Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells

Question 1

Prokaryote:

Answer 1

o One Circular chromosome, not membrane bound.
o No organelles.
o Peptidoglycan cell walls if bacteria.
o Pseudomurein cell walls if archaea.
o Binary fission (split into two daughter cells).

Question 2

Eukaryote:

Answer 2

o Paired chromosomes, in nuclear membrane.
o Organelles.
o Polysaccharide cell walls.
o Mitotic Spindle.

Question 3

Prokaryotic Cell Shapes:

Answer 3

o Avg. size: 0.2 –1.0 µm × 2 – 8 µm.

o Most monomorphic - A few are pleomorphic.

Question 4

Basic Cell Shapes:

Answer 4

o	Coccus (spherical).
o	Bacillus (rod-shaped).
•	Coccobacillus.
o	Spiral:
•	Spirillum.			
•	Vibrio.			
•	Spirochete.
•	Pleomorphic.

Question 5

Basic Cell Arrangements:

Answer 5

o	Pairs (Diplo-).
o	Clusters (Strepto-).
o	Chains (Staphylo-).
o	Group of 4 (Tetrad).
o	Group of 8 (Sarcinae).

Question 6

Structure of Prokaryotic Cells Contain:

Answer 6

o	Glycocalyx.
o	Nucleoid.
o	Pilus and Flagellum.
o	Plasmid.
o	Ribosomes.
o	Fimbrae.
o	Inclusion Body.
o	Cytoplasm.
o	Cell membrane and Cell wall and LPS layer.

Question 7

The Bacterial Cell Wall:

Answer 7

o Surrounds plasma membrane.
o Protects cell from changes in water pressure.
o Made of peptidoglycan, also called “murein”.
o Two large groups differentiated by Gram Stain:
• Gram Positive.
• Gram Negative.

Question 8

The Gram Stain:

Answer 8

o Developed in 1884 By Han Christian Gram.
o Differential Stain.
o Used to classify bacteria into two large groups:
• Gram Positive (Darker Pink).
• Gram Negative (Bright Pinkish-Red).

Question 9

Peptidoglycan:

Answer 9

o Sugar backbone.
o Protein side-chain.
o Present in most bacteria.
o Provides strength.

Question 10

Peptidoglycan in Gram-Positive Bacteria:

Answer 10

o Many layers of Peptidoglycan.
o Linked by polypeptides.
o Contain teichoic acids.

Question 11

Gram-Positive Cell Walls:

Answer 11

o Teichoic acids:
• Lipoteichoic acid links to plasma membrane.
• Wall teichoic acid links to peptidoglycan.
o Thick Peptidoglycan.
o Penicillin Sensitive.
o Disrupted by lysozyme.
o 2 ring basal body.

Question 12

Gram Negative Outer Membrane:

Answer 12

o	Protection from phagocytes, complement, and antibiotics.
o	O polysaccharide antigen, e.g., E. coli O157:H7.
o	Lipid A is an endotoxin.
o	Porins (proteins) form channels through membrane.

Question 13

Gram Negative Bacterial Cell Walls:

Answer 13

o	Lipopolysaccharide- (LPS) surrounds thin Peptidoglycan layer.
o	LPS provides a barrier against some digestive enzymes and some antibiotics.
o	Lipopolysaccharide (LPS):
•	O polysaccharide.
•	Core polysaccharide.
•	Lipid A.
•	Periplasmic space.
•	Peptidoglygan layer.
•	Periplasmic space.
•	Plasma membrane.
o	Thin Peptidoglycan.
o	LPS outer membrane.
o	Endotoxin.
o	Tetracycline sensitive.
o	4 ring Basal body.

Question 14

The Gram Stain Mechanism:

Answer 14

o Crystal violet-iodine (CV-I) crystals form in cell.
o GRAM-POSITIVE:
• Alcohol dehydrates peptidoglycan.
• CV-Iodine crystals do not leave.
o GRAM-NEGATIVE:
• Alcohol dissolves outer membrane and leaves holes in peptidoglycan.
• CV-I crystals wash out.

Question 15

Atypical Cell Walls:

Answer 15

o	Acid-fast cell walls:
•	Modified gram-positive structure.
•	Mycolic Acid / thin peptidoglycan layer.
•	Mycobacterium, spp.
o	Mycoplasmas: 
•	Lack cell walls.
•	Sterols in plasma membrane.
o	Archaea:	
•	Wall-less of walls of pseudomurein.

Question 16

Why are drugs that target cell wall synthesis useful?

Answer 16

o Eukaryotic cells (animal cells) don’t have cell walls.

Question 17

Why are Mycoplasmas resistant to antibiotics that interfere with cell wall synthesis?

Answer 17

o Mycoplasmas don’t have cell walls.

