Transcript Key Area 1 Cell Structure

Cell structure
Learning Intention:
Investigate the structure of plant, animal, fungal
and bacterial cells.
Success Criteria:
Be able to identify the main structures found in
typical plant and animal cells
Be able to identify the main structures found in
typical fungal and bacterial cells
Be able to state the functions of these structures
Be able to do calculations concerning cell size and
cell growth
Starter Activity:
Answer the following question in your jotter.
1. Name three types of cells in your body.
2. Approximately how many cells are there in
the human body?
3. How many cells are there in an Amoeba?
Answers
1. Blood, nerve, muscle, bone, brain, liver,
skin etc
2. 100 trillion (100 million million)
3. One
UNIT ONE
CELL BIOLOGY
NATIONAL 5 BIOLOGY
Key Area 1
Cell structure
Animal and plant cells
Learning Intention:
To review cell structure
Success Criteria:
•Be able to name the structures common to animal
and plant cells which are visible under a light
microscope.
•Be able to name the structures found only in plant
cells which are visible under a light microscope.
•Be able to label these on a diagram and state their
functions.
•Be able to calculate cell size from a picture.
What is a cell?
• The following video clips will introduce
you to the basic features of cells.
What is a cell? (BBC)
Plant and animal cell structures (BBC)
What is a cell? (Glow)
Examining Onion Cells
Aim:
To observe and draw onion cells using a
microscope.
Equipment:
• Glass slide
• Cover slip
• Onion skin
• Iodine stain
• Microscope
• Lamp
Method:
•
•
•
•
•
•
•
•
Collect a thin piece of onion skin.
Spread the skin on a slide. The skin must not overlap.
Stain the cells by adding 2 drops of iodine stain.
Place a cover slip over the skin. Use a pencil or
mounted needle to lower the cover slip gently so the
air is pushed out.
Examine the cells under low then medium power. You
should be able to see lots of cells arranged like bricks
in a wall.
Adjust the microscope to a higher power.
Draw exactly what you see through the “field of view”
using a pencil.
Label as many structures as you can see.
Onion cells in iodine
nucleus
cell wall
cytoplasm
Examining Pondweed Cells
Aim:
To observe and draw pondweed cells using a
microscope.
Equipment:
• Glass slide
• Cover slip
• Small leaf from Elodea or Cabomba
• Microscope
• Lamp
Method:
• Collect a small leaf of pondweed.
• Place it in a drop of water on a slide.
• Use a pencil or mounted needle to lower the cover
slip gently so the air is pushed out.
• Examine the cells under low then medium power. You
should be able to see lots of cells arranged like bricks
in a wall. Look for green chloroplasts inside the cells.
• Adjust the microscope to a higher power.
• Draw exactly what you see through the “field of view”
using a pencil.
• Label as many structures as you can see.
• Return the slide and pack your microscope away
carefully.
Pondweed cells
• These cells are from
a pondweed called
Elodea.
• These cells are from
a pondweed called
Cabomba.
What two plant cell structures can you see in
the pictures?
Other plant cells
• These cells are from a
beetroot. The red dye
makes it hard to see the
nucleus but if you look
closely you will see them.
•These are the cells in the
stem of a plant. Some of
these cells carry water
upwards to the leaves, while
others carry sugars from the
leaves to other parts of the
plant.
A Typical Plant Cell
vacuole
nucleus
cell membrane
cell wall
green
chloroplast
cytoplasm
Cell size calculation
• The field of view in
this picture is
0.5mm wide.
• Calculate the width
of one cell (clue:
count the number of
cells from one side
to the other across
the line shown).
• Now estimate the
cell length.
Examining Cheek Cells
Aim:
To make a slide of cheek cells and draw
them.
Equipment:
• Glass slide
• Cover slip
• Cotton bud
• Methylene blue stain
• Microscope and lamp
• Paper towel
Method:
• Rub the cotton bud over the inside of your cheek to
remove some of the cells.
