Transcript Cells - Glow Blogs

UNIT ONE
CELL BIOLOGY
NATIONAL 4 BIOLOGY
Starter Activity:
Answer the following question in your jotter,
in sentences
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
Key area 1
Cell structure and cell division
Learning Intentions
• To know that a microscope can be used
to magnify cells
• Identify the parts of a microscope
• Be able to set up and use a microscope
to view different cells
Cells
• Cells are very small and they
cannot be seen by the naked
eye.
• We need to use a microscope to
help us see them.
• A microscope contains special
lenses to magnify cells.
Parts of a Microscope
Eyepiece Lens
Coarse Focus
Fine Focus
Arm
Stage Clip
Base
Objective Lens
Stage
Mirror
Microscope parts and
functions
Name of Part
Function (What it does)
Rough Focus
Wheel
Gets a sharp picture with large adjustments
Stage Clip
Holds slide in place
Objective Lens
Lens above the slide that magnifies the
specimen
Eyepiece Lens
Lens that you look through, helps to magnify
the specimen
Mirror
Helps focus the light onto the specimen
Fine Focus Wheel
Gets a sharp picture with small adjustments
How to use a microscope
• Carry the microscope using two hands.
•
Plug it in and switch it on.
• Put the lowest power lens in place (the smallest one).
• Using the rough focus wheel, move the stage away from the lens.
• Place the slide on the stage and hold it with the slide clips.
• Look at the microscope from the side. Turn the rough focus wheel
until the slide is very close to the lens, but not touching it. (It
should stop automatically)
• Look down the microscope. Turn the rough focus so the slide
moves downwards.
• Stop when the slide is in focus. You may need to adjust it using
the fine focus.
• Now move the medium power lens into place. Use the fine focus
wheel to re-focus it.
• When you have finished, return the slide and pack away the
microscope carefully.
Using a microscope to look at
everyday objects
• Look at each of the slides in turn.
• In your booklet make drawings of what you
see in the circles.
• Give each drawing a title, and say what
magnification you used (either x 40, x 100 or
x 400).
• E.g
cotton wool x 100
Animal and plant cells
Learning Intention:
To review cell structure and function
Success Criteria:
Be able to name the structures common to animal
and plant cells
Be able to name the structures found in plant cells
only
Be able to label these on a diagram
To be able to state the functions of these
structures
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 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.
Return the slide and pack your microscope away
carefully.
Onion cells in iodine
nucleus
cell wall
cytoplasm
A Typical Plant Cell
vacuole
nucleus
cell membrane
cell wall
green
chloroplast
cytoplasm
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
Comparison of Cell Types
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
• Each of these cell
structures has a
specific job to do in
the cell.
• This is called its
function.
• Do you know the
functions of any of
the cell structures?
Nucleus
•The nucleus contains
the genetic material of
an organism.
•It controls the cell’s
chemical reactions.
•It also controls the
growth and development
of a cell.
nucleus
Cell membrane
•Cells take in many
chemicals from their
surroundings, and
release other chemicals
into their surroundings.
•The cell membrane is a
very thin boundary
which controls the
entry and exit of these
materials.
Cytoplasm
•There are many
chemical reactions
happening in all of
your cells. They
happen in the
cytoplasm.
•These reactions
keep the cell alive
and allow it to carry
out its specific
function.
Cell wall
•The cell wall is a
rigid structure made
of a tough mesh of
cellulose fibres.
•It helps to support
a plant cell.
Vacuole
•The vacuole is
filled with water
and pushes out
towards the cell
wall.
•This provides
support for the
plant.
Chloroplasts
•Plant cells may also
contain chloroplasts
in the cytoplasm.
•These contain a
chemical called
chlorophyll which
absorbs light energy
for photosynthesis.
•This allows plant
cells to make food.
•Only the green
parts of a plant
contain chloroplasts.
1.
Try the matching cards
2. Complete the table in your booklet
Cell structure
Function (what it does)
nucleus
cytoplasm
thin boundary to cell, controls
what goes in and out of cell
thick boundary for support in
plant cells
vacuole
chloroplasts
Answers on next slide
Answers
Cell structure
Function (what it does)
nucleus
controls centre of the cell
cytoplasm
chemical reactions happen here
cell membrane
thin boundary to cell, controls
what goes in and out of cell
cell wall
thick boundary for support in
plant cells
vacuole
store of fluid in plant cells
chloroplasts
carry out photosynthesis
Cell division
Learning Intention:
To understand the process of cell division
Success Criteria:
Be able to state the importance of cell
division to living organisms
Be able to describe the process of cell
division
Importance of cell division
• Every living organism
produced by sexual
reproduction starts life
as one cell.
• In plants, this cell is
formed when an egg cell
is fertilised by a pollen
grain.
• The fertilised egg cell
then divides into many
cells to form a seed.
• The seed can then grow
into a new plant.
pollen grain
pollen tube
pollen
nucleus
egg cell
Importance of cell division
• In animals, this cell is
formed when an egg
cell is fertilised by a
sperm cell.
• The fertilised egg
then divides into
many cells to form an
embryo.
• The embryo
continues to grow
into a new animal.
Growth
• All living organisms
grow during their
lifetime.
• All of this growth
happens due to cells
dividing to form new
cells.
Repair to tissues
• When we get
injured, new cells
are made to repair
and replace the
damaged tissues.
• New skin cells
form to heal a cut
or graze, and new
bone cells grow to
repair a broken
bone.