Question 18

Structures External to Cell Wall:

Answer 18

o	GLYCOCALYX:
•	Gelatinous polymer. 
o	FLAGELLA:
•	Filamentous appendage -  propels.
o	AXIAL FILAMENTS:
•	Corkscrew movement.
o	FIMBRIAE:
•	Adherence.
o	PILI:
•	DNA exchange and motility.

Question 19

Glycocalyx:

Answer 19

o Outside cell wall.
o Sticky.
o Helps Prevent phagocytosis.
o Capsule vs. Slime Layer.

Question 20

Why Bacterial Capsules are Medically Important:

Answer 20

o May protect pathogens from phagocytosis.
o May help them adhere to surfaces.
o May provide nutrients.
o Helps prevent desiccation.

Question 21

Flagella in a Prokaryote:

Answer 21

o Long filamentous appendages consisting of a filament, hook, and basal body.
o Rotate to push the cell.
o FLAGELLAR (H) protein is an ANTIGEN that helps serotype species of gram-negative bacteria.
o Think E. Coli.

Question 22

The Structure of a Prokaryotic Flagellum in the Gram-Positive Bacterium:

Answer 22

o Outside cell wall.
o Made of chains of FLAGELLIN.
o Attached to a protein HOOK.
o Anchored to the wall and membrane by the BASAL BODY.

Question 23

Motile Cells:

Answer 23

o ROTATE FLAGELLA TO RUN OR TUMBLE.
• Moving in one direction for a long time is a run.
• In a tumble flagella have reversed direction of rotation.
o MOVE TOWARD OR AWAY FROM STIMULI (TAXIS).
• Positive taxis is moving toward an attractant.
• Negative taxis is moving away from a repellent.

Question 24

Axial Filaments:

Answer 24

o Also called ENDOFLAGELLA.
o In spirochetes.
o Anchored at one end of a cell.
o Rotation causes cell to move.

Question 25

Fimbrae and Pili:

Answer 25

o	FIMBRIAE – attachment.
•	Few to several hundred.
•	Biofilms.
•	Adherence to mucus membranes.
o	PILI – longer than fimbriae.
•	One or two per cell.
•	Transfer of DNA.
•	Motility.

Question 26

Prokaryotic Membrane:

Answer 26

o	Inside cell wall.
o	Encloses cytoplasm.
o	Consists mainly of phospholipids.
o	Exception – mycoplasmas – Why?
•	No cell wall and PM contains sterols.

Question 27

The Plasma Membrane:

Answer 27

o Phospholipid bilayer.
o Peripheral proteins.
o Integral proteins .
• Transmembrane Proteins.

Question 28

Fluid Mosaic Model:

Answer 28

o	Viscous as olive oil.
o	Ability to form self-sealing bi-layer.
•	Breaks and Tears heal themselves.
o	Membrane embedded with proteins.
o	Glycoproteins and glycolipids.
•	Protect and lubricate the cell.
•	Involved in cell-to-cell interaction.
o	In eukaryotes, PM is an attachment site for Influenza virus and toxins that cause cholera and botulism.

Question 29

Plasma Membrane Functions:

Answer 29

o Selective Barrier.
o Breakdown of nutrients (production of energy).
o Bacterial PM contains enzymes.
• Catalyze chemical reactions that breakdown nutrients and produce ATP.
• Photosynthesis: chromatophores and enzymes.

Question 30

Destruction of Plasma Membrane by Antimicrobial Agents:

Answer 30

o Alcohols.
o Quarternary Ammonium.
o Polymyxin antibiotics.

Question 31

Movement of Materials Across Membranes:

Answer 31

o	PASSIVE PROCESSESS:
o	Substances cross the membrane from area of HIGHER conc. to area of LOWER conc.
•	SIMPLE DIFFUSION.
•	FACILITATED DIFFUTION.
o	ACTIVE PROCESSESS:
o	Requires energy to move substance from area of LOWER conc. to area of HIGHER conc.
•	ACTIVE TRANSPORT.
•	GROUP TRANSLOCATION.

Question 32

Simple Diffusion:

Answer 32

o Net movement from high concentration to lower concentration.
o Water molecules pass through the lipid bilayer by simple diffusion or aquaporins.

Question 33

Facilitated Diffusion:

Answer 33

o Solute combines with a transporter.
o Moves down the concentration gradient.
o No energy expended.

Question 34

Osmotic Solutions:

Answer 34

o Isotonic solution: No net movement of water.
o Hypotonic solution: Net movement into a cell.
o Hypertonic Solution: Net movement out of a cell.

Question 35

When Simple Diffusion and Facilitated Diffusion Aren’t Enough:

Answer 35

o ACTIVE TRANSPORT: Requires a transporter protein and ATP.

o GROUP TRANSLOCATION: Requires a transporter protein and PEP.

Question 36

Cytoplasm:

Answer 36

Substance inside the plasma membrane.