• Wipe the cotton bud over the surface of a glass slide.
• Place the cotton bud in disinfectant.
• Stain the cells with 2 drops of methylene blue stain.
• Remove some of the stain using paper towel.
• Use a mounted needle to lower the cover slip so the
air is pushed out.
• Draw the cells and label the structures.
• Once you have finished, place the slide and cover slip
in disinfectant.
• Pack away your microscope carefully.
Cheek cells in methylene blue
nucleus
cell membrane
cytoplasm
Typical Animal Cell
nucleus
cytoplasm
cell membrane
Cheek cell size calculation
• The field of
view in this
picture is
200 µm.
(1mm=1000 µm)
200 µm
• Estimate the
size of these
cheek cells.
(Clue : how
many would
fit across
the line?)
Comparison of Cell Types
Copy the table and put a tick or a cross in each
box. (Answers on next slide)
Structure
cell wall
cell membrane
nucleus
cytoplasm
chloroplasts
vacuole
Plant Cell
Animal Cell
Comparison of Cell Types
Structure
Plant Cell
Animal Cell
cell wall
yes
no
cell membrane
yes
yes
nucleus
yes
yes
cytoplasm
yes
yes
chloroplasts
yes
no
vacuole
yes
no
Functions of cell structures
Magnified cell structures (BBC)
• Each cell structure has a different job
within the cell. This is called its
function.
• Copy the table on the next slide which
summarises the functions of the main
structures in plant and animal cells.
Structure
Nucleus
Cell Membrane
Cytoplasm
Cell Wall
Description
Large round structure containing
genetic material
Very thin layer surrounds the
cytoplasm
Function
Controls cell activities
Controls the passage of
substances into and out of the
cell
Fluid, jelly-like material
Site of biochemical reactions
Outer layer made of mesh of
Provides plant cells with
cellulose fibres
support
Stores water and minerals and
Vacuole
Fluid-filled sac in the cytoplasm
provides extra support for
plant
Chloroplasts
Disk-like structures containing
Trap light energy for making
green chlorophyll
food by photosynthesis
Animal and plant cells
Learning Intention:
To review cell structure
Success Criteria:
•Be able to name the structures common to animal
and plant cells which are visible under a light
microscope.
•Be able to name the structures found only in plant
cells which are visible under a light microscope.
•Be able to label these on a diagram and state their
functions.
•Be able to calculate cell size from a picture.
Starter Activity:
Starter Activity:
E
C
Cell ultrastructure
Learning Intention:
To investigate more detailed structures in plant
and animal cells
Success Criteria:
Be able to state that cell structures can be seen
clearer and at higher magnification using an
electron microscope
Be able to name some structures in animal and plant
cells which are visible under an electron microscope
Be able to label these on a diagram and state their
functions
The History of Microscopes
The history of microscopes (Glow)
Electron microscopes
• Light microscopes like
the ones in the lab can
magnify up to 400
times. Some light
microscopes can
magnify up to 1000
times.
• Electron microscopes
use a beam of
electrons instead of
light. Some can magnify
up to 2 million times.
• This allows us to see
other smaller
structures inside cells.
Light microscope v electron
microscope
• Image of pollen
grains under the
light microscope
• Image of pollen grains
under the electron
microscope
High magnification images of
pollen using electron microscope
Animal cell under electron
microscope
• Many new
structures
can be seen in
the cytoplasm
that are not
seen using a
light
microscope.
Plant cells under electron
microscope
What is a cell? (Glow)
Cell ultrastructure
• In the
cytoplasm of
plant and
animal cells
there are
structures
called
mitochondria.
• They are the
site of aerobic
respiration.
Mitochondria
Nucleus
• The nucleus is made up of many chromosomes.
• These are not normally seen very clearly as they
wound up around each other like a ball of string.
• They are made of DNA and are the genetic
material of the cell.
• How many chromosomes are in each human cell?
Ribosomes
• Even smaller
structures can
be seen in the
cytoplasm called
ribosomes.
