Download cell organelles

MIDDLETOWN HIGH
SCHOOL SOUTH
BIOLOGY
THE CELL AND TRANSPORT
BOOKLET 13
NAME: _________________________________
CLASS: _____________
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LEARNING OUTCOMES
Cell Variety
(a) There are variations in cell structure and different types of tissue
(b) There are different types of cells; prokaryotic and eukaryotic cells
(c) Unicellular organisms can be found.
(d) The structural similarities and differences between animal and plant
cells.
(e) The relationship of structure to function
Absorption and secretion of materials
(a) Diffusion Osmosis and Active Transport as cell processes
(b) Understand the terms/definitions Hypotonic, Hypertonic and Isotonic.
(c) State what happens to animal and plant cells when placed in these
solutions
(d) The structure and function of the plant cell wall.
(e) The structure and function of the cell membrane
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EUKAROTIC CELLS
•
All living things are composed of cells
•
Cells are the basic units of structures and function in living things
•
All cells come from preexisting cells.
•
Eukaryotic cells include both plant and animal cells.
•
They are referred to as eukaryotic because they contain membrane
bound nuclei.
•
Prokaryotic cells include bacteria and their relatives.
•
These are usually unicellular organisms.
•
They are referred to as prokaryotic because they do not contain a
membrane bound nucleus.
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CELL ORGANELLES
Both plant and animal cells contain “mini organs” known as
organelles.
These organelles do specific jobs for the cell to ensure that normal
functioning occurs for the whole organism.
The diagrams below show the organelles present in animal and plant
cells. You should recognize most of these from previous topics.
Task 1: Collect the Cell Coloring
sheets from your teacher and
complete them both using this page
to help you.
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Task 2: Label the organelles in the diagrams below. Try to do this
without looking at the previous page.
Plant cell
THE FUNCTIONS OF CELL ORGANELLES
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Golgi apparatus
•
•
Packages and secretes complex molecules.
Form lysosomes
Secretory vesicles
•
Move to the surface of a cell and discharge their contents
Mitochondria
•
Site of aerobic respiration.
Chloroplasts
•
Site of photosynthesis.
Smooth endoplasmic reticulum
•
•
Large surface area for transport of lipids.
Detoxification of drugs, fat metabolism.
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Ribosomes
•
Site of protein synthesis.
Nucleus:
•
Controls cell activities and contains DNA and mRNA
Centrioles:
•
Involved in spindle fiber formation in meiosis/mitosis
Lysosomes
•
Contains powerful enzymes which digest redundant structures.
Cytoplasm:
•
Fluid in which many chemical reactions take place.
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Task 3: Complete the questions that follow. Make sure that you check
with your teacher to ensure you have the correct answers.
The following table contains a description of an organelle. Write in the
name of the organelle that matches the description.
Organelle
Description
I am surrounded by a doublemembrane, I am the site of respiration
reactions called the Krebs' cycle and
oxidative phosphorylation, I make
ATP. I evolved from bacteria many
millions of years ago. I have my own
DNA. What am I?
I am a membrane-bound organelle, I
am involved in preparing protein for
secretion, I am named after an Italian
scientist. What am I?
I am a membrane bound organelle, I
contain water and dissolved
substances, I enlarge if the cell is
placed in a hypotonic solution. What
am I?
I am a formed when the ends of Golgi
body pinches off, I move towards the
cell membrane, I contain protein that
is about to be secreted. What am I?
I am membrane-bound, I am studded
with ribosomes, I make protein that is
locked inside my centre. What am I?
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I am a small pore around the control
centre of the cell, I allow messages
used to make protein to get into the
cytoplasm. What am I?
I am not really an organelle, I am
flexible and surrounded by many
organelles. What am I?
I am used to separate chromosomes
during mitosis and meiosis; I am set
of two protein chains arranged at 90°
to each other. What am I?
I evolved from bacteria millions of
years ago, I have a part that absorbs
light and a part that turns carbon
dioxide into sugar, I contain the
pigment chlorophyll, I contain my own
DNA. What am I?
