Ch 4 functional anatomy of prokaryotic & eukaryotic cells

Three main shapes of bacteria

Bacillus (rod), Coccus (spheres), and Spirillus (spiral)

What shape is this?

The shape is Vibrio

What shape Is this?

The shape is Spirillum

What shape is this?

The shape is Spirochete

What shape and arrangement is this?

The shape and arrangement is Staphylococcus

What shape and arrangement is this?

The shape and arrangement is Streptobacillus

What shape is this?

The shape is Bacillus (singles)

Structures found in all bacteria

Cell membrane (cytoplasmic membrane), Cytoplasm, ribosomes, cytoskeleton, one (or a few) Chromosomes. In most → cell wall, glycocalyx

External structure of a bacterial cell

Appendages: Flagella, pili, frimbriae. Surface layers: S layer, glycocalyx, Capsule slime layer.

Cell envelope of a bacterial cell

(Outer membrane), Cell wall, Plasmic membrane

Internal of Bacterial cells

Cytoplasm, ribosomes, inclusions, nucleoid/chromosomes Call Mom cytoskeleton, endospore, plasmid, microcompartments

Cytoplasmic membrane

Phospholipid Bilayer, fluid mosaic. Regulate the passage of materials in and out of the cell. Site for chemical reactions such as ATP synthesis and nutrient processing.

What can pass through a phospholipid bilayer?

Small and neutral (hydrophobic) Molecules

What is a bacterial cell wall made

Peptidoglycan

If the cell wall consists of a cell membrane and a thick layer of Peptidoglycan Then it is what?

Gram-positive cell wall

If the cell wall consists of a cell membrane, thin layer of Peptidoglycan, and outer membrane layer, what is it?

Gram negative cell wall

Peptidoglycan

Repeating framework of long glycan chains cross-linked (provides strength/sturdy) by short peptide (protein) Fragments.

Gram-positive cell wall

Made of peptidoglycan (thick) with lipo/teichoic acids in it, And cytoplasmic membrane. More resistant to physical stress.

Gram-negative cell wall

Made of outer membrane with porin protein And lipopolysaccharide (LPS) in it, peptidoglycan (thin), And cytoplasmic membrane. More resistant to chemical stress than physical.

Lipopolysaccharide (LPS)

Found an outer membrane of gram-negative bacteria. O-antigen: highly varied among species, important for immune response. Core polysaccharide- connects lipid A to O-antigen. Function as signaling molecules & receptors. Lipid A- anchors into bacterial membrane, endotoxin → induces shock & fever

Lipoteichoic acid and teichoic acid

Found in the cell wall of gram-positive bacteria Making the cell negative. Lipo= anchored to lipid. Maintains cell structure

What is the surface charge of gram-positive bacteria? Why?

Negative surface charge due to the teichoic and lipoteichoic acids

What is the surface charge of gram-negative bacteria? Why?

Negative surface charge due to the lipopolysaccharides

Functions of the bacterial cell wall

Determine shape, structural support → Resist, bursting or collapsing, due to changes in osmotic pressure

Effect of penicillin on the bacterial cell wall

Anabiotic That affects whether a cell is able to grow/live. Targets peptidoglycan layer, prevents the synthesis of peptide bridges that cross link the glycan chains of pepidoglycan

What is the purpose of a gram stain?

A way that we are able to distinguish the different types cell walls a bacterial has

Mycoplasma

A bacteria with no cell wall, cytoplasmic membrane contains sterols (rigid lipids)

Mycobacterium

Contain mycolic acid (wax) in their cell wall, use acid fast staining

At the cell wall protects the bacterium, why do bacteria need a cell membrane?

