Q1: Transport Mechanisms Flashcards
It refers to the movement of substances across the cell membrane.
Cell Transport
The most important feature of a cell’s phospholipid membrane is that they are ____________________, i.e., it has control over what molecules or ions can enter or leave the cell.
selectively permeable
True or False:
The permeability of a membrane is not dependent on the organization and characteristics of the membrane lipids and proteins.
False
True or False:
Cell membranes help maintain a state of homeostasis within cells (and tissues, organs, and organ systems) so that an organism can stay alive and healthy.
True
Types of Transport
- Passive Transport
- Active Transport
It involves the movement of material along a concentration gradient.
Passive Transport
It does not require the expenditure of energy.
Passive Transport
The net movement of molecules from a region of high concentration to a region of low concentration.
Simple Diffusion
This directional movement along a
gradient is passive and will continue until molecules become evenly dispersed (equilibrium).
Simple Diffusion
Molecules that will be able to freely diffuse across cell membranes (e.g. O2, CO2, glycerol).
Small and non-polar (lipophilic) molecules
The rate of diffusion can be influenced by a number of factors, including:
- temperature
- molecular size
- steepness of gradient
Main types of passive transport
- simple diffusion
- osmosis
- facilitated diffusion
The net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached).
osmosis
The diffusion of free water molecules and hence occurs from regions of low solute concentration.
osmosis
True or False:
In osmosis, solute will move to equalize the two solutions, because water cannot cross a cell membrane unaided.
False
In osmosis, water will move to equalize the two solutions, because solute cannot cross a cell membrane unaided.
True or False:
The movement of water across cell membranes and the balance of water between the cell and its environment are crucial to organisms.
True
The passive movement of molecules across the cell membrane via the aid of a membrane protein.
facilitated diffusion
It is utilized by molecules that are unable to freely cross the phospholipid bilayer (e.g. large, polar molecules and ions).
facilitated diffusion
Facilitated diffusion is mediated by
two distinct types of transport proteins namely:
- channel proteins
- carrier proteins
It uses energy to move molecules against a concentration gradient.
active transport
Active transport may either be generated by:
- primary active transport (direct hydrolysis of ATP)
- secondary active transport
The indirect coupling transport with another molecule that is moving along its gradient.
secondary active transport
Types of Solution
- Isotonic
- hypertonic
- hypotonic
A solution whose osmotic pressure is equal to that of the cell, no change will occur thus a balance is maintained.
isotonic solution
A solution whose osmotic pressure is greater than that of the cell.
hypertonic solution
It will cause water to leave the cell, thus the cell will shrink or crenate.
hypertonic solution
A solution whose osmotic pressure is lower that of the cell.
hypotonic solution
It will cause water to enter the cell, thus the cell will swell or hemolyze or even burst in animal cell.
hypotonic solution.