Question 37

The Nucleoid:

Answer 37

o Contains bacterial chromosome.
• Single long Ds DNA, frequently circular.
• Plasmid.

Question 38

The Prokaryotic Ribosome:

Answer 38

o	Protein synthesis.
o	Prokaryotic = 70S.
•	50S + 30S subunits.
o	Sites of protein synthesis.
o	Great site for antibiotics:
•	Streptomycin.
•	Gentamicin.
•	Erythromycin.
•	Chloramphenical.

Question 39

Metachromatic Granules:

Answer 39

o Phosphate Reserve – VOLUTIN.
o Used in the synthesis of ATP.
o Found in Algae, Fungi, Protozoa and Bacteria.
o Characteristic of Corynebacterium diptheriae.

Question 40

Polysaccharide Granules:

Answer 40

o	Energy Source.
o	Glycogen and Starch.
o	Stain with Iodine.
•	Glycogen – Reddish Brown.
•	Starch – Blue.

Question 41

Lipids:

Answer 41

o Energy Source.
o Stain with Sudan Dyes.
o Mycobacterium, Bacillus, Spirillum.

Question 42

Sulfur Granules:

Answer 42

o Energy Source.
• Derived by oxidizing the sulfur.
• Chromatium, also Thiobacillus.

Question 43

Carboxysomes:

Answer 43

o Found in Photosynthetic Bacteria.
o Contains An Enzyme Required For CO2 Fixation.
o Ribulose 1,5-diphosphate carboxylase.
o Nitrifying Bacteria, Cyanobacteria and Thiobacilli.

Question 44

Gas Vacuoles:

Answer 44

o Often found in aquatic prokaryotes.

o Helps maintain buoyancy.

Question 45

Endospores:

Answer 45

o	Unique to bacteria.
o	Usually gram positive.
o	Internal to the cell membrane.
o	Highly durable.
o	Released into the environment, endospores can survive:
•	Extreme Heat, Lack of Water, Toxic Chemicals, Radiation
o	7,500 year old endospores.
o	25-40 Million year old endospores.

Question 46

Sporulation:

Answer 46

o Endospore Formation.
• Don’t carry on metabolic functions.
• Contain: DNA, RNA, Ribosomes, Enzymes, and a few important molecules (dipicolinic acid, and Ca++)
• Can remain dormant for thousands of years or more.

Question 47

Germination:

Answer 47

o Endospores return to vegetative state:
• Triggered by physical or chemical damage to the endospore coat.
• Endospore enzymes then break down the extra layers surrounding the endospore.
• Water enters and metabolism resumes.

Question 48

Eukaryotic Flagella and Cilia:

Answer 48

o Flagella are few and long in relation to cell length.
o Cilia are short and numerous.
o Both are used for motility.
o In addition, Cilia are used to move substances along the surface of cells.
o Both are anchored to the plasma membrane with a basal body.

Question 49

Eukaryotes:

Answer 49

o Algae, protozoa, fungi, plants, and animals.
o Size: 10-100 um.
o True nucleus, nuclear membrane, nucleolus.
o Membrane-bound organelles.
o Flagella- Complex, multiple microtubules.
o Glycocalyx present in some cells that lack a cell wall.
o Cell wall when present is chemically simple, chitin and cellulose.
o Plasma membrane sterols and carbs.
o Cytoplasm, cytoskeleton, and cytoplasmic streaming.
o Ribosomes- 80s (70s in organelles).
o Chromosome- Multiple linear chromosomes with histones.
o Cell division involves mitosis.
o Sexual Recombination involves meiosis.

Question 50

Prokaryotes:

Answer 50

o Bacteria, archea.
o Size 0.2-2.0 um.
o No nuclear membrane or nucleolus.
o No membrane-enclosed organelles.
o Flagella – 2 proteins.
o Glycocalyx present as capsule or slime layer.
o Cell wall usually present, chemically complex, peptidoglycan.
o Plasma Membrane, No carboydrates, generally lacks sterols.
o No cytoskeleton, no cytoplasmic streaming.
o Ribosomes Smaller – 70S.
o Chromosome: Circular, single strand.
o Cell Division - Binary fission.
o Sexual Recombination – none, however transfer of DNA possible.

Question 51

The Cell Wall:

Answer 51

o	Animal Cells do not have a Cell Wall.
o	Protozoans have a flexible outer protein called a “pellicle” that acts as their cell wall.
o	Algae, Plants and some Fungi.
•	Cellulose cell walls.
o	Most fungi as well as the exoskeleton of insects and Crustaceans.
•	Chitin cell walls.
o	Yeast.
•	Glucan and mannan.

