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Notes: Cell MembraneI. Introduction:
A basic principle in biology is that all living things are made of ________________.
While they come in a wide variety of sizes and shapes, all cells are filled with ________________, a
fluid filled inside (made up mostly of _________________) and are surrounded by a cell membrane.
A. The cell membrane, also known as the ____________________ ____________________, is the boundary that separates all living cells from their nonliving surroundings. The job of this membrane is to:
1) ________________ the cell from the outside environment
2) control chemical _______________ into & out of the cell (decides what can enter & leave).
It is described as being __________________ ___________________ which means it allows some substances to cross more easily than others.
B. In 1972 S.J. Singer and G.L. Nicolson created the ______________ ________________ Model, which describes the structure of the cell membrane (shown below).
1) The cell membrane is made up of three main types of organic compounds:
__________________________ (phospholipids make up most of the cell membrane)
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__________________________ (large/dark structures… act as gateways)
__________________________ (look like antennae… these are ID tags)
2) The cell membrane is not solid, rather it is _____________________ and fluid*
3) By creating a barrier between the cell and its environment, it allows the cell to maintain
___________________________ (internal balance).
*If cell membranes were solid, molecules such as oxygen and water would not be able to move into/out of the cell very easily.
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II. Parts of the Fluid Mosaic Model (the Cell Membrane)Compound Main function(s) Additional info:
Lipids
Many _______________________ bond together make up the majority of the cell membrane.
The heads are water-soluble
(hydrophilic =_________ ________).
The tails are not water soluble
(hydrophobic = _________ __________)
The phospholipids line up ________ to ________
to form a _________________(double layer).
The hydrophobic tails are protected from the water on the inside and outside of the cell.
_________________________ - is a lipid that helps hold the cell membrane together.
Proteins
Primary Function: To control chemical ____________ in & out of the cell.
Integral proteins pass ____________________ the lipid bilayer … They allow large and/or charged molecules get
into or out of the cell.
Proteins are also used to receive ______________ ______________ from outside the cell.
Hormones have a specific shape and travel through the blood until they find their ‘target cell’.
Peripheral proteins located on the _______________ of the cell membrane.
Carbohydrates
These “antenna’ are used by the cells to help ________________ one another.
Nicknamed the cell’s ________ _________; These are unique for each person; Determine things like your ___________ ____________.
Can attach to the ____________________ or the ____________________ on the outer surface of a cell.
Match the cell membrane structure or its function with the correct letter from the diagram below.
1. _______ protein (only)
2. _______ surface carbohydrates (only)
3. _______ lipid bilayer
4. _______ phosphate head
5. _______ fatty acid tail
6. _______ involved in cell-to-cell recognition (a cell ID tag)
7. _______ glycoprotein (carbohydrate attached to a protein)
8. _______ glycolipid (carbohydrate attached to a lipid)
9. _______ involved in moving large material across the membrane
10. __E____ Cholesterol (a type of lipid)…helps hold the membrane together.
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Cell Membrane Diagram and QuestionsDirections: Pictured below is the cross section of a typical cell membrane. Use the numbers and terms to label and color each part. Terms 1-4 with a next to them should also be colored on the diagram. By the time you have finished, all parts of the membrane should be colored in and all numbers should be labeled.1. Phospholipid (two parts) Two kinds of Proteins: 4. Carbohydrates 1a. head (hydrophilic) 3a. Integral protein 1b. tail (hydrophobic) 3b. Peripheral protein2. Cholesterol (another lipid) The opening in the middle of the protein is called the protein channel
Use the above diagram AND your notes to answer the following questions.1. The ___________________ _________________________ separates the cell from its surroundings.
2. The cell membrane is made up of three of the four organic compounds, they are
_______________________, __________________________ and ______________________________.
3. Which of type of organic compounds makes up the majority of the cell membrane? __________________.
4. The heads of the phospholipids are _________________________ which means they are water loving.
5. The tails of the phospholipids are _________________________ which means they are water fearing.
6. The cell membrane is also called the ____________________ ________________________ model.
7. How many layers make up the cell membrane? _______________________________________________
8. What type of compound forms channels that allow large molecules to pass through the membrane?
___________________________________________________________________________________
9. Which type of compound acts as an identification marker? _____________________________________
10. What are the primary functions of the cell membrane?
a. _______________________________________________________________________________
b. _______________________________________________________________________________
)
Notes: Passive movement of material across the cell membrane (Part 1)Differences in concentration:
Concentration of a solution is determined by the amount of _________________ (dissolved material) you have in the amount of __________________________ (liquid its dissolved in).
The glass on the left does not have an equal concentration throughout. The bottom of the glass is more concentrated than the top (which is dilute).
If left alone, the molecules will spread out in the glass until the concentration is equal throughout the glass (like the glass on the right).
