RIN Met L1 : Energy reactions in cells

Question 1

Define metabolsim

Answer 1

is the set of processes which derive energy and raw materials from food and use them to support repair, growth and activity of tissues to sustain life

Question 2

What does the metabolic pathways consist of?

Answer 2

• start points
• intermediates
• end points
• interconnections

Question 3

What is catabolic pathway?

Answer 3

• Break down larger molecules into smaller ones
• release free energy
• oxidative

Question 4

What is anabolic pathway?

Answer 4

• synthesis larger important cellular componets from intermediary metabolites
• use energy released from catabolism
• reductive

Question 5

What are the functions of catabolism products?

Answer 5

1. Building block materials

• sugars, a.a, f.a
• for cell growth, repair and division

2. Organic precursors
   * allow for interconversion of building blocks
3. Biosynthetic reducing power
4. Energy

Question 6

What type of cellular work is performed where energy is used?

Answer 6

• Biosynthetic work - synthesis cellular componets
• transport work - maintenance of ion gradients and nutrient uptake
• Mechanical work - muscle contraction
• Electrical work - nervous impulse conduction
• osmotic work - kidney

Question 7

What is an energy balance?

Answer 7

Ave daily energy intake = Ave daily expenditure

Question 8

What is the SI unit of Energy content in food?

Answer 8

Joule (J)

Question 9

1kCal is how many joules?

Answer 9

4.2 kJ

Question 10

What are the energy values for fat, carbohydrate, protein and alcohol?

Answer 10

• Fat : 37 kJ/g
• Alcohol : 29 kJ/g
• Carbohydrate : 17 kJ/g
• Protein : 16 kJ/g

Question 11

What are the energy requirements of the body?

*think about how to calculate total energy needed

Answer 11

1. Basal Metabolic Rate : Energy required by awak individual during physical, digestive and emotional rest at 18dc. Sum of all the tissues in the body (1700/1400 kcal)
2. Specific dynamic action of food - Energy cost of ingestion, digestion and absoprtion of food (150kcal)
3. Activity : 1000-3000kcal

Question 12

What happens to excess energy ?

Answer 12

• use for growth
• stored as adipose tissue

Question 13

What is exergonic and endergonic reactions?

Answer 13

Exergonic : chemical reaction that releases energy

Endergonic : chemical reaction that requires energy

Question 14

What are the examples of proton carrier molecules?

Answer 14

• NAD+
• NADP+
• FAD

Question 15

What is the function of H carrier molecules?

Answer 15

• ATP production
• Biosynthesis

Question 16

What is the characteristics of H-carrier molecules?

Answer 16

• Complex molecules
• Converted to reduced form
• H+ dissociates into solution

Question 17

How can energy released during oxidative metabolism be used?

Answer 17

• Directly : eg use of NADPH in biosynthesis
• Indirectly : eg mitochondrial system to couple NADH to the production of intermediate ‘energy currency’ molecule

Question 18

What is the amount of energy released for hydrolysis of ATP and ADP?

Answer 18

-31kJ/mole

Question 19

What is the energy released in exergonic reactions used to drive?

Answer 19

synthesis of ATP

Question 20

Why does ATP undergo cycle in cells?

Answer 20

• Limited concentration of ADP
• Carrier, not a store

Question 21

What are high energy signals?

Answer 21

• ATP
• NADH
• NADPH
• FAD2H

Question 22

What do high energy signals activate?

Answer 22

Anabolic pathway

Question 23

What are low energy signals?

Answer 23

• ADP, AMP
• NAD+
• NADP+
• FAD

Question 24

What do low energy signals activate?

Answer 24

Catabolic pathway

Question 25

What is the fucntion of Adenylate kinase?

Answer 25

* Synthesis ATP from 2ADP * 2ADP --\> ATP + AMP * During heavy demands of energy

Question 26

What is the function of creatine phosphate?

Answer 26

* stores phosphate bond energy when ATP levels are high * provides short term boost to [ATP] when ATP levels are low * high energy store reserve that can be used immediately

Question 27

What cell types utilises creatine phosphate?

Answer 27

* cells which need to increase metabolic activity rapidly * Eg : skeletal muscle

Question 28

How is creatine phosphate formed? \*chemical formula

Answer 28

Creatine + ATP \<--creatine kinase--\> Creatine Phosphate + ADP

Question 29

What clinical marker does Creatine Kinase serve as?

Answer 29

Myocardial infarction

Question 30

How is CK used to diagnose MI

Answer 30

* CK released from damaged cardiac myocytes in MI * CK appear in blood after few hours

Question 31

What is the CK isoform combination in heart muscle and skeletal muscle

Answer 31

* Heart muscle : 70% CK-MM, 30% CK-MB * Skeletal muscle : 98% CK-MM, 1% CK-MB

Question 32

How is creatinine produced?

Answer 32

Through the **spontaneous** **breakdown** of Cr and PCr at **constant rate**

Question 33

How is creatinine used as a clinical marker?

Answer 33

* creatinine is excreted via kidneys * **Measure muscle mass** : creatinine excretion/24hrs proportional to muscle mass * **Marker of urine dilution** : creatinine concentration in urine * **Estimate true urinary loss** **of many substances** : hormones released in urine is standardised against creatinine - gives true amount of hormone in body * **Kidney Function** : high [creatinine] in blood if kidneys are damaged