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