Quiz 8 BIOC

Can you define the types of membrane transport?

Active Transport: Uses requires energy input

Passive Transport: does not require energy

What is an example of a channel protein?

K+ channel… btw these are always passive… use facilitated or simple diffision

What are the general functions of membrane proteins?

Transport (move molecules across membrane), enzymatic activity, signal transduction (bind signals → cellular response), and cell-cell recognition (interact with other cells/ECM).

What is an aquaporin and what is its function?

Channels to specifically transport h20

What is the GLUT transporter and how does it operate?

moves glucose in the direction of high to low concentration (glucose is polar not much would cross the membrane if there was not a transporter to facilitate the movement)

What are the key features of the Na+/K+ pump?

Concentration of Na+ is much higher extracellular where as K+ concentration is higher in the cell, the pump maintains this. it pumps 3 Na+ out of cell and 2K+ into the cells using the energy of ATP hydrolysis.

What are examples of membrane receptors and cell signaling?

glucose uptake in fat and muscle cells mediated by insulin

• insulin stimulates muscles and fat cells to increase glucose uptake… exo and endo-cytosis of GLUT transporter

epinephrine and flight-or-flight response

• epinephrine is released in seconds from adrenal glands in response to stress, which goes the second messenger cascade and ends up increasing glucose as a source of energy

Neurtransmitter ACh

What are the roles of insulin, glucose and epinephrine in terms of the

degradation of glycogen?

Insulin: increases glycogen production

Glucose: increases glycogen production

Epinephrine: breaks down glycogen

What is cAMP?

a second messanger within the cell

How can you compare glucose and fatty acid/lipid metabolism?

Glucose = quick, short-term, can be anaerobic; Fatty acids = slow, long-term, aerobic, higher ATP yield.

How does acetylcholine transmit a nerve signal?

Change in ion permeability of postsynaptic neurons initiates nerve impulses in the neuron , with the message delivered, acetylcholinesterase in the synaptic cleft catalyzes the decomp of ACh.

why are do fats have more energy density but need oxygen to break down?

because they are in a lower oxidation state and oxygen is the final electron acceptor

lipase role

catalyze the breakdown of fats (triglycerides) into free fatty acids and glycerol

role of bile acids

emulsify fats droplets and aid in their digestion

role of chylomicron

transport dietary fats from small intestine to peripheral tissues of the liver

role of lipids

delivered to cells by chlymicrons for energy or storage

process of food from mouth to cell

Lipids are broken down from dietary fats into smaller units (fatty acids, monoglycerides) via lingual/gastric lipases and emulsified by bile in the small intestine to increase surface area for digestion. They are absorbed, reassembled in intestinal cells, packaged into chylomicrons, transported via the lymph to the blood, and finally delivered to cells for energy or storage

where are triglycerides stored

in white adipose tissue in the form of lipid droplets

what hormones stimulate lipolysis

hormones that respond to fasting conditions (glucagon) or stress (epinephrine)

lipolysis steps generally summed up

bile salts emulsify dietary fats in SI, lipase degrade TAGs, FA and other products taken up by mucosa and converted back into TAGs, TAGs are incorporated with cholesterol and apolipoproteins into chylomicrons (CMs), CMs move through lymphatic and blood to tissues, lipoprotein lipase activated by apoC-II in capillary and converts TAG into FA and Glycerol, FA enter cells, FA oxidized as fuel or re-esterfied for storage

apolipoprotein C-II (ApoC-II)

vital protein cofactor synthesized primarily in the liver that activates lipoprotein lipase (LPL) that hydrolyzes TAGs in plasma.

how is fatty acyl-CoA transferred into the mitochondrial matrix? (transfer)

fatty acyl coA is transiently transferred to carnitine, acyl carnitine is transferred across inner mitochondrial membrane by a specific transporter , once inside carnitine is removed and CoA is added back to the acyl group this is the control point for beta oxidation!

activation or fatty acid oxidation

conversion of fatty acid to fatty acyl-coa in cytoplasm

oxidation in fatty acid oxidation

step wise removal of 2-carbon acetyl coa units from carboxyl terminal end (beta ox) to convert all carbons of FA to acetyl-coa

products of fatty acid oxidation

one acetyl coa, NADH and FADH2

how many ATP equivalents is acetyl coa

12

how many ATP equivalents are NADH and FADH2

NADH is 3, FADH is 2