massive macro study set 🍓

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 (which 2 pathways does this affect and how)

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 :))

key role of the cell membrane

receptors sensitive to external stimuli and channels that regulate movement throughout the cell

key role of the cytoplasm

provides support and controls movement of organelles and connects cellular components with microtubules

key role of the nucleus and what does it contain

“chief executive officer”

contains DNA (instructions)

key role of the mitochondria

produce the most ATP used by cells (why its the powerhouse)

key roles of the oral cavity (3)

teeth: mastication

salivary glands: lubrication

swallowing

key role of the esophagus and two structures within

transportation

UES opens during swallowing - bolus slides to the stomach

LES allows food to enter the stomach - cannot return, prevents reflux (GERD)

key role of the stomach

digestion & passing food into small intestine

regulation of gastric secretions

mechanical: grinding food

chemical: gastric juice (producing chyme)

secretions of the stomach and their functions

Mucus & bicarbonate – neutralize HCl along tissue wall (protects mucosa)

HCl – protein denaturation

Intrinsic factor – binds vitamin B12 and carries to ileum for absorption

Gastric lipase – hydrolyzes triglycerides (mostly short and medium chain)

Pepsinogen – first converted to pepsin

Pepsin is an endopeptidase – direct digestion of protein within the protein chain

Gastrin – stimulates parietal and chief cells to release HCl and pepsinogen, respectively

key roles, portions, and cells (1) of the small intestine

main site for nutrient digestion and absorption

duodenum, jejunum (most), ileum

enterocytes (absorptive cells of the SI) turn over every 3-5 days

4 processes of absorption in the small intestine

diffusion – substances freely cross membrane

facilitated diffusion – requires a carrier

active transport – requires a carrier and ATP

pinocytosis – engulfed by cell membrane a released on the inside of the cell

key roles of the large intestine

ascending, transverse, and descending 

transportation and absorption

secretion of mucus (lubricant and protectant from bacteria) and bicarbonate (neutralize acids)

movement of material

key role of the pancreas

insulin and glucagon production

key roles of the liver

energy metabolism

produces bile to aid in digestion

emulsification of dietary lipids

• Brings fats into liquid suspension

• enzymes better able to break down lipids

• solubilization of lipid digestion products for absorption

• bile is a critical component of micelles – spherical structure that facilitates lipid absorption

key roles of the gallbladder

stores bile

CCK stimulates contraction and bile release

TCA cycle 

• location

• what is metabolized

• products

• main goal

in the mitochondria (after molecules become acetyl coA)

carbohydrates, fatty acids, and amino acids metabolized

products from one cycle: 3 NADH (3 ATP later), 1 FADH2 (2 ATP later), 1 ATP, CO2 = 12 ATP total

produces a lot of electron carriers to make ATP later on

positive and negative regulators of the TCA cycle

positive: AMP or ADP (low energy)

negative: end products of certain reactions (citrate inhibits citrate synthase) or end products of the TCA cycle (NADH, ATP)

electron transport chain

• where it occurs

• what needs to happen before

• end goal

occurs in the mitochondria (inner membrane)

occurs after TCA cycle (because we have electron carriers NADH and FADH2)

• we need to extract the electrons and transfer to form a proton (H+) gradient

40% of energy is for ATP synthesis and 60% is heat

at the end, electrons are transferred to oxygen (producing H2O)

ETC complex 1

• enzyme

• what it contains

• end goal

NADH coenzyme Q oxidoreductase

contains several Fe-S clusters

accepts e- from NADH, leaks some e- generating free radicals

ETC complex 2

• enzyme

• what it does

• what it contains

• fun fact

succinate dehydrogenase

accepts e- from FADH2

contains Fe-S cluster

the only complex that isn’t a H+ pump

coenzyme Q

• what is it

• what does it do

lipid soluble molecule that diffuses within the lipid bilayer

transfers e- from complexes 1 and 2 to complex 3

ETC complex 3

• enzyme

• what does it contain

coenzyme Q cytochrome c oxidoreductase

contains 3 cytochromes and an Fe-S protein

cytochrome c

• what does it do

transfers e- from complex 3 to complex 4 within the inter-membrane

complex 9

• enzyme

• what does it contain

• function

cytochrome c oxidase

contains Fe and Cu dependent proteins

transfers e- from cytochrome c to oxygen producing H2O

after TCA cycle and ETC, what happens?

H+ flow down concentration gradient through ATP synthase

for every pair of e- through the complex, 3 ATP are generated

CHO digestion pathway

oral cavity → stomach → SI

what occurs during CHO digestion in the oral cavity

digests polysaccharides (starches) using salivary alpha amylase

disaccharides are not digested here

what occurs during CHO digestion in the stomach

starch: small amount of digestion via alpha amylase until inactivated

disaccharides are not digested here

what occurs during CHO digestion in the SI

duodenum and jejunum starch digestion via amylase

at the brush border, remaining things are hydrolyzed and glucose is absorbed

at the brush border, disaccharides are digested producing lactase, sucrase, maltase, trehalase

which of the following organelles are involved in protein synthesis and export? nucleus, smooth ER, rough ER, golgi apparatus

nucleus, rough ER, golgi apparatus

Allosteric enzyme regulation involves directly blocking the enzyme “active site.” T/F

False

Insulin binding the insulin receptor is an example of….