IMPORTANT TERMS TO KNOW: ____________________ – a solution with a higher concentration than another solution. ____________________ – a solution with a lower concentration than another solution. ____________________ – a solution that has an equal concentration to another.
Passive Transport – the movement of material across a cell membrane without the use of energy. Three types of passive transport include:
o Diffusion, osmosis & facilitated diffusion1. DIFFUSION
_________________________ - The process in which molecules of a substance move from areas of higher concentration to an area of lower concentration.
_________________________ is reached when the concentration is equal throughout.
How does diffusion affect a cell? Cell membranes are described as being _________________ ___________________ which means they allow
some substances to pass through, but not others. The oval represents a _________________________
The dotted line is the ________ ___________________
Dots in the diagram are ____________________ (dissolved material)
In the first picture, the solution ______________ the cell has a higher solute concentration than the solution _______________ of it.
Therefore we say the inside is _________________________ to the outside of the cell.or the outside is _________________________ to the inside of the cell.
When the solute is small enough to pass across the cell membrane:1. It will move from a high concentration to a low concentration. Draw an arrow on
the “before” diagram to show if the solute would move in or out of the cell.
2. Always label your arrows (with words like dots, solute, etc) so that you know what is moving across the cell membrane.
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Before diffusion
Goal of diffusion
Before facilitated diffusion
2. FACILITATED DIFFUSION (Facilitate = to ____________________) Facilitated diffusion - molecules are moved across a cell membrane from an area of higher
concentration to lower concentration with the help of a ______________ ______________. Proteins are usually needed to move solute across the cell membrane when the
solute is too __________ or _______________ and can’t pass between the phospholipids.
The carrier protein or channel simply opens up a larger hole in the cell membrane and allows the solute to flow from one side of the cell membrane to the other (does not require ___________).
Practice Problems: Understanding Passive Transport
When answering the questions, consider the following information: The oval in each diagram below represents a cell. The black line around the oval is the cell membrane. The space between the dots represents the water (solvent) that the solute is dissolved in. The solute (dots) AND solvent (water) is small enough to pass across the cell membrane.
Cell #1 Cell #2 Cell #3CONCENTRATION DIFFERENCES:1. The solution outside cell #1 has a/an (higher; lower; equal) concentration of solute compared to the solution inside the cell.
2. The solution outside cell #1 is (hypertonic; hypotonic; isotonic) to the solution inside the cell.
3. The inside of cell #1 is (hypertonic; hypotonic; isotonic) to the solution surrounding it.
4. The solution outside cell #2 has a/an (higher; lower; equal) concentration of solute compared to the solution inside the cell.
5. The solution outside cell #2 is (hypertonic; hypotonic; isotonic) to the solution inside the cell.
6. The inside of cell #2 is (hypertonic; hypotonic; isotonic) to the solution surrounding it.
7. The solution outside cell #3 has a/an (higher; lower; equal) concentration of solute compared to the solution inside the cell.
8. The solution outside cell #3 is (hypertonic; hypotonic; isotonic) to the solution inside the cell.
DIFFUSION:
9. If diffusion was to occur to cell #1, in which direction would most of the solute be moving? (into /out of) the cell.
10. If diffusion was to occur to cell #2, in which direction would most of the solute be moving? (into /out of) the cell.
11. Describe what happens to the movement of solute for cell #3. ___________________________________________________
12. Due to the process of diffusion, the solute or dissolved material tries to move from an area of higher concentration into an area of lower concentration (someplace where it can spread out more). According to this statement, which of the above cells would lose the most solute due to diffusion? (CELL #1, CELL #2, CELL #3)
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Goal of osmosis
Notes: Passive movement across the cell membrane (continued)
Osmosis - The diffusion (movement) of _______________ molecules across a selectively permeable membrane. Since it does not require any energy – it is also a form of PASSIVE TRANSPORT.
The goal of the water molecules is to get the substance on either side of the membrane to be at ________________ (same concentration throughout).
Below we see a concentration _____________________ (difference) between the inside and the outside of the cell. The dots are solute (sugar)
The ____________________ is represented by the space around the dots.
Since water is a ____________________ molecule, it is able to move across the cell membrane very quickly.
Water moves from an area with more water (lower solute concentration) into an area that has less water (a higher solute concentration) to dilute it.
HOW DO CELLS RESPOND TO BEING PLACED INTO SOLUTIONS OF DIFFERENT CONCENTRATIONS:
___________________________ – the bursting of an animal cell when placed in a hypotonic solution.
___________________________ – the force that pushes out on a plant’s cell wall when it is placed into a hypotonic solution.
___________________________ – the shrinking of a plant cell placed in a hypertonic solution.
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Before Osmosis
Ani
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Cel
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Cel
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Practice Problems: Osmosis1. Osmosis is the movement of ________________ across the cell membrane. The goal is to make the concentration on the
inside and outside of the cell the same.
