Download - Cells ppt
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Unit 5Unit 5Anatomy and Anatomy and PhysiologyPhysiology
CellsCells
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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.
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The human body is made up The human body is made up of:of:
• CellsCells
• TissuesTissues
• Organs Organs
• SystemsSystems
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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
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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
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A Human CellA Human Cell
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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
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NucleusNucleus• The largest organelle.• Cell survival and reproduction
happens here• Contains DNA, the chromosomes
and proteins and the chromatin
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Nuclear EnvelopeNuclear Envelope• a physical barrier (membrane)
separating the contents of the nucleus from the surrounding cytoplasm
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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
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RibosomesRibosomes• Produce the protein in a cell.
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CytoplasmCytoplasm• This is the fluid that fills the cell. • The cells organelles are suspended in
the cytoplasm.
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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
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LysosomeLysosome• Lysosomes hold enzymes that were
created by the cell. • The purpose of the lysosome is to
digest things.
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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.
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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
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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
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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
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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
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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
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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
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PhospholipidsPhospholipids• They are usually drawn
like this• The head (phosphate
group) is hydrophilic• The tail (fatty acids)
are hydrophobic
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And if you shake them
up in water?....
A MICELLE forms!
What happens if you place them in water?....
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So how are fats arranged in the So how are fats arranged in the cell membrane?...cell membrane?...
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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
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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
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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)
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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
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Practical task Practical task
• On A3 paper label a cell leaving space for the model of the cell membrane and label it.