Question 52

Glycocalyx in Eukaryotic Organisms:

Answer 52

o GLYCOCALYX
• Substantial, sticky carbohydrate layer covering the plasma membrane
• Some proteins and lipids are bound to the carbohydrate layer
o Forms glycoproteins and glycolipids.
• Anchor the glycocalyx to the cell.
o Strengthen the cell surface.
o Helps with cell attachment to each other.
o Cell-cell recognition.

Question 53

Plasma Membrane in Eukaryotes:

Answer 53

o PHOSPHOLIPID BILAYER – similar to prokaryotes.
o PERIPHERAL PROTEINS.
o INTEGRAL PROTEINS.
o TRANSMEMBRANE PROTEINS.
o STEROLS.
• Adds stability to membrane; helps to resist lysis.
o Selective permeability allows passage of some molecules.
o Simple diffusion.
o Facilitative diffusion.
o Osmosis.
o Active transport.
o Endocytosis:
• Phagocytosis: Pseudopods extend and engulf particles.
• Pinocytosis: Membrane folds inward, bringing in fluid and dissolved substances.

Question 54

Cytoplasm of Eukaryotes:

Answer 54

o CYTOSKELETON:
• Microfilaments, intermediate filaments, microtubules.
• Provides structure and a transport system – think rails.
o CYTOPLASMIC STREAMING:
• Movement of cytoplasm throughout cells.
• Helps to distribute nutrients throughout the cell.

Question 55

Organelles of Eukaryotes:

Answer 55

o NUCLEUS: Contains chromosomes.
o ER: Transport network.
o GOLGI COMPLEX: Membrane formation and secretion.
o LYSOSOME: Digestive enzymes.
o VACUOLE: Brings food into cells and provides support.
o MITOCHONDRION: Cellular respiration.
o CHLOROPLAST: Photosynthesis.
o PEROXISOME: Oxidation of fatty acids; destroys H2O2.
o CENTROSOME: Consists of protein fibers and centrioles.

Question 56

The Eukaryotic Nucleus:

Answer 56

o Spherical or oval.
o Contains chromosomes.
o Consists of: Nuclear Envelope, Nuclear pores, Nucleoli.

Question 57

Rough E.R.:

Answer 57

o Continuous with Nuclear envelope.
o Outer surface studded with ribosomes.
o Processes and sorts ribosomes.
o Synthesizes secretory proteins, membrane molecules, including phospholipids.
o Enzymes within cisterns attach proteins to Carbohydrates.

Question 58

Smooth E.R.:

Answer 58

o Smooth ER has no Ribosomes on outer surface.
o Does not synthesize proteins.
o Does synthesize phospholipids, fats and steroids (Estrogens and testosterone).

Question 59

Golgi Complex:

Answer 59

o Consists of flattened sacs called “cisterns”.

o Functions in membrane formation and protein secretion.

Question 60

Lysosymes:

Answer 60

o Formed by golgi complexes.

o Contain as many as 40 different digestive enzymes.

Question 61

Vacuoles:

Answer 61

o Cavity enclosed by a membrane, “tonoplast”.
o Derived from the golgi complex.
o In plants, can be 5-90 percent of the cell volume.
o May serve as temporary storage spaces.

Question 62

Mitochondria:

Answer 62

o Powerhouse of a cell – central role is ATP production.
o Number varies, 1000-2000 per liver cell.
o Contain ribosomes and their own DNA.
o Can replicate, transcribe, and translate info from their DNA.

Question 63

Chloroplasts:

Answer 63

o Algae, Green plants.
o Pigment Chlorophyll.
o Enzymes for photosynthesis.
o Contain ribosomes and their own DNA.
o Can replicate, transcribe, and translate info from their DNA.
o Thylakoids: flattened membrane sacs that contain chlorophyll.
o Granum: stacks of thylakoids.

Question 64

Peroxisome:

Answer 64

o Contain enzymes that can oxidize a variety of organic compounds, H2O2 is often of oxidation reactions.
o Peroxisomes also contain catalase, an enzyme that breaks down H2O2.

Question 65

Centrosome:

Answer 65

o Pericentriolar area and the centrioles.

o Involved in formation of the mitotic spindle in dividing cells and microtubles in non-dividing cells.

Question 66

Endosymbiotic Theory of Eukaryotic Evolution:

Answer 66

o EUKARYOTIC CELLS EVOLVED FROM SYMBIOTIC PROKARYOTES LIVING INSIDE OTHER PROKARYOTIC CELLS.
o MITOCHONDRIA AND CHLOROPLASTS:
• Resemble bacteria in size and shape.
• Which contain circular DNA.
• Can replicate independently of their host.
• Ribosomes resemble those of bacteria.
• The same antibiotics that inhibit protein synthesis on bacterial ribosomes, inhibit protein synthesis on their ribosomes.

Question 67

Origin of Flagella and Cilia:

Answer 67

o Eukaryotic Flagella and Cilia are believed to have originated from symbiotic associations between the Plasma Membrane of early eukaryotes and spirochetes