Chapter 4 - Cells Exchange Materials Flashcards
What is meant by a fluid mosaic model?
Fluid - because the molecules of the cell membrane are flexible and constantly changing.
Mosaic because it is composed of many different kinds of molecules.
Explain and label the structure of the cell membrane
- composed of phospholipid molecules, which are lipids that contain a phosphate group.
- there are two layers of phospholipid molecules that are referred to as the bilayer.
- each molecule has a hydrophilic head (water loving) and a hydrophobic tail (water hating).
- there are many proteins that assist in the transport of material into and out of the cell.
Describe the four main functions of the cell membrane
A physical barrier - separates the cell cytoplasm from the cell’s surrounding environment.
Regulation of the passage materials - controls the movement of materials into and out of the cell.
Sensitivity - sensitive to molecules in the cells immediate environment.
Support - gives support to the whole cell.
What are the four main types of membrane proteins?
- receptor proteins
- channel proteins
- carrier proteins
- cell identity markers
What does differentially permeable mean?
Cell membranes are classified as differentially permeable because they allow particular ions and molecules to pass through but restrict the movement of others.
What are the differences between passive and active processes?
Active processes require energy because they are going from a low concentration of materials to a high concentration, where as passive processes do not because they do the opposite.
What is diffusion?
Diffusion is a passive process in which involves the spreading out of particles so that they are evenly distributed over the space available.
What is a concentration gradient?
A concentration gradient is the difference of concentrations in a particular space. The greater the difference in concentrations, the steeper the concentration gradient.
What are some substances that can undergo diffusion?
Alcohol, steroids, fat soluble substances, oxygen and carbon dioxide.
What is osmosis?
The diffusion of water across the concentration gradient.
What is a carrier - mediated transport?
There are two main types of carrier - mediated transport ; facilitated diffusion and active transport.
Some important characteristics of carrier mediated transport are
- carrier proteins are specific, they will only bind to a particular type of molecule.
- carriers can become saturated.
- carrier activity is regulated by substances such as hormones
Facilitated diffusion can transport glucose and amino acids.
Active transport can transport certain ions, glucose and amino acids.
What is Vesicular transport?
Vesicular transport is an active transport that transports materials via vesicles.
Exocytosis is when molecules from inside the cell are pushed to the outside by binding to the cell membrane.
Endocytosis is the opposite.
What is the difference between phagocytosis and pinocytosis?
Phagocytosis is the transport of solids where as pinocytosis is the transport of liquids.
