Microbiology: Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells

Cell Structure Order

1. Capsule 2. Cell Wall 3. Plasma Membrane

How are Gram + and Gram - flagella different?

A Gram + flagellum has only two rings in its basal body; Gram - each have four.

Peptidoglycan Consists of

A polymer consisting of NAG and NAM and short chains of amino acids.

Pathogenic Bacteria

Can be identified and classified by differences in their flagellar proteins.

Describe Fimbriae

Can occur at the poles of the bacterial cell or can be evenly distributed over the entire surface of the cell. Have a tendency to adhere to each other and to surfaces. Are involved in forming biofilms and other aggregations on the surfaces of liquids, glass, and rocks.

Organelles only in prokaryotes?

Capsule

Which structure protects bacteria from being phagocytizied?

Capsule

Chemotaxis

Cell movement towards chemicals.

Phototaxis

Cell movement towards light.

Main material of fungal cell walls is...?

Chitin

In bacteria, photosynthetic pigments are found in...?

Chromatophores

A Gram + bacterium suddenly acquires resistance to the antibiotic methicillin. This trait most likely occurred due to acquisition of new genetic information through...?

Conjugation

Axial filaments are composed of?

Endoflagella

Cytoplasm

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

Taxis

Movement of a bacterium toward or away from a particular stimulus.

Capsules provide what benefits to bacteria?

Protect pathogens from phagocytosis. Enable adherence to surfaces, prevent desiccation, and may provide nutrients..

Endoplasmic Reticulum

Provides a surface for chemical reactions and serves as a transport network. Protein synthesis and transport occur on the rough ER; lipid synthesis occurs on the smooth ER.

What is the glycocalyx?

(Capsule, Slime Layer, or Extracellular Polysaccharide) A gelatinous polysaccharide and/or polypeptide covering.

Prokaryotic Cells Contain:

1. 70s Ribosomes 2. Flagella that rotate, composed of flagellin. 3. Peptidoglycan containing cell wall. 4. Circular chromosome, not enclosed within a nuclear envelope.

Eukaryotic Cells Contain:

1. 80s Ribosomes 2. Cellulose or Chitin Containing Cell Wall 3. Flagella that wave, composed of microtubules. 4. Endoplasmic Reticulum 5. Mitochondria 6. Lysosomes 7. Linear chromosomes enclosed within a nuclear envelope. 8. Golgi Apparatus

Chief Distinguishing Characteristics of Eukaryotes

1. DNA is not found in the cell's nucleus, which is separated from the cytoplasm by a nuclear membrane. DNA is found in multiple chromosomes. 2. DNA is consistently associated with chromosomal proteins called histones and with nonhistones. 3. Have a number of membrane-enclosed organelles. 4. Cell walls, when present, are chemically simple. 5. Cell division usually involves mitosis.

Chief Distinguishing Characteristics of Prokaryotes

1. Their DNA is not enclosed within a membrane and is usually a singular, circularly arranged chromosome. 2. DNA is not associated with histones. 3. Generally lack organelles. 4. Cell walls almost always contain peptidoglycan. 5. Usually divide by binary fission.

Gram - Bacteria contain how many rings in the basal body?

2 Pairs of Rings Outer pair of rings is anchored to various portions of the cell wall. And the inner pair of rings is anchored to the plasma membrane.

What kind of ribosomes are found in the cytoplasm prokaryotic cells?

70S ribosomes. Ribosomes consist of rRNA and protein.

What ribosomes are found in eukaryotic cells?

80S ribosomes are found in the cytoplasm or attached to the rough endoplasmic reticulum.

Mycoplasma

A bacterial genus that naturally lack cell walls.

Twitching Motility

A pilus extends by the addition of subunits of pilin, makes contact with a surface or another cell, and then retracts (power stroke) as the pilin subunits are dissembled.

Monotrichious

A single flagellum at one pole.

Lophotrichous

A tuft of flagella coming from one pole.

Glycoprotein

A type of peripheral protein above that can be used as a receptor in enzymatic functions.

Which membrane transport mechanism requires ATP?

Active Transport

Plasma membranes can be destroyed by...?

Alcohols and Polymyxins

Nonspecific Permeases

Allow a variety of molecules to cross the cytoplasmic membrane.

In Gram - bacteria, the thin layer of peptidoglycan is surrounded by...?

An outer membrane of phospholipids, lipopolysaccharides, and proteins.

The rings of the flagellum?

Anchor the flagellum to the cell membrane.

Which type of active transport protein uses one protein to pump two different molecules?

Antiport and Symport

Centrioles

Are 9 triplet microtubules involved in formation of the mitotic spindle and microtubules.

Polar Flagella

At one or both poles or ends of the cell.

If chemotactic signal is positive...?

Attractant, the bacteria move toward the stimulus with many runs and few tumbles.

Plasmids

Bacteria contain them which are circular, extrachromosomal DNA molecules.

Monotrichous

Bacteria have a single flagellum.

Atrichous

Bacteria that lack flagella.

How is the genetic information of bacterial cells organized differently from that of eukaryotic cells?

