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 2Biology 11

Biology is a natural science concerned with the study of life and living organisms, including their: –Structure, –Function, –Growth, –Evolution, –Distribution and –Taxonomy 3Biology 11

Biology as a Science progressed by observation. The hypotheses proposed by early scientists were rarely tested by experiments. 5Biology 11

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 6Biology 11

Proposed by Aristotle who observed rotting meat and flies. People Believed this for 2000 years! 7Biology 11

Biogenesis is the principle that living organisms develop from other living organisms and not from non living matter. 8Biology 11

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 9Biology 11

~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! 10Biology 11

In 1668 Francesco Redi (Italian physician) tested Aristotle’s hypothesis (meat  flies) 11Biology 11

12Biology 11

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. 13Biology 11

John Needham (1713 – 1781) English botanist Reexamined theory of Abiogenesis Observed meat broth left unsealed soon changed colour (evidence of microorganisms). 14Biology 11

Experiment: Boiled flasks of meat broth to kill microorganisms Left the flasks unsealed! Flasks soon become murky and full of microbes 15Biology 11

Conclusion: Abiogenesis This conclusion sent many scientists down the wrong path. 16Biology 11

25 years later Spallanzani repeated experiment more carefully Boiled flasks longer and sealed flasks Critics again objected to sealed flasks! 17Biology 11

Louis Pasteur ( ) Developed the swan neck flask in 1864 This led to great scientific break through! 18Biology 11

19Biology 11

Experiment: Boiled broth, air could enter but microbes were trapped in curved flask Broth remained clear  Biogenesis finally proven! 20Biology 11

Unit 1 Chapter 1 Biology 11 21

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. Biology 1122

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 Biology 1125

Biology 1126

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. Biology 1127

Biology 1128

Biology 1129

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. Biology 1130

Nucleus –One or more per cell -- Control center of the cell –Spherical shape –Denser than surrounding cytoplasm -- made of DNA (deoxyribonucleic acid) Biology 11 31

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 Biology 1135

Biology 1138

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 39

Biology 1140

Biology 1141

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 Biology 1142

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 Biology 1144

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 Biology 1147

Microfilaments MicrotubulesCytoskeleton

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 Biology 1150

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 Biology 1151

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 Biology 1155

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.

Biology 1159

Plant CellsAnimal 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 Biology 1161 Video

Biology 1162