EXSS 256 Exam 1 - Membrane Transport + Metabolism

O2; CO2

Greater outside the cell; greater inside the cell

Na; K

Greater outside the cell, greater inside the cell (ions)

Simple diffusion, facilitated diffusion, osmosis

Types of passive transport

Primary, secondary, vesicular

Types of active transport

Factors that INCREASE rate of diffusion

Steeper gradient, higher temperature, smaller particle, greater surface area, smaller diffusion distance

Leakage channels

Gates alternate from open to closed (Na+ and K+)

Voltage-gated channels

Open in response to a change in membrane potential (Na+ and K+)

Ligand-gated channels

Open and close in response to chemical stimuli like hormones, neurotransmitters, or other ions

Facilitated Diffusion

Solute binds to a specific transporter protein so that it undergoes a conformational change (carrier proteins)

Hydrostatic pressure

Pressure that the water column exerts

Osmotic pressure

Pressure that the solution exerts when its particles are not permeable

Primary Active Transport (Na/K Pump)

Cell uses ATP to change the shape of the transporter, pumping particle against its concentration gradient

Secondary Active Transport

Na+ or H+ moves down their concentration gradient, using their store energy to drive other substances against their concentration gradient

- Symporter: same direction

- Antiporter: opposite directions

vesicular transport

Vesicular sac buds off the membrane

- Endocytosis

- Exocytosis

Monosaccharides

Glucose, fructose, galactose

Disaccharides

Sucrose (glucose + fructose)

Lactose (glucose + galactose)

Maltose (glucose + glucose)

Polysaccharides

Glycogen, cellulose, starch

Main polysaccharide in the body and the storage form of glucose

Glycogen; stored in liver and skeletal muscles

Location of Glycolysis:

End products of Glycolysis:

Cytoplasm

2NADH, 2 pyruvate, 2 ATP

PFK

Key enzyme for regulating glycolysis

- Increased PFK = Increased glycolysis

What stimulates PFK?

Low O2, low pH, and increased ADP

What inhibits PFK?

Lots of ATP, citrate, and Glucose-6-Phosphate

Lactate Dehydrogenase (LDH)

Converts pyruvate to lactate

Pyruvate Dehydrogenase (PDH)

Converts pyruvate to Acetyl-coA

Hexokinase

Converts glucose to G-6-P in glycolysis

What stimulates gluconeogenesis?

Cortisol and glucagon

What stimulates glycogenesis vs. glycogenolysis

insulin vs. glucagon and epinephrine

Electron transport chain

- Electron donors NADH and FADH2 carry electrons to the cytochrome carriers, reducing them in the process

- Releases energy that moves protons from the matrix to the intermembrane space (PMF)

- Terminal electron acceptor

- Protons flow back to matrix, spinning the ATP synthase in the process to produce ATP

How do we store fat in the body?

Triglycerides (glycerol + 3 fatty acids)

Lipoprotein chylomicrons

Transport dietary lipids to adipose tissue

Very-low-density lipoproteins (VLDLs)

Transport triglycerides from hepatocytes to adipocytes

Low-density lipoproteins (LDLs)

Carry the body's cholesterol in blood and deliver it to cells

High-density lipoproteins (HDLs)

Remove excess cholesterol from body cells and the blood and transport it to the liver for elimination

Can lipids be oxidized to produce ATP

Only when oxygen is present

Lipolysis

Splits triglycerides into fatty acids and glycerol

- Beta oxidation turns fatty acids into acetyl CoA

Lipogenesis

Synthesizes lipids from glucose or amino acids

When does lipogenesis occur and what stimulates it?

Lipogenesis occurs during the absorptive state, and insulin stimulates it

What are Ketone Bodies?

Ketone bodies are used as back up fuel when glucose is scarce

- Acetoacetic acid, beta-hydroxybutyric acid, acetone

What organs prefer to use ketone bodies for ATP instead?

Heart and kidney cortex

Essential vs. Non-essential amino acids?

Essential - Body doesn't produce, so we must obtain them through food

Non-essential: Body produces

Digested proteins are...

Not stored; either oxidized to produce ATP or used to synthesize new proteins

What happens during the Postabsorptive State?

Lysis of glycogen, lipids, and proteins

Genesis of glucose

Major hormones: glucagon, cortisol, epinephrine

What happens during the absorptive state?

- Diffusion of glucose into cells

- Active transport of amino acids into cells

- Genesis of glycogen, lipids, and proteins

Major hormones: Insulin