Bacterial DNA floats free within the cytoplasm and is not enclosed within a nuclear envelope, whereas eukaryotic DNA is enclosed in nucleus.

Describe Axial Filaments/Endoflagella

Bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell. Propel in a spiral motion.

Hydrophobic molecules move across a membrane?

By passive transport directly across the membrane.

Which structure is responsible for the transfer of genetic information between two cells in prokaryotic cells?

Conjugation Pili

Flagella and Cilia are arranged how in eukaryotic cells?

Consist of an arrangement of nine pairs and two single microtubules.

Gram + Cell Walls

Consist of many layers of peptidoglycan and also contain teichoic acids.

Golgi Complex

Consists of flattened sacs called cisternae. It functions in membrane formation and protein secretions.

Centrosome

Consists of the pericentriolar material and centrioles.

Describe Filament

Constant in diameter and contains the globular protein flagellin arranged in several chains that intertwine and form a helix around a hollow core.

Chloroplasts

Contain chlorophyll and enzymes for photosynthesis.

In the presence of lysozyme, Gram + cell walls are...?

Destroyed, and the remaining cellular contents are referred to as a protoplast.

Gram - Bacterial Cell Wall

Dual lipid bilayer membranes. Periplasmic Space Thin layer of peptidoglycan. Lipopolysaccharides

Group Translocation

Energy is expended to modify chemicals and transport them across the membrane.

Endosymbiotic Theory

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

Is blood in the urine a classic sign and/or symptom of a urinary tract infection? True/False

False

What structural part of a bacterial flagellum is composed of flagellin?

Filament

Describe Hook

Filament is attached to a slightly wider hook, consisting of a different protein.

What are the three basic parts of the flagellum?

Filament, Hook, and Basal Body

Which structural feature of E. coli is most responsible for the signs and symptoms of a urinary tract infection?

Fimbriae

Many Gram - bacteria contain hairlike appendages that are shorter, straighter, and thinner than flagella called?

Fimbriae and Pili. Consist of a protein called piling arranged helically around a central core.

Amphitrichous

Flagella at both poles of the cell.

Peritrichous

Flagella distrusted all over.

H antigen

Flagellar protein useful for distinguishing among serovars, or variations within a species, of Gram - bacteria.

Lysosomes

Formed from golgi complexes. Store digestive enzymes.

Yeast cell walls consist of...?

Glucan and Mannan

Organelles only in eukaryotes?

Gogli Complex, Rough Endoplasmic Reticulum, Mitochondria, Nucleus

Which Gram bacteria contains teichoic acids in its cell wall?

Gram +

L Forms

Gram + or Gram - bacteria that do not make a cell wall. Wall-less cells that swell into irregular shapes.

Which Gram bacteria contains porins in its cell wall?

Gram -

Which Gram bacteria is resistant to many antibiotics?

Gram -

Which Gram bacteria posses lipid A (endotoxin) responsible for symptoms associated with infection in its cell wall?

Gram -

Describe Spirochetes

Group of bacteria that have unique structure and motility.

You have isolated a motile, Gram + cell with no visible nucleus. You can safely assume that the cell...?

Has a cell wall.

Acid Fast Cell Walls

Have a layer of mycolic acid outside a thin peptidoglycan layer.

Gram - Cell Walls

Have a lipopolysaccharide-lipoprotein-phospholipid outer membrane surrounding a thin peptidoglycan layer.

Archea Cell Walls

Have pseudomurien; they lack peptidoglycan.

The Gram + cell walls protect the cell from what environment?

Hypertonic Environment

Functions of the glycocalyx include?

Increased virulence. Biofilm formation. Source of nutrition. Protection against dehydration.

Identify antibacterial strategies that would likely be selectively toxic for bacteria.

Inhibition of fimriae synthesis. Inhibition of peptidoglycan synthesis. Interfering with translation at 70s ribosomes.

How does Penicillin kill bacteria?

Interfere with cell wall synthesis.

Mesosomes

Irregular inholdings of the plasma membrane, are artifacts, not true cell structures.

What is the advantage to spirochetes of the corkscrew movement provided by axial filaments?

It allows the cells to move more easily through viscous human tissues and fluids, such as mucus.

Which organelle would play the most direct role in eliminating bacteria engulfed by a phagocytic white blood cell?

Lysosome

Monomorphic

Maintain a single shape.

Active Transport

Materials move from areas of low to high concentration by transporter proteins, and the cell must expend energy.

Pleomorphic

Means they can have many shapes, not just one.

Vacuoles

Membrane-enclosed cavities derived from the golgi complex or endocytosis. Are usually found in plant cells that store various substances and provide rigidity to leaves and stems.

Inclusions found in bacteria.

Metachromatic Granules: Inorganic Phosphate Polysaccharide Granules: Usually Glycogen or Starch Lipid Inclusions Sulfur Granules Carboxysomes: Ribulose 1,5-Diphosphate Carboxylase Magnetosomes: Fe3O4 Gas Vacuoles

Simple Diffusion

Molecules and ions move until equilibrium is reached.

How do bacterial flagella move?

Moves the cell by rotating fro the basal body.

In the presence of lysozyme, Gram - cell walls are...?