• They are the
site of protein
synthesis in
plant, animal and
bacterial cells.
Ribosomes
(attached to
a membrane)
(free floating)
• Ribosomes
can be found
free floating,
or attached
to membranes
in the cell.
Cell membrane
• The cell membrane can be seen in more detail
when using the electron microscope.
Plant cell walls
Cellulose fibres
When viewed with an electron microscope,
the cell wall of plant cells can be seen to be
made up of fibres of a material called
cellulose. Small molecules can easily pass
through the spaces between the fibres.
Cell ultrastructure
Label the handout
diagram using
these words :
• nucleus
• cytoplasm
• ribosomes
• mitochondria
• chromosomes
Functions of cell structures
• Match up the cell structures with their function.
• Draw a table, with headings, to display this
information. Use a ruler!
ribosomes
Site of aerobic
respiration
chromosomes
Site of protein
synthesis
Made of DNA. Contain
genetic material of the
cell.
mitochondria
Cell ultrastructure
Learning Intention:
To investigate more detailed structures in plant
and animal cells
Success Criteria:
Be able to state that cell structures can be seen
clearer and at higher magnification using an
electron microscope
Be able to name some structures in animal and plant
cells which are visible under an electron microscope
Be able to label these on a diagram and state their
functions
Starter Activity:
Starter Activity:
C
Starter Activity:
Answer the following question in your jotter.
1. a) What cell structures are made of DNA?
b) How many of these are there in a normal
human body cell?
2. What is the function of ribosomes?
3. Where in the cell are mitochondria found?
4. Which are the smallest – chromosomes,
ribosomes or mitochondria?
5. What kind of microscope is needed to see these
clearly?
Answers
1.
2.
3.
4.
5.
a) Chromosomes b) 46
Protein synthesis
In the cytoplasm
Ribosomes
Electron microscope
Fungal and bacterial
cells
Learning Intention:
To investigate the structure of fungal and
bacterial cells
Success Criteria:
Be able to name the structures found in fungal
cells which are visible under a microscope
Be able to label these on a diagram
Be able to name the method of reproduction in
yeast
Be able to name the main structures found in
bacterial cells
Be able to state the function of plasmids
Be able to do calculations of cell growth
Fungal cells
• Fungi are a group of organisms
that includes mushrooms, moulds,
yeast and toadstools.
• Yeast is a unicellular fungus –
made of single cells.
• It has cytoplasm, a nucleus and a
cell wall like plant cells.
• It has no chloroplasts and cannot
photosynthesise.
• It reproduces by ‘budding’.
• Yeast cells can reproduce rapidly
if they have a source of food
(sugar)and a suitable
temperature.
Looking at yeast
Collect the following:
• Microscope, slide, yeast suspension, dropper,
cover slip.
Method
• Place one drop of yeast suspension in the middle
of a microscope slide, and lower on a cover slip.
• View the yeast cells at low and high power. Look
for cells that are budding.
Small bud forming
Yeast cell
Yeast cells under the microscope
Typical fungal cell
Yeast budding
( a method of reproduction)
• Copy the diagram.
yeast cell
Uses of Yeast
Brewing
Industries
Alternative Fuel
Industries
Bread-making
Industries
Bacterial cells
• Bacterial cells are very tiny compared
to other plant and animal cells. Viruses
are even smaller!
Looking at bacterial cells
• Your teacher will give you prepared
slides of bacterial cells to view under
the microscope.
• They have been stained to show them up
more clearly.
• You will need to use the highest power
of lens to see them clearly.
• Start by focusing at low power, then
increase to medium power then high
power.
Structure of a typical bacterial
cell
• Here you can see
that bacterial
cells have some
of the
structures we
have already
seen in plant and
animal cells.
• These details
can only be seen
under electron
microscope.
Structure of a typical bacteria
cell membrane
cell wall
Copy the
cytoplasm
diagram,
labels and
notes below.
main DNA ring
(single chromosome)
plasmid (additional DNA)
flagellum for movement
(not always present)
• The DNA in bacteria is not in a proper nucleus.
