Lecture 1 - macros Flashcards
1
Q
CARBS:
- combination of which 3 atomes?
- generic formula?
- 3 types of saccharides. how long?
A
- 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
2
Q
- what are the 3 disaccharides?
- they are all ________ ________ –> formula
- what bond links them?
A
- sucrose = glucose + fructose
- lactose = glucose + galactose
- maltose = glucose + glucose
- structural isomers –> C12H22O12
- glycosidic bonds
3
Q
- give real life examples of polysacs?
- what is a complex carb?
- what is glycogen?
A
- 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
4
Q
what are the 3 stores of glucose (ish) in the body and how much?
- total CHO stored in body? = ? kcal?
A
- liver glycogen: 100g = 400 kcal
- blood glucose: 0.9g/L = 4g = 16 kcal
- skeletal muscle glycogen: 400g = 1600 kcal
TOTAL: 504g = 2016 kcal
5
Q
- 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
A
- 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
6
Q
what are the 4 roles of CHO in body?
A
- 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.
7
Q
when _________ stores are limited, excess sugar is converted and stored as what?
A
glycogen stores
stored as fat
8
Q
what are the 3 important CHO conversions?
A
- glycogenesis: synthesis of glycogen from glucose
- glycogenolysis: glucose formation from glycogen
- gluconeogenesis: glucose synthesis largely from structural components of nonCHO nutrients (protein –> glucose)
9
Q
explain the 5 steps of glycogenesis
A
- 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
10
Q
- 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?
A
- glycogen synthase
- a-1,4 glycosidic bond
- activation of glucose by UDP-glucose pyrophosphorylase
- 2 moles
11
Q
explain the 3 ish steps of glycogenolysis
A
- 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
12
Q
explain the 4 basic steps of gluconeogenesis
A
- 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
13
Q
- _____A____ play a key role in regulating liver and muscle glycogen stores by controlling ____what?_____
- explain the 2 opposing roles of the 2 ____A_______
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
14
Q
- what is the predominant CHO energy source during early stages of exercise?
- what happens after? as exercise intensity increases?
A
- 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
15
Q
- 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?
A
- 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
16
Q
- 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 ____ ___________
A
- glycogen stored in active muscle supplies almost all energy in initial transition…
- liver and muscle glycogen supply btw 40-50% –> rest if fat catabolism
17
Q
- 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?
A
- fat!
- plasma glucose concentration decrease + FFA take over
18
Q
as intensity increases (65 vs 130 vs 200 watts), what happens to leg glucose uptake? (GRAPH)
A
- 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
19
Q
study showed that CHO deficient diet depletes what and negatively impacts performance in what activities (2)
A
- depletes muscle and liver glycogen
- in short term anaerobic activity and prolonged intense aerobic activities
20
Q
what are the 3 types of lipids?
- what?
- how much in body?
A
- 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
21
Q
saturated vs unsaturated vs trans FA
A
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
22
Q
4 roles of lipids in body
A
- 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
23
Q
why is fat ideal energy source? (3)
A
- transports and stores easily
- readily available
- lots of energy: 9kcal/g
24
Q
what are the 3 reactions that are key in lipid metabolism?
A
- 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
25
explain the 3 steps of lipolysis
1. hydrolysis: add H2O to TG. Hormone sensitive lipase removes a FA: TG --> 1,2-diacylglycerol + FFA
2. hydrolysis again. DG --> 2-monoacylglycerol + FFA, using HSL
3. hydrolysis again: MG --> glycerol + FFA, using HSL and monoglyceride lipase
*FFA can enter tissues via bloodstream and go through b-oxidation for energy
26
explain the 5 steps of b-oxidation
1. dehydrogenation of fatty acyl-coA: introduce double bond btw a and b carbon using acyl-coA dehydrogenase. creates FADH2 + trans-enoyl-coA
2. hydration: add water across the double bond to make b-hydroxylacyl-coA using enoyl-coA hydratase
3. dehydrogenation: b-hydroxylacyl-coA to b-ketoacyl-coA + NADH through L-hydroxyacyl-coA dehydrogenase. oxidizes hydroxyl group of beta carbon to a keto group
4. 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).
5. 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.
27
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
28
5 "benefits" of fat oxidation during endurance exercise
1. sustains energy supply
2. preserves glycogen
3. prolongs performance
4. enhances endurance efficiency
5. reduces risk of fatigue
29
as time increases, increase ______ use as energy and decrease _______ use as energy
increase fat
decrease carb
30
- 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
31
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
32
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
33
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)
34
what are the 6 roles of protein in the body?
1. synthesize tissue (repair and growth)
2. serves as primary constituents for plasma membranes and internal cellular material
3. catalyze virtually all chemical reactions in the body (enzymes)
4. regulate gene expression
5. regulate immune system
6. initiate cellular death
35
what are the 3 reactions ish in protein metabolism?
1. deamination: loss of nitrogen (amine group) from an aa in the liver to form urea. aa catabolism for E
2. 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
3. protein turnover: replacement of older proteins as they are broken down within the cell
36
explain the 3 steps for deamination
1. remove NH3+ group from aa. amino acid --> a-keto acid + ammonia (NH3)
2. NH3 rapidly converted to urea bc ammonia is toxic
3. a-keto acid/C skeleton of the aa is converted into a compound that enters Krebs cycle
37
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
38
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
39
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
40
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
41
what is a biomarker of protein use?
sweat! measure units of urea per volume of sweat!
