Intro to Microbiology- Module 2 (Ch 4-8)

prokaryote characteristics

one circular chromosome, not in a membrane; no histones, no organelles, divides by binary fission

bacteria characteristics

prokaryote, peptidoglycan cell wells

archaea characterisitics

prokaryote, pseudomurein cell walls

eukaryote characteristics 

paired chromosomes, in nuclear membrane, histones, organelles, polysaccharide cell walls, when present, divides by mitosis

what appendages do prokaryotes have on the outside?

flagella, pili (fimbriae)

flagella

responsible for movement

bacteria are unicellular, and most of them multiply by _____

binary fission

most bacteria are what size ?

0.2 to 2.0 micrometers in diameter and 2 to 8 micrometers in length

3 basic bacteria shapes

coccus, bacillus, spiral

coccus

spherical

bacillus

rod shaped

spiral

twisted

pleomorphic bacteria

can assume several shapes

glycocalyx

(capsule, slime slayer or extracellular polysaccharide) is a gelatinous polysaccharide and/or polypeptide covering.

capsules may protect pathogens from what?

phagocytosis

glycocalyxes enable what? 

adherence to surfaces, prevent loss of water, and may provide nutrients 

external structures to the cell wall

glycocalyx, flagella, archaella, axial filaments, fimbriae and pili

What do bacterial flagella and archaeal archaella do to move the cell?

they rotate to push the cell.

What are the three main parts of a bacterial flagellum?

a filament, hook, and basal body.

What is taxis in motile bacteria?

Directed movement in response to stimuli.

What is positive taxis?

Movement toward an attractant.

What is negative taxis?

Movement away from a repellent.

Which protein of the flagellum is used to distinguish serovars of gram-negative bacteria?

The flagellar protein, H antigen

What are spiral cells that move by an axial filament (endoflagellum) called?

Spirochetes

How are axial filaments similar to and different from flagella?

They are similar to flagella but wrap around the cell instead of projecting outward.

What is the main function of fimbriae?

They help cells adhere to surfaces.

What are the functions of pili?

They are involved in twitching motility and DNA transfer.

What does the cell wall do for bacterial cells?

Surrounds the plasma membrane and protects the cell from changes in water pressure.

what is the bacterial cell wall made of?

Peptidoglycan (polymer of NAG, NAM, and short amino acid chains).

What characterizes gram-positive cell walls?

Many layers of peptidoglycan and teichoic acids.

What characterizes gram-negative cell walls?

A thin peptidoglycan layer surrounded by a lipopolysaccharide-lipoprotein-phospholipid outer membrane.

What does the outer membrane of gram-negative bacteria protect against?

Phagocytosis, penicillin, lysozyme, and other chemicals

What are porins and what do they do?

Proteins in the outer membrane that allow small molecules to pass; specific channel proteins let other molecules move through.

What are the two components of the lipopolysaccharide (LPS) in the outer membrane?

sugars (O polysaccharides- function as antigens) and lipid A (endotoxin)

In gram staining, what does the crystal violet–iodine complex combine with?

Peptidoglycan.

What does the decolorizer do in gram-negative bacteria?

Removes the lipid outer membrane and washes out the crystal violet.

Which bacterial genus naturally lacks cell walls?

Mycoplasma.

What do archaeal cell walls contain instead of peptidoglycan?

Pseudomurein.

What characterizes acid-fast cell walls?

A layer of mycolic acid outside a thin peptidoglycan layer.

What happens to gram-positive cell walls in the presence of lysozyme?

They are destroyed, leaving a protoplast.

What happens to gram-negative cell walls in the presence of lysozyme?

They are not completely destroyed, leaving a spheroplast.

What are L forms?

Gram-positive or gram-negative bacteria that lack a cell wall

How do antibiotics such as penicillin damage bacteria?

By interfering with cell wall synthesis.

What does the plasma membrane enclose, and what is its structure?

It encloses the cytoplasm and is a lipid bilayer with peripheral and integral proteins (fluid mosaic model).

Is the plasma membrane selectively permeable?

yes

What metabolic roles can plasma membranes have?

They contain enzymes for nutrient breakdown, energy production, and photosynthesis.

What are mesosomes, and are they true cell structures?

Irregular infoldings of the plasma membrane; they are artifacts, not true structures.

What can destroy plasma membranes?

certain alcohols and polymyxins.

What distinguishes passive processes from active processes in membrane transport?

Passive: materials move high → low concentration, no energy used.
Active: materials move low → high concentration, energy required.

What happens during simple diffusion?

Molecules and ions move until equilibrium is reached.

How does facilitated diffusion differ from simple diffusion?

It uses transporter proteins to move substances from high → low concentration.

What is osmosis?

the movement of water across a selectively permeable membrane from low → high solute concentration until equilibrium.

What is required for active transport?

transporter proteins and energy expenditure to move substances low → high concentration.

What is group translocation?

A process where energy is used to chemically modify substances as they are transported across the membrane.

What is the cytoplasm?

The fluid component inside the plasma membrane.

What does the cytoplasm contain?

