Energy Metabolism

Question 1

Metabolism

Answer 1

the entire network of chemical processes involved in maintaining life and encompasses all these sequences of chemical reactions that occur in the bodies cells
or the sum of chemical reactions that occur in the body to make energy

Question 2

Pathway

Answer 2

progression of metabolic chemical reaction

Question 3

Intermediates

Answer 3

compounds formed from a pathway

Question 4

Anabolic Pathway

Answer 4

building of compounds; uses energy

start with small compounds build larger ones, requires the input of energy

Question 5

Catabolic Pathway

Answer 5

breaking down compounds into smaller components; releases energy
breakdown of larger compounds into smaller compounds

Question 6

What are the end products of a catabolic reaction (energy metabolism)?

Answer 6

H20 CO2 and ATP

Question 7

What are the three major categories of work that use ATP?

Answer 7

Mechanical Work
Synthetic Work
Transport work
(also heat)

Question 8

Mechanical work

Answer 8

muscular contraction

Question 9

Chemical/Synthetic Work

Answer 9

biosynthesis, chemical work, turn over cells, create proteins and enzymes

Question 10

Osmotic/Transport Work

Answer 10

Active transport around the body (into/out of cells)

Question 11

Glycolysis

Answer 11

Glucose metabolism: break down glucose to pyruvate; 6 carbon glucose into 2 3 carbon pyruvates
a series of chemical reactions catalyzed by enzymes that degrades monosaccharides, generates energy, provides building blocks for synthesizing other compounds
generates some ATP, NADH
reversible but requires ATP

Question 12

Sources of Glucose

Answer 12

diet
glycogen stores-mostly liver (also muscles)
gluconeogenesis: use AA to form glucose, (the opposite of glycolysis), occurs in the liver
Lactate (cori cycle)

Question 13

Cori Cycle

Answer 13

converts lactate back to glucose, lactate travels to liver gets turned into pyruvate

Question 14

TCA cycle

Answer 14

Pyruvate is converted to acetyl CoA after glycolysis and before entering TCA cycle
Acetyl CoA enters and generates NADH, FADH2, GTP and CO2

Question 15

Electron Transport Chain

Answer 15

chains of electron carrier molecules
converts NADH, FADH2, to ATP
NADH, FADh2 deliver hydrogen (protons) to a series of reactions and at the end you get the generation of ATP and water (generates H20)

Question 16

Lipolysis & beta oxidation

Answer 16

the breakdown (metabolize) of fat
triglycerides are stored in adipose cells and are catabolized into glycerol and fatty acids
reaction is catalyzed by hormone sensitive lipase (HSL)
Glycerol enters one of the three carbon intermediate compounds in glycolysis: produce pryuvate, generate acetyl CoA, enter TCA cycle, and eventually produce atp
fatty acid chain goes through beta oxidation broken down into two carbon molecules at the beta carbon
produces one NADH and one FADH2 and one acetyl CoA and it enters teh TCA cycle when ATP is needed

Question 17

Incomplete Oxidation

Answer 17

Incomplete oxidation of fat
we cannot get glucose from fat because we need carbohydrates for fatty acid oxidation
absence of carbohydrates means any fatty acids you have cannot be metabolized into ATP

Question 18

Ketosis

Answer 18

• Ketones are products of incomplete fatty acids oxidation
• Low CHO intake, insufficient insulin
• Acetyl CoA cannot enter the TCA cycle
• Acetyl CoA accumulates form ketones or ketone bodies
• can be reversed with the consumption of carbohydrates
• ketosis can occur when fasting

Question 19

What two conditions cause Ketosis?

Answer 19

Low Carb Diets

Diabetes

Question 20

Urea Cycle

Answer 20

AA will form amonia
Build up of Ammonia is toxic to cells
Liver forms Urea
Urea is excreted via Kidneys

Question 21

How is metabolism regulated?

