Metabolism L3: Understanding metabolic pathways and its influence on cell physiology

Question 1

Which organ is important for metabolic processes?

Answer 1

Liver = overshadows all metabolic pathways and processes

Question 2

Metabolic pathways are _____- reactions that lead to biosynthesis or breakdown of natural molecules within a cell or tissue

Answer 2

enzyme-mediated biochemical

Question 3

The Glycolysis & Krebs cycle metabolic pathways, produce _______ (primary/secondary) metabolite (the ATP)

Answer 3

primary

Eg. from glucose –> breakdown –> ATP

Question 4

Why is it called “primary” metabolites?

Answer 4

What we need for our body use energy (cells can function using ATP)

Question 5

Other metabolic pathways (not Glycolysis & Krebs cycle) produce _____ metabolites.

Answer 5

secondary

Question 6

What are the 4 dedicated purposes of the metabolic pathways?

Answer 6

1. Extraction of energy
2. Storage of fuels
3. Synthesis of important building blocks
4. Elimination of waste materials

Question 7

Both _____ and ____ reaction occur within a cell. Which reaction do we want more of?

Answer 7

Anabolic and catabolic

• Catabolic = produces energy = positive
• Catabolic reactions must be “AHEAD” of anabolic reactions = need to have enough ATP
• Cell cannot function on negative energy = will go into apodosis and die

Question 8

What are the 3 stages in the metabolic pathways to create energy (ATP) from nutrients such as protein, carbohydrates and fat?

Answer 8

Question 9

Which out of the 3 (out of protein, carbs, fats) is absorbed by passive diffusion ?

POSSIBLE EXAM QUESTION

Answer 9

Fat

Question 10

Amino acids are rarely (almost never used) to produce energy. What do they do then?

Answer 10

Go straight to building protein that is important for our survival and growth

Question 11

What happens when there is too much glucose?

Answer 11

Stored as glycogen = glycogenesis

Question 12

All 3 nutrients converge into the process of glycolysis. What is the process and the result?

Answer 12

Which help to produce pyruvic acid –> acetyl co- A –> krebbs cycle –> oxidative phosphorylation –> ATP is produced

Question 13

What are the 3 steps to produce ATP? (going from glucose or any other nutrients to ATP)

Answer 13

1. Glycolysis
2. Krebbs cycle
3. Oxidative phosphorylation

Question 14

Which one of the 3 nutrients gives the highest about of ATP? Why?

Answer 14

• Carbohydrates (glucose) = can produce 38 ATP
  
  • As it enters straight into the cycle
  • Eg. doesn’t need ATP to break it down first
  • Eg. fatty acids need ATP to break it down and goes into the Acetyl Co-A part for Krebbs Cycle

Question 15

What is ATP?

Answer 15

ATP – the principal molecule for storing & transferring energy

Question 16

Most food energy is converted into _____ in the body. Why?

Answer 16

heat

This is why people who live in cold climates tend to eat food that is more fattening (with lots of fat) because they need to create more energy

• Need more energy to break down fat molecules When living in a hot climate = see less “fatty” food

Question 17

What are 3 things that ATP supplies energy for?

Answer 17

1. Synthesis to make macromolecules
2. Transport (pumps)
3. Muscle contractions & cellular motility

Question 18

NADH & FADH2 are _____ (high/low) energy molecules. What does that mean?

Answer 18

high

• Move and carry different H+ ions along side these carrier molecules
• Different stepping of the carrier molecules allows ATP to be produced

Question 19

What are the 7 reactions in fuel metabolism?

Answer 19

Question 20

If you have just had a meal and your blood sugar levels go up, what happens to try and get your blood sugar levels back to normal (decrease)?

Answer 20

Just had a meal –> blood sugar goes up –> insulin is release by Beta cells in pancreas –> activates receptors glycogenesis occurs –> blood sugar goes back to normal (decreases)

Question 21

If you have eaten for a while and your blood sugar levels go down, what happens to try and get your blood sugar levels back to normal (increase)?

Answer 21

Having had a meal for a while –> blood sugar levels go down –> glucagon released by pancreas –> Turns glycogen (that has been stored) into glucose –> glycogenolysis occurs –> blood sugar levels goes back to normal (increase)

Question 22

When does gluconeogenesis (amino acid –> glucose) occur?

Answer 22

• Usually don’t touch amino acids
• Starvation (survival)
• Always carbs then lipids then proteins (eating up yourself –> deteriorating muscles)

Question 23

Rarely break down amino acids into glucose (to produce energy) but do break down proteins to produce amino acids. Why?

Answer 23

• There are certain amino acids that can’t be produced/synthesised naturally, must be introduced in diet
• Must be broken down to be accessible

Question 24

What are 7 of the most important metabolic reactions in humans?

Answer 24

1. Glycolysis
2. Citric acid cycle (Krebs’ cycle)
3. Oxidative phosphorylation
4. Pentose phosphate pathway
5. Urea cycle
6. Fatty acid β-oxidation
7. Gluconeogenesis

Question 25

Cellular respiration oxidizes glucose molecules to produce \_\_\_\_\_.

Answer 25

ATP

Question 26

In carbohydrate metabolism, how does cellular respiration occur?

Answer 26

Question 27

Where in the cell does glycolysis occur?

Answer 27

In the cytosol

Question 28

Where in the cell does Krebbs cycle and oxidative phosphorylation occur?

Answer 28

In the mitochondria (power house of the cell= produces all the energy)

Question 29

Which one out of the catabolic and anabolic reactions should always be positive? Why?

Answer 29

* Catabolic reactions must be "AHEAD" of anabolic reactions = need to have enough ATP * Cell cannot function on negative energy = will go into apodosis and die

Question 30

Where is bile produced?