Cell division
Learning Intention:
Investigate the process of cell division
Success Criteria:
Be able to describe what happens during cell
division
Be able to describe the cells produced from
cell division
Be able to explain how cancer occurs
Starter Activity:
On a Show Me Board, answer the following
questions:
1. Name the three main parts found in both
animal and plant cells.
2. Name two other structures which are
found in plant cells only.
3. Why are your cells dividing just now?
Cell division
• Cells are able to
make new cells by
cell division.
• The parent cell
splits to form two
cells.
• Each new cell is
identical to the
original parent cell.
Embryonic cell division
Cells and chromosomes
• Inside the nucleus
of a cell there are
chromosomes which
carry the genetic
information of the
organism.
• Human cells have
46 chromosomes in
their nucleus.
Chromosomes and cell division
Chromosomes
duplicate
Two identical cells
Chromatids
separate
• Each new cell ends up with the same number
of chromosomes as the parent cell.
• This means each new cell has all the genetic
information of the original cell.
Revision checktest
1.
2.
3.
4.
5.
6.
One part found in all cells is the cytoplasm. Name
the two other parts found in all cells.
Plant cells have a thick structure around the
outside for support. What is it called?
What are the green structures in plant cells called?
What name is given to the structures in the nucleus
of a cell which carry genetic information?
How many of these are there in human cells?
Your cells are able to divide to make new cells. Give
a reason why cells in your body need to divide.
Cell division in bacteria
• Bacteria are single celled
living organisms.
• They are too small to see
with the naked eye.
• Bacterial cells can divide
very rapidly to form new
cells.
• When they do this, they
form colonies of millions
of cells which can be
seen with the naked eye.
• Your teacher will show
you how to grow bacteria
on an agar plate like the
one shown in the bottom
picture.
Growing bacteria on an agar plate
Equipment : Sterile petri dish with agar
Broth culture of bacteria
Inoculating loop
Bunsen burner
Disinfectant
Sticky tape
Label
Method :
1.
Wash your hands and sterilise the bench with disinfectant.
2.
Label the petri dish at the edge with your initials.
3.
Heat the inoculating loop in a blue flame until it glows red hot. Allow
it to cool for 20 seconds.
4.
Dip the loop into the broth and remove. Replace the lid on the broth
quickly.
5.
Take the lid off the petri dish and gently spread the liquid onto the
surface of the agar.
6.
Replace the lid on the petri dish as quickly as possible.
7.
Put the loop back into the flame until it glows red hot again.
8.
Seal the dish with two pieces of sticky tape at opposite sides.
9.
Sterilise the bench with disinfectant and wash your hands.
Growing bacteria on an agar plate
• Results :
Make a drawing of your petri dish after it
has been incubated in an oven for 2-3
days. (Do not open the dish!)
Bacteria all around us
• We are surrounded by
bacteria all the time.
• They can be found on
your skin, on surfaces
like your desk, in water,
in the air – in fact they
are everywhere!
• Most of the bacteria
around us are harmless,
but some can be harmful.
We sometimes call these
harmful bacteria germs.
Bacteria all around us
• Your teacher will show you how to use a swab
(cotton bud) to collect bacteria from
different places in the classroom.
• You will grow these bacteria on agar in petri
dishes.
• After 3 days you will look at the results.
• It is very important to keep the dishes fully
sealed when looking at them as there may be
harmful bacteria growing in the dish.
Bacteria all around us
• It is important to
protect ourselves
from becoming ill
due to these
harmful bacteria.
• Write down three
ways in which you
can avoid infection
by harmful bacteria
at home.
Avoiding infection at home
•
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Wash hands before handling food.
Wash hands after using the toilet.
Keep kitchen surfaces and utensils clean.
Keep fresh food in a fridge.
Check sell-by dates on food.
Cook meat properly, especially chicken and
pork.
• Store cooked meat away from raw meat.
• Cover left over food and store in the
fridge.
• Did you have any others?
Cell division
Learning Intention:
Investigate the process of cell division
Success Criteria:
Be able to explain how cancer occurs
Be able to describe how limbs and organs can
regenerate
Growing human cells in a lab
• Scientists can grow cultures of human cells in special
dishes in a lab. This is called tissue culture.
• The cells produced can be used for creating new skin
for skin grafting and to assist healing of wounds.
• Tissue culture can also be used in the diagnosis and
treatment of cancer.
To do: Read the newspaper article about a three year
old girl who was treated with skin grafts grown in a
lab.
What do you think all of these
have in common?
They can all
grow back
damaged
parts of
their bodies!!
How this works?!
• Where the animal has lost its limb, the
cells begin to divide.
• The new cells do not have a function
yet.
• They then develop into the type of cell
required: bone cell, nerve cell, muscle
cell...
• Salamanders
Cancer cells
• Normal cells divide in a controlled way, and
will stop dividing when they are not needed.
• Cancer cells divide in an uncontrolled way and
continue to divide to form tumours.
NORMAL CELLS
CANCER CELLS
Types of cancer
• There are many
different types of
cancer.
• Some cancers are
easy to treat and
the person can
make a full
recovery.
• Others are more
difficult to get rid
of.
Research homework
•
Investigate one of the following and write a
report on it.
• Your report should be 1-2 pages long and
could include diagrams or pictures.
• You can hand write it or do a word document.
TOPICS to choose from :
1. Uses of tissue culture to help fight disease.
2. Diagnosis and treatment of cancer.
3. Healing of wounds in humans.
4. Regeneration of damaged tissues in
salamanders and starfish.