I am part of the nucleus, I make
ribosomes. What am I?
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THE PLASMA MEMBRANE
The cell membrane is not one solid piece. Everything in life is made of
smaller pieces and a membrane is no different.
Compounds called proteins and phospholipids make up most of the
cell membrane.
Scientists describe the organization of the phospholipids and proteins
as the fluid mosaic model. This is because the structure is not hard or
solid and the scattering of proteins throughout gives a mosaic effect.
That model shows that the phospholipids are in a shape like a head
and with two tails.
The heads like water (hydrophilic) and the tails do not like water
(hydrophobic).
The tails bump up against each other and the heads are out facing the
watery area surrounding the inside or outside of the cell.
The two layers of cells are called the bilayer.
There are various different proteins in the cell membrane. Some span
the entire length of the membrane and some are partially embedded on
one side.
One of the most important functions of proteins in the cell membrane is
to transport molecules into or out of the cell. There are two ways this
can happen
o Passive transport (does not require any energy)
o Active transport (does require energy)
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Task 4: Complete the questions that follow. Make sure that you check
with your teacher to ensure you have the correct answers.
1. Complete the descriptions in the diagram but adding in the appropriate
word.
2. What are the two components that make up a cell membrane?
3. Proteins transport substances into and out of the cell.
a. Name two substances that would be transported into a cell
b. Name two substances that would be transported out of a cell
4. What is meant by the term “passive transport”?
5. Where to cells get the energy from to transport molecules across a cell
membrane?
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6. Complete the diagram of a cell membrane using the labels below.
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TYPES OF TRANSPORT ACROSS THE CELL
MEMBRANE
DIFFUSION
Diffusion is the movement of molecules in a liquid or gas from high to
low concentration until they are evenly spread out.
Diffusion will stop when all the molecules are evenly spread out.
In animals, the gas oxygen diffuses into cells and the gas carbon dioxide
diffuses out of cells.
Other small molecules such as glucose and water also diffuse into our
cells, while waste products diffuse out of cells.
Diffusion is an important process to animals because it allows useful
substances to enter cells and harmful ones to leave.
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Task 5: Complete the questions that follow. Make sure that you check
with your teacher to ensure you have the correct answers.
1. Substances enter and leave cells by the process of
A
B
C
D
dissolving
evaporating
breathing
diffusing
2. Substances enter and leave cells by passing through the
A
B
C
D
nucleus
membrane
cytoplasm
vacuole
3. In diffusion, substances move from
A
B
C
D
high concentration to low concentration
high concentration to high concentration
low concentration to low concentration
low concentration to high concentration
4. Diffusion stops when molecules
A
B
C
D
are at high concentration
are a low concentration
are at even concentration
stop moving completely
5. In which diagram do the black molecules have the highest concentration?
A
B
C
D
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6. The diagram shows the concentrations of black molecules in four cells
Cell 1
Cell 3
Cell 2
Cell 4
In which direction will the black molecules diffuse?
A
B
C
D
From cell 1 to cell 2
From cell 2 to cell 4
From cell 4 to cell 3
From cell 3 to cell 1
7. Which of these can enter or leave cells by the process of diffusion?
A
B
C
D
carbon dioxide only
carbon dioxide and dissolved food only
oxygen and dissolved food only
oxygen, carbon dioxide, and dissolved food
8. Diffusion is important to animals. One reason is that
A
B
C
D
they breathe by diffusion
oxygen enters their blood by diffusion
blood moves by diffusion
carbon dioxide enters their cells by diffusion
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OSMOSIS
Selectively permeable membranes allow certain molecules to
pass through but not others.
Pores in the cell membrane are small,
so only small molecules such as
water, glucose, oxygen and carbon
dioxide can get through.
Large molecules such as starch
cannot pass through.
Osmosis is the special
diffusion of water from high
water concentration to low water
concentration through a selectively
permeable membrane.
