Exam 2 Flashcards
Chapters 13 - 15 (no chapters 17-19
Plasma membrane is
selectively permeable
Proteins in plasma membrane:
Ion channels
transporters
pumps
Movement with concentration gradient =
passive diffusion
movement against concentration gradient =
active transport
Facilitated diffusion has to what?
Bind to a receptor
Active transport uses what?
energry
Random movement powered by concentration gradient
diffusion
Diffusion is moving toward
equilibrium
Diffusion of 1 substances does not interfere with what?
diffusion of another substance in the same solution
Net movement of diffusion depends on what?
1) concentration gradient
2) particle size
3) permeability of the compound in the barrier it is trying to cross
The two types of diffusion are?
- simple/passive
2. facilitated
Simple/passive diffusion requires a carrier protein. (T/F)
False (no carrier protein interaction)
Facilitated diffusion requires what?
A carrier protein
What type of diffusion can use pores or channels?
Simple/passive diffusion
This type of diffusion binding occurs.
Facilitated Diffusion
Diffusion of lipid-soluble molecules through a lipid bilayer depends on?
lipid solubility
What molecules are highly lipid soluble & able to diffuse through lipid bilayer?
O2, N2, CO2, alcohols
Rate of diffusion is dependent on what?
The degree of lipid solubility
Pore channels are available for what?
small molecules to pass through
_____ ______ and _____ ______ on amino acids determines selectivity of passage.
Pore diameter & electrical charges
Two types of gating of protein channels?
Voltage gating and chemical gating
Sodium channels & potassium channels open when?
&
This is an example of what type of gating?
Inside cell membrane becomes positively charged
Voltage gating
With chemical gating what may open or close the gate?
Binding a molecule
Also known as carrier-mediated diffusion
facilitated diffusion
Facilitated diffusion transport proteins sometimes called
permeases
Each carrier protein has a specific ____ for ____ a molecule
affinity, binding
The affinity for binding a molecule is measured by
Km
Facilitated diffusion can max out _____ if all available transport proteins are ____ to substrates
transporters, bound
Vmax is?
When transporters are maxed out
Addition of more substrate (solute) will not make facilitated diffusion go faster when it is maxed out of transporters. (T/F?)
True
When Vmax occurs carrier proteins are
saturated
Facilitated diffusion deals with movement of ____ and most ____ ___
glucose, amino acids
Rate of solute transport is measured by?
1/2 Vmax
Km =
solute concentration that will give 1/2 Vmax
Saturation of carrier protein reflected by leveling off of rate of transport is the?
Vmax
What is the transfer of liquid through a semipermeable membrane that does not allow solutes to pass?
Osmosis
With osmosis, water passes through _____ (____ ___) in plasma membranes
aquaporins (water pores)
Osmoses moves from ____ concentration to ___ concentration.
high, low
Net movement of water is?
Usually zero
Changes in solute concentration does not impact water movement (T/F)
False
Net movement of water occurs to area of ____ free water
less (higher concentration of solute)
Goal of osmosis is what?
Equalize concentration of solutes on both sides of barrier
Pressure applied to stop the flow of water to side of highest solute concentration is known as?
Osmotic pressure aka hydrostatic pressure
The hydrostatic pressure is the pressure applied to the ____ to ___ the flow of water
chamber, stop
Lower solute concentration ____ osmotic pressure
lower
What causes osmotic pressure differences on each side of the barrier?
differences in solute concentration
When the osmotic pressure is the same in the inside & outside of the cell?
isotonic
In relation to cell volume, hypotonic does what?
- osmotic pressure is greater in cytosol
- movement of water into the cell
- increases cell volume
In relation to cell volume, hypertonic does what?
- osmotic pressure is greater in extracellular fluid
- movement of water out of the cell
- cell will shrink
Isotonic, no volume change (T/F)
True
Hypotonic, cell volume ____ & may ____
increases, burst
Hypertonic cell volume increases (T/F)
False
Effects of solutions on cells: Cells with a cell wall that are hypertonic are _____?
plasmolyzed
Effects of solutions on cells: Cells with a cell wall that are isotonic are _____?
flaccid
Effects of solutions on cells: Cells with a cell wall that are hypotonic are _____?
turgid
Intracellular fluids primary cation
K+
Extracellular fluids primary cation
Na+
There is more what in intracellular fluid vs. extracellular fluid?
