All living organisms are
made of cells. Cells are the
building blocks of life.
Cells are the
smallest units found
in an organism.
Organisms such as bacteria can be
formed from a single cell. Millions of cells
can join together to form a person.
Cells are so small that about
100 animal cells would fit across
the width of this tiny full stop.
Seeing cells
Cells were first seen
about 350 years ago.
To see cells you have to
look through a microscope.
Making
observations
To see very small object
in detail, you need to use
a microscope.
This magnifies the image using lenses.
Looking carefully and in detail at an object
is called making an observation.
The object you wish to observe needs
to be very thin so that light can travel
through it. you might need to add
coloured die so you can see the object
easier.
Magnification
The eyepiece lens and
objective lens in a microscope
have different magnification.
for example, if you have an
eyepiece lens of x10 and an
objective lens of x20 the
object would be magnifies
200 times
Plant and
animal cells
when you look through a microscope, you will see the have
smaller parts inside them. these parts, components, all have an
important function. animal cells and plant cells contain some of
the same compoonents. however, some parts are different.
Animal cells have an irregular shape.
they contain four components - a
nucleus, a cell membrane, cyoplasm and
many mitochondrion
Plant cells have a more regular structure than animal cells.
they contain a nucleus, a cell membrane, cyoplasm and many
mitochondrion, like animal cells but they also have a cell wall, a
vacuole, and chloroplasts.
cytoplasm - this is a 'jelly-like'
substance where the chemical
reactions in a cell take place.
cell membrane - this is a barrier
around the cell. it controls what can
come in and out of the cell.
nucleus - this controls the cell and contains
genetic material. Genetic information is
needed to make new cells.
Mitochondria - this is where
respiration happens. Respiration is a
reaction that transfers energy for
the organism.
cell wall - this
strengthens the cell and
provides support.
Vacuole - this contains a
watery liquid called cell sap.
it keeps the cell firm.
Chloroplasts - this is
where photosynthesis
happens
specialised cells
most cells in the human body contain a nucleus, cell
membrane, cytoplasm, and mitochondria. However
some cells have changes shape and structure so that
they can carry out a particular job.
Nerve cells carry electrical impulses around your
body. they are long and thin and have connections at
each end where they can join to other nerve cells
around your body
Red blood cells
Red blood cells transport
oxygen around the body
they contain
haemoglobin, a red
pigment that joins to
oxygen
unlike most animal
cells they have no
nucleus
they have a different
shape, this increases their
surface area for carrying
oxygen.
sperm cells
sperm cells
carry male
genetic
material.
they have a streamlined
head and a long tail. this
allows it to move through
liquid.
they contain lots of
mitochondria to transfer
energy
Leaf cells
a cell from the top of
a leaf. its scientific
name is a palisade cell.
The cells at the top of
the leaf carry out
photosynthesis.
The cells are long and thin and
packed with chloroplasts. this
means they have a large surface
area for absorbing energy
transferred from the sun
unicellular
a unicellular organism
is an organism that is
made up of just one
cell.
Amoeba
an amoeba is a unicellular
organism that has no fixed
shape, it just looks like a blob
of jelly.
they can be found in
fresh water,salt water,
wet soil and even inside
animals.
an amoeba consists of a cell membrane
filled with cytoplasm. inside the cell there
is also a nucleus, which controls growth
and reproduction
an euglena is a microscopic organism,
found in fresh water. it is like a
Amoeba but it contains a cytoplasm
and a nucleus and also they have
chlorolasts.