PROKARYOTES
Plasma Membrane
Cytoplasm
The Nuclear Area
Ribosomes
phospholipid bilayer with
proteins embedded in and attached to
the inner (intracellular) and outer
(extracellular) surfaces
Function
Selectively permeable barrier ⚠
Synthesizes cell wall components
Assists in DNA replication
Carries on respiration
Captures energy as ATP
Destruction of plasma membrane
plasmolysis: cells shrink
Lysis:cell burst
Uptake of nutrients
• Macroelements (macronutrients)
– C, O, H, N, S, P
• found in organic molecules such as proteins, lipids,
carbohydrates, and nucleic acids
– K, Ca, Mg, and Fe
• cations and serve in variety of roles including
enzymes, biosynthesis
– required in relatively large amounts
• Micronutrients (trace elements)
– Mn, Zn, Co, Mo, Ni, and Cu
– required in trace amounts
– often supplied in water or in media components
– ubiquitous in nature
– serve as enzymes and cofactors
The movement of materials
across membranes
Passive Process
Active process
Facilitated Diffusion
Osmosis
Simple Diffusion
Group Translocation
Active trasnport
About 80% water.
Also contains proteins (enzymes), carbohydrates,
lipids, inorganic ions and many low molecular
weight compounds
Thick, aqueous, semitransparent and elastic
The major structures in the prokaryotic cytoplasm
are DNA, ribosomes and inclusions.
Single long circular molecule of double-stranded
DNA (bacterial chromosome).
• Bacterial chromosome do not include histones and
are not surrounded by nuclear envelope.
In addition to the bacterial chromosome, bacteria
often contain small circular, double-stranded DNA
molecules called plasmid.
the sites of protein
synthesis.
70S ribosomes
Two subunit (small subunit-30S subunit
and large subunit-50S subunit). S refer
to Svedberg unit
Each subunit consists of protein and
RNA called ribosomal RNA or rRNA.
can be inhibited by certain antibiotics
Cell wall
surrounds the cytoplasmic
membrane
not selectively permeable
– anything that can fit ,can
pass through the cell wall
composed of a macromolecular network called
peptidoglycan (also known as murein).
Function
Prevent bacterial cell from rupturing when
the water pressure inside the cell is greater
than that outside the cell
Contributes to pathogenicity
maintains characteristic shape
provides a rigid platform (a point of anchorage)
counters the effects of osmotic pressure
Classification
2 Major Types
Gram-Positive
Gram-Negative
thick peptidoglycan layer
Consist of one or very few layers of
peptidoglycan
The peptidoglycan is bonded to
lipoprotein.
Structures external to the cell wall
Glycocalyx
Flagella
Axial filaments
Fimbriae and Pili
Archae
Cell wall
Gram-Positive
Gram-negative
A layer/2 of thick protein or glycoprotein
outside plasma membrane
Pseudomurein (in methanogenes)
Different chemistry
Single thick
homogenous layer
Resistant to
lysozyme and β-
lactam antibiotics
Susceptible to
lysozyme and β-
lactam antibiotics