Microb 201-- Exam 1

characteristics of prokaryotes

• unicellular (1microM)

• lack a nucleus and other membrane bound organelles

• archaea or bacteria

• DNA is circular or linear

Prokaryotic cell structure

• nucleoid region, cytoplasm, cell membrane, cell wall, capsule, flagella

Nucleiod Region

region containing DNA

cytoplasm

contains ribosomes for protein makeup

cell membrane

separates cell from environment

cell wall

rigid structure which protects the cell from bursting

capsule

protective barrier which helps cells adhere to surfaces

immune system response

flagella

tail-like projection, helps with mobility

cytoplasmic membrane

“fluid mosaic model”

composed of phosopholipids, glycolipids, glycoproteins, and proteins

phospholipid bilayer characteristics

• amphipathic — contains both hydrophobic (fatty acid) and hydrophilic (phosphate) domains

• bilayer makes up most of the cytoplasmic membrane

• Impermeable bilayer, only allows small, uncharged molecule

proteins functions in membrane

• increases rigidity — cell structure is more stable

• involved cell signaling and recognition — enables communication between cells

• involved in adhesion — enables cells to “stick” to things in enviro

• involved in transport — forms pores to allow transportation through bilayer membrane (selective permeability)

membrane proteins — receptor

binds to chemical messenger sent by other cells (ex. hormones)

membrane proteins — enzyme

breaks down chemical messenger and terminates its effects

membrane proteins — channel

constantly open and allows solute to pass into and iut of cell

membrane proteins — gated channel

opens and closes to allow solutes through only at certain times

membrane proteins — cell-identity marker

glycoprotein acting as a cell-identity marker distinguishing the body’s own cells from forgein ones

membrane proteins — cell-adhesion molecule (CAM)

binds one cell to another

diffusion (passive transport)

Movement of high concentration to low concentration without the use of energy

• CHAOS!!! = no atp needed

active transport

movement of low concentration to high concentration with using ATP

• NO chaos = atp needed

group translocation

movement of ions/molecules across a cell membrane via being chemically transformed

simple diffusion

doesnt require a membrane protein

only small molecules can diffuse

ex. oxygen

facilitated diffusion

requires a membrane channel protein

only large or charged ions

non-specific and specific facilitated diffusion

specific facilitated diffusion

membrane protein is specific for a particular substance

nonspecific facilitated diffusion

multiple substances can use the same channel

osmosis

• molecules of solvent pass through semipermeable membrane from low to high solute concentration

• solvent goes from high to low concentration

semipermeable membrane

permeable to solvent, NOT solute

solvent

the liquid the solute is dissolved in (usually water)

solute

a substance dissolved in a solvent (Na+, K+, Cl-)

isotonic solution

external solution has same concentration as the cell

• no change to cell

hypertonic solution

external solution has a higher solute concentration than cell

• cell shrinks as it loses water

hypotonic solution

external solution has lower concentration than the cell

• cells will lyse without a cell wall as they take in H2O

salt

• ability of cell to grow depends on toleration of environments salt concentration

• salt used to preserve food

• salt favors the growth of microorganisms

halotolerant and halophilic salt

• halotolerant — adapts to salt

• halophilic — requires salt

• both adapted to high salt concentrations

• species thrive at low/moderate salt concentrations

• some require salt to grow

habitats where halophilic/halotolerant live

• ocean/salt lakes

• animal skin (staphylococcus epidermidis)

• food (staphylococcus aureus)

bacterial cell walls functions

• provide structure and shape to cells

• prevents damage from osmosis (lysis)

• used in adherence in environments

• prevents chemicals from penetrating the cell

components of cell wall

• peptidoglycan (most prominent) attached to phospholipid bilayer

  • sticky protein sugar layer used to makeup cell wall

  • reason for difference in staining for gram neg and gram pos bacteria

shapes of bacteria — cocci

circle shaped

shapes of bacteria — rod

rod shaped

shapes of bacteria — spirillum

“s-shaped”

shapes of bacteria — spriochete

spiral staircase

shapes of bacteria — filamentous

“fungi” /// “filaments”

shapes of bacteria — budding and appendaged

“golf clubs” /// “tadpoles”

“stalk” /// “hypha”

microbes

prokaryotes:

• bacteria

• archaea

Non-living:

• virsues

eukaryotes:

• fungi

• protists

• algae

prokaryotes vs eukaryotes characteristics

Prokaryotes:

• unicellular organism

• lack cell membrane

• simple structure

• no separation between DNA, RNA, and proteins

• DNA is circular or linear, NOT stored in nucleus

• all bacteria and archaea

Eukaryotes:

• unicellular or multicellular

• DNA stored within nucleus

• complex structure

• various compartments segregating cellular functions

• plants, fungi, and animals

viruses characteristics

• nonliving