Download Transport Within Cells

BIO 2 GO!
3211, 3212
Transport Within Cells
One of the major problems for a cell is how to get food into and
waste materials out of the cell.
Upon successful completion of this unit, you should be able to do the following:
1. Describe and explain the basic function of cells.
2. Distinguish between a unicellular and multicellular organism.
3. Describe and explain how food gets into and waste materials get out of a
typical cell.
4. Describe and explain how the circulatory system works in most animals.
5. Describe and explain how the vascular system works in most plants.
6. List, describe, and explain the 4 ways that cells get materials through a
membrane.
7. Describe and explain each of the following: diffusion, osmosis, facilitated
diffusion, active transport.
8. Explain the role of ATP in active transport.
9. Be able to use the following words in correct context and understanding:
cell
diffusion
osmosis
passive transport
active transport
ATP
facilitated diffusion
high concentration
low concentration
circulatory system
vascular system
waste
transport
Transport Within Cells
3211, 3212
Cells
All living things, all plants, animals, and humans, are composed of cells. A cell is
the smallest living unit of matter. They are membrane covered structures that
contains all of the materials necessary for life. You are composed of cells. Some
living organisms are only 1 cell. They are called unicellular. There are both plants
and animals that are unicellular. Most plants and animals, including humans are
multicellular which means they are made of more than 1 cell.
In a multicellular organism, there are many different types of cells with
different functions. For instance, there are skin cells, muscle cells, and nerve
cells. They all have a different function. Usually cells work together, like the
muscle cells that make your heart work. Sometimes, cells act alone, such as a
unicellular organism.
REMEMBER THIS !!!
All living things are made from 1 or more cells.
work alone, sometimes they work together.
Sometimes the cells
Interesting Scientific Fact: You are composed of trillions of cells. So is a tree.
Question 1. What is a simple definition for a cell?
Question 2. What is the difference between a unicellular and a multicellular
organism?
Transport problem:
One of the problems for cells is how to get food into and waste materials out
of the cell. For most cells, the nutrients and gasses (O2 or CO2) are brought to
and wastes removed from them by either the circulatory system for animals or
vascular system for plants.
Once a food has been delivered to a cell, it still has to go through the cell
membrane which surrounds each cell. The same for the waste as it leaves the cell.
Living things have 2 types of transportation that are important to each cell:
1) Getting nutrients and gasses to the cell and waste away from the cell
2) Getting nutrients and gasses into the cell and waste out of the cell.
Transport- Getting nutrients to the Cell:
It is important for living things to be able to get food, gasses, and water to each
cell and waste materials away from each cell. In animals, this is accomplished by
the circulatory system. In plants, this is accomplished by the vascular system.
Circulatory System: (animals)
In most animals, food, gasses, and water are delivered to each cell by the
circulatory system. In humans and most large animals, the circulatory system is a
series of tubes (arteries and veins) that contain a fluid (blood) which is pushed
through the tubes by a pump (heart). The heart is a pump which moves the blood
through the arteries and veins so that the food and water reach every cell and the
cell wastes are taken away from every cell.
Vascular System: (plants)
The vascular system in plants is very similar to the circulatory system in
animals. Its job is to transport food and water to the cells and cell wastes
away from each cell.
In both the circulatory system and the vascular system, specialized cells
allow the flow of food, gasses, water, and waste in all directions. Without
these specialized cells, gravity would determine the direction of flow and would
seriously limit the growth of all plants and animals. In humans, the specialized
cells become organs like the heart and blood vessels. In plants, the specialized
structures are call xylem, for carrying water and phloem for carrying food.
REMEMBER THIS!!!
The circulatory system in animals and the vascular system in plants are
responsible for bringing food and water to every cell and removing the cell’s
waste from each cell.
Interesting Scientific Fact: The transport systems allow plants and animals to
reach large sizes. Without transport systems, no plant or animal could be very tall
because food and water could not be transported against the pull of gravity.
Question 3. What are the transport problems faced by all living things?
Question 4. What are the specialized transport structures found in humans and
large animals that compose the circulatory system? What is the function of each?
Question 5. What are the specialized transport structures in plants. What is the
function of each?
Transport - Getting into and out of a cell:
Every cell is surrounded by a cell membrane. Remember! A cell membrane
is made with phospholipids, a special type of lipid. The purpose of a cell
membrane is to:
1) Hold the contents of the cell
2) To control what goes into and out of a cell. By regulating what enters and
exits the cell, the membrane helps the cell maintain homeostasis: pH,
temperature, and water balance.
Because of this, getting food and water into a cell and the cell’s waste out of the
cell is a problem for all cells.
Before you can understand diffusion and osmosis, you must understand that
solutions are made up of a type of solute (like salt) dissolved in a solvent (like
water). Think of the solute as the dissolve and the solvent as the dissolver.
Concentration refers to the amount of solute or solvent in a solution.
A concentration gradient is the difference in concentration of a solute or solvent
between one area and another area. Molecules always move, or diffuse, down a
concentration gradient like a ball rolls down a hill.
Question 6. Describe the two parts of a solution?
Question 7. In a saltwater solution, identify the solute and the solvent.
Question 8. What does concentration mean, and how does it affect the diffusion
of molecules?