Answer 30

Liver

Question 31

Fats (lipids) absorbed from _____ or synthesized by the \_\_\_\_\_

Answer 31

food; liver

Question 32

What are the 3 main types of fat in the body?

Answer 32

1. Triglycerides (glycerol + 3 fatty acids): stored in fat cells 2. Cholesterol involved with cell structure/membranes and Hormones/steroids, bile acids, signalling molecules 3. Phospholipids part of cell structure

Question 33

Which 2 main fat types can travel in the blood?

Answer 33

1. Triglycerides (glycerol + 3 fatty acids): stored in fat cells 2. Cholesterol involved with cell structure/membranes and Hormones/steroids, bile acids, signalling molecules

Question 34

What are the 3 major lipid pathways?

Answer 34

1. Lipolysis - is the hydrolysis of the lipids (mainly TG) produce glycerol &fatty acids. 2. β-oxidation: conversion of fatty acids into acetyl CoA (fatty acids catabolism) 3. Lipogenesis - lipid anabolism (cholesterol synthesis, ketogenesis, synthesis of other lipids)

Question 35

All lipid athways converge to \_\_\_\_\_. What does that mean?

Answer 35

Acetyl-CoA Can only enter here (unlike glucose which enters from the beginning)

Question 36

What does the major lipid pathway look like?

Answer 36

Question 37

Lipids enter the energy production process at a different entry point. Where is this point?

Answer 37

Acetyl Co-A

Question 38

Fat has higher calories than glucose but give less ATP than glucose. Why?

Answer 38

* Very expensive (uses to much energy to go from lipids to energy) as it requires ATP to break down * Too much energy used to break down lipid that the end yield is less ATP (overall) * Uses higher amount of ATP to break down lipid compared to glucose

Question 39

What does the pathways of protein metabolism look like?

Answer 39

Question 40

What is one time/point in life that we actually rely heavily on proteins and fats?

Answer 40

During first months of life (drink milk) * Milk is made of fat and proteins = need high amount of calories for growth (amino acids)

Question 41

When too much amino acid, what happens to baby's breath?

Answer 41

Very strong bad breath of urea (from deamination)

Question 42

What is deamination?

Answer 42

In the case that need to use amino acids, need to remove groups (ammonia and CO2= forms urea) as it is too toxic = deamination

Question 43

What are occurs in the breakdown of amino acids?

Answer 43

Question 44

What are the 3 major nutrients which break down to produce energy?

Answer 44

Can enter any point of the cycle

Question 45

What are 3 catabolic hormones?

Answer 45

1. Cortisol 2. Glucagon 3. Adrenaline/epinephrine

Question 46

What is the function of the catabolic hormone, cortisol?

Answer 46

Released from the adrenal gland in response to stress; its main role is to increase blood glucose levels by gluconeogenesis (breaking down fats and proteins)

Question 47

What is the function of the catabolic hormone, glucagon?

Answer 47

Released from alpha cells in the pancreas either when starving or when the body needs to generate additional energy; it stimulates the breakdown of glycogen in the liver to increase blood glucose levels; its effect is the opposite of insulin; glucagon and insulin are a part of a negative-feedback system that stabilizes blood glucose levels

Question 48

What is the function of the catabolic hormone, adrenaline?

Answer 48

Released in response to the activation of the sympathetic nervous system; increases heart rate and heart contractility, constricts blood vessels, is a bronchodilator that opens (dilates) the bronchi of the lungs to increase air volume in the lungs, and stimulates gluconeogenesis

Question 49

Why do you need to activate catabolic pathways? (2 hormones- cortisol and adrenaline)

Answer 49

•Fight or flight situation -\> need more ATP --\> eg.able to "run" * Need to produce a large amount

Question 50

What are 5 anabolic hormones?

Answer 50

1. Growth Hormone (GH) 2. Insulin-like growth factor (IGF) 3. Insulin 4. Testosterone 5. Oestrogen

Question 51

What is the function of the anabolic hormone, growth hormone?

Answer 51

Synthesized and released from the pituitary gland; stimulates the growth of cells, tissues, and bones

Question 52

What is the function of the anabolic hormone, insulin-like growth factor?

Answer 52

Stimulates the growth of muscle and bone while also inhibiting cell death (apoptosis)

Question 53

What is the function of the anabolic hormone, insulin?

Answer 53

Produced by the beta cells of the pancreas; plays an essential role in carbohydrate and fat metabolism, controls blood glucose levels, and promotes the uptake of glucose into body cells; causes cells in muscle, adipose tissue, and liver to take up glucose from the blood and store it in the liver and muscle as glucagon; its effect is the opposite of glucagon; glucagon and insulin are a part of a negativefeedback system that stabilizes blood glucose levels

Question 54

What is the function of the anabolic hormone, testosterone?

Answer 54

Produced by the testes in males and the ovaries in females; stimulates an increase in muscle mass and strength as well as the growth and strengthening of bone

Question 55

What is the function of the anabolic hormone, oesterogen?

Answer 55

Produced primarily by the ovaries, it is also produced by the liver and adrenal glands; its anabolic functions include increasing metabolism and fat deposition

Question 56

The bulk of stored metabolic fuel is in the form of triacylglycerols in adipose tissue which is sufficient to prolong life for ____ months

Answer 56

3

Question 57

Protein is the second most abundant stored fuel (\_\_\_\_ days worth of energy) which is spared for as long as possible to permit mobility.

Answer 57

14

Question 58

In an ideal case, A normal person can live up to ____ months on a desert island with just water. How do they get energy?

Answer 58

3.5 Can be self sufficient for a while if you have water (have enough fat and protein)