Lecture 3: Cell Structures

Question 1

Atomic Force Microscopy

Answer 1

Enables visualization of untreated cells by detection of Van der Waals forces

Question 2

Inclusion in bacterial cell structures

Answer 2

Large deposits of foreign, aggregated proteins

Question 3

Periplasmic space

Answer 3

Space found only in gram-negative bacteria between inner and outer membranes

Question 4

Phospholipid Bilayer

Answer 4

Hydrophilic phosphate outward, hydrophobic lipid inward

Question 5

Hopanoid

Answer 5

Class of lipid acting as a stiffening agent of cell to improve membrane integrity

Question 6

Role of membrane proteins

Answer 6

-Structural support
-Detection of environmental signals
-Secretion
-Transport
-Respiration

Question 7

Passive diffusion

Answer 7

-Small uncharged molecules
-No Transporters needed
-Down gradient

Question 8

Passive transport

Answer 8

-Charged, hydrophilic, large molecules
-No transporter needed
-Down gradient

Question 9

Active transport

Answer 9

-Charged hydrophilic, or large molecules
-Need transporter proteins
-Against gradient
-Often accompanied with ATP hydrolysis to use energy from the reaction to move things up a gradient (Unfavorable)

Question 10

Cardiolipin

Answer 10

Double phospholipid joined by a third glycerol to allow for curvature in cells

Question 11

Movement of acids & bases across membrane

Answer 11

Equilibrium with weak acids and bases is always possible and allows neutral charged to cross the membrane

Question 12

Effect of cyclization of membrane lipids

Answer 12

Reduces fluidity to allow stiffness in the membrane for cell integrity

Question 13

Effect of penicillin on peptidoglycan

Answer 13

Blocks the cross-bridge formation with D-Alanine

Question 14

Effect of vancomycin on peptidoglycan

Answer 14

Binds D-Ala to D-Ala to block cross-bridge formation

Question 15

Teichoic Acid

Answer 15

Regulates enzymes that kill peptidoglycan & promotes cell integrity by threading through multiple layers (GRAM POSITIVE ONLY)

Question 16

Amino acids linkages in peptidoglycan (Stereochem)

Answer 16

Ribosome protein synthesis always makes L-amino acids, therefore, the D-amino acids must be added separately

Question 16

GT Glycosyltransferase subunit

Answer 16

Catalyzes polymerization of lipid to form glycan chain of NAG & NAM via lipid polymerization to form a glycosidic bond.

Question 17

PBP Transpeptidase subunit

Answer 17

Catalyzes the cross-linkages of peptidoglycan layers using pentaglycine

Question 18

Affect of Beta-Lactam antibiotics

Answer 18

Blocks cross-linking of peptidoglycan layers by blocking transpeptidase active site to prevent pentaglycine formation

Question 19

Slime Layer

Answer 19

-Found in both gram-positive & negative bacteria
-Crystalline sheet made of protein or peptidoglycan
-May help bacteria interact with the host, form biofilm, or swim

Question 20

Lipopolysaccharide

Answer 20

-Found in many Gram-negative bacteria
-Stimulates host responses
-Endotoxin causing immune system to activate when bacterial cell is lysed
-Provides protection to cell from antibodies

Question 21

Pili

Answer 21

-Smaller structures more abundant than flagella
-Aid in cell secretion
-Aid in adhesion via biofilm
-Allow twitching motility
-Conjugation

Question 22

Nucleoid

Answer 22

Region where DNA is condensed and packed since bacteria lack nuclei

Question 23

ParB

Answer 23

-Protein that forms dimers that recognizes and binds to centromere-like sites on DNA known as parS sites
-ParB clusters will form a cage

Question 24

ParB-parS

Answer 24

Complex of ParB forming dimers around ParS that stimulates ParA ATPase activity and releases ParA from the nucleoid

Question 25

ParB-ParA

Answer 25

Interaction that drives a partition of chromosome that segregates DNA attached to ParB dimers

Question 26

Result of ParABS

Answer 26

Liquid like biomolecular condensates

Question 27

Degradation of ParA

Answer 27

Fusion of DNA since there is no force to cause segregation

Question 28

Thylakoids

Answer 28

Photosynthetic double membrane in phototrophs

Question 29

Carboxysome

Answer 29

Protein covered bodies packed with the rubisco enzyme for CO2 fixation

Question 30

Gas vesicle

Answer 30

Provides buoyancy in water in autotrophs, made of protein