macro exam 1 study session/review

what are the two ways to get ATP

substrate level phosphorylation and oxidative phosphorylation

substrate level phosphorylation overview:

what does it do

how much ATP

slow or fast

what processes are included

driven by?

direct transfer of a phosphate group (ADP→ATP)

faster but produces less ATP

occurs in glycolysis and TCA

driven by delta G (energy)

oxidative phosphorylation overview

how much ATP

slow or fast

what processes are included

TCA cycle, ETC, and ATP synthase

slower, but more ATP generated

glycolysis important points

what is it

when does it occur

what does it require

two important enzymes

highly regulated step

glycose → pyruvate

occurs more rapidly when we need ATP from glucose

requires the input of ATP early on

hexokinase and glucokinase are important enzymes

PFK is the highly regulated step!!

whats the highly regulated step in glycolysis

PFK

what are the two most important enzymes in glycolysis?

hexokinase and glucokinase

2 regulatory mechanisms for glycolysis (broad)

hormonal or allosteric

hormonal regulation of glycolysis (2 things)

insulin and glucagon

allosteric regulation (negative and positive)

negative: reduce enzyme activity (ATP)

positive: increase enzyme activity (AMP)

PFK 1 (regulated by) vs PFK 2 (activated/inhibited by)

PFK 1: directly involved in glycolysis, regulated by AMP and ATP

PFK2: indirectly involved, activated by insulin (high glucose → more glycolysis), inhibited by glucagon (low glucose), produces a product that activated PFK1

pyruvate in aerobic conditions (where does it go & what does it undergo)

enters the mitochondria for oxidation

pyruvate in anaerobic conditions - what does it convert to? (during intense bout of exercise, RBCs, poorly oxygenated tissue)

pyruvate converts to lactate

pyruvate with oxygen normally

what does it become and where does it go

pyruvate → acetyl coA

enters TCA

enters oxidative phosphorylation (ETC and ATP synthase)

glycogenesis

• whats formed

• what stimulates it

• what is the opposite :)

formation of glycogen in either the liver or muscle

stimulated by insulin (we need to store glucose) using branching enzymes

glycogenolysis is the complete opposite

when does glycogenolysis occur in the liver

between meals (raising BG)

when does glycogenolysis occur in the muscle

during activity, doesn’t affect BG levels

overview of gluconeogenesis

forming glucose from non carb sources (triggered by low BG and high glucagon)

occurs during overnight fasting

occurs in the liver but in kidneys if in starvation

what 3 substrates are involved in gluconeogenesis

amino acids, lactate, and glycerol

what relies on gluconeogenesis

RBCs, brain, and other CNS tissues

timeline of glycogenolysis and gluconeogenesis (in relation to BG): include before breakfast, after a meal, between meals, and overnight

before breakfast: gluconeogenesis

after a meal: BG directly from glucose

in between meals: glycogenolysis (liver)'

overnight: gluconeogenesis

pentose phosphate pathway

pathway when glucose is readily available

what are the two important products produced by the pentose phosphate pathway

ribulose-5-phosphate (1) and NADPH (2)

disrupted glucose and insulin signaling in T2DM

unable to activate glycogenesis (unable to use glucose) and unable to turn off liver gluconeogenesis (release glucose)

what causes insulin resistance in organs

ectopic fat accumulation (fat stored in organs like the liver and muscle)

where is fat more favorably stored

subcutaneous fat (below the skin)

oxidative phosphorylation sequence

1. macronutrient digestion and absorption

2. TCA cycle

3. ETC

4. ATP synthase

TCA cycle starting product

acetyl coA (from pyruvate from glycolysis)

whats the purpose of the TCA cycle

creating high energy electrons

products of one TCA cycle

3 NADH

1 FADH2

1 ATP

Co2

what are the regulators of the TCA cycle (positive & negative)

positive (when energy is low): AMP or ADP

negative (when energy is high): end products of certain reactions (accumulation) and end products of the TCA cycle (NADH and ATP)

where does the ETC occur

the inner membrane of the mitochondria

purpose of ETC

e- are extracted from NADH and FADH, energy is released and forms a proton gradient (1, 3, and 4 generate protons)

what happens after e- go through the ETC

h+ flow down the concentration gradient through ATP synthase producing ATP

G cell role in digestion (2)

secrete gastrin to stimulate parietal and chief cells

what pathways occur in low energy status/low BG

glycolysis (oxidation of glucose to pyruvate)

glycogenolysis (breakdown of glycogen)

gluconeogenesis (creating glucose from non carbs)

what pathways occur with good energy status

glycogenesis (produce glycogen)

lipid synthesis (for later :))