Mr Exham IGCSE Biology - Cells
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Transcript of Mr Exham IGCSE Biology - Cells
MAKING SENSE OFCELLS
IGCSE Biology1.1 Life Processes – Cells
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Learning Objectives• Can you remember the processes in MRS C
GREN that are common to most living things?• Can you recognise cell structures such as the
nucleus, cytoplasm, cell membrane, cell wall, chloroplast and vacuole, and describe their functions?
• What are the major differences between plant and animal cells?
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MRS GREN• MRS C GREN stands for the 8 characteristics of
living things. • All living organisms from a simple bacteria to
plants and animals, can do all of these processes.
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MovementReproductionSensitivity
GrowthRespirationExcretionNutrition
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Control
Cells – The Building Blocks Of Life
• All living organisms are composed of cells.• The simplest organisms are made of one
single cell.• More complex organisms like animals and
plants are made of many cells and are called multicellular organisms.
• In multicellular organisms there are many different types of cells that are specialised to carry out particular functions.
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Watch this video clip about cells
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A general animal cellCell membrane
Cytoplasm
Nucleus
Mitochondria
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A general plant cellCell membrane
Cell wall
Mitochondria
Vacuole
Cytoplasm
Chloroplast
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Nucleus
Nucleus• Largest organelle.• Controls the activities of the cell.• Contains chromosomes.• Chromosomes carry genes.• The genes determine which proteins the cell
can make.
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Nucleus
Cell Surface Membrane• Forms a boundary between the cytoplasm and
the outside of the cell.• Some chemicals can pass through this barrier
and the cell can control what comes in and out. • It is selectively permeable.
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Cell membrane
Cytoplasm• Jelly like substance which contains all of the
organelles (e.g. nucleus and mitochondria). • Many of the cell’s chemical reactions take place
in the cytoplasm. • These are called metabolic reactions.
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Cytoplasm
Mitochondria• Carry out some of the reactions of respiration. • Therefore releasing energy for the cell.• Cells that have a high demand for energy
usually have many mitochondria, such as muscle cells.
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Mitochondria
Cell Wall• Found only in plant cells.• It is made of a non-living material called
cellulose.• Helps the cell keep its shape.• It is freely permeable.
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Cell wall
Chloroplast• Found in some plant cells.• Contains chlorophyll.• Chlorophyll is a green pigment.• It absorbs light energy to make food in the
process of photosynthesis.
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Chloroplast
Vacuole• Found only in plant cells.• Filled with cell sap.• Cell sap is a store of dissolved sugars, mineral
ions, and other solutes.• Helps keep the cell’s shape.
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Vacuole
SummaryCell structures and their functions
Cell structure Plant or animal cell Function
Nucleus Both Controls the activity of the cell using genes
Cell Membrane Both Controls what enters and leaves the cell
Cytoplasm Both Location of cell metabolic reactions
Mitochondria Both Site of respiration
Cell Wall Plant only Made of cellulose, gives cell strength
Chloroplast Plant only Site of photosynthesis
Vacuole Plant only Contains cell sap which helps keep cell’s shape
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