Prokaryotic Cell Structure and Function

bacteria

• no nucleus or bound organelles

• single circular chromosome

• no histones (basic or positively charged proteins)

• cell walls of peptidoglycan (polymer of NAG & NAM cross-linked with polypeptide chain)

• small ribosomes

• binary fission

glycocalyx

a coating or layer of molecules external to the cell wall

• sugar coat

• capsule

• protects and prevents from drying and from phagocytes

• slimy and a component in biofilms

nucleoid

site where the large DNA molecule is condensed into a packet

pilus

an elongate, hollow appendage used in transfers of DNA to other cells and in cell adhesion

mesosome

an extension of the cell membrane that folds into the cytoplasm and increases surface area

flagellum

specialized appendage attached to the cell by a basal body that holds a long rotating filament; movement pushes the cell forward and provide motility

ribosomes

tiny particles composed of protein and RNA that are the sites of protein synthesis

cell membrane

a thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool

cell wall

a semirigid casing that provides structural support and shape for the cell

• macromolecule, polysaccharide

• repeating sugars (NAG & NAM cross-linked)

• certain antibiotics work by inhibiting cell wall synthesis (e.g., penicillins)

granule/inclusion

stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed

fimbriae

fine, hairlike bristles from the cell surface that help in adhesion to other cells and surfaces

steps of binary fission

1. duplication of chromosome

2. continued growth of the cell

3. division into two cells

draw and label the 4 types of flagella

• monotrichious

• amphitrichous

• lophotrichous

• peritrichous

bacterial envelope

structures on the outside of bacteria

gram - bacteria

• outer membrane

• LPS (lipopolysaccharide)

• lipoprotein

• phospholipids

• cause infections (fever, shock, diarrhea)

• less sensitive to penicillin as a result of a thinner cell wall and an outer membrane

steps of grams stain

1. fixation

2. crystal violet

3. iodine treatment

4. decolorization

5. counter stain safranin

gram + bacteria

• techoic acid

• lipotechoic acid

• peptidoglycan

• cell membrane

• protein

• phospholipid

draw the six types of bacterial cell shapes

• bacillus, pl. bacilli

• round, coccus, cocci pl., in chains Streptococcus

• staphylococcus, clusters

• diplococcus

• spirillum, spirilla pl.

• vibrio, comma shaped

cell shape

determined by the genetic character of the organism

genes code for synthesis of cell wall material and cell division mechanisms

diffusion

concentration gradients go from high to low

osmosis

diffusion of water across a semipermeable membrane

isotonic

even concentration between water in and out of the cell

hypertonic

higher concentration outside of the cell (shriveled)

hypotonic

higher concentration inside cell (swelled)

active transport

down the concentration gradient by using energy ATP

phagocytosis

the process by which a phagocyte, such as a macrophage or neutrophil, surrounds and internalizes large particles

cells engulf extracellular fluid and dissolved solutes through the formation of small vesicles called pinosomes

plasmid

extrachromosomal DNA; not part of genome

endospores

hardiest of bacterial structures; difficult to kill with heat or chemicals

uses of Bergey’s manual

1. cell wall

2. cell morphology (shape)

3. biochemical characteristics: sugars they ferment, enzymes like catalase and oxidase, decarboxylase, etc.