Microbiology 20 - Ch 3 Lecture Notes

Prokaryotes

"Before nucleus" Bacteria and archaea No organelles

Eukaryotes

"True nucleus" Eukarya Organelles

This is the only bacteria genus that lacks a cell wall

*Mycoplasma*

Streptobacillus

A bacillus growing in twisted chains

Spirochete

A bacterium having a spiral shape (plural = spirochetes). Its curves are more *flexible* and can *change in number and direction*.

Streptococcus

A chain of cocci

Staphylococcus

A cluster of cocci

Sarcinia

A cube structure containing eight cocci

Phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes. The polar hydrophilic head points outward while the hydrophobic tail points inward.

Diplococcus

A pair of cocci

Peripheral protein

A protein *loosely bound to the surface of a membrane* or to part of an integral protein and not embedded in the lipid bilayer. (A) It is more temporary.

Bacillus

A rod-shaped bacterium

Diplobacillus

A rod-shaped double bacillus

Coccus

A spherical bacterium.

Spirillum

A spiral-shaped bacterium. It is more *rigid* and its curvature is more *permanent.*

Tetrad

A square structure containing four cocci

Conjugation

A temporary union of two organisms for the purpose of DNA transfer.

Integral protein

A transmembrane protein with hydrophobic regions that extend into and often *completely span the hydrophobic interior of the membrane and with hydrophilic regions* in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein). This structure is more permanent.

Palisade

A zigzag-shaped rod (A)

Cell membrane Major functions

Aids in cell structure integrity. It controls what enters and leaves the cell. It can communicate with other cells.

Archaea Cell wall Contents

All archaea have cell walls. Their cell walls contain *pseudopeptidogylcan*, protein, and other polysaccharides.

These eukaryotes lack cell walls

Animals Protozoa

Name the non-membranous structure that is present only in eukaryotic cells.

Centrioles

Cell wall contents Eukaryotes Plants

Contain *cellulose*

Cell wall contents Eukaryotes Algae

Contain *cellulose* and *other polysaccharides*

Cell wall contents Eukaryotes Fungi

Contain *chitin*

Eukaryotes Genetic material

Contains *multiple, linear* shaped chromosomes inside a nucleus.

Prokaryotes: Genetic material

Contains a *single circular* chromosome and a *plasmid*

Cell/plasma membrane

Controls entry into and out of cell. Present in prokaryotic and eukaryotic cells.

Prokaryotes Non-membranous structures

Cytoskeleton Ribosomes Cytoplasmic inclusions

Eukaryotes Non-membranous structures

Cytoskeleton Ribosomes Cytoplasmic inclusions Centrioles

Prokaryotes vs eukaryotes: Cell division More complex

Eukaryotes

Cell walls Gram-positive vs gram-negative: Contains *periplasmic space*

Gram-negative

Cell walls Gram-positive vs gram-negative: Contains a *lipopolysaccharide layer*

Gram-negative

Cell walls Gram-positive vs gram-negative: Contains an *outer membrane*

Gram-negative

Cell walls Gram-positive vs gram-negative: Is more resistant to antibiotics

Gram-negative

Cell walls Gram-positive vs gram-negative: The peptidoglycan backbone is *thin*

Gram-negative

Cell walls Gram-positive vs gram-negative: Contains *mycholic acid*

Gram-positive

Cell walls Gram-positive vs gram-negative: Contains *teichoic acid*

Gram-positive

Cell walls Gram-positive vs gram-negative: The peptidoglycan backbone is *thick*

Gram-positive

Mycobacteria Staining concerns

It does not stain properly with a gram stain to the extent that it is neither positive nor negative. It must be detected by *acid fast staining*.

Peptidoglycan backbone Structure

It has a repeating pattern of *N-acetylglucosamine (NAG)* and *N-acetylmuramic acid (NAM)*. It has peptides that function as rails.

Why is gram-negative bacteria more resistant to antibiotics?

It is protected by its unique *outer membrane* and *lipopolysaccharide layer*.