CONCENTRATION GRADIENTS
•
Like the ball on the slope, water also moves down a gradient from high
to low
•
Solutions are made up of a solute dissolved in a solvent ex. sugar
dissolved in water.
•
Concentrations of the mass of solute are written in percentages.
Ex. 1 % sugar solutions contain 1% sugar as the solute and 99% water
as the solvent.
Selectively permeable membrane
•
Water moves down a concentration gradient by
osmosis from high to lower water
concentration. The water will stop moving
when the two concentrations are equal.
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Water
Sugar molecule
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WATER CONCENTRATIONS
•
If we think about solutions in terms of their water concentrations, it is
easier to recognize which direction water molecules will flow in.
•
A dilute sugar solution will have a high concentration of water.
•
A concentrated sugar solution will have a lower water concentration.
OSMOTIC EFFECTS ON CELLS
A hypotonic solution has a higher water concentration than the
water concentration within the cell.
The water concentration outside the cell is greater than that inside
the cell so water moves into the cell by osmosis.
(HWC) 0.1%
Salt Solution
Cell
1% Salt
A hypertonic solution has a lower water concentration than the
water concentration within the cell.
The water concentration outside the cell is lower than that inside
the cell so water moves out of the cell by osmosis.
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(LWC) 15% Salt
Solution
Cell
1% Salt
An isotonic solution has a water concentration that is equal to the
water concentration within the cell.
Water is constantly moving in both directions so there is no net gain of
water molecules in either direction.
H2O concentration
1% salt =
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Cell
1% Salt
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PLANT CELLS AND OSMOSIS
Hypotonic solution: more water outside of the cell than inside,
therefore water will move into the cell by osmosis. This causes the cell
to swell and become turgid. The cell wall prevents it swelling any
further.
Hypertonic solution: more water inside the cell than outside, therefore
water will move out of the cell by osmosis. This causes the cell to
become softer or flaccid.
Total water loss from a plant cell is known as plasmolysis. If this
happens, the plant cell is said to be plasmolyzed.
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ANIMAL CELLS AND OSMOSIS
The effects of osmosis on animal cells are totally different to plant cells
because animals cell structures are different.
Animals cells do not have:
o Cell walls
o Vacuoles
Red blood cells (RBCs) float in a solution called plasma which is
isotonic.
RBCs in isotonic plasma do not change size because the water has
no concentration gradient to follow.
RBCs in hypotonic and hypertonic plasma will change because there
is a concentration gradient for water to follow.
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Task 6: Complete the questions that follow. Make sure that you check
with your teacher to ensure you have the correct answers.
1. State what is meant by the term osmosis.
2. The cell membrane is described as “selectively permeable”. Describe
what this means and give some examples of molecules that can and
cannot pass across the cell membrane.
3. Describe what is meant by a concentration gradient. Give an example
in your answer.
4. Using the words hypertonic, isotonic and hypotonic, decide which
word best describes the following solutions when compared to a plant
cell with 1% sugar in its vacuole.
a) 15% sugar solution.
b) 1% sugar solution.
c) 100% pure water.
5. Why must red blood cells be kept in an isotonic plasma solution?
6. Look carefully at the diagram below. For each cell in the different
solutions, write down a word from the list below to describe it.
Turgid, Plasmolyzed, Shrunk, Burst, Normal
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Task 7: Complete the questions that follow. Make sure that you check
with your teacher to ensure you have the correct answers.
1. Which term best describes how water enters and leaves cells?
A
B
C
D
Diffusion
Osmosis
Evaporation
Permeation
2. Which statement best describes a selectively permeable membrane?
A
B
C
D
It lets all substances through
It does not let any substances through
It is equally permeable to all substances
It lets some substances through but not others.