2. The cells below have just been placed into 3 different solutions. Complete each column by using the picture at the top.
Cell #1 Cell #2 Cell #3Determine how osmosis would affect each
cell shown here.
What kind of solution is each cell in? (ISOTONIC, HYPOTONIC or HYPERTONIC)
If osmosis was to occur, which direction would water move? (IN, OUT or IN & OUT)
How will the cell change? Will it SHRINK, GROW or STAY THE SAME SIZE.
WHAT DOES THIS MEAN… For each statement, circle the appropriate word inside each set of parentheses.
3. Since an animal cell lacks a cell wall, it is important that it be surrounded by a/an (hypertonic; hypotonic; isotonic) solution, so that it does not shrink & shrivel up or swell & rupture due to the effects of osmosis.
4. If red blood cell is surrounded by a hypotonic solution, then the cell would most likely (shrink, swell or stay the same size).
5. When plant cells are full of water, the pressure within the cell pushes out onto the cell wall, thus allowing the cell to become more rigid (has turgor pressure). Since this is a good thing for them, plant cells should be surrounded by a/an (hypertonic; hypotonic; isotonic) solution.
6. If a plant is watered with saltwater (hypertonic), then the cells would most likely (shrink, swell or stay the same size).
7. The passive movement of large molecules across the cell membrane with the help of a protein channel is called (diffusion, osmosis, facilitated diffusion).
A red blood cell (RBC) is placed in 3 different solutions below. Then it was observed to see if the RBC changed.
Draw dots in/out of the cell to show what this would look like.
Question #1 Question #2
Did the red blood cell (RBC) change? _______
If the RBC did change, explain what happened to it?
What type of solution is found outside the red blood cell? Hypotonic Hypertonic Isotonic
Did the red blood cell (RBC) change? _______
If the RBC did change, explain what happened to it?
What type of solution is found outside the red blood cell? Hypotonic Hypertonic Isotonic
Did the red blood cell (RBC) change? _______
If the RBC did change, explain what happened to it?
What type of solution is found outside the red blood cell? Hypotonic Hypertonic Isotonic
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Passive Transport of Materials Across a Cell MembraneDirections: Use each diagram below to answer the questions about the movement of molecules across the cell membrane. To get full credit – you must show the direction of movement (into or out of the cell) by drawing an arrow on each picture!!!
The process taking place is diffusion The dots represent oxygen (O2).
1. What molecules are moving in this example? ______________2. Draw the arrows on the diagram above to show the direction of movement in this example.3. Why are the arrows pointing in that direction? ___________________________________________
The process taking place is osmosis The dots represent sugar molecules
4. What molecules are moving in this example? ______________5. Draw the arrows on the diagram above to show the direction of movement in this example.6. Why are the arrows pointing in that direction? __________________________________________
The process taking place is facilitated diffusion The dots represent Calcium ions (Ca+)
7. What molecules are moving in this example? ______________8. Draw the arrows on the diagram above to show the direction of movement in this example.
The process taking place is osmosis The dots represent starch molecules
9. What molecules are moving in this example? ______________10. Draw the arrows on the diagram above to show the direction of movement in this example.
The process taking place is facilitated diffusion The dots represent Sodium ions (Na+)
11. What molecules are moving in this example? ______________12. Draw the arrows on the diagram above to show the direction of movement in this example.
The process taking place is diffusion The dots represent oxygen (O2).
13. What molecules are moving in this example? ______________14. Draw the arrows on the diagram above to show the direction of movement in this example.
Page 9.
Notes: Movement of Material across the Cell Membrane…Active Transport
Active Transport – requires _______________ to get material across a cell membrane against a concentration difference (or gradient).
Substance are forced to move from an area of ______________ concentration into an area of
_______________ concentration (into a place that is already more crowded).
There are several different forms of Active Transport:
1. __________________ – a special type of ________________ _________________ that is used to
push molecules from an area of low concentration into an area of high concentration.
Ex: Sodium (Na+) and Potassium (K+) pumps.
2. _____________________– taking material into the cell, usually by forming pockets (called vesicles)
around the material (the cell membrane folds around something
outside of the cell).A. ______________________ – intake of large particles or cells
(solid material) through the cell membrane w/in a vesicle.
B. ______________________ – using a vesicle or pocket to take in liquid or dissolved substances (solutes).
3. _________________________ – A vesicle from inside the cell fuses with the cell membrane, releasing their contents into the external environment.
The _______________________________ prepares proteins to leave the cell by putting them in a vesicle.
The process taking place is Active Transport by a protein pump. The dots represent Na+ molecules
1. What molecules are moving in this example? ______________
Draw the arrows on the diagram above to show the direction of movement in this example.
2. Explain why the arrows are pointing in that direction?
Page 10.
