Unit 1: Cells and Proteins 1 Flashcards
The three main roles of membrane proteins are:
- Movement of molecules across membrane - Transmission of extracellular signals - Detecting and amplifying stimuli
Can it pass through the membrane?
Hydrophobic molecules
Yes!
Can it pass through the membrane?
Steriod Hormones
YES!
Can it pass through the membrane?
Small uncharged polar molecules
YES! (Slowly)
Can it pass through the membrane?
Larged uncharged polar molecules
NO!
Can it pass through the membrane?
Ions
NO!
What molecules pass through the membrane the easiest?
Smaller, less hydrophillic molecules
Give an example of a hydrophobic molecule
Oxygen, Nitrogen
Give an example of a steriod hormone
Testosterone
Give an example of a small uncharged polar molecule
WATER!
Give an example of a large uncharged polar molecule
Glucose
Proteins that span the membrane are called
TRANSMEMBRANE PROTEINS
There are two types of transport proteins:
Channels and Transporters
Are channels active or passive?
PASSIVE
Are Transporters active or passive?
BOTH!
Channel proteins tend to be gated, by:
Ligands or Voltage gated
A transporter becomes active when molecules are being moved from a low concentration to a
high concentration
From left to right, name the transport
Diffusion, Channel, Transporter (Passive), Transporter (Active)
Concentration gradient + Charged molecules =
Electrochemical Gradient
The electrochemical gradient does what?
Creates a charge on the membrane surface which either helps or hinders transport of molecules.
In this example, do you think the charge on the membrane created by the electrochemical gradient helps or hinders transport ?
It helps! Since the postive molecules are attracted to the negative charge on the inside of the membrane
In this example, do you think the charge on the membrane created by the electrochemical gradient helps or hinders transport ?
Hinders! The positive molecules are not attracted to a postive membrane, so they have no pull towards the inside of the cell.
Objective: Decrease pH of endomembranes compartments, how is this accomplished?
Proton pumps, pump H+ which acidifies the lumen
Objective: To pass on nerve impulse
Method: 1. Ion gated channel at muscle synapse…
- opens to neurotransmitter
- Change in membrane potential
- Chemical signal generates an electrical signal which passes along the nerve.
