3.2 Structure and Composition of Prokaryotes

basic structure

cell membrane that regulates traffic in and out, nucleoid where DNA is, cytoplasm around rest of material and ribosomes free in cytoplasm

specialised features

cell wall and capsule, flagellum and pili

gram staining

dye added - if stained (gram positive) cell is bacteria with a thick layer of peptidoglycan

results of gram staining

stained = gram positive - single cell wall with thick multilayers of peptidoglycan, no outer membrane, susceptible to antibodies, less toxic

unstained = gram negative - double cell wall with thin single peptidoglycan layer, outer membrane resistant to antibodies, more toxic

cell wall

A relatively rigid structure that encloses cells of plants, fungi, many protists, and most prokaryotes, and which gives these cells their shape and limits their expansion in hypotonic media.

capsule

layer of polysaccharide or protein surrounding cell wall that protects cell and enables it to adhere to other cells

flagellum

A long, whiplike appendage that propels cells. Prokaryotic flagella differ greatly from those found in eukaryotes

pili

A structure that links prokaryote cells at the beginning of conjugation

ribosome

A small particle in the cell that is the site of protein synthesis

nucleoid

non-membrane bound region where chromosomes are

cytosol

The fluid portion of the cytoplasm, excluding organelles and other solids.

cell membrane

The membrane that surrounds the cell, regulating the entry and exit of molecules and ions. Every cell has a cell membrane