Active Transport of Materials across a Cell MembraneUse each diagram below to answer the questions about the movement of molecules across the cell membrane.
A Pump is moving the material in this example.
The dots represent Calcium ions (Ca+); the space represents water
1. If a pump is moving material across the cell membrane, the pump requires ______________ to work
because it is trying to push molecules AGAINST / WITH (circle one) the concentration gradient.
2. Unlike passive transport, a pump is trying to make the concentration of the inside and the outside of
the cell EQUAL / UNEQUAL (circle one).
3. If active transport (a pump) is moving calcium in the above picture, which way is the calcium being
pushed? INTO / OUT OF (circle one) the cell. Draw the arrows on the diagram above to show the direction of movement.
4. Explain why you think the arrow should be point in that direction? ____________________________ __________________________________________________________________________________
The diagram to the left depicts phagocytosis by a white blood cell.
The large dot represents a bacteria cell; the space represents water5. Phagocytosis means _________________________________________________________________
6. That means that that something is moving ______________ (in to / out of) a cell.
7. What is going in/out of the cell in this example? ________________________________________
The process taking place is pinocytosis
The dots represent dissolved solute; the space represents water8. Pinocytosis means __________________________________________________________________
9. What is moving? _____________________ What direction (in/out)?__________________________
The process taking place is exocytosis
The dots (particles) represent proteins; the space represents water10. What direction is the ‘stuff’ moving? ____________Why? ________________________________
Draw the arrows on the diagram above to show the direction of movement in this example.
A Pump is moving the material in this example.
The dots represent starch molecules; the space represents water11. What is moving? ____________Why? __________________________________________________
Draw the arrows on the diagram above to show the direction of movement in this example.
Page 11.
Test Review: Cell Transport and Boundaries1. The cell is filled with a fluid filled cytoplasm made up mostly of _____________________________.2. Another term for the cell membrane is the _________________ membrane. 3. What are the functions of the cell membrane? __________________________________________
_______________________________________________________________________________4. This majority of the cell membrane is made up of _________________________ 5. The cell membrane is called a lipid ____________________, which means a double layered sheet,
which is seen to the right.6. What is the difference between the function of the proteins & carbohydrates attached to a cell membrane?
Proteins - ________________________________________________________________________Carbohydrates - ___________________________________________________________________
7. What does it mean that biological membranes are selectively permeable? ___________________________________________________________________________________________________
DIFFUSION THROUGH CELL BOUNDARIES:8. The cytoplasm of a cell is a solution of many different substances dissolved in ________________.9. To determine the concentration of a solution you must compare the amount of _________________
and the amount of ____________________. 10. A concentration _______________________ is the difference between the concentration of a
particular molecule in one area and the concentration in an adjacent area.11. The passive movement of material from a high to low concentration is called ___________________.
12. Is the solute moving from aLOW TO HIGH
concentration or a
HIGH TO LOWconcentration?
Would this be passive or active transport?
What specific type of transport is shown here?
OSMOSIS13. How is osmosis different than diffusion?_________________________________________________14. In order to survive, animal cells need to be surrounded by ________________________ solutions,
while plant cells need to be surrounded by _________________________ solutions.15. A hypertonic salt solution has a higher concentration of solutes than a blood cell. Explain what
happens when a blood cell is placed in a hypertonic solution. _____________________________________________________________________________________________________________
16. Water moves from an area with a _________ concentration to an area of ___________ concentration.
Matching:17. _____ Two solutions are isotonic18. _____ A solution is hypotonic19. _____ A solution is hypertonic
a. The solution has a higher concentration of soluteb. The solutions are the same strengthc. The solution has a lower concentration of solute
FACILITATED DIFFUSION
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20. Explain how facilitated diffusion is different from diffusion? ____________________________________________________________________________________________________________
21. What is the role of protein channels in facilitated diffusion? ________________________________________________________________________________________________________________
22. ____________ True or False. Facilitated diffusion does not require the cell to use energy.
ACTIVE TRANSPORT23. The energy-requiring process that moves material across a cell membrane against a concentration
difference is called __________________ _____________________.24. The energy needed to fuel active transport is provided by molecules of _____________________.25. True or False. All forms of active transport require transport proteins during the process.
Complete the table about the types of active transport.Type Description
Pumps 26.
Endocytosis 27.
Exocytosis 28.
29. Label the parts of the fluid mosaic model shown below. Labels should include: phospholipid bilayer, hydrophobic tail, hydrophilic head, integral protein, peripheral protein, carbohydrate, protein channel.
30. Label the four different arrows on your diagram with the letters A, B, C or D. Each arrow is meant to show a different process (you need to consider the direction of movement and how it’s crossing the cell membrane).
A. Diffusion B. Facilitated Diffusion
C. Osmosis D. Protein Pump
Page 13.
A solution with a 5% solute
concentration
A solution with a 20% solute
concentration
