Chapter 4- Functional Anatomy of Prokaryotic and Eukaryotic Cells

Question 1

Prokaryotic cell shape

Answer 1

Monomorphic mainly, (rhizobium and Corynebacterium are pleomorphic), 0.2 - 2 microns in diameter, about 2-8 microns in length

Question 2

Glycocalyx

Answer 2

viscous polymer composed of polysaccharide and/or polypeptide external to the cell wall; can be a capsule if tightly attached to the cell wall, or slime layer if unorganized and diffuses easily; important for biofilms, adherence, inhibit nutrient loss, virulence and dehydration.

Question 3

Flagella (prokaryotic)

Answer 3

Long filamentous appendages outside the cell wall for propulsion. Consists of non membranous filament (globular flagellin that carries H antigen), basal body (rod and series of rings that attaches flagellum to the wall/membrane), hook (flexible coupling between the filament and the basal body.

Question 4

Bacterial flagella arrangement

Answer 4

Peritrichous- flagella surrounding the whole cell
Lophotrichous/polar- tuft of flagella like a ponytail
monotrichous- single flagellum
amphitrichous- flagella on each end

Question 5

Axial filaments

Answer 5

Specialized flagella in spirochetes that lie between the cell wall and outer sheath

Question 6

Fimbriae and Pili

Answer 6

Both: comprised of pilin, hairlike appendages that are shorter/straighter/thinner than flagella, present in most gram-negative bacteria.
Fimbriae: on poles or evenly distributed, few-hundreds, allow attachment to each other and surfaces.
Pili: normally longer than fimbriae, only 1-2 per cell, facilitate DNA transfer, used for twitching/gliding motility.

Question 7

Gram + cell walls

Answer 7

cell membrane>thick peptidoglycan cell wall.

contains teichoic acids that provide rigidity, negative charge to regulate cation movement, and that are antigenic.

Question 8

Gram - cell walls

Answer 8

inner cell membrane > thin peptidoglycan layer > outer cell membrane

has periplasm, lipopolysaccharide, strong negative charge (which is beneficial against phagocytes and complement system), provides a barriere against antibiotics/lysozyme but not small metabolites due to porins.

Question 9

Lipopolysaccharide

Answer 9

Lipid A>Core polysaccharide> O polysaccharide

Lipid a- released when they die which is highly antigenic and is an endotoxin.

Core polysaccharide- contains unusual sugars which provide stability

o polysaccharide- antigen useful for distinguishing gram - species.

Question 10

Atypical cell walls

Answer 10

Mycoplasma- lacks cell walls/sterols in plasma membrane

Archaea- wall-less or walls of pseudomurein, which has N-acetyltalosaminuric acid instead of NAM and lacks D-amino acids).

Question 11

Protoplast

Answer 11

cell wall entirely removed (lysozyme digestion of gram + cells)

Question 12

Spherplasts

Answer 12

cell wall only partially removed (lysozyme digestion of gram - cells) EDTA is necessary for lysozyme efficacy on gram - cells because it’s a divalent cation chelator that removes Mg+ cations so the lipid A portions repel each other, disrupting the outer membrane which will expose the cell wall.

Question 13

L form

Answer 13

cells that lose their cell walls and swell into irregular shapes in response to lysozyme or penicillin.

Question 14

Mesosomes

Answer 14

Irregular folds that happen from preparing a specimen for microscopy.

Question 15

antimicrobial agents that damage the plasma membrane

Answer 15

Disinfectants: alcohols and quarternary ammonium compounds

antibiotics: polymyxins that interact with phospholipids and disrupt membrane structure resulting in leakage of intracellular contents.

Question 16

Plasmids

Answer 16

self-replicating double-stranded DNA molecules that contain 5-100 genes that can be used for antibiotic resistance; not crucial for survival.

Question 17

Metachromatic granules

Answer 17

inclusions of inorganic phosphate; formed by cells in phosphate-rich environments

Question 18

polysaccharide granules

Answer 18

reverse of glycogen/ starch

Question 19

sulfur granules

Answer 19

sulfur reserves that can be used for energy

Question 20

carboxysomes

Answer 20

inclusions that contain ribulose 1,5-diphosphate carboxylase for CO2 fixation.

Question 21

Gas vacuoles

Answer 21

hollow cavities found in aquatic prokaryotes that maintain buoyancy

Question 22

magnetosomes

Answer 22

inclusions of iron oxide to orient bacteria as well as protect from H2O2

Question 23

Endospores

Answer 23

Dehydrated cells with thick walls and resistant to desiccation, radiation, heat and chemicals; contain only DNA, little RNA, ribosomes and a few important molecules. NOT METABOLICALLY ACTIVE; found in gram + bacteria; NOT A FORM OF REPRODUCTION

Question 24

Flagella (eukaryotic) and cilia

Answer 24

Both have 9+2 arrangement of microtubules (tubulin), encased in cell’s membrane, and anchored to membrane via a basal body. Also, the eukaryotic flagellum moves in a wavelike manner, as opposed to the prokaryotic one’s rotation

Question 25

Eukaryotic cell wall

Answer 25

animal and protozoan cells lack cell walls (protozoans have outer protein coat called a pellicle)

algae and plant cells have cell walls of cellulose

fungi have cell walls of chitin; molds :NAG polymer and/or cellulose; yeasts: chitin, glucan, and mannan

Question 26

ribosomes (eukaryotic vs prokaryotic)

Answer 26

80S in eukaryotes (can be membrane bound, and the 2 subunits assemble in the nucleolus and join together in the cytoplasm)

70S in prokaryotes and mitochondria and chloroplasts.

Question 27

Nucleus

Answer 27

Contains most of the cellular DNA, has nuclear pores and a nuclear envelope; has a compact, nonmembrane-bound region of rRNA genes called the nucleolus.

Question 28

Endoplasmic reticulum

Answer 28

Rough: Site of protein synthesis that’s continuous with the nucleus, where proteins are initially glycosylated and membrane-bound/secretory proteins are synthesized.

Smooth: phospholipid synthesis.

Question 29

golgi Complex

Answer 29

Receives transport vesicles from the ER, proteins/lipids move from cis-cis via vesicles; rxns yield glycolipids, glycoproteins and lipoproteins.

Question 30

Lysosomes

Answer 30

a single membranous compartment that contains digestive enzymes that break down cell components or molecules.

Question 31

Vacuoles

Answer 31

enclosed golgi-derived membrane-bound sac (tonoplast) that is small in animal cells but can be very large in plant cells. Can store proteins, sugars, organic/inorganic ions, act as degradative compartments, or to store poisons. in plants, they can take up water to provide rigidity.

Question 32

Centrosome

Answer 32

organization center for microtubule formation in nondividing cells and for the mitotic spindle during cell division.

Has pericentriolar area which is a region of small protein fibers, and centrioles (cylindrical structures which has 9 clusters of 3 microtubules arranged in a 9+0 array).