Prokaryotic Cell Structure

Question 1

Prokaryotic cells

Answer 1

• Prokaryotic cells do not have a nucleus or any membrane-bound organelles (except ribosomes)
• All prokaryotes are single celled bacteria
• Prokaryotic cells are much older and are smaller (0.1-10nm) than eukaryotic cells

Question 2

Structure and Function of prokaryotic cells

Answer 2

• Cell Wall - Strong and rigid, made of murein (not cellulose) which is glycoprotein
• Cell Membrane - made of phospholipids and proteins, like eukaryotic membranes. Controls movement in and out of cell
• DNA - single strand coiled up forming a nucleoid. Not closed within a nucleus. Less information than eukaryotic cell
• Plasmid - circular DNA, separate the DNA loop. Used to exchange DNA between bacterial cells, and contain genes for antibiotic resistance. Used in genetic engineering

Question 3

Differences between prokaryotic and eukaryotic cells

Answer 3

• Type of genetic material - Prokaryotic cells (A naked loop of DNA) Eukaryotic cells (Four or more chromosomes consisting of strands of DNA, associated with protein)
• Location of genetic material - Prokaryotic cells (in the nucleoid) Eukaryotic cells (in the nucleus - in the nuclear envelope)
• Mitochondria - Prokaryotic cells (Small - 70s) Eukaryotic cells (Large - 80s)
• Internal membranes - Prokaryotic cells (Few or none) Eukaryotic cells (Many internal membranes into the cytoplasm

Question 4

Viruses

Answer 4

• Very small - only seen by electron microscope
• Made up of protein coat and DNA (or RNA) - no cells / organelles
• Can only reproduce via living cells which they then destroy when bursting out

Question 5

Bacteriophage

Answer 5

Bacteriophage are viruses that only infect bacteria

Question 6

Comparison of Virus to cells

Answer 6

Similar:
-All have genetic material
-All have proteins
Differences:
-No cell
-No organelles

Question 7

Steps of reproduction in viruses

Answer 7

1) Attachment - Virus attached to cell surface
2) Penetration - Viral DNA is injected into the cell; the coat of the virus remains outside
3) Replication - Nucleic acid is replicated in host cell
4) Synthesis - New protein coats are synthesized within the host cells
5) Assembly - Mature virions are assembled within the cell
6) Release - Sell ruptures, releasing mature virus particles