There are 4 ways that cells use to get materials through their membrane:
1. Diffusion
2. Osmosis
3. Facilitated diffusion
1. Diffusion:
Diffusion and osmosis are similar. In both cases, materials move through a cell
membrane from a high concentration to a lower concentration. In diffusion, the
materials that move through the cell membrane are wastes (like CO2), nutrients
(like glucose or sugar), minerals (like salt or potassium), and vitamins.
Question 9. Describe what happens in diffusion.
2. Osmosis:
Osmosis is similar to diffusion, except osmosis only refers to the movement of
water. Osmosis is the movement, or diffusion, of water through a cell membrane
from an area of high WATER concentration to an area of lower WATER
concentration.
REMEMBER THIS!!!
Osmosis and diffusion move materials through a cell membrane from an
area of high concentration to an area of lower concentration. Osmosis refers
to the movement, or diffusion, of water through a cell membrane.
Question 10. Describe what happens in osmosis.
3. Facilitated Diffusion:
Some molecules are either too large to fit through the membrane, or they are
polar and cannot diffuse through the mostly non-polar membrane. These molecules
need the help of specialized proteins gates within the membrane. When this
happens it is called facilitated diffusion. Facilitate means “to help”. So in
facilitated diffusion, the protein gates help larger and polar molecules across the
membrane.
Interesting Scientific Fact: Osmosis, diffusion, facilitated diffusion do not
require any energy from the cell. This is why these are forms of PASSIVE
TRANSPORT. However, if they were to stop, the cell would die.
Question 11. What helps molecules across the membrane during facilitated
diffusion. Why do these molecules need help?
SUMMARY
Transport Within Cells
Everything that moves into or out of a cell must go through the cell
membrane. The cell membrane is made of two layers of lipid molecules with
proteins in it. When molecules move from an area of higher concentration to an
area of lower concentration across the membrane, it is called diffusion. It
occurs without the cell spending any energy. When water diffuses through the cell
membrane from an area of high concentration to an area of low concentration, it
is called osmosis.
Some molecules can diffuse through the proteins found in the cell
membrane. This is called facilitated diffusion.
Diffusion, osmosis, and facilitated diffusion do not require energy from
the cell. Together, they are referred to as passive transport.
Sometimes a cell must force molecules into or out of the cell, and use energy
to do it. When a cell uses energy (ATP) to move something across its membrane,
it is called active transport.
Transport Within Cells
Test Yourself
Matching
____1. diffusion
___ 2. osmosis
___ 3. facilitated diffusion
___ 4. passive transport
____5. solution
a. the diffusion of water
b. mixture of a solute and solvent
b. the movement of a solute from an area of high
concentration to an area of low concentration
c. diffusion of molecules through special protein
gates in a cell membrane
d. osmosis, diffusion, facilitated diffusion
True or False
____ 1. Everything that moves into or out of a cell must go through the cell
membrane.
____ 2. Molecules cannot move between the lipid molecules in a cell membrane.
____ 3. Small, nonpolar molecules can move between the lipid molecules in a cell
membrane through simple diffusion without help
____ 4. A cell membrane is made of phospholipid molecules with proteins
embedded.
____ 5. A cell membrane is made proteins
____ 6. Diffusion occurs when molecules move from an area of high
concentration to an area of low concentration.
____ 7. Diffusion occurs when molecules move from an area of low
concentration to an area of high concentration.
____ 8. Diffusion occurs without the cell using energy.
____ 9. Osmosis is the diffusion of water.
Fill in the Blank –
passive transport
low concentration
small
high concentration
Some words may be used twice.
diffusion
phospholipids
proteins
large
osmosis
facilitated diffusion
energy
1. A cell membrane is made of two layers of ________________ with
________________ embedded.
2. If molecules are ____________ and nonpolar, they may be able to move
between the lipid molecules.
3. If molecules are _____________ , they may be able to move through
__________________________ in the cell membrane. This process is
called
__________________________.
4. _______________________ is the movement of molecules from an area of
______________________ to an area of ________________________.
5. ____________ is the diffusion of water through a cell membrane.
6. Diffusion, osmosis, and facilitated diffusion are called
__________________ _______ because none of these processes requires
energy.
7. Sometimes a cell must expend __________ ____ to move molecules in or out of
a cell.
8. A cell must expend energy when it must move substances from
__________________________ to a ___________________________.
Answer the Following
1. Describe what the cell membrane is made out of.
2. What is diffusion? What kinds of molecules use diffusion?
3. What is osmosis? What is the only molecule that used osmosis?
4. What kinds of molecules need facilitated diffusion to get across the cell
membrane and HOW do they get across?
5. List and explain the problems with the transport of materials both to and from
cells and into and out of cells.
6. List and explain 3 ways the cells transport materials.
Transport Within Cells
Answer Sheet
Question 1. What is a simple definition for a cell?
Question 2. What is the difference between a unicellular and a multicellular
organism?
Question 3. What are the transport problems faced by all living things?
Question 4. What are the specialized transport structures found in humans and
large animals that compose the circulatory system? What is the function of each?
Question 5. What are the specialized transport structures in plants. What is the
function of each?
Question 6. Describe the two parts of a solution?
Question 7. In a saltwater solution, identify the solute and the solvent.
Question 8. What does concentration mean, and how does it affect the diffusion
of molecules?
Question 9. Describe what happens in diffusion.
Question 10. Describe what happens in osmosis.
Question 11. What helps molecules across the membrane during facilitated
diffusion. Why do these molecules need help?
Question 12. What is the main difference between passive and transport? What
are the three kinds of passive transport?
Question 13. Why does active transport require energy?