cells and cell membrane

1. Unit 5Unit 5
Anatomy andAnatomy and
PhysiologyPhysiology
CellsCells

2. Aim: To introduce the fundamentals ofAim: To introduce the fundamentals of
anatomy and physiology and cell function.anatomy and physiology and cell function.
Learning Intentions:
• To secure knowledge by being able to
identify the component parts of a cell.
• To further develop our knowledge by
describing the functions of the main cell
components.
• To show excellence by creating an
annotated display which explains the
structure and function of cells.

3. The human body is made upThe human body is made up
of:of:
• CellsCells
• TissuesTissues
• OrgansOrgans
• SystemsSystems

4. What is a cell?What is a cell?
• The “building block” of all living
things.
• All living things made up of 1 or
more cells
• Organised in groups each of which
have specific functions

5. Cells - the factsCells - the facts
• The human body is made up of millions ofThe human body is made up of millions of
tiny cellstiny cells
• These can only be seen under aThese can only be seen under a
microscopemicroscope
• They appear in many different shapes andThey appear in many different shapes and
sizes and have different functionssizes and have different functions
• Each cell has a nucleus which contains theEach cell has a nucleus which contains the
genetic coding called DNAgenetic coding called DNA
• Cells cannot function by themselvesCells cannot function by themselves

6. A Human CellA Human Cell

8. What is?What is?
• DNA (Deoxyribonucleic acid)
The chemical containing the genetic
code
• CHROMOSOME
A thread shaped body consisting of
DNA

9. NucleusNucleus
• The largest organelle.
• Cell survival and reproduction
happens here
• Contains DNA, the chromosomes
and proteins and the chromatin

10. Nuclear EnvelopeNuclear Envelope
• a physical barrier (membrane)
separating the contents of the
nucleus from the surrounding
cytoplasm

11. Endoplasmic reticulumEndoplasmic reticulum
• is concerned with the manufacture
and transportation of materials in the
cell.
• Rough ER - are important in the
production and transportation of
proteins.
• Smooth - creates and stores steroids

12. RibosomesRibosomes
• Produce the protein in a cell.

13. CytoplasmCytoplasm
• This is the fluid that fills the cell.
• The cells organelles are suspended in
the cytoplasm.

14. MitochondriaMitochondria
• Mitochondria are know as the
powerhouses of the cell.
• They take in nutrients, break them
down and creates energy for the cell
• This process is known as cellular
respiration

15. LysosomeLysosome
• Lysosomes hold enzymes that were
created by the cell.
• The purpose of the lysosome is to
digest things.

16. Golgi ComplexGolgi Complex
• Is a packaging organelle.
• It gathers simple molecules and
combines them to make molecules
that are more complex.
• It then takes those big molecules,
packages them in vesicles, and
either stores them for later use or
sends them out of the cell.

18. The Cell MembraneThe Cell Membrane
L.O understand theL.O understand the
organisation of the humanorganisation of the human
bodybody
Cell organelles “2”Cell organelles “2”
Learning Intentions:
To secure knowledge by being able to identify the
component parts of a cell.
To further develop our knowledge by describing the
functions of the main cell components.
To show excellence by building a cell membrane
model

19. Why do cells need membranes?Why do cells need membranes?
• Control entry and exit of substances
• Contain the cell contents and organelles;
compartmentalise individual cell
processes
• Communication with external
environment
• Site of chemical reactions
• Allows cell to change shape
• Transport and packaging within a cell

20. What are cell membranes madeWhat are cell membranes made
of?of?
• Most of the cell membrane is
impenetrable to water soluble
substances – it is composed of LIPIDS
• Water-soluble substance and other
molecules can pass into the cell through
passageways composed of PROTEINS

21. Fats and WaterFats and Water
• These two substances do not
mix
• Water is a polar molecule
(the oxygen end is slightly
negative and the hydrogen
end slightly positive)
• Fats are non-polar and do not
form hydrogen bonds with
water
• Fats are said to be
hydrophobic and lie on the
surface of the water to
reduce the surface area in
contact between the fat and
the water

22. Dietary lipids…Dietary lipids…
• The fats that make up the cell membrane are
different in structure to the dietary fats we have
come across before
• Dietary fats are composed of one glycerol backbone
with three fatty acids attached to it
• The fatty acids are non-polar and do not form
hydrogen bonds with water so they are insoluble

23. Lipids in the cell membraneLipids in the cell membrane
• These are
phospholipids
• They are composed of
a glycerol backbone,
two fatty acid chains
and a phosphate group
• The fatty acid chains
are non-polar
• The phosphate group
is polar

24. PhospholipidsPhospholipids
• They are usually drawn
like this
• The head (phosphate
group) is hydrophilic
• The tail (fatty acids) are
hydrophobic

25. And if you shake them
up in water?....
A MICELLE forms!
What happens if you place them
in water?....

26. So how are fats arranged in theSo how are fats arranged in the
cell membrane?...cell membrane?...

27. The Fluid Mosaic Model…The Fluid Mosaic Model…
• The phospholipid bilayer
is not a fixed structure
• Although the bilayer will
always remain arranged
in this configuration,
the individual
phospholipids are able
to move, hence why it is
also known as the fluid
mosaic model
• The phospholipids
rotate on their axis
• They can ‘swap' places
with the phospholipid
next to them
• They can occasionally
‘swap’ places with the
phospholipid directly
opposite them, though
this is rare
All of these movements increase the fluidity of the
membrane

28. What about the proteins in theWhat about the proteins in the
membrane?membrane?
• Some proteins are transmembrane – they span the
width of the phospholipid bilayer
• Others are fixed into the bilayer on one side only;
these are peripheral proteins
• The proteins have several different functions

29. Transmembrane ProteinsTransmembrane Proteins
• Water soluble substances pass
through proteins channels in the
bilayer
• These channels can be
permanent or temporary
• Gated channels allow selected
molecules through: conditions
within the cell determine
whether they are open or closed
• Other channels allow substances
to pass through freely in both
directions
• Some channels are active carrier
systems which use energy to
transport substances across
(e.g. the Sodium-Potassium
pump)

30. Peripheral proteinsPeripheral proteins
• Glycoproteins, found on the cells
surface, are protein molecules
with a carbohydrate group
attached
• These allow cells to
communicate with one another
• Individual groups of cells have
their own glycoproteins,
recognisable by the immune
system
• Proteins on the cells surface
also act as receivers for
incoming messages, such as
hormones
• Intracellular cell membranes
may also contain enzymes for
cell surface reactions

31. Practical taskPractical task
• On A3 paper label a cell leaving
space for the model of the cell
membrane and label it.