Capsule functions

It protects the cell from chemicals, radiation, desiccation, and phagocytosis by immune cells.

Lysosomes vs peroxisomes: Can only break down molecules

Lysosomes

Eukaryotic cell Membranous organelles

Mitochondria Smooth endoplasmic reticulum Rough endoplasmic reticulum Golgi complex/apparatus Chloroplasts Lysosomes Peroxisomes

Bacteria type that contains mycholic acid

Mycobacteria

Describe the two key characteristics of *passive transport*.

Passive transport systems *do not require energy* to operate. Instead, they operate spontaneously. Passive transport systems transport substances *along their concentration gradient*.

Lysosomes vs peroxisomes Can build up molecules

Peroxisomes

These eukaryotes have cell walls

Plants Fungi Algae

Prokaryotes vs eukaryotes: Cell division Less complex

Prokaryotes

Prokaryotes vs eukaryotes: Cell division Only copies the chromosome(s)

Prokaryotes

Prokaryotic cell Membranous organelles

Prokaryotic cells contain no membranous organelles

Differentiate between prokaryotic and eukaryotic ribosomes

Prokaryotic ribosomes are smaller and are called 70S ribosomes whereas eukaryotic ribosomes are bigger and are called 80S ribosomes.

This ER has ribosomes

Rough

This ER produces proteins for export

Rough

This ER functions in detoxification

Smooth

This ER is prominently found in the liver

Smooth

This ER produces lipids

Smooth

Glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication. Prokaryotic cells have a slime layer and a capsule.

*Periplasmic space*

The space between the inner and outer cell membranes in Gram-negative bactera. The peptidoglycan cell wall is found in the periplasmic space, and this space sometimes contains enzymes to degrade antibiotics.

Endosymbiotic theory

The theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms (aerobic bacteria, photosynthetic bacteria)

*Teichoic acid*

These are anchoring lipids.

Eukaryotes Genetic material Mitochondria and chloroplasts

These energy-producing structures have their own chromosome. Their circular shape places them closer to prokaryotic cells.

Eukaryotic cell Cytoplasmic inclusions

These eukaryotic non-membranous structures are patches of macromolecules that aid in *storage*.

Eukaryotic cell Centrioles

These eukaryotic non-membranous structures assist with *cell division* in *meiosis* and *mitosis*.

Peroxiosomes

These organelles *break down* and *produce* molecules.

Chloroplasts

These organelles are present in plant and algal cells. They perform *photosynthesis* and contain the green pigment chlorophyll.

Prokaryotic cell Cytoplasmic inclusions

These prokaryotic non-membranous structures are patches of macromolecules that aid in *storage*

Other lipids in the cell plasma membrane

They vary based on organism. Animals, for example use cholesterol.

Cell wall Thick or thin: Can retain crystal violet

Thick

Cell wall Thick or thin: Cannot retain crystal violet

Thin

Eukaryotic cell Ribosomes

This eukaryotic non-membranous structure functions in *protein synthesis*. It exists as *Free-floating* and *attached* structures.

Eukaryotic cell Cytoskeleton

This eukaryotic non-membranous structure is composed of protein structures and functions to *anchor organelles, support cell shape,* and *aid in transportation* within the cell. It is much *more complex* and has a *greater* prominence within the cell.

Mitosis and meiosis

This form of cell division is carried out by *eukaryotes*.

*Pinocytosis*

This form of endocytosis is characterized as "*cell drinking*". It takes in *smaller* molecules.

*Phagocytosis*

This form of endocytosis is characterized as "*cell eating*". It takes in *larger* particles

*Receptor-mediated endocytosis*

This form of endocytosis relies on *specific* receptors to take in specific particles. This includes pinocytosis and phagocytosis.

*Facilitated diffusion*

This form of passive transport is *aided by transport carrier proteins*. It functions in the transportation of *large, charged* particles.

*Simple diffusion*

This form of passive transport is *not aided by specialized proteins*. It functions in the transportation of *small, uncharged* particles.