• Signals leading to a distinct event within the cell

• 2nd messenger signaling

• External stimuli

external stimuli

T or F: Taking a creatine supplement should improve marathon running by significantly contributing to ATP supply during the course of the race

False

Which of the following best describes the end result of the TCA cycle?

• Generates large amounts of ATP to be used for energy

• Generates large amounts of NADH and FADH2 to be used as energy

• Generates large amounts of NADH and FADH2 to be used as electron carriers

Generates large amounts of NADH and FADH2 to be used as electron carriers

T or F: NADH and FADH2 transfer their e- to the same ETC complex

false

Which stomach glands are most directly related to protein digestion?

• cardiac

• oxyntic

• pyloric

oxyntic

Most macronutrient absorption takes place in the ileum T/F

false

The PFK step in glycolysis is regulated by which of the following (select all that apply)?

• Protein Kinase A

• Glucagon

• AMP

• Fructose 2,6 bisphosphate

• Insulin

• ATP

glucagon, AMP, fructose 2,6 bisphosphate, insulin, ATP

Lactate is a waste product of intense exercise. T/F

false

The principal issue with all glycogen storage diseases is that the brain has an inadequate supply of glucose. T/F

false

what are the three monosaccharides

fructose glucose, galactose

T/F To the best of our current knowledge, the negative effects of HFCS are because it increases calorie intake.

true

the principal reason dietary fiber has a lower caloric value than starch is…

• Humans don’t have enzymes to digest the β-glycosidic bonds between monosaccharides within fiber

• Fiber has a faster gastric transit time and therefore is not well absorbed

• Fiber is a heteropolymer of monosaccharides, making it harder to digest

Humans don’t have enzymes to digest the β-glycosidic bonds between monosaccharides within fiber

At Thanksgiving, you eat so much turkey that the only other thing you eat is 0.5 slices of pie. The sugar from that pie will be absorbed by….

• GLUT4

• SGLT1

• GLUT2

• Amino acid receptors

SGLT1

Which of the following best describes beta cell failure?

• Early in type 2 diabetes, the pancreas secretes very little insulin

• Later in type 2 diabetes, the pancreas secretes a large amount of insulin

• Later in type 2 diabetes, the pancreas secretes very little insulin

• Early in type 2 diabetes, the pancreas secretes a large amount of insulin

Later in type 2 diabetes, the pancreas secretes very little insulin

T/F One must have obesity to develop type 2 diabetes.

false

What biomarker of glucose homeostasis would be best for monitoring the efficacy of a long-term (6 month) lifestyle intervention in people with type 2 diabetes?

A1c

Which of the following is NOT characterized by insulin resistance?

• PCOS

• Type 2 diabetes

• Type 1 diabetes

T1D

T/F there is one cause of lactose intolerance

false

Which of the following can enter the gluconeogenic pathway? (select all that apply)

• Acetyl CoA

• Fatty acids

• Lactate

• Amino Acids

• Glycerol

lactate, amino acids, glycerol

Which of the following are physiological actions of glucagon? (select all that apply)

• Promoting glucose uptake by skeletal muscle

• Promoting glucose uptake by adipose

• Activating glycogenesis

• Activating glycogenolysis

• Activating gluconeogenesis

activating glycogenolysis and activating gluconeogenesis

Between breakfast and lunch, which pathway supplies glucose to prevent hypoglycemia?

glycogenolysis

T/F When consumed in excess (positive energy balance), fructose contributes more to liver fat than glucose.

true

Avoiding dietary CHO at all costs could lead to which of these unfavorable effects (select all that apply)

• Avoiding many foods high in fiber

• Increasing many foods high in fiber

• Increasing saturated fat intake

• Avoiding many foods high in fiber

• Increasing saturated fat intake

T/F Overfeeding CHO and fat to the same degree induces similar weight gain.

true

Select all that are true.

• Non-celiac gluten sensitivity appears to be a real condition

• Non-celiac gluten sensitivity is present in 25% of the population

• There are good biomarkers for non-celiac gluten sensitivity

• Symptoms associated with non-celiac gluten sensitivity are definitely due to gluten (not another component of wheat)

non-celiac gluten sensitivity appears to be a real condition

pancreas digestion secretions:

• acinar cells: digestive enzymes

• duct cells: bicarbonate

pancreatic juice secretions contain:

• Electrolytes (Na+, K+, Cl-)

• Enzymes that act on all three energy nutrients:

  • Carbohydrases → hydrolyze carbohydrates (~50%)

  • Lipases → hydrolyze lipids (~90%)

  • Proteases → hydrolyze proteins (~50%)

• Bicarbonate: neutralizes the acidic chyme arriving in the small intestine from the stomach

cell membrane structure

sheet-like composed primarily of lipids and proteins

mostly phospholipid (PL), also cholesterol – regulates membrane fluidity

carbohydrate chains are often attached to membrane proteins

its dynamic (fluid mosaic model: lateral diffusion, proteins dispersed)

What mechanisms occur in the cytoplasm

glycolysis, glycogenesis, glycogenolysis, pentose phosphate pathway, fatty acid synthesis

what is the largest organelle

nucleas

what is embedded within the mitochondria

the ETC

what are cristae

protrusions that increase surface area of mitochondria - more room for proteins (important for metabolism)

what the general structure of the mitochondria

outer membrane (relatively porous) & inner membrane (selectively permeable)  

where does lipid and carb digestion begin

the oral cavity through digestive enzymes

where does protein digestion begin

the stomach