Exam 2 (7-9)

Question 1

What bond forms between molecules of water in a beaker of water?

Answer 1

Hydrogen bonds

Question 2

What is the building block of polymers?

Answer 2

Monomers

Question 3

What is the site on an enzyme where enzymes bind?

Answer 3

Active site

Question 4

What is the purpose of fermentation?

Answer 4

Regenerate NAD+

Question 5

What is metabolism?

Answer 5

All the reactions in a cell/organism

Question 6

What is a pthway that breaks down glucose to make pyruvate in certain microbes?

Answer 6

Entner-Doudoroff (ED) pathway

Question 7

When does substrate level phosphorylation occur?

Answer 7

Glycolysis, Kreb’s cycle

Question 8

What is the definition of chemiosmosis?

Answer 8

Movement of hydorgen ions through ATP synthase

Question 9

Does anaerobic respiration involve the reduction of an organic final electron receptor?

Answer 9

No (it’s for aerobic)

Question 10

What are the 4 categories of microbes based on temperature?

Answer 10

1. Psychrophile (-10 to 20) - fridge is 4
2. Mesophile (20 to 45) - internal body is 37
3. Thermophile (40 to 70)
4. Hyperthermophile (65 to 110)

Question 11

What are the ways pH and temperature affect metabolic functions and how might it be overcome? (4)

Answer 11

PROTEIN ACTIVITY (Temp/pH) - denaturation
* Alter protein structure (thermophiles: increase secondary bonds for rididity; psychorophiles: use hydrophobic residues to exclude water and avoid freezing)

MEMBRANE (Temp) - fluidity/rigidity
* Alter phospholipid structure (psychrohpiles: use unsaturated lipids; thermophiles: use saturated lipids)

NUCLEIC ACID ACTIVITY (Temp/pH) - DNA denaturation
* Increase GC content

ETC PRODUCTION (pH) - H+ gradient
* Active transport (proton pumps) and use different ions (Na+)

Question 12

Optimal pH ranges of organisms (3)

Answer 12

• Acidophile: low pH
• Neutrophile: around pH 7
• Alkaliphile: high pH

Question 13

What are the 5 categories of microbes based on O2 requirements?

Answer 13

• Obligate aerobe: requires O2
• Microaerophile: requires low O2
• Facultative anaerobe: doesn’t need O2, but grows better
• Aerotolerant anerobe: tolerates O2
• Obligant anaerobe: killed in O2

Question 14

What are the enzymes a microbe can use to detoxify oxygen and the chemical reactions involved? (3)

Answer 14

• Catalase: H2O2=H2O+O2
• Peroxidase: H2O2+H=H2O
• Superoxide dismutase: O2+H=H2O+O2

Question 15

What are the different types of of media used to grow microbes? (4)

Answer 15

• Chemically defined: exact composition is known
• Complex: exact composition is unknown
• Selective: encourage some, supress others
• Differential: distinguishes different colonies

Question 16

What are the 4 phases of microbial growth?

Answer 16

• Lag: preparation
• Log: exponential growth
• Stationary: plateau, running out of space/nutrients
• Death: exponential decrease

Question 17

What is a biofilm?

Answer 17

• Clusters of microbes attached to surface and encased on matrix
• Provides protection, keeps cells together, and has division of labor
• Wound, teeth, rocks, etc

Question 18

What is quorum sensing?

Answer 18

• Mechanism where microbes coordinate gene expression based on cell density
• Signaling peptides/hormones (more signal = more population)

Question 19

Oxygen is a strong […] agent

Answer 19

Oxidizing (steals electrons) – can be very damaging

Question 20

What are the different bonds? (5)

Answer 20

• Covalent: 2 or more atoms share electrons
• Polar covalent: unequal sharing
• Nonpolar: equal sharing
• Hydrogen: very weak bonds between polar molecules (e.g. H2O, DNA base pairing)
• Ionic: between ions of opposite charge (cations/ions)

Question 21

Condensation vs hydrolysis

Answer 21

• Condensation makes bonds and has H2O in the end products (synthesis/anabolism)
• Hyrolysis uses water to break bonds (decomposition/catabolism)

Question 22

Acid vs bases

Answer 22

• Acids release H+ ions (lower pH)
• Basics release OH- ions (higher pH - basic)

Question 23

What are the 4 levels of protein structure?

Answer 23

• Primary: AA squence, peptide bonds
• Secondary: bending/coiling, H bonds
• Tertiary: 3D shape, R group interactions
• Quaternary: 2+ polypeptides, subunit attraction

Question 24

Redox, oxidation & reduction

Answer 24

• Oxidation: loss of electrons
• Reduction: gain of electrons
• Redox: pairing of oxidation + reduction (moving of e- and protons at same time, carried by H)

Question 25

What are the 3 mechanisms of how ATP can be generated?

Answer 25

• Substrate level phosphorylation: glycolysis, Krebs
• Oxidatative of phosphorylation: ETC
• Photophosphorylation: photosynthesis

Question 26

Enzyme sites and inhibitors (5)

Answer 26

• Active site: where substrate binds
• Allosteric site: site other than active site that regulates activity
• Competitive inhibtor: binds to active site (blocks acitivity)
• Noncompletitve inhibtor: binds to allosteric site inducing shape change
• Feedback inhibtor: enzyme end product ends on 1st enzyme and shuts down pathway (slows down production for homeostasis)

Question 27

Apoenzyme, cofactor, and holoenzyme

Answer 27

• Apoenzyme: protein portion of enzyme that is inactive
• Cofactor: nonprotein components needed for activity
• Holoenzyme: apoenzyme + cofactor (active)

Question 28

Where is prokaryotic respiration?

Answer 28

Cytoplasm, cell membrane

Question 29

Steps to respiration

Answer 29

1. Glycolysis (energy investment, payoff)
2. Intermediate Pathway (convert pyruvate to acetyl coA)
3. Krebs Cycle (ADP>ATP, NADH+FADH2)
4. ETC (H+ gradient, ATP synthase, ATP, final acceptor is O2)

Question 30

Alternatives to glycolysis

Answer 30

PPP: used when cells need to make nucleic acids alongside glycolysis
ED: replaces glycolysis, not in eukaryotes (G-)