Answer 21

Enzymes
Hormones: insulin, glucagon, epinephrine, hormones can control regulate glucose metabolism
Blood glucose levels
ATP concentration

Question 22

Glycogenolysis

Answer 22

when fasting, the blood glucose levels decrease.
Liver glycogen is converted back to glucose; circulated back into blood, provides energy to glucose dependent tissues/organs. Skeletal muscle glycogen converted back to glucose; and used for ATP production within its own cells
Body’s glycogen stores may be depleted after 1 hour of strenuous exercise or after 24 hours of fasting, most restored over half the day

Question 23

Wasting Metabolism

Answer 23

Suppressed appetite
Slowed metabolism
Lowered body temperature
Reduced resistance to disease

Question 24

breakdown on protein

Answer 24

AA are deaminated
nitrogen group is excreted via the kidneys as urea
carbon skeletons yield acetyl CoA or intermediary compound
most enter TCA cycle

Question 25

metabolic consequence of excess (feasting) CHO intake

Answer 25

storage! first used to maximize glycogen stores, once glycogen stores are full carbohydrates consumed in excess will be stored in they body as fat

Question 26

metabolic consequence of excess (feasting) Lipid intake

Answer 26

lipids consumed in excess go immediatly into storage of adipose tissue as triglycerides Lipogenesis

Question 27

metabolic consequences of excess (festing) protein intake

Answer 27

first fill any AA needs then converted to triglycerides and stored as fat

Question 28

fate of nutrients when fasting

Answer 28

when macronutrients from a meal are no longer available to provide energy (2-3 hours after finishing a meal) the body draws on its glycogen and fat stores (ATP) 3-24 hours after eating glycogenolysis glycogen will be used for red blood cells, nerve cells, brain cells fatty acids from adipose tissue supply acetyl CoA TCA cycle will go forward and supply ATP as long as glucose lasts

Question 29

fate of nutrients when fasting

Answer 29

glycogen stores are depleted after 24 hours of fasting body begins to break down protein to AA to produce glucose (to supply brain and nervous system) fatty acids converted to ketones (alternate energy source for cells) which slows breakdown of body proteins (liver) proteins meet glucose needs (gluconeogenesis) wasting metabolism

Question 30

Shift to ketosis during starvation

Answer 30

suppression of appetite, slowing metabolism, adaption to prolonged fast can maintain life for 2 months

Question 31

Define ATP

Answer 31

adenosine triphosphate the main form of energy the body uses major end product of energy metabolism

Question 32

Give an example of an anabolic reaction

Answer 32

* Glucose to glycogen * Glycerol and fatty acids to triglycerides * AA to proteins

Question 33

Give an example of a catabolic reaction

Answer 33

* Glycogen to glucose * Triglyceride into glycerol and fatty acids * Protein to AA

Question 34

Identify where energy metabolism occurs in the cell

Answer 34

``` ATP IS PRODUCED IN MITOCHONDRIA Glucose enters the cell Glycolysis occurs in the cell cytoplasm Pyruvate enters mitochondria and is irreversibly converted to acetyl CoA TCA cycle occurs inside the mitochondria ETC in mitochondrial membrane ```

Question 35

Identify 3 major metabolic pathways through which macronutrients are converted to energy

Answer 35

``` Glycolysis • Glucose to Pyruvate • Uses and generate ATP • Reversible, but requires ATP (Irreversible conversion of pyruvate to acetyl CoA) TCA Cycle • Cycle generates NADH, FADH2, GTP and CO2 ETC • Oxidative phosphorylation • NADH, FADH2, converted to ATP • H20 generated ```

Question 36

Examine the general differences in breakdown of CHO FAT PRO to ATP

Answer 36

Carbohydrates • Digested into glucose • Glucose broke down to 2 3 carbon pyruvate molecules • Pyruvate the Acetyl CoA • Acetyl CoA enters the tca cycle • Generates NADH FADH2 GTP and CO2 • Electron transport chain • Converts NADH and FADH2 to ATP and h20 Proteins • AA are deaminated • Nitrogen group is excreted via the kidneys as urea • Carbon skeletons yield pyruvate or acetyl CoA or intermediary compound • Most enter TCA cycle Lipids • Breadown of fat Lipolysis • Triglycerides stored in adipose cells are catabolized into glycerol and fatty acids • Reaction is catalyzed by HSL hormone sensitive lipase • Glycerol enters one of the three carbon intermediate compounds in glycolysis • Produce pyruvate • Generate acetyl CoA • Enter tca cycle and • Eventually produce ATP • Fatty acids chain goes through beta-oxidation • Fatty acid chain broken down into two carbon molecule at the beta carbon • Produces one NADH one FADH2 and one acetyl CoA and it enters the TCA cycle when atp is needed

Question 37

Besides ATP, list the other 2 compounds produced in cells after food is completely metabolized

Answer 37

CO2 and H20