circular, Usually no introns
Eukaryotic - DNA is linear and bound to protein, Usually contains introns
Organelles:
Prokaryotic - No nucleus, 70S ribosomes
Eukaryotic -Has a nucleus, 80S ribosomes
Reproduction:
Prokaryotic - Via binary fission, single chromosome
Eukaryotic - Via mitosis and meiosis, paired chromosomes
Average size:
Prokaryotic- Smaller (~1 – 5 µM)
Eukaryotic - Larger (~10 – 100 µM)

Question 5

Bacterial Cell Division

How do prokaryotes divide?

Answer 5

Prokaryotes divide via a process of asexual reproduction known as binary fission.

Question 6

Bacterial Cell Division

The process of prokaryotic cell division

Answer 6

1. The circular DNA is copied
2. The DNA loops attach to the membrane
3. The cell elongates, separating the loops
4. Cytokinesis occurs to form two cells

Question 7

Eukratic cells - Animall versus Plant Cells

Animal cells

Answer 7

No chloroplast
No cell wall
No plasmodesmata
Temporary vacuoles
Cholesterol present in the cell membrane
Glucose → glycogen

Question 8

Eukratic cells - Animall versus Plant Cells

Plant cells

Answer 8

Have chloroplast
Cell wall (cellulose)
Plasmodesmata
Large central vacuole
No cholesterol in the cell membrane
Glucose → starch

Question 9

Bacterial Cell Division

The process of prokaryotes dividing

Answer 9

Prokaryotes divide via a process of asexual reproduction known as binary fission:
The circular DNA is copied
* The DNA loops attach to the membrane
* The cell elongates, separating the loops
* Cytokinesis occurs to form two cells