K+, Mg2+, Phospates, Amino acids and proteins
Intracellular fluid pH =
7.0
Intracellular fluid buffer
proteins
There is more what in extracellular fluid vs. intracellular fluid?
Na+, Ca2+, Cl- and glucose
Extracellular fluid pH =
7.4
Extracellular fluid buffer
HCO3
Active transport requires energry as ____ in primary active transport
ATP
Carrier protein in Active transport is necessary, called _____ in primary active transport
ATPases
The movement of ions makes ion gradient powering what?
secondary active transport
Types of active transport?
Primary & Secondary
Primary active transport pumps: P-class
Ions (Na+, K+, Ca^2+, H+)
ex. sodium-potassium ATPase
Primary active transport pumps: F-class
Protons (H+)
ex. ATP synthase in mitochondria
Primary active transport pumps: V-class
Protons (H+)
Maintains low pH in lysosomes
Primary active transport pumps: ABC-class
Ions, drugs
Ex. cystic fibrosis transmembrane regulator (CFTR)
Important feature for sodium-potassium pump it to ____ ____ ____
control cell volume
Without the ___ pump the cell would swell until it burst
sodium-potassium pump
2 subunit carrier protein for sodium-potassium pump?
a & b
___ binding sites for sodium on the inside of the cell
3
___ binding sites for potassium on the outside of the cell
2
Inside the cell near Na+ binding has _____ activity
ATPase
Highly active cells (nerves) may devote 60-70% of cells’ energy to what?
sodium-potassium pump
___ is maintained at very low concentration in cytosol
calcium
2 types of Ca pumps?
1 located in the cell membrane & pumps Ca out of the cell
1 pumps Ca into endoplasmic reticulum or mitochondria
Both Ca pumps act as?
ATPases
Hydrogen pumps (aka proton pumps) are located in?
Parietal cells of gastric glands in stomach
renal tubules
Parietal cells of gastric glands in stomach….
secretes H+ that can combine with secreted Cl- to form HCL in stomach
Renal tubules functions:
Large amounts of H+ are secreted from the blood into the urine
Has a buffering function
Secondary active transport is broken up into?
Co-transport (symporters)
Counter-transport
antiporters
Secondary active transport is not driven by ____, but instead by what?
ATP, Ion concentration gradient
Secondary active transport: transporters do not have what?
ATPase activity
Coupled transport includes?
symporters and antiporters
This, transports molecules in the same direction across plasma membrane
symporters
With symporters, Molecule 1 is move with the gradient [high to low] (T/F)
True
Symporters, molecule 2 is actively transporters _____ the concentration gradient
against (low to hight)
(Sodium-glucose transporter) Glucose is actively taken up from
gut
(Sodium-glucose transporter) Glucose is passively released for use by
other tissues
Step 1. active transport
Sodium binds carrier protein
Step 2. active transport
Compound binds carrier protein
Step 3 active transport
carrier protein releases sodium & compound inside enterocyte
Step 4: active transport
Sodium is pumped out of enterocyte and potassium is pumped in using ATP
Antiporters transport molecules in the ______ direction across plasma membrane
opposite
Antiporters: Molecule 1 is moved against the gradient (high to low) into the cell (T/F)
False (moved with)
Antiporters: Molecule 2 is what?
moved out of the cell
Co-transport uses
glucose and amino acids
counter-transport uses
calcium and hydrogen
All P-class pumps are phosphorylated on
aspartate
V-class pumps maintain what?
low pH in lysosomes
Glucose transport occurs by ____ ____ through most of the body & ____ ____ ____ in small intestine & kidneys
facilitated diffusion, secondary active transport
Active transport of glucose is used when?
Glucose concentration in cell is higher than extracellular space
A type of secondary active transport?
