Lecture 1 - macros Flashcards
CARBS:
- combination of which 3 atomes?
- generic formula?
- 3 types of saccharides. how long?
- carbon, hydrogen, oxygen
- (CH2O)n
- monosacs: simple sugars: glucose, fructose, galactose
- oligosaccharides: 2-10 monosacs
- polysaccharides: 3 or more (up to thousands) of sugar molecules
- what are the 3 disaccharides?
- they are all ________ ________ –> formula
- what bond links them?
- sucrose = glucose + fructose
- lactose = glucose + galactose
- maltose = glucose + glucose
- structural isomers –> C12H22O12
- glycosidic bonds
- give real life examples of polysacs?
- what is a complex carb?
- what is glycogen?
- starch: cereals, seeds, corn, pasta and pastries
- dietary starch representing most important dietary source of carb in diet –> take longer to break down = longer source of energy
- storage carbohydrate within mammalian muscle and liver
what are the 3 stores of glucose (ish) in the body and how much?
- total CHO stored in body? = ? kcal?
- liver glycogen: 100g = 400 kcal
- blood glucose: 0.9g/L = 4g = 16 kcal
- skeletal muscle glycogen: 400g = 1600 kcal
TOTAL: 504g = 2016 kcal
- muscle glycogen levels vary based on (2)
- liver glycogen goes from _____g to _____g during overnight fast
- what are the arrows btw the 3 sources of glucose in body? explain
- based on amount of muscle you have + amount of CHO you eat
- from 100g to 50g
- liver glycogen <–> blood glucose –> muscle glycogen. muscle glycogen cannot go back into blood bc no glucose-6-phosphatase to get glucose out
what are the 4 roles of CHO in body?
- primarily serve as energy fuel, particularly during intense PA/exercise
- protein sparer: adequate CHO intake helps preserve tissue protein (no protein is used as energy)
- prevents ketosis: adequate CHO intake prevents need for utilizing ketones as fuel (high levels of ketones dangerous for diabetic)
- fuel for central nervous system: nervous system requires uninterrupted stream of CHO for proper function (120g glu/day to function)
4.
when _________ stores are limited, excess sugar is converted and stored as what?
glycogen stores
stored as fat
what are the 3 important CHO conversions?
- glycogenesis: synthesis of glycogen from glucose
- glycogenolysis: glucose formation from glycogen
- gluconeogenesis: glucose synthesis largely from structural components of nonCHO nutrients (protein –> glucose)
explain the 5 steps of glycogenesis
- glucose uptake from blood via GLUT4 (for muscle) and GLUT2 (for liver)
- glucose is phosphorylated by hexokinase using ATP –> becomes glucose-6-phosphate which is trapped in the muscle + more reactive for further metabolic processes
- isomerization = essential step: glucose 6-phosphate to glucose-1-phosphate using phosphoglucomutase
- activation of glucose for glycogen synthesis: G1P + UTP becomes UDP glucose + PPi, using UDP-glucose pyrophosphorylase. ensures that glucose is energetically favorable for incorporation into glycogen
- glycogen synthase adds UDP glucose to chain, forming a-1,4 glycosidic bonds. for each glu unit added, 2 moles of ATP convert to ADP + Pi
- key regulatory enzyme for glycogen synthesis?
- what type of bond is formed btw glucose molecules in glycogen?
- what steps ensures that glu is energetically favorable for incorporation into glycogen?
- how many moles of ATP needed to add 1 glu to glycogen chain?
- glycogen synthase
- a-1,4 glycosidic bond
- activation of glucose by UDP-glucose pyrophosphorylase
- 2 moles
explain the 3 ish steps of glycogenolysis
- add inorganic phosphate to C1 of a glucose unit of glycogen, using glycogen phosphorylase –> cuts bond and releases G1P
- G1P –> G6P by phosphoglucomutase
3A. G6P enters glycolysis and becomes pyruvate (in muscle and liver)
3B. G6P + H2O –> glycose + Pi using glucose 6 phosphatase. only in liver. glucose goes to blood via GLUT2
explain the 4 basic steps of gluconeogenesis
- lactate, glycerol or certain aa converted to pyruvate
- pyruvate –> oxaloacetate through pyruvate carboxylase. oxaloacetate –> phosphoenolpyruvate, through phosphoenolpyruvate carboxykinase (PEPCK, present in mitochondria and cytoplasm)
- PEP –> fructose-1,6-biphosphate
- F16BP –> glucose, which can enter circulation
- _____A____ play a key role in regulating liver and muscle glycogen stores by controlling ____what?_____
- explain the 2 opposing roles of the 2 ____A_______
- hormones! –> control blood glucose levels
INSULIN: - secreted by b cells of pancreas when high blood sugar
- insulin stimulates glu uptake from blood into cell tissues + stimulates glycogen formation in liver = lowers blood sugar
GLUCAGON: - secreted by a cells of pancreas when low blood sugar
- stimulates glycogen breakdown in liver = raises blood sugar
- what is the predominant CHO energy source during early stages of exercise?
