Metabolism

Question 1

Metabolism

Answer 1

1. Sum total of all chemical reactions occurring in a cell. Involves acquisition/use of energy (capacity to do work).
2. Anabolism (synthesis) and catabolism (degradation) involved

Question 2

Metabolism in Animals

Answer 2

Animals use the energy stored in chemical bonds of organic molecules to accomplish biological work

Question 3

Activation energy

Answer 3

Energy input required by most chemical reactions to start

Question 4

Catalyst

Answer 4

Substance that decreases activation energy of a reaction, and therefore accelerates its rate, but does not get used up during the reaction

Question 5

Enzyme catalysts

Answer 5

Necessary to aid in metabolic reactions occuring at temperatures and concentrations too low

Question 6

Enzymes

Answer 6

1. Lower the activation energy barrier.

2. Several enzymes operate in sets called enzymatic pathways.

Question 7

Enzyme Specificity

Answer 7

Enzymes = proteins.

Have active site defined by unique molecular shape, that allows it to combine with a specific substrate (reactant).

Question 8

Regulation of Metabolism

Answer 8

Metabolism regulated:

either by relative concentration of substrates & products OR by the quantity & activity of enzymes.

Question 9

Enzymes

Answer 9

Activated or inhibited by changing the protein shape w/ cofactors (vitamins & metal ions), concentration of substrates & products, temperature, pH, etc.

Question 10

Feedback inhibition

Answer 10

when the final product of a metabolic pathway inhibits the first enzyme in the pathway

Question 11

ATP (adenosine triphosphate)

Answer 11

ATP stores & releases energy for driving cellular reactions.
NOT A FUEL just a temporary store
Breakdown of ATP is coupled with synthesis of something else
Synthesis of ATP is coupled with breakdown of something else

Question 12

Metabolic reactions

Answer 12

coupled reactions consisting of an anabolic and a catabolic reaction

Question 13

Cellular respiration

Answer 13

Coupled Oxidation-reduction (redox) reactions provide energy to a cell

Question 14

Oxidation

Answer 14

involves electron donor ie hydrogen atoms of a carb molecule

Question 15

Reduction

Answer 15

involves electron acceptor ie O2

Question 16

oxidation of fuel molecule

Answer 16

energy is released and ATP formed

Question 17

Aerobic respiration

Answer 17

when final electron acceptor is O2

Question 18

Anaerobic respiration

Answer 18

if final electron receptor is some other molecule (ie lactic acid or ethanol)

Question 19

Why anaerobic respiration still persists

Answer 19

Used by:

1. many microorganisms living in O2 depleted habitats
2. skeletal muscles of vertebrates during short bursts of activity. White muscle fibers have few mitochondria and primarily use anaerobic metabolism
3. diving birds and diving mammals
4. some parasitic animals

Question 20

glycolysis

Answer 20

the enzymatic breakdown of a carbohydrate (as glucose) by way of phosphate derivatives; produces pyruvic or lactic acid ATP.

Question 21

Acetyl-CoA (acetyl coenzyme A)

Answer 21

important molecule whose main function is to convey the carbon atoms within the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.

Question 22

Krebs cycle

Answer 22

the sequence of reactions that generate energy during the process of aerobic respiration. It takes place in the mitochondria, consuming O2, producing CO2 & H20 as waste products, & converting ADP to energy-rich ATP.

Question 23

Glucose + 2 ATP + 36 ADP + 36 P + 6 O2—> 6 CO2 + 2 ADP + 36 ATP + 6 H20

Answer 23

Shows how glucose combines with ATP and phosphates and O2; O2 is consumed, ATP & ADP is produced & CO2 & H20 are waste

Question 24

Lipid Metabolism

Answer 24

Stored fats:

1. greatest reserve fuel in body
2. Produce > ATPs than carbs becuase contain > Hydrogen (electron donor in electron transport chain that –> ATP)
3. Triglycerides (most of the fats) are hydrolyzed to glycerol & fatty acids. Glycerol enters glycolytic pathway & fatty acids enters Krebs cycle

Question 25

Protein Metabolism

Answer 25

Nitrogen in amino acids (constituents of proteins) is removed by deamination (producing ammonia as waste product) and the carbon chain enters the Krebs cycle

Question 26

Phosphofructokinase

Answer 26

Metabolism’s main controlling enzyme
Shuts down glycolysis if ATP begins to accumulate
Turns on glycolysis if ADP begins to accumulate