Sodium-glucose transport proteins (SGLT)
Where does active transport of glucose happen?
Choroid plexus
Proximal tubules of kidney
brush border epithelial cells of the small intestine
GLUTs transport glucose from ___ to ___ concentration
high, low
Facilitated transport of glucose: rate of transport varies based on:
Glucose available & number GLUT proteins
Facilitated transport of glucose: is able to transport…
both directions across membranes
GLUT2 transports
glucose, galactose & fructose out of the cell & into the portal blood
Insulin-Insensitive facilitated transport of glucose is found in ____ ____
most tissues
Insulin-insensitive facilitated transport of glucose requires…
concentration gradient of glucose
Insulin-insensitive facilitated transport of glucose uses
GLUT 1, 2, & 3
Insulin-insensitive facilitated transport of glucose is found in
RBC, WBC, liver, brain cells, etc.
Insulin-sensitive facilitated transport of glucose is found in
skeletal muscle, adipose tissue
Insulin-sensitive facilitated transport of glucose uses
GLUT 4
Peptide hormone secreted from the ___ of the islets of langerhans in the pancreas
B cells
Insulin is secreted in response to
glucose & amino acids in the blood
Insulin is inhibited by
epinephrine
How many GLUTs are there, and how many are involved with glucose transport?
14, 11
Insulinotropic amino acids
leucine, phenylalanin, tyrosine, arginine
Required to get glucose out of blood and into muscle and/or adipose tissue
Insulin
Insulin transports glucose, amino acids, and ____ into insulin-sensitive cells
potassium
Anabolic function of insulin?
Increases stores of carbs (glycogen), fat (adipose tissue) and protein (muscle)
Within minutes insulin stimulates
Protein synthesis, stimulates glycolysis and glyocogen synthesis, inhibites phospohorylase and glucogenic enzymes
Effects of insulin on Adipose tissue (increases)
- glucose entry
- fatty acid synthesis
- glycerol phosphate synthesis
- tryglyceride deposition
- activation of lipoprotein lipase,
- K+ uptake.
Effects of insulin on adipose tissue (decreases)
hormone-sensitive lipase
Effects of insulin on muscle tissues: (increases)
- glucose entry
- glycogen synthesis
- amino acid uptake
- protein synthesis
- ketone uptake
- K+ uptake
Effects of insulin on muscle: (decreases)
- protein breakdown
- release of glucogenic amino acids
Effects of insulin on liver tissues: (increases)
- lipid synthesis
- protein synthesis
Effects of insulin on liver tissues: (decreases)
ketogenesis and glucose output
GLUT2 located in
pancreatic beta cells
GLUT2 is in charge of
releasing insulin to blood
GLUT2 has ____ affinity for glucose
low
Normal blood glucose is
5mM
Insulin is not secreted until blood glucose is
> 5 mM
Muscle: Insulin binds to
insulin receptor
Muscle: Insulin receptor ____ get recruited to the receptor
substrate 1 (IRS-1)
Muscle: IRS-1 begins a signal transduction cascade to tell ____ to make ____
golgi complex, GLUT4
Muscle: GLUT4 is translocated from golgi complex to the….
plasma membrane
Muscle: Glucose is able to enter muscle and ____ for use or storage
adipocytes
Muscle: once insulin levels decrease, GLUT4 are removed from plasma membrane by ____
endocytosis
Muscle: Vesicles fuse to form an organelle celled the ____
endosome
Type I diabetes
beta cells are destroyed (no insulin is released)
treatment for type I diabetes
exogenous insulin
type II diabetes
- insulin resistance
- insulin regulation of GLUT2 does not function in insulin-resistance
type II diabetes treatment
can be reversed with diet and exercise
Insulin resistant muscle cell, excess inflammation (C-reactive protein [CRP]) abnormally ______ IRS-1 causing it not to signal properly
phosphorylates
Intestinal apical GLUT2 diabetes
insulin resistance due to high carb or high saturated fat diet. This leads to increase in GLUT2 and loss of insulin regulation