biology - prokaryotic cells

eukaryotic and prokaryotic cell differences

1. Eukaryotic cells have a nucleus but prokaryotic cells don’t

2. Eukaryotic cells are bigger than prokaryotic cells

3. Eukaryotic cells have 80s ribosomes but prokaryotic cells have 70s ribosomes

4. Prokaryotic cell wall is made of murein but eukaryotic cell is made of cellulose

Prokaryotic structure

• lacks membrane bound organelles

• cell wall is made of murein

• no nucleus

What is always present in a prokaryote?

• murein cell wall & cell membrane

• circular DNA

• cytoplasm

• ribosomes

What is sometimes present in a prokaryote?

• flagellum (enables prokaryote to move)

• capsule (protects bacteria from drying out)

• plasmid (loop of DNA)

Structure of virus

• nucleic acid core (single or double stranded DNA or RNA)

• protein coat called capsid

• attachment protein molecules

• no ribosomes or cell wall so antibiotics arent effective against them

why are viruses described as non-living and acellular

• non living → cant independently respire

• acellular → has no cell surface membrane

describe how viruses are replicated

1. Attachment proteins bind to receptors

2. Nucleic acid core enters cell

3. Reverse transcriptase produces DNA from RNA

4. Viral proteins are assembled and released

Describe binary fission

1. Cell grows and circular DNA and plasmids are replicated

2. DNA moves to opposite ends of cell

3. Cell wall grows

4. Cytoplasm divides and 2 identical daughter cells are made with varying number of plasmids

Suggest two ways in which the environmental conditions could be altered to increased the growth rate of the bacteria. 

• increased temperature

• increased glucose

• increased respiration