Prokaryotic Cells

Advanced Higher Biology

Prokaryotic Cells“pro” – before “karyo“– nucleus

Prokaryotes were probably the first forms of life on earth. Their heredity material (DNA) is not enclosed within a nuclear membrane. There are no membrane bound organelles within a prokaryotic cell.

Prokaryotic Cells

The absence of a true nucleus only occurs in 2 groups.– Bacteria– Blue green algae (cyanobacteria)

Five structures, which are always present in a prokaryotic cell, are:– cell wall, plasma membrane,

cytoplasm, ribosome, circular DNA

Bacterial Cells

Hove no membrane bound organelles

Have a single circular molecule of DNA

“naked” DNA – not associated with histones

Cell wall made of peptidoglycan

Prokaryotic cells Structure

Structure informationCapsule Glycogalyx – firm or disorganised

Adherence and protection

Nucleoid Region containing bacterial chromosome

Pili (fimbriae) Anchoring functions

Flagella Motility; 3 parts – basal body, hook and filament

Cell Wall Growth and divisionPeptidoglycan

Plasma membrane

Phospholipids

Cell structures Cytosol – fluid filled portionRibosomes – “free” or inner surface PM

Spores and cysts Survive unfavourable environmental conditions (metabolically inactive)

Structure of a bacterial cell

Activity

Copy and complete the following table

Include organelles, DNA, RNA and protein synthesis, ribosome, cell division, cell wall, cellular organisation.

prokaryotic Eukaryotic

organisms

Cell size

metabolism

Comparison of prokaryotic and eukaryotic cells

prokaryotic Eukaryotic

organisms Bacteriacyanobacteria

Protista, fungi, plants, animals

Cell size 1 – 10 µm 10 –100 µm

metabolism Anaerobic and aerobic

Aerobic

organelles No membrane bound organelles

Nucleus, mitochondria, chloroplasts, RER, SER

prokaryotic Eukaryotic

DNA Circular DNA in cytoplasm

DNA organised into chromosomes bounded by nuclear envelope

RNA and Protein Synthesis

Synthesised in same compartment

RNA synthesised and processed in nucleusProtein synthesis in cytoplasm

Ribosomes 70S Type 80S Type

Cell Division Binary fission Mitosis or meiosis

Comparison of prokaryotic and eukaryotic cells

Essay – 15 marks

List the similarities and differences between prokaryotic and eukaryotic cells