- what happens after? as exercise intensity increases?
- muscle glycogen!
- as exercise intensity increases, there is an increase in demand for ATP in active skeletal muscle = increase demand for glucose = increase liver glucose release
- at 75-90% of VO2 max –> ___which source of glu____ may supply up to ___% of total energy for active muscles
- how much is liver glycogen depleted after 1h vs 2h?
- blood glucose: 30%
- 1h: decrease liver glycogen 55% (not sure if 55% left or -55%)
- 2h: almost depletes glycogen stores of liver and active muscle au complet
- at 50-60% and 25-30% of VO2 max: __which source of glu___ supplies ____% of energy in initial transition from rest to moderate exercise
- during next 20min, which source of glu supplies btw ___-____% of energy, with the remainder being provided by ____ ___________
- glycogen stored in active muscle supplies almost all energy in initial transition…
- liver and muscle glycogen supply btw 40-50% –> rest if fat catabolism
- during low intensity (prolonged exercise), what serves as primary energy substrate?
- as muscle glycogen decreases and liver glucose output fails to keep pace with glucose use by muscle, what happens?
- fat!
- plasma glucose concentration decrease + FFA take over
as intensity increases (65 vs 130 vs 200 watts), what happens to leg glucose uptake? (GRAPH)
- all start near 0
- in the first 10min, 200W goes to 5.4g glu/min, 130W –> 2.7g, 65W –> 1.45g
- then from 10min to 40min, steady similar increase in all 3 intensities
study showed that CHO deficient diet depletes what and negatively impacts performance in what activities (2)
- depletes muscle and liver glycogen
- in short term anaerobic activity and prolonged intense aerobic activities
what are the 3 types of lipids?
- what?
- how much in body?
- SIMPLE LIPIDS:
- neutral fats (bc no electronically charged groups)–> mostly triacylglycerols
- constitutes major storage form of fat in fat cells/adipocytes - COMPOUND LIPIDS:
- TG components combined with other chemicals ie phospholipids (membrane fluidity, blood clotting, structural integrity of cell/nerves( and lipoproteins (transporting lipids in blood)
- represent about 10% of body’s fat content - DERIVED LIPIDS:
- formed by simple and compound lipids
- ex: cholesterol: precursor for vit D, adrenal gland and sex hormones
saturated vs unsaturated vs trans FA
SATURATED:
- contain only single covalent bonds btw C atoms; all of the remaining bonds attach to H
UNSATURATED:
- contain one or more double bonds along the main C chain
- MUFA or PUFA
- generally speaking, healthier fats
TRANS:
- derive from partial hydrogenation of unsat corn/sunflower oil
- detrimental effects on serum lipoproteins and overall heart health
4 roles of lipids in body
- energy source and reserve
- about 80-90% of our E requirement at rest
- 1g of pure lipid contains 9kcal of E, more than twice E in CHO and prot - protection of vital organs
- up to 4% of body’s fat protects against trauma to vital organs - thermal insulation
- fat stored below skin = subcutaneous fat - vitamin carrier:
- consuming 20g of dietary fat daily provides sufficient source and transport medium for fat-soluble vits
why is fat ideal energy source? (3)
- transports and stores easily
- readily available
- lots of energy: 9kcal/g
what are the 3 reactions that are key in lipid metabolism?
- lipolysis:
- TG catabolism = breakdown of fat and other lipids by hydrolysis to release FA and glycerol - b-oxidation
- catabolic process by which FA molecules are broken down in the mitochondria to general acetyl-coA - ketogenesis:
- production of ketone bodies by breaking down FA and ketogenic aa
explain the 3 steps of lipolysis
- hydrolysis: add H2O to TG. Hormone sensitive lipase removes a FA: TG –> 1,2-diacylglycerol + FFA
- hydrolysis again. DG –> 2-monoacylglycerol + FFA, using HSL
- hydrolysis again: MG –> glycerol + FFA, using HSL and monoglyceride lipase
*FFA can enter tissues via bloodstream and go through b-oxidation for energy
explain the 5 steps of b-oxidation
- dehydrogenation of fatty acyl-coA: introduce double bond btw a and b carbon using acyl-coA dehydrogenase. creates FADH2 + trans-enoyl-coA
- hydration: add water across the double bond to make b-hydroxylacyl-coA using enoyl-coA hydratase
- dehydrogenation: b-hydroxylacyl-coA to b-ketoacyl-coA + NADH through L-hydroxyacyl-coA dehydrogenase. oxidizes hydroxyl group of beta carbon to a keto group
- thiolysis: b-ketoacyl-coA to fatty-acyl-coA (2C shorter) + Acetyl-coA through thiolase (uses coA-SH to cleave bond btw a and beta C).
