Cells

Cell Theory

• All organisms are composed of one or more biological cells
• a cell is the most basic unit of organisms
• All cells come from pre-existing cells

Animal Cell - Sub-cellular structures

• Double membrane nucleus - contains DNA, control center of cell
• Endoplasmic reticulum - modification and synthesis of exocellular proteins
• Rough endoplasmic reticulm - rER
• Golgi apparatus - protein packaging
• Plasma membrane - separates water in cell from water out of cell and controls transport of substances into and out of cell
• Ribosomes - protein synthesis
• Lysosyme - waste removal
• Centrioles - cell division
• Mitochondria - cellular respiration
• Cytoplasm - contains structures and chemical reactions and organelles
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Plant Cell - Sub-cellular structures

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• As above
• Cholorplasts - trap sunlight and photosynthesize
• Permeable vacuole - maintain turgor pressure
• Cellulose cell wall - maintain shape of cell, prevent from bursting

Single celled Unicellular organisms

• Chlorella - single cell green algae with chloroplasts, lives off photosynthesis
• Paramecium - unicellular protozoa with oral cavity, gut, anal pore and cilia to move

Exceptions to Cell Theory

• One cell/one nucleus are found if cells divide fully and finish separation rather than not completing process or fusing together e.g. muscle fibres fuse
• Larger surface area to volume ratio means better absorption of glucose and heat regulation; in effect single cell organisms bigger than 1mm3 do not survive
• Volume of a cell controls rate of heat/energy production and waste removal
• Multicellular organisms being as single cell/fertilized egg/zygote
• During development cells differentiate to specialise for their function
• Each cell only expresses a fraction of the organisms genome

Differentiation of Cells

• Differentiation occurs during development
• Stem cells have capacity to divide and differentiate along required paths
• Stem cell - unspecified cell

Target Diseases for Therapeutic Use of Stem Cells

• Stargardt's Disease
• Arthritis
• Parkinson's disease
• Burn victims
• Type I diabetes

Prokaryotic Cells

• Peptidoglycan cell wall - protects from bursting, prevents attack from viruses and antibodies
• Pili - involved in attachment
• 70s Ribosome - protein synthesis
• Plasmid - circular DNA
• DNA - naked, no nucleus
• Plasma Membrane
• Flagella - some species, used to move
• A sexual reproduction - cloning or binary fission
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