*Filtration*

This form of passive transport relies on *physical force, pressure,* and *gravity*, to move particles. It does not rely on concentration gradients.

*Wall teichoic acid*

This form of teichoic acid *does not penetrate* the cell wall. It is *not embedded* to the cell wall either.

*Lipoteichoic acid*

This form of teichoic acid *is embedded and penetrates the cell wall*. It also holds the cell wall together.

*80S ribosome*

This is a eukaryotic ribosome, it is bigger.

*Endocytosis*

This is a form of active transport characterized by moving substances *into the cell*.

*Exocytosis*

This is a form of active transport characterized by moving substances *out of the cell*.

Binary fission

This is a form of cell division carried out by *prokaryotes*

Capsule

This is a glycocalyx that is *more rigid and organized* and *more permanently* attached.

Slime layer

This is a glycocalyx that is *unorganized* and *loosely attached* to the cell wall

*70S ribosome*

This is a prokaryotic ribosome, it is smaller.

*Pili*

This is a structure outside the cell membrane and is only found in prokaryotic cells. They are *larger* and *fewer* than fimbriae. They aid in *locomotion, attachment*, and the *exchange of genetic material* during *conjugation*.

Cilia

This is a structure outside the cell membrane. These are hairlike projections that extend from the plasma membrane and are used for locomotion. They are *smaller* than flagella and *prominently present in eukaryotic cells*. Depending on the cell, this structure's functions also include feeding.

Flagella

This is a structure outside the cell membrane. These are whip-like extensions that aid in motility. They are relatively common in prokaryotic cells versus eukaryotic cells.

Fimbriae

This is a structure outside the cell membrane. They are *plentiful* and *small*. Their aid in their *attachment* to other cells and surfaces. They found only in *prokaryotic cells*.

*Plasmid*

This is an extrachromosomal double DNA strand in a circular shape and more commonly present in prokaryotic cells. They are present in fungi but absent in most animals. Its genetic material is not necessary for survival.

*Mollicutes*

This is an informal group of bacteria characterized as having *no cell wall*.

*Nucleoid region*

This is the center region of a prokaryotic cell that contains genetic material.

Golgi complex/apparatus

This organelle *receives* and *modifies protein* by attaching *glucose molecules* to create *glycoproteins* which are then shipped via vesicles.

Mitochondria

This organelle engages in *aerobic respiration* and produces 95% of ATP in animal cells.

Rough endoplasmic reticulum

This organelle has *ribosomes* studded on its surface. It functions in the production of *Secretory proteins* destined for export. It is also the intermediate structure between the cytoplasm and Golgi apparatus.

Smooth endoplasmic reticulum

This organelle has no ribosomes on its surface. It functions in *lipid synthesis* and *detoxification* in the liver.

Lysosomes

This organelle stores *hydrolytic enzymes* that break down molecules.

*Osmosis*

This passive transport process is the simple diffusion of water along its concentration gradient.

Prokaryotic cell Ribosomes

This prokaryotic non-membranous structure functions in *protein synthesis*. It exists only as *free-floating* structures.

Prokaryotic cell Cytoskeleton

This prokaryotic non-membranous structure is composed of protein structures and functions to *maintain the shape* of the cell. Its presence in the cell is *minimal* and the structure is *less* complex.

Cell wall

This structure outside the cell membrane Is more present in prokaryotes than eukaryotes.

Describe the two key characteristics of *active transport*

This transport mechanism is characterized as *requiring energy* to transport particles *against their concentration gradient*.

*Vesicular transport*

Transport of large particles and macromolecules across plasma membranes. *ALL* are *ACTIVE TRANSPORT*. *NOT ALL ACTIVE TRANSPORT IS VESICULAR TRANSPORT*.

V-shaped

V-shaped bacilli

Vibrio

comma shaped, curved rod

*Lipopolysaccharide layer*

outer membrane embedded with LPS comprised of *O-specific polysaccharides*, core polysaccharides, *lipid A* (anchors sugars to outer membrane) & proteins (some make pores to allow things to pass through)