Metabolism Flashcards
Explain what is happening in the following diagram.
- Protein, Carbs and fats are taken and catabolized into smaller subunits.
- These molecule can be used to produce energy (ATP) and reducing power (NADPH)
- ATP and NADPH can then be used to form large molecules using the intermediates that are create following catabolism - anabolic/synthetic pathways.
- This forms large macromolecules that can be used for growth - e.g. contributing to cell structures.
What is the krebs/citric acid cycle?
Krebs cycle or citric acid cycle is a series of chemical reactions that takes place in mitochondria and is used to release stored energy derived from carbohydrates fats and proteins in the body.
It is used by organisms to generate energy for various metabolic processes.
Outline what happens in the kreb’s cycle - general overview of the steps.
One trip around the cycle produces…
1. 3 x Reduced NAD - NADH/H+
2. 1 x Reduced FAD - FADH2
3. 2 x CO2
4. 1 x ATP
What is the main molecule that enters into the krebs cycle? What vitamin is important for its formation?
Acetyl-CoA - enters the krebs cycle
Formed by Acetyl (derivative of pyruvate) and Co-enzyme A
Vitamin B5 helps make coenzyme A
What is the molecule that fuels all of life’s reactions?
ATP!
What is important to remember about the intermediates in the krebs cycle?
Intermediates can be used for production of fatty acids/sterols, amino acids, nucleotides and other functional groups
What does reduced NAD carry?
Nucleotide – NADP – carries electrons and hydrogen ions on its nicotinamide ring.
What is the pentose-5-phosphate pathway?
The pentose phosphate pathway is a metabolic pathway parallel to glycolysis.
It generates NADPH, pentoses as well as ribose 5-phosphate, a precursor for the synthesis of nucleotides.
What is the role of NADP in the body?
Nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all organisms, and provides thereducing powerfor anabolic reactions and redox balance.
Nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all organisms, and provides thereducing powerfor anabolic reactions and redox balance.
What are the different enzymes released by different parts of the digestive tract?
Outline how starch is digested into glucose.
Amylose converted into maltose
Amylopectin converted into maltose and isomaltose
Glucoamylase converts maltose into glucose
Isomaltose converts isomaltose into glucose
Outline how the sugars lactose and sucrose are broken down into glucose?
Sucrase split sucrose into fructose and glucose
Lactase – splits lactose into glucose and galactose
Why do we see differences in people when it comes to their ability to digest lactose?
Lactase enzymes – all babies express but as we age we either lose expression or it significantly drops
Some population have picked up lactase persistence mutations, which means they continue expressing lactase into older age.
Other populations have not resulting in intolerance.
How much ATP is produced from glucose during anaerobic and aerobic respiration?
What are triglycerides/triacylglycerols?
Triacylglycerols or triglyceridesare formed by ester linkage of fatty acids to three alcohol groups in glycerol.
Animals can synthesize and store large quantities of Triacylglycerols in the form of fats in adipose tissue, to be used later as fuel.
When energy is needed,lipasesin adipose tissue (fat cells) are activated to hydrolyze stored triacylglycerols into fatty acids and glycerol and release them into the bloodstream. Once the fatty acids reach their destination (muscle or liver cells) they are used to generate acetyl-CoA and eventually ATP.
Outline how triacylglycerol is digested, absorbed and transported around the body.
- TAG split into MAG and FA by pancreatic lipase and absorbed
- Joined together in the intestinal mucosa and transported around the body as chylomicrons
- Transported to muscle, liver and adipose tissue – where lipoprotein lipase breaks down TAG into fatty acids and glycerol which can then be transported into the target tissue
What are chylomicrons?
Chylomicrons are large triglyceride-rich lipoproteins produced in enterocytes from dietary lipids - allows for transport around the body
Outline what this diagram tells you about protein metabolism?
Protein metabolism is in constant flux - can’t store protein so we need a constant intake
Amino acids can be…
1. Used to create biosynthetic products
2. Urea - excreted
3. N-free intermediates - used to form glucose, ketones or used in the krebs cycle to form ATP and NAPDH
What are the different proteinases? How do they become activated?
We need to produce proteinases in inactive form (zymogen) as otherwise it would chomp away at everything.
- Pepsinogen is activated to form pepsin by acidic environment and autocatalysis
- Trypsinogen is activated to form trypsin by enteropeptidase or autocatalysis
- Chymotrypsinogen, Proelastase and Procarboxypeptidase A,B are all activated by trypsin.
What is the urea cycle?
Theurea cycle(also known as theornithine cycle) is a cycle ofbiochemicalreactions that producesurea(NH2)2CO fromammonia(NH3) - waste product of amino acid metabolism
The urea cycle takes place primarily in theliverand, to a lesser extent, in thekidneys.
What are essential amino acids?What are the 9 essential amino acids?
Anessential amino acid, is anamino acidthat cannot be synthesized by the body and must therefore come from the diet.
Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are…. valine,isoleucine,leucine,methionine,phenylalanine,tryptophan,threonine,histidine, andlysine.
What effect does insulin have on the liver, muscle and adipose tissue in a normally healthy person.
- Liver – Glycogen synthesis
- Muscle – Glucose uptake, glycogen synthesis and protein synthesis
- Adipose tissue – Glucose uptake, TAG synthesis (decreases in lipolysis)
What happens to liver, muscle and adipose tissue metabolism in type one diabetes?
Insulin not there – glucose not being deliverd
- Liver - Break down glycogen and gluconeogenesis
- Muscle - Break down of glycogen
- Adipose tissue – increases lipolysis – confused as it is not receiving glucose
Lipids that are released into metabolism get metabolized into ketones – toxic/acidic at high levels
What happens to liver, muscle and adipose tissue metabolism in type two diabetes?
Insulin is there but cells are not responding - insulin insensitivity.
- Liver - Break down glycogen and gluconeogenesis
- Muscle - Break down of glycogen
- Adipose tissue – still somewhat sensitive to insulin, therefore we see increase TAG synthesis and increased adiposity.
No Ketones produced
What are the roles of ghrelin, cholecystekinin and gastric inhibitory peptide?