Not completely destroyed, and the remaining cellular contents are referred to as a spheroplast.

Hallmark of passive transport across cell membranes?

Occurs along an electrochemical gradient, and may involve the use of transport proteins.

Gram + Bacteria contain how many rings in the basal body?

Only the inner pair of rings is present.

Antibiotics that target cell wall synthesis ultimately cause bacterial cell death as a result of...?

Osmotic Lysis

Why are most Gram - bacteria resistant to the actions of penicillin?

Penicillin is unable to pass through the outer membrane of the cell wall.

How does penicillin kill bacteria?

Penicillin will interfere with peptidoglycan synthesis, ultimately weakening the cell wall and leading to cellular lysis.

Fimbriae and pili differ in that?

Pili are used for transfer of DNA and motility.

Conjugation (Sex) Pili

Pili used to bring bacteria together, allowing the transfer of DNA from one cell to another, process called conjugation.

Gram - Cells Stain

Pink

Where are phospholipids most likely found in a prokaryotic cell?

Plasma Membrane

Where are phospholipids most likely found in a eukaryotic cell?

Plasma Membrane and Organelles

In a hypertonic solution, a bacterial cell will simply...?

Plasmolyze

Which molecules will not be able to easily pass directly through the phospholipid portion of the cell membrane?

Polar Molecules

Following term refers to a bacterium moving towards a light source?

Positive Phototaxis

Mitochondria

Primary sites of ATP production.

Gram - Cell Wall Characteristics

Protect the cell in a hypotonic environment. They are toxic to humans. Have an extra outer layer composed of lipoproteins, lipopolysaccharides, and phospholipids. They are sensitive to penicillin.

Porins

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

Gram + Cells Stain

Purple

If chemotactic signal signal is negative...?

Repellant, the frequency of tumbles increases as the bacteria move away from the stimulus.

Inclusions

Reserve deposits found in prokaryotic and eukaryotic cells.

Organelles in both eukaryotes and prokaryotes?

Ribosomes, Flagella, Cytoplasm, Plasma Membrane

Protein synthesis occurs where in prokaryotic cells?

Ribosomes, and can be inhibited by certain antibiotics.

The basal body is comprised of which structural components of flagella?

Rods and Rings

As a bacterium approaches a food source, one would expect?

Runs to become more frequent.

Composition of Bacterial Cell Wall

Short amino acids chains, NAG, NAM, and some lipid proteins.

How is simple diffusion different from other types of passive transport?

Simple diffusion does not require a permease.

How do spirochetes and spirilla differ?

Spirilla have external flagella but spirochetes have axial filaments.

Axial filaments are found on?

Spirochetes

How does streptomycin attacks bacterial cells?

Streptomycin targets the 70S ribosome and inhibits protein synthesis.

Facilitated Diffusion

Substances are transported by transporter proteins across membranes from areas of high to low concentration.

Lipopolysaccharide component of the outer membrane consists of...?

Sugars (O Polysaccharides), which function as antigens, and lipid A, which is an endotoxin.

Which type of active transport protein moves two molecules into the cell at the same time?

Symport

The terms "run" and "tumble" are generally associated with?

Taxic movements of the cell in response to attractants or repellents.

How do axial filaments differ from regular bacterial flagella?

The axial filament is located between the cell membrane and the outer membrane.

Why is no energy required in passive transport?

The concentration gradient drives the movement.

Tumbles occur when?

The flagella rotate clockwise.

Peritrichous bacteria make a run when?

The flagella turn counterclockwise and become bundled.

Osmosis

The movement of water from areas of high to low concentration across a selectively permeable membrane until equilibrium is reached.

Why are receptors on the cell surface necessary for bacterial movement?

The receptors physically alter shape to steer the bacterium.

Gliding Motility

The smooth gliding movement of myxobacteria. Provides a means for microbes to travel in environments with a low water content, such as biofilms and soil.

Gram + Bacterial Cell Wall

Thick layer of peptidoglycan. Single lipid bilayer. Teichoic Acids

Describe Basal Body

Third portion of a flagellum which anchors the flagellum to the cell wall and plasma membrane. Composed of a small central rod inserted into a series of rings.

Integral proteins are mostly involved in?

Transport Function

Antibiotics that target the cell wall are an effective treatment agains many pathogenic bacteria. True/False

True

If you observe rod-shaped cells after the Gram stain, you can assume their cell walls contain endotoxin. True/False

True

How do eukaryotic flagella move?

Undulate in wave like motion.

Which transport protein employs transports that move molecules only in one direction?

Uniport and Symport

Describe Pili

Usually longer than fimbriae and number only one or two per cell. Involved in motility and DNA transfer.

How is osmosis different from simple diffusion?

Water movement is driven by the concentration of solutes rather than its own concentration.

Which of the following statements best describes what happens when a bacterial cell is placed in a solution containing 5% NaCl?

Water will move out of the cell.

Describe the motility of flagella?

When a bacterium moves in one direction for a length of time, the movement is called a "run". "Runs" are interrupted by periodic, abrupt, random changes in direction called "tumbles". then, a "run" resumes. "Tumbles" are caused by a reversal of flagellar movement.