3. A concentration gradient exists between two solutions of
A
B
C
D
equal concentration of the same substance
equals concentrations of different substances
different concentrations of the same substance
different concentrations of different substances
4. Osmosis is special diffusion of water from
A
B
C
D
high concentration to lower concentration through a selectively
permeable membrane
high concentration to lower concentration through a fully permeable
membrane
low concentration to higher concentration through a selectively
permeable membrane
low concentration to higher concentration through a fully permeable
membrane
5. A 5% sugar solution contains
A
B
C
D
5% water and 95% sugar
95% sugar and 95% water
5% sugar and 95% water
5% sugar and 5% water
6. Osmotic effects are different on plant cells compared with animal cells
because
A
B
C
D
plant cells have cytoplasm
animal cells have cell walls
animal cells do not have chloroplasts
plant cells have cell walls and vacuoles
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7. Solution X is hypertonic to solution Y. Which of these statements is true?
A
B
C
D
X has higher water concentration than Y
X has a lower water concentration than Y
Y has the same water concentration as X
Y has a lower water concentration than X
8. A plant cell is flaccid if its vacuole is
A
B
C
D
swollen and pushing the cytoplasm against the cell wall
shrunken and pulling the cytoplasm away from the cell wall
shrunken and pushing the cytoplasm against the cell wall
swollen and pulling the cytoplasm away from the cell wall
9. What solution should a plant cell be placed in to make it fully turgid?
A
B
C
D
hypotonic
very hypertonic
isotonic
slightly hypertonic
10. If blood plasma became hypertonic, the red blood cells would
A
B
C
D
burst
shrink
become plasmolyzed
show no change
11. Red blood cells placed in a solution are observed to burst. Which type of
solution were they immersed in?
A
B
C
D
hypotonic
slightly hypertonic
very hypertonic
isotonic
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ACTIVE TRANSPORT
Active transport is an energy requiring process.
It involves the movement of molecules against a concentration
gradient.
In active transport, molecules cross the membrane by passing through
protein channels or carriers in the membrane
In the diagram above, molecules are crossing the plasma membrane in the opposite
direction of diffusion.
Here, molecules are moving from a low concentration to a high concentration.
Imagine you are in a crowd of people all going in one direction and you are going the
opposite way. It would be easier to get swept up in the crowd and it takes an extra
effort to “go against the flow”.
The same is true for molecules that travel by active transport. These molecules are
able to travel against the concentration gradient by using energy in the form of ATP.
ATP gives the protein pump energy to move these molecules in the opposite
direction.
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Task 8: Learn the words and definitions listed below. Your teacher
may test you on these.
Word
Description
Cell Wall
Protects and supports plant cells
Cell membrane
Protects the cell, performs active transport and
passive transport, moves materials in and out
of the cell, communication
Cytoplasm
Pads and supports organelles inside the cell.
The site of many chemical reactions.
Nucleus
Controls all of the cell’s activities
Nuclear membrane
Covers and protects the nucleus. Allows
genetic material to leave the nucleus
Nucleolus
Produces ribosome’s
Smooth Endoplasmic Reticulum
Transports materials like proteins around the
cell
Ribosome
The site of protein synthesis.
Mitochondria
Supplies ATP for the cell through cell
respiration using glucose and oxygen
Vacuole
Storage tank for food, water, wastes or
enzymes. Provides structural support for plant
cells.
Chloroplast
Captures sunlight and uses it to produce food
through photosynthesis
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Golgi Body
Packages and secrets proteins for use in and
out of the cell
Lysosome
Digests older cell parts, food or other objects
Centriole
Used with the spindle apparatus during mitosis
Osmosis
The diffusion of water from an area of high
water concentration to an area of lower water
concentration
Diffusion
The movement of molecules in a gas or a
liquid from an area of high concentration to an
area of low concentration
Hydrophobic
Water fearing
Hydrophilic
Water loving
Active transport
The movement of molecules and ions across a
cell membrane against the concentration
gradient. This process requires energy.
Phospholipid
Molecules that make up the majority of the cell
membrane. Made of a head region and a tail
region.
Isotonic
A solution with an equal water and solute
concentration
Hypertonic
A solution with a higher solute concentration
and lower water concentration
Hypotonic
A solution with a higher water concentration
and lower solute concentration.
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