Cycles and Processes

Question 1

How does mammal blood buffering (natural buffering) work?

Answer 1

H2CO3 ----- (HCO3-) + (H+)
-when H+ produced, pH decreases 
(HCO3-) + (H+) ----- H2CO3
-reaction occurs and removes excess H+
- when H+ is used, pH increases
H2CO3 ----- (HCO3-) + (H+)
-adds H+ back, pH is restored

Question 2

Describe the polymerization reaction.

Answer 2

• form by dehydration (loss of water)
• monomer+monomer=polymer
• energy required
• assisted by enzyme
• for each monomer addition, a water molecule is produced

Question 3

Describe the depolymerization reaction.

Answer 3

• broken apart by hydrolysis (addition of water molecule)
• assisted by enzyme
• releases energy
• during digestion
• polymer = monomer+monomer
• uses a water molecule for each break

Question 4

What are the four levels of protein structure? What are their unique characteristics?

Answer 4

1) primary : beads on a string, held together by peptide bonds
2) secondary : repeated coils and folds (helices or sheets), held together by hydrogen bonding
3) tertiary : two or more secondary structures held together, hydrogen bonding/ionic bonds/disulfide bridges
4) quaternary : multiple folded polypeptides in association with one another

Question 5

Explain homeoviscous adaptation.

Answer 5

• change in phospholipid composition of a membrane to counter temperature induced change, usually in bacteria and fish
• high temperatures raise membrane fluidity: response is to increase percentage of saturated fatty acids, and fluidity decreases
• lower temperatures decrease membrane fluidity: response is to decrease percentage of saturated fatty acids, and fluidity increases

Question 6

Show the order in which molecules are secreted and membrane proteins are produced.

Answer 6

1) protein synthesized by bound ribosomes
2) protein enters ER through pore
3) protein starts to fold into shape
4) carbohydrates attached and forms glycoproteins
5) protein is wrapped in ER membrane
6) membrane surrounding protein becomes a vesicle
7) vesicle buds from ER
8) vesicle moves and joins cis golgi
9) protein can be modified by golgi
10) vesicle forms around protein that leaves through trans golgi
11) vesicle moves toward cell membrane
12) vesicle fuses with cell membrane
13) contents are released to outside (secreted)
13) contents become part of the cell membrane (integral membrane protein)

Question 7

Describe the process in which mitochondrion and chloroplasts came to evolve, supporting the endosymbiotic theory.

Answer 7

1) infolding of plasma membrane to form the nuclear membrane and the ER
2) engulfing of an aerobic prokaryote, allowing the host to be able to use the oxygen and benefit its metabolism
3) host uses nutrients from photosynthesis of the endosymbiont

Question 8

Explain the connection and mechanical signaling through the animal extracellular matrix.

Answer 8

1) collagen
2) fibronectins
3) integrins
4) cytoskeleton (microfilaments)

Question 9

How does the sodium potassium pump work?

Answer 9

1) three Na+ binds to the pump
2) phosphorylation of ATP
3) protein changes shape
4) three Na+ is expelled outside the cell
5) two K+ binds on the extracellular side and triggers release of the phosphate group
6) restoration of protein’s shape
7) two K+ is released
8) cycle repeats

Question 10

How does the sucrose hydrogen pump work?

Answer 10

1) proton pump pumps hydrogen ions out of the cell against the gradient using ATP
2) increase of H+ ion concentration outside of the cell
3) movement of H+ back into the cell along the gradient releasing energy
4) sucrose H+ cotransporter uses energy released to move sucrose against its gradient back into the cell

Question 11

Explain the role of ATP in metabolism.

Answer 11

1) catabolism reaction releases ATP
2) ATP is hydrolyzed (water added)
3) anabolism reaction consumes ATP to do cellular work
4) dephosphorylation of ATP, inorganic phosphate is no longer attached to the molecule
5) cycle restarts

Question 12

What is the catalytic cycle of enzymes?

Answer 12

1) substrates enter the active site
2) enzyme-substrate complex is formed
3) substrates are held in the active site by weak interactions
4) substrates are converted to products
5) products are released
6) active site is now available for new substrates
7) cycle restarts

Question 13

Redox reactions of NAD+ and NADH

Answer 13

NAD+ is reduced to NADH

NADH is oxidized to NAD+

Question 14

What is the cycle process of glycolysis?

Answer 14

1) investment phase of energy
2) molecule split in half
3) NAD+ (electron carrier) picks up electrons and hydrogen atoms from glucose (carbon containing compound)
4) NAD+ is reduced to NADH
5) payoff stage where 2 ATP produced for every glucose
6) 2 pyruvic acid molecules produced (glucose oxidized to pyruvate)

Question 15

What is the cycle process of the citric acid cycle or Krebs cycle?

Answer 15

1) pyruvic acid molecule enters mitochondrion
2) one carbon is removed, forming CO2 as a by-product
3) electrons stripped, forming NADH
4) coenzyme A attaches to a 2-carbon fragment, forming acetyl CoA
5) coenzyme A removed
6) 4-carbon molecule attaches to the 2-carbon molecule
7) 6-carbon chain partially broken down
8) CO2 released
9) electron carriers capture electrons
10) more CO2 released
11) 2 ATP produced by citric acid cycle for each molecule of glucose
12) electron carriers keep taking electrons

Question 16

What is the cycle process of oxidative phosphorylation?

Answer 16

1) NADH deliver electrons to electron transport chain in the inner membrane of the mitochondria
2) electrons transferred from one electron carrier in large protein complexes of the chain to the next
3) as electrons move along the chain, they give up a bit of energy
4) O2 pulls electrons from the transport chain
5) H20 formed as a by-product
6) energy released by electrons is used to pump hydrogen ions across the inner membrane, creating an area of increasing [H+]
7) H+ flows back across the membrane through the turbine, which makes it spin, activating production of ATP (produces most of the ATP)