- shortened fatty-acyl-coA reenters b-oxidation cycle until fatty acid chain is converted into acetyl-coA units. Acetyl-coA goest to TCA + FADH2 & NADH go to electron transport chain for energy prod.
what are the sources of energy at moderate-intensity activity? vs low intensity
- what if exercise > 1h at this level?
approximately equal amounts of carbs and fat supply energy VS mostly fat at low intensity
- >1h –> fat catabolism gradually supplies a greater percentage of energy, coinciding with glycogen depletion
5 “benefits” of fat oxidation during endurance exercise
- sustains energy supply
- preserves glycogen
- prolongs performance
- enhances endurance efficiency
- reduces risk of fatigue
as time increases, increase ______ use as energy and decrease _______ use as energy
increase fat
decrease carb
- what are the building blocks of proteins? how many in nature? vs how many in human body?
- what is peptide bond?
- polypeptide vs protein
- amino acids! over 500 aa in nature, only 20 make up proteins found in human body
- peptide bond: link aa in chains that take on diverse forms and chemical combinations
- polypeptide = a chain containing 50 to more than 1000 aa
- protein = combination of more than 50 aa
what are the different components/group attached to the central carbon of an aa?
- amino group (N terminal)
- carboxyl group (C terminal)
- Hydrogen
- side chain
what are the 2 types of aa?
ESSENTIAL (indispensable)
- body is unable to synthesize and must be obtained through food consumption
- isoleucine, leucine, valine, lysine, histidine (for children and diseased), threonine, methionine, phenylalanine, tryptophan
NON-ESSENTIAL:
- remaining aa that body is able to synthesize from other compounds already in body at a rate that meets the body’s needs for normal growth and tissue repair
complete vs incomplete protein
COMPLETE:
- includes a full complement of essential aa in the quantity and correct ratio to maintain nitrogen balance and to allow tissue growth and repair
- typically coming from animal sources (milk, beef, egg, fish, soy)
INCOMPLETE PROTEIN:
- lacks one or more essential aa
- typically coming from plant sources (lentil, quinoa, pea, rice, oat)
what are the 6 roles of protein in the body?
- synthesize tissue (repair and growth)
- serves as primary constituents for plasma membranes and internal cellular material
- catalyze virtually all chemical reactions in the body (enzymes)
- regulate gene expression
- regulate immune system
- initiate cellular death
what are the 3 reactions ish in protein metabolism?
- deamination: loss of nitrogen (amine group) from an aa in the liver to form urea. aa catabolism for E
- transamination: transfer for an amino group from an aa (donor) to a ketoacid (acceptor), with the formation of a new aa and a new ketoacid
- protein turnover: replacement of older proteins as they are broken down within the cell
explain the 3 steps for deamination
- remove NH3+ group from aa. amino acid –> a-keto acid + ammonia (NH3)
- NH3 rapidly converted to urea bc ammonia is toxic
- a-keto acid/C skeleton of the aa is converted into a compound that enters Krebs cycle
explain the steps of transamination
aa (ie L-glutamate) gives its amino group to pyruvate/a-keto acid (acceptor). catalyzed by alanine aminotransferase (ALT) OR glutamate-pyruvate transminase (GPT) –> reaction is reversible!
- L-glutamate loses amino group and becomes a-ketoglutarate (a-keto acid)
- pyruvate becomes L-alanine (an aa)
*happens in muscle so L-alanine can be used in liver
muscle protein balance is regulated by which 2 dynamic variables?
- formula
- muscle protein synthesis (MPS): process of producing new muscle proteins –> can be influenced by diet and exercise
- muscle protein breakdown (MPB) = degradation of muscle proteins
- MPS - MPB = net protein balance
- loss of muscle mass (atrophy) if MPB > MPS
- gain of muscle mass (hypertrophy) if MPS > MPB
- maintained muscle mass if MPB = MPS
mucles proteins turnover at a rate of __-___% per day
- what rate can you change? vs what rate can you not change?
- 1-2% per day!
- you can’t change rate of protein breakdown
- you can change rate of synthesis through exercise and protein intake –> need to accumulate positive hills (bigger than negative losses) in order to gain muscle
is protein ever used during exercise?
- protein use as energy during exercise is minimal
- highest level of protein use as energy = during glycogen depleted state
what is a biomarker of protein use?
sweat! measure units of urea per volume of sweat!
