Harvesting Chemical Energy

Question 1

Mitochondria

Answer 1

the ATP factory

Question 2

Mitochondria-the ATP factory

Answer 2

The hydrolysis水解 of ATP to ADP and inorganic phosphate releases energy

Question 3

Many cellular processes require energy in the form of ATP

Answer 3

ATP cycle: the transfer of energy between complex and simple molecules in the body, with ATP as the mediator

Anabolism合成代谢: ‘building up’
Catabolism分解代谢:’breaking down’

Question 4

Human cells will generate energy through the hydrolysis of ATP to fuel a reaction that requires energy

Answer 4

Simple molecules such as glucose, amino acids, glycerol, and fatty acids.

Anabolic reactions transfer energy from ATP to complex molecules. And heat is released.

Complex molecules such as glycogen, proteins, and triglycerides.

Catabolic reactions transfer energy from complex molecules to ATP. And heat is released.

Question 5

Fuel is needed to generate ATP

Answer 5

Our major categories of fuel:
•Carbohydrates: broken down into simple sugars
•Proteins: broken down into amino acids
•Fats: broken down into simple fats

Question 6

Cellular respiration:

the controlled release of energy from organic compounds to produce ATP

Answer 6

Conversion of glucose to ATP is due to 4 main steps:

1. Glycolysis 糖酵解
2. Pyruvate oxidation 丙酮酸氧化
3. Citric acid cycle (or Krebs cycle) 柠檬酸循环(或克雷布斯循环)
4. Electron transport chain 电子传递链

Question 7

Where does cellular respiration occur?

Step 1: Glycolysis糖酵解 invests and produces ATP – but not much

Occurs in the cytosol and oxygen is not required

Answer 7

Energy investment phase:
two ATP are invested

Energy Payoff Phase:
four ATP are produced

Net:
two ATP and 2NADH are produced (net)

NADH is an electron carrier later in the electron transport chain

Question 8

Step 2: Pyruvate oxidation丙酮酸氧化 to form Acetyl乙酰基 CoA

This step links glycolysis糖酵解 to the citric acid cycle柠檬酸循环

Answer 8

Occurs in the mitochondrial matrix and oxygen IS required

produces no ATP, but produces 1 NADH per pyruvate (or 2 per glucose) plus 1 CO2

The acetyl CoA enables the 2 carbon acetyl group to enter the citric acid cycle.

Question 9

Step 3: Citric acid cycle柠檬酸循环 (simplified)

Answer 9

Occurs in the mitochondrial线粒体 matrix基质

Results in :

2 ATP
6 NADH
2 FADH2
4 CO2 (per glucose molecule)

Requires oxygen – it is an aerobic有氧 process

Question 10

Step 4: the Electron Transport Chain

Answer 10

Occurs at proteins within the inner membrane

Requires oxygen – it is an aerobic process

Electrons transfer from protein-to-protein along the chain in a series of redox reactions

At each transfer, each electron gives up a small amount of energy which enables H+ ions to be pumped into the intermembrane space.

Oxygen “pulls” the electrons down the chain, and is then the final electron acceptor where it is reduced to water

NADH and FADH2 from Glycolysis and the Citric acid cycle are used here

Question 11

Step 4 continued: Chemiosmosis 化学渗透

Answer 11

The hydrogen ions in the intermembrane膜间隙 space rush down their concentration gradient (chemiosmosis) through ATP synthase.

This causes the “turbine涡轮” within ATP synthase to turn

The rotation of the ATP synthase turbine enables the phosphorylation of ADP to generate ATP

This results in the production of 26 or 28 ATP

Question 12

Step 4: ETC and chemiosmosis = oxidative氧化 phosphorylation磷酸化

Answer 12

This is much more efficient than substrate phosphorylation

the bulk of ATP production occurs here

“fall” of electrons down the chain enables movement of H+ ions into intermembrane space and generates a proton gradient which “drives” the ATP synthase turbine

Oxygen is required

oxygen is the final electron acceptor –cyanide blocks passage of electrons to O2=death of cell

Question 13

Cellular respiration is versatile多功能的

Answer 13

We can derive energy from more than just glucose

Fats, proteins and more complex carbohydrates generate ATP also

Monomers enter glycolysis and the citric acid cycle at different points

Question 14

Control of cellular respiration

Answer 14

Phosphofructokinase磷酸果糖激酶 can be rate-limiting for glycolysis

inhibited抑制 by citrate柠檬酸盐 and ATP
ie. products of cellular respiration

stimulated刺激 by AMP
which accumulates积累 when ATP is being used rapidly

Question 15

Homeostasis of blood glucose

Answer 15

Insulin 胰岛素
and
Glucagon 胰高血糖素

Question 16

Insulin

Answer 16

• Produced by beta cells of Islets of Langerhans胰岛 in the pancreas胰腺
• Function: promote glucose uptake into cells (for ATP production or storage in the liver)

Question 17

Glucagon

Answer 17

• Produced by alpha cells of Islets of Langerhans in the pancreas
• Function: Stimulates刺激 the breakdown of glycogen糖原 to increase blood sugar levels

Question 18

What happens if you lose the function of insulin?

Answer 18

• No glucose in cells
• No ATP from glucose
• No glycogen stored for harder times

Question 19

Diabetes Mellitus:

糖尿病

Answer 19

the ability to produce or respond to the hormone insulin is impaired results in abnormal metabolism of carbohydrates and elevated levels of glucose in the blood

Question 20

Lack of functional insulin = Diabetes Mellitus

Answer 20

Type 1 or insulin-dependent胰岛素依赖型 diabetes:

• Body does not produce insulin, as beta cells of the pancreas are destroyed, often this is autoimmune自身免疫的, or genetic or through environmental factors
• Affects 5 – 10 % of diabetics, and onset发病 usually occurs in children or adolescents青少年.
• Requires insulin replacement需要胰岛素替代

Question 21

Lack of functional insulin = Diabetes Mellitus

Answer 21

Type 2 or non-insulin-dependent diabetes:

• Body produces insulin, but receptors are non-functional (insulin resistance胰岛素抵抗)
• Most (>90%) diabetics are Type II, usuallly adults over the age of 40
• Can be linked to other pathologies病状 and obesity肥胖, but not sure how or why