• Instead it consists of a main ring or coil of DNA.
• In addition to this, there are other smaller rings of
DNA called plasmids.
• Plasmids are involved in bacterial reproduction.
Cell Wall Structure
• The cell walls that surround plant cells
are made of cellulose fibres.
• The cell walls that surround bacterial
cells and fungal cells are not made of
cellulose!
Reproduction in yeast and
bacterial cells
• Single celled organisms like yeast and
bacteria reproduce by dividing into two cells.
• If the conditions are right, yeast and
bacterial cells can divide to make two cells
once every 30 minutes. This means that the
number of cells can double every 30 minutes!
• What do you think would be the ideal
conditions for this to happen?
Answer :
Source of food, suitable temperature, oxygen
available
REPRODUCTION IN YEAST AND BACTERIAL CELLS
30 mins
1 hour 30 mins
2 hours
2 hours 30 mins
1 hour
Yeast dividing calculation
•
One yeast cell is placed in a sugar
solution. It divides to form 2 cells in
30 minutes. How many yeast cells will
there be after 12 hours?
• How to work it out
12 hours = 24 divisions
• Number doubles each division
The answer is on the next slide!
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
16777216
Answer = 16,777,216 yeast cells
Cell variety
• We have looked at the structure of typical animal, plant, fungal
and bacterial cells. However, not all animal cells look the same.
• The same is true of plant, fungal and bacterial cells.
• The structure of each type of cell is related to its function.
Bioviewer activity
• Examine the biosets provided on cell variety.
•Read the notes that go with each slide.
Types of cells (Glow)
Cell variety challenge
• Your challenge is to use your biological knowledge to
identify plant, animal, fungal and bacterial cells.
• Examine each of the microscope slides under the
microscope. Do not uncover the label.
• Look at the structures that are visible at low and high
power.
• Decide whether the cells are animal, plant, fungal or
bacterial.
• Write down the evidence that led you to your
decision.
• Reveal the label to find out what each type of tissue
is.
Cell variety challenge
Copy the table
Slide Plant/animal/
Evidence
fungal/bacterial
A
B
C
D
E
Name of
tissue
C
Fungal and bacterial
cells
Learning Intention:
To investigate the structure of fungal and
bacterial cells
Success Criteria:
Be able to name the structures found in fungal
cells which are visible under a microscope
Be able to label these on a diagram
Be able to name the method of reproduction in
yeast
Be able to name the main structures found in
bacterial cells
Be able to state the function of plasmids
Be able to do calculations of cell growth
Cell
Variety
Challenge
Your task is to produce an A5 information booklet about cell
structure and function.
You must include…
 Labelled diagrams of the four main cell types:
- Plant
– Animal
– Bacterial
- Fungal
 Describe the functions (jobs) of each labelled part.
You should include…
 Examples of specialised cells from each of the four cell types.
 Draw labelled diagrams of your examples and add
information about how their special features make them well
suited to their special functions.
You could include…
 A set of ten questions at the back of your booklet about the
information inside.
To help you gather information with this task you may use any text book in
the classroom (Int.2, higher) and the books in the library cupboard and box.
You may also use the Bioviewer slide packs and can have 10 minutes per
pair on the computers for research.
Cell Variety Challenge
Your task is to produce an A5 information booklet about cell
structure and function.
You must include…
 Labelled diagrams of the four main cell types:
- Plant
– Animal
– Bacterial
- Fungal
 Describe the functions (jobs) of each labelled part.
You should include…
 Examples of specialised cells from each of the four cell types.
 Draw labelled diagrams of your examples and add
information about how their special features make them well
suited to their special functions.
You could include…
 A set of ten questions at the back of your booklet about the
information inside.
To help you gather information with this task you may use any text
book in the classroom (Int.2, higher) and the books in the library
cupboard and box. You can have 10 minutes each on a computer.