Metabolism L3: Understanding metabolic pathways and its influence on cell physiology Flashcards
Which organ is important for metabolic processes?
Liver = overshadows all metabolic pathways and processes
Metabolic pathways are _____- reactions that lead to biosynthesis or breakdown of natural molecules within a cell or tissue
enzyme-mediated biochemical
The Glycolysis & Krebs cycle metabolic pathways, produce _______ (primary/secondary) metabolite (the ATP)
primary
Eg. from glucose –> breakdown –> ATP
Why is it called “primary” metabolites?
What we need for our body use energy (cells can function using ATP)
Other metabolic pathways (not Glycolysis & Krebs cycle) produce _____ metabolites.
secondary
What are the 4 dedicated purposes of the metabolic pathways?
- Extraction of energy
- Storage of fuels
- Synthesis of important building blocks
- Elimination of waste materials
Both _____ and ____ reaction occur within a cell. Which reaction do we want more of?
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
What are the 3 stages in the metabolic pathways to create energy (ATP) from nutrients such as protein, carbohydrates and fat?
Which out of the 3 (out of protein, carbs, fats) is absorbed by passive diffusion ?
POSSIBLE EXAM QUESTION
Fat
Amino acids are rarely (almost never used) to produce energy. What do they do then?
Go straight to building protein that is important for our survival and growth
What happens when there is too much glucose?
Stored as glycogen = glycogenesis
All 3 nutrients converge into the process of glycolysis. What is the process and the result?
Which help to produce pyruvic acid –> acetyl co- A –> krebbs cycle –> oxidative phosphorylation –> ATP is produced
What are the 3 steps to produce ATP? (going from glucose or any other nutrients to ATP)
- Glycolysis
- Krebbs cycle
- Oxidative phosphorylation
Which one of the 3 nutrients gives the highest about of ATP? Why?
- 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
What is ATP?
ATP – the principal molecule for storing & transferring energy
Most food energy is converted into _____ in the body. Why?
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
What are 3 things that ATP supplies energy for?
- Synthesis to make macromolecules
- Transport (pumps)
- Muscle contractions & cellular motility
NADH & FADH2 are _____ (high/low) energy molecules. What does that mean?
high
- Move and carry different H+ ions along side these carrier molecules
- Different stepping of the carrier molecules allows ATP to be produced
What are the 7 reactions in fuel metabolism?
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)?
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)
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)?
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)
When does gluconeogenesis (amino acid –> glucose) occur?
- Usually don’t touch amino acids
- Starvation (survival)
- Always carbs then lipids then proteins (eating up yourself –> deteriorating muscles)
Rarely break down amino acids into glucose (to produce energy) but do break down proteins to produce amino acids. Why?
- There are certain amino acids that can’t be produced/synthesised naturally, must be introduced in diet
- Must be broken down to be accessible
What are 7 of the most important metabolic reactions in humans?
- Glycolysis
- Citric acid cycle (Krebs’ cycle)
- Oxidative phosphorylation
- Pentose phosphate pathway
- Urea cycle
- Fatty acid β-oxidation
- Gluconeogenesis
Cellular respiration oxidizes glucose molecules to produce _____.
ATP
In carbohydrate metabolism, how does cellular respiration occur?
Where in the cell does glycolysis occur?
In the cytosol
Where in the cell does Krebbs cycle and oxidative phosphorylation occur?
In the mitochondria (power house of the cell= produces all the energy)
Which one out of the catabolic and anabolic reactions should always be positive? Why?
- 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
Where is bile produced?
Liver
Fats (lipids) absorbed from _____ or synthesized by the _____
food; liver
What are the 3 main types of fat in the body?
- Triglycerides (glycerol + 3 fatty acids): stored in fat cells
- Cholesterol involved with cell structure/membranes and Hormones/steroids, bile acids, signalling molecules
- Phospholipids part of cell structure
Which 2 main fat types can travel in the blood?
- Triglycerides (glycerol + 3 fatty acids): stored in fat cells
- Cholesterol involved with cell structure/membranes and Hormones/steroids, bile acids, signalling molecules
What are the 3 major lipid pathways?
- Lipolysis - is the hydrolysis of the lipids (mainly TG) produce glycerol &fatty acids.
- β-oxidation: conversion of fatty acids into acetyl CoA (fatty acids catabolism)
- Lipogenesis - lipid anabolism (cholesterol synthesis, ketogenesis, synthesis of other lipids)
All lipid athways converge to _____. What does that mean?
Acetyl-CoA
Can only enter here (unlike glucose which enters from the beginning)
What does the major lipid pathway look like?
Lipids enter the energy production process at a different entry point. Where is this point?
Acetyl Co-A
Fat has higher calories than glucose but give less ATP than glucose. Why?
- 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
What does the pathways of protein metabolism look like?
What is one time/point in life that we actually rely heavily on proteins and fats?
During first months of life (drink milk)
- Milk is made of fat and proteins = need high amount of calories for growth (amino acids)
When too much amino acid, what happens to baby’s breath?
Very strong bad breath of urea (from deamination)
What is deamination?
In the case that need to use amino acids, need to remove groups (ammonia and CO2= forms urea) as it is too toxic = deamination
What are occurs in the breakdown of amino acids?
What are the 3 major nutrients which break down to produce energy?
Can enter any point of the cycle
What are 3 catabolic hormones?
- Cortisol
- Glucagon
- Adrenaline/epinephrine
What is the function of the catabolic hormone, cortisol?
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)
What is the function of the catabolic hormone, glucagon?
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
What is the function of the catabolic hormone, adrenaline?
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
Why do you need to activate catabolic pathways? (2 hormones- cortisol and adrenaline)
•Fight or flight situation -> need more ATP –> eg.able to “run”
- Need to produce a large amount
What are 5 anabolic hormones?
- Growth Hormone (GH)
- Insulin-like growth factor (IGF)
- Insulin
- Testosterone
- Oestrogen
What is the function of the anabolic hormone, growth hormone?
Synthesized and released from the pituitary gland; stimulates the growth of cells, tissues, and bones
What is the function of the anabolic hormone, insulin-like growth factor?
Stimulates the growth of muscle and bone while also inhibiting cell death (apoptosis)
What is the function of the anabolic hormone, insulin?
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
What is the function of the anabolic hormone, testosterone?
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
What is the function of the anabolic hormone, oesterogen?
Produced primarily by the ovaries, it is also produced by the liver and adrenal glands; its anabolic functions include increasing metabolism and fat deposition
The bulk of stored metabolic fuel is in the form of triacylglycerols in adipose tissue which is sufficient to prolong life for ____ months
3
Protein is the second most abundant stored fuel (____ days worth of energy) which is spared for as long as possible to permit mobility.
14
In an ideal case, A normal person can live up to ____ months on a desert island with just water. How do they get energy?
3.5
Can be self sufficient for a while if you have water (have enough fat and protein)