Mostly water, plus inorganic and organic molecules, DNA, ribosomes, inclusions, and cytoskeleton proteins.

Does cytoplasmic streaming occur in a bacterial cytoplasm?

No, even though a cytoskeleton is present.

What does the nucleoid contain?

The DNA of the bacterial chromosome.

What are plasmids?

Circular, extrachromosomal DNA molecules found in bacteria.

What type of ribosomes are found in prokaryotic cytoplasm?

70S ribosomes, consisting of rRNA and protein.

What occurs at ribosomes, and how can it be affected?

Protein synthesis occurs and can be inhibited by certain antibiotics.

What are inclusions in cells?

Reserve deposits found in prokaryotic and eukaryotic cells.

Name some types of bacterial inclusions.

Metachromatic granules (inorganic phosphate)

polysaccharide granules (glycogen or starch)

lipid inclusions

sulfur granules

carboxysomes (ribulose 1, 5-diphosphate carboxylase)

gas vacuoles 

magnetosomes (Fe3O4).

What are endospores and their function?

Resting structures formed by some bacteria that allow survival during adverse environmental conditions.

How do eukaryotic flagella and cilia differ in number and length?

Flagella are few and long; cilia are numerous and short.

What are the functions of flagella and cilia?

Both are used for motility; cilia also move substances along the cell surface.

What is the microtubule arrangement in eukaryotic flagella and cilia?

Nine pairs of microtubules surrounding two single microtubules (9+2 arrangement).

What do the cell walls of many algae and some fungi contain?

Cellulose.

What is the main material in fungal cell walls?

chitin 

What do yeast cell walls consist of?

Glucan and mannan.

What surrounds animal cells and what are its functions?

Glycocalyx; it strengthens the cell and provides attachment to other cells.

What is the structure of the eukaryotic plasma membrane?

A phospholipid bilayer containing proteins, like prokaryotic membranes.

What features distinguish eukaryotic plasma membranes from prokaryotic ones?

They contain carbohydrates attached to proteins and sterols (except Mycoplasma bacteria).

How do eukaryotic cells move materials across the plasma membrane?

By passive and active transport (like prokaryotes) and by endocytosis (phagocytosis, pinocytosis, receptor-mediated).

What does the cytoplasm of eukaryotic cells include?

Everything inside the plasma membrane and external to the nucleus.

How do the chemical characteristics of eukaryotic cytoplasm compare to prokaryotic cytoplasm?

they are very similar

What structural feature and movement does eukaryotic cytoplasm exhibit that prokaryotic cytoplasm does not?

A cytoskeleton and cytoplasmic streaming.

What type of ribosomes are found in eukaryotic cytoplasm or on the rough ER?

80S ribosomes

What are organelles?

Specialized membrane-enclosed structures in the cytoplasm of eukaryotic cells.

What is the most characteristic eukaryotic organelle?

The nucleus, which contains DNA in the form of chromosomes.

What is the nuclear envelope connected to?

The endoplasmic reticulum (ER), a system of membranes in the cytoplasm.

what are the functions of the ER?

Provides a surface for chemical reactions and a transport network; rough ER synthesizes and transports proteins, smooth ER synthesizes lipids.

What is the structure and function of the Golgi complex?

flattened sacs called cisterns; functions in membrane formation and protein secretion.

How are lysosomes formed and what do they store?

Formed from Golgi complexes; store digestive enzymes.

What are vacuoles and where are they usually found?

Membrane-enclosed cavities derived from Golgi or endocytosis; usually in plant cells for storage.

What is the primary function of mitochondria?

ATP production; contain 70S ribosomes, DNA, and multiply by binary fission.

What do chloroplasts contain and what is their function?

chlorophyll and enzymes for photosynthesis; contain 70S ribosomes, DNA, and multiply by binary fission.

What occurs in peroxisomes?

Oxidation of organic compounds; catalase destroys hydrogen peroxide.

What is the centrosome and what is its function?

Consists of pericentriolar matrix and centrioles; organizes the mitotic spindle during cell division.

What are centrioles made of and what do they do?

Triplet microtubules; involved in formation of the mitotic spindle.

What does the endosymbiotic theory propose about eukaryotic evolution?

Eukaryotic cells evolved from symbiotic prokaryotes living inside other prokaryotic cells.

What is metabolism?

The sum of all chemical reactions within a living organism.

What is catabolism?

chemical reactions that break down complex molecules into simpler substances, usually releasing energy.

What is anabolism?

Chemical reactions that combine simpler substances to form complex molecules, usually requiring energy.

How are catabolic and anabolic reactions linked?

Energy released from catabolic reactions drives anabolic reactions.

Where is the energy for chemical reactions stored?

In ATP.

What is required for chemical reactions to occur?

collisions between reactants with enough energy (activation energy) to break or form chemical bonds.

What are enzymes and what is their main function?

Proteins produced by living cells that catalyze chemical reactions by lowering activation energy.

What is the general structure of enzymes?

Globular proteins with characteristic three-dimensional shapes.

What are some properties of enzymes?

Efficient, operate at relatively low temperatures, and subject to cellular controls.