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Unit 5Unit 5Anatomy and Anatomy and PhysiologyPhysiology
CellsCells
Aim: To introduce the fundamentals of Aim: 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.
The human body is made up The human body is made up of:of:
• CellsCells
• TissuesTissues
• Organs Organs
• SystemsSystems
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
Cells - the factsCells - the facts• The human body is made up of millions of The human body is made up of millions of
tiny cellstiny cells• These can only be seen under a These can only be seen under a
microscopemicroscope• They appear in many different shapes and They appear in many different shapes and
sizes and have different functionssizes and have different functions• Each cell has a nucleus which contains the Each cell has a nucleus which contains the
genetic coding called DNAgenetic coding called DNA• Cells cannot function by themselves Cells cannot function by themselves
A Human CellA Human Cell
What is?What is?• DNA (Deoxyribonucleic acid)The chemical containing the genetic code
• CHROMOSOMEA thread shaped body consisting of DNA
http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/cells/dnarev1.shtml
NucleusNucleus• The largest organelle.• Cell survival and reproduction
happens here• Contains DNA, the chromosomes
and proteins and the chromatin
Nuclear EnvelopeNuclear Envelope• a physical barrier (membrane)
separating the contents of the nucleus from the surrounding cytoplasm
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
RibosomesRibosomes• Produce the protein in a cell.
CytoplasmCytoplasm• This is the fluid that fills the cell. • The cells organelles are suspended in
the cytoplasm.
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
LysosomeLysosome• Lysosomes hold enzymes that were
created by the cell. • The purpose of the lysosome is to
digest things.
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.
The Cell MembraneThe Cell MembraneL.O understand the L.O understand the
organisation of the human organisation 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
Why do cells need Why do cells need membranes?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
What are cell membranes What are cell membranes made of?made 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
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
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
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
PhospholipidsPhospholipids• They are usually drawn
like this• The head (phosphate
group) is hydrophilic• The tail (fatty acids)
are hydrophobic
And if you shake them
up in water?....
A MICELLE forms!
What happens if you place them in water?....
So how are fats arranged in the So how are fats arranged in the cell membrane?...cell membrane?...
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
What about the proteins in the What 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
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)
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
Practical task Practical task
• On A3 paper label a cell leaving space for the model of the cell membrane and label it.