The cell membrane regulates transport of substances and is a site of key metabolic processes while the cell wall provides structural support and protect protection

Gram type

Refers to the structural characteristics of the cell wall

Gram reaction

Refers to the observed color of the cells after the gram staining procedure

Morphology

Looks at external features: Shape, size, structure, and color. Helps identify in group organisms

cocci

Round, but not oval, elongated, or flatten on the one side

Streptococci

Spherical bacteria that remain attached in chain like patterns

Tetrads

Spherical bacteria that divide two planes and remain in groups of four

Sarcinae

Spherical bacteria that divide in three planes and remain attached in groups of eight

Staphylococci

Spherical bacteria that divide in multiple planes inform grape light clusters or broad sheets

Bacilli

Singular rod shaped bacteria, divide only across their short axis

Diplobacilli

Rod shaped bacteria that appear in pairs after division

Streptobacilli

Rod shaped bacteria that occur in chains after division

Vibrio

Bacteria that look like curved rods, or comma shaped

Spirilla / spirillum

Bacteria that have have a helical shape, like a cork shrew, and fairly rigid bodies. Use propeller like external appendages called flagella to move

Spirochete

Then, flexible, spiral shaped bacteria that move in a distinctive corkscrew motion. Move by means of axial filaments

Monomorphic

Maintain a single shape

pleomorphic

can have many shapes, not just one

Bacterial Glycocalyx

(Sugar coat) Substances that surround cells. Viscous (sticky) , Gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypeptide, or both. Made inside the cell and secreted to the cell surface.

Capsule

If the glycocalyx is organized and is firmly attached to the cell wall. Protect pathogenic bacteria from phagocytosis (ingestion and digestion of microbe)

Extracellular polymeric substance (EPS)

Glycocalyx that helps cells in a biofilm attached to their target environment. Protect cells within, facilitates communication among them, and enables the cells to survive by attaching to various surfaces in their natural environment.

Flagella (Singular: Flagellum)

Long filamentous appendages that propel bacteria. Locomotion (rotate 360°)

Slime layer

If the glycocalyx Is unorganized and only loosely attached to the cell wall, Protects against dehydration

What are the three basic parts of flagellum?

Filament: Long outermost region, contains protein flagellin, arranged in several chains that intertwine and form a helix around a hollow core

Hook: Where filament is attached to

Basal body: Anchors the flagellum to the cell wall in plasma membrane

Monotrichous

A single flagellum at one end of cell

Lophotrichous

Tuft of flagella on one end of the cell

Amphitrichous

One or more flagella on both ends of the cell

Peritrichous

Flagella distributed all over cell surface

Chemotaxis

Movement in response to chemical signals

Artichous

Bacteria that lack flagella, no projections

Motility

The ability of an organism to move by itself

Positive chemotaxis

Bacteria moving toward a stimulus

Negative chemotaxis

Bacteria moving away from stimulus

Axial filaments

Found on spirochetes , The rotation of filaments producing movement of the outer sheath that propels the spirochetes in a spiral motion (Corkscrew)

fimbriae

Short numerous bristle like fibers made of pilin. Help bacteria attach to each other or the surfaces. Involved in forming bio films.

Pilus

Compose of pilin, Long and few. Attachment of cell to cell to transfer DNA (Conjugation)

S Layer (the armor)

Single layers of thousands of copies of single protein linked together like a tiny chain mail, only made under hostile environment

What can pass through a cell membrane?

small, not charged, nonpolar molecules, Hydrophobic

What cannot pass through a cell membrane?

Large, charged molecules

Passive transport

Movement of molecules across the cell membrane without energy, molecules, move down their concentration gradient (High → low Concent.) No proteins required. Small not charged/Not polar molecules

Facilitated diffusion

No energy required, moves down its concentration gradient, a transport protein is required To move across cell membrane(channel or carrier). Large, polar, or charged molecules

Active transport

Requires energy to remove molecules across cell membrane, solute going up concentration gradient [low] → [hi]. Transport protein.

Group translocation

Type of active transport In bacteria, the substance being transported is chemically modified as it Crosses the membrane. Modification traps, the molecule inside the cell.

Osmosis

Passive movement of water molecules across a Selectively permeable membrane, Low solute concentration → High solute concentration

Hypotonic solution

A lower solute concentration outside of the cell compared to inside. Water moves into the cell. Cells can swell and may burst (lysis)

Isotonic solution

Has the same solute concentration inside and outside the cell. Water moves in and out at equal rates.

Hypertonic solution

Higher solute concentration outside the cell compared to inside. Water moves out of the cell. Self shrinks (crenation)