Post on 29-Jan-2016
Cellular Functions
• Chapter 1– The Cell Theory– Cell Structure– Organelles– Animal and Plant Cells
• Chapter 2– Nutrients– Nucleic Acids– Cell Membrane– Transport– Respiration and Photosynthesis
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• Biology is a natural science concerned with the study of life and living organisms, including their:– Structure, – Function, – Growth,– Evolution,– Distribution and – Taxonomy
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• Biology as a Science progressed by observation.
• The hypotheses proposed by early scientists were rarely tested by experiments.
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• Abiogenesis is the belief that living organisms can be created, or arise, from non living matter.
• Many abiogenesis hypothesis proposed by scientists were rarely tested by experiments.
• For Example:– Pond dries up – no fish or frogs– Rain comes – fish and frogs
Therefore: It rained fish and frogs
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• Proposed by Aristotle who observed rotting meat and flies.
• People Believed this for 2000 years!
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• Biogenesis is the principle that living organisms develop from other living organisms and not from non living matter.
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• There were a number of important Scientists who contributed to the theory of Abiogenesis and Biogenesis. Some of these include:
– Jean Van Helmont– Francesco Redi– John Needham– Lazzaro Spallanzani– Louis Pasteur
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• ~300 years ago
Belgian doctor Jean van Helmont – concluded that mice could be created from a dirty shirt.
• He placed grains of wheat and a dirty shirt in a container and in 21 days mice appeared.
• Conclusion: Sweat caused wheat to ferment into mice. Abiogenesis!
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• In 1668 Francesco Redi (Italian physician) tested Aristotle’s hypothesis (meat flies)
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• 4 sets of jars with meat (snake, eel, fish, veal)
one set was open (experimental group)
one set was sealed (control group)
• Maggots appeared on open jars of meat
• Conclusion: Flies come from flies!
• Biogenesis – life from life.
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• John Needham (1713 – 1781) English botanist
• Reexamined theory of Abiogenesis
• Observed meat broth left unsealed soon changed colour (evidence of microorganisms).
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Experiment:
• Boiled flasks of meat broth to kill microorganisms
• Left the flasks unsealed!
• Flasks soon become murky and full of microbes
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Conclusion:
• Abiogenesis
• This conclusion sent many scientists down the wrong path.
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• 25 years later Spallanzani repeated experiment more carefully
• Boiled flasks longer and sealed flasks
• Critics again objected to sealed flasks!
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• Louis Pasteur (1822-1895)
• Developed the swan neck flask in 1864
• This led to great scientific break through!
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Experiment:
• Boiled broth, air could enter but microbes were trapped in curved flask
• Broth remained clear Biogenesis finally proven!
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Unit 1 Chapter 1
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• All living things are composed of one or more cells.
• The cell is the basic unit of structure and function of all living things.
• All cells arise only from pre-existing cells.
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• What is a prokaryotic cell?
– Prokaryotes and unicellular organisms that lack a nucleus and membrane bound organelles.
– These are the most simple types of living cells.
– Examples: cyanobacteria, E.Coli
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• Eukaryote cells do have a nucleus and membrane bound organelles.
• Eukaryotes can be multicellular– organisms made of many cells
OR
• Eukaryotes can be unicellular– organisms made only of one cell
• Plants, Animals, Fungus and Protists are all eukaryotes.
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• Within cells there is an intricate network of organelles that all have unique functions.
• These organelles allow the cell to function properly.
• Here is a description of common organelles and their location.
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• Nucleus– One or more per cell
-- Control center of the cell– Spherical shape– Denser than surrounding cytoplasm
-- made of DNA (deoxyribonucleic acid)
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Chromosome-Usually in the form of chromatin-Contains genetic information-Composed of DNA-Thicken for cellular division-Set number per species (i.e. 23 pairs for human)
• Nuclear membrane– Surrounds nucleus– Composed of two layers– Numerous openings (pores) for nuclear traffic
• Nucleolus– Spherical shape– Visible when cell is not dividing– Contains RNA for protein manufacture– Makes ribosomes
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• Endoplasmic reticulum– Tubular network fused to nuclear membrane– Goes through cytoplasm onto cell membrane– Stores, separates, and serves as cell's transport system– Smooth type: lacks ribosomes– Rough type (pictured): ribosomes embedded in surface
• Golgi Apparatus– Protein 'packaging plant‘– A membrane structure found near nucleus– Composed of numerous layers forming a sac
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• Ribosomes– Each cell contains thousands– Miniature 'protein factories‘– Composes 25% of cell's mass– Stationary type: embedded in rough endoplasmic
reticulum– Mobile type: injects proteins directly into cytoplasm
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• Cytoplasm– Collective term for cytosol and organelles contained
within– Colloidal suspension– Cytosol mainly composed of water with free-floating
molecules– Viscosity constantly changes
• Centrioles– Paired cylindrical organelles near nucleus– Composed of nine tubes, each with three tubules– Involved in cellular division– Lie at right angles to each other
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• Chloroplasts– A plastid usually found in plant cells– Contain green chlorophyll where
photosynthesis takes place
• Cytoskeleton– Composed of microtubules– Supports cell and provides shape– Aids movement of materials in and out of cells
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Microfilaments Microtubules Cytoskeleton
Mitochondira– Second largest organelle with
unique genetic structure– Double-layered outer membrane with inner folds
called cristae– Energy-producing chemical reactions take place
on cristae– Controls level of water and other materials in cell– Recycles and decomposes proteins, fats, and
carbohydrates, and forms urea
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• Lysosome– Digestive 'plant' for proteins, lipids, and
carbohydrates– Transports undigested material to cell membrane
for removal– Vary in shape depending on process being
carried out– Cell breaks down if lysosome explodes
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Vacuoles-Membrane-bound sacs for storage, digestion, and waste removal-Contains water solution-Contractile vacuoles for water removal (in unicellular organisms)
• Cell Wall– Most commonly found in plant cells– Controls turgity– Extracellular structure surrounding plasma
membrane– Primary cell wall: extremely elastic– Secondary cell wall: forms around primary cell
wall after growth is complete
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Plasma membrane-Outer membrane of cell that controls cellular traffic-Contains proteins (left, gray) that span through the membrane and allow passage of materials-Proteins are surrounded by a phospholipid bi-layer.
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Plant Cells Animal Cells
Have chloroplasts and cell Walls
Do Not have chloroplasts and cell
walls
Do not usually have centrioles
Have centrioles
Have a large central vacuole
Do Not have a large central vacuole
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Video
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