Prokaryotic Cells ch. 4

Methods in bacterial IDing

Morphology=shapes

Gram positive bacteria

Thick layer of peptidoglycan in their cell walls. Stains purple.

Atypical cell walls

-Some bacteria have walls with lipids: very wary. Resistant to chemicals and dyed in gram staining. -some bacteria have no cell walls.

Glycocalyx

2 types: slime layer and capsule

Bacteria with flagella can move in response to

A chemical signal

Fimbriae

Allows bacteria to attach to things. Ashort, bristle-like fibers that spout off of many bacteria.

Inclusions

Storage shacks for nutrients.

Prokaryotic cells with peptidoglycan in their cell walls

Bacteria

Endotoxins and gram negative bacteria

Cause fever and shock reactions in the host.

All bacteria have

Cell membrane, cytoplasm, ribosomes, one chromosome

Most bacteria have

Cell wall and surface coating

Species

Collection of bacterial cells that share a similar pattern of traits. Members of a species can show variation(ex: structure, metabolism). Called strain or subspecies. Bacteria strain have same parents, change over time.

Granules

Contain inorganic compounds. Type of inclusion.

Cell membrane encased by

Cytoplasm, a dense, gelatinous solution.

Spore production

Depletion of nutrients and/or high temps. Cause bacteria to produce endospore.

Cell wall

Determines shape of cell. Structural support.

Bacterial endosposre

Dormant bodies that are produced by gram positive bacteria. Vegetative cell phase. Spore production. Survive in extreme heats, and conditions.

How can bacterial endospore survive in a high temp.?

Endospores contain high levels of calcium. Calcium removes water from endospore. This makes it less sensitive to heat.

Classification systems

Established in order to keep track of organisms.

Physiological/biochemical charcteristics

Ex: presence/absence of enzyme. Ex: oxidase decarboxylases

Some bacteria have

Flagella Pili Fimbriae Capsules Slime layers Granules

Peritrichous

Flagella all around cell. See slide for pictures

Polar arrangement(3 types)

Flagella at either one or both ends. Monotrichous, lophotricious, amphitrichous. See slide for pictures.

Pili and fimbriae

For attachment

Flagella

For movement

Capsules

For protection

Cell membranes have ability to

Form mesosomes (increases surface area for activities). See more often in gram positive bacteria.

Peri plastic Flagella(axial filaments)

Found on spirochetes. Consist of foiled threads which provide a wriggle-like movement.

Structure of cell wall

Functions: structure and shape Rigid

Gram + vs gram -

Gram negative bacteria are harder to kill than gram positive bacteria because of outer membrane. Drug treatments: some kill both. Some kill just positive or negative.

Cell wall separates out

Gram positive and gram negative bacteria

Toxic proteins and

Gram positive bacteria.

What happens to bacterial proteins of no endosposre?

If there is no endospore, heat will cause the protein to denature and the bacteria will die.

Prokaryotic cells location

In bacteria and archaea

Eukaryotic Cells location

In fungi, protozoa, algae, plants, and animals

Membrane-bound organelles

Internal cellular structures that carry out a particular function

A pilus

Involved in mating in which there is a partial DNA transfer from one cell to another. Ielongate, rigid tubular-like structure, composed of pilin

3 classification systems

Most important: a system that groups medically important bacteria according to morphological and physiological features.

Chemotaxis

Movement towards or away from a chemical signal

Negative chemotaxis

Moving away from an unfavorable stimulus. Ex: bacteria away from antibiotics.

Positive chemotaxis

Moving towards a favorable stimulus. Ex: bacteria towards food.

Plasmids

Nonessential pieces of DNA. Circular in shape. Can be free or integrated into chromosomes.

Why are plasmids interesting?

Not needed for bacterial survival. However, can be passed onto offspring. Plasmids carry traits. Ex: antibiotic-resistance can be modified and make cell do what we want.

Eukaryotic cells have

Nucleus and other membrane-bound organelles

Prokaryotic cells DO NOT have

Nucleus or other membrane-bound organelles

Classification based on medical microbiology

Only classifies bacteria that cause disease. Depends less on nomenclature, more on morphology, Divides bacteria into gram positive, gram negative, those without cell walls, and then subgroup them with respect to cell shape, arrangement, and physiological traits like oxygen use.

Slowest cells

Peritrichous rods. Ex: E. Coli is slow

Granules

Pockets that hold items or elements

Fastest cells

Polar flagellated cells

Slime layers

Prevent dehydration/water loss

Capsule

Protects bacteria from white blood cells. Ex: streptococcus pneumoniae more resistant against immune system

Slime layer

Protects cell from water and nutrient loss.

Flagella

Provide motility Has helical structure composed of numerous proteins Filament:a helical structure composed of proteins, and it is inserted in the hook. Hook(sheath): attached to cell by the basal body Basal body: stack of rings anchored through the cell wall to the cell membrane

Cell envelope

Provides protection Is a chemically complex eternal covering that is situated outside the cytoplasm. Layers: Glycocalyx, cell wall, cell membrane

Cell membrane functions

Reactions occur ATP Regulation

Cell membrane

Regulates what comes in and out of the cell. ATP is made at cell membrane (eukaryotic cells: ATP made in mitochondria)

What does cytoplasm contain?

Ribosomes Granules A ton more stuff

Both prokaryotic and eukaryotic cells have

Ribosomes, where proteins are made

Structured of bacteria

See chart on slide

Cytoplasm functions

Serves as a cell solvent for a variety of substances including sugar, amino acids, and salts.

Bacterial chromosomes

Singular strand of DNA. No nucleus. Nucleoid. Long segment of DNA that is coiled into a ball(needs to fit into bacteria cell)

Ribosomes function

Site of protein synthesis. Can freely floating the cytoplasm or attach to cell membrane. Consists of rRNA.

Type of arrangement determines ?

Speed of bacteria cell

Gram negative bacteria

Thin layer of peptidoglycan in their cell walls. Also, have outer membrane in cell wall. Stain pink/red.

Cell membrane structure

Thin, flexible sheet that surrounds the cytoplasm. Lipid belayer with embedded proteins.

Chemical analysis

Uses chemical structures to identify bacteria

Macroscopic morphology

Uses morphology on macroscopic level to identify bacteria. Ex: colors/edges of bacteria(smooth or rough)

Microscopic morphology

Uses morphology on microscopic level to identify bacteria. Gram staining.

Serological analysis

Uses surface markers called antigens on bacteria to id bacteria

Genetic and molecular analysis

Using genetic material to ID bacteria. Some bacteria have more G and C pairs than A and T pairs.