Cells. Prokaryotic vs. Eukaryotic Euakryotic cells are generally one to one hundred times bigger than prokaryotic cells

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1 Cell Theory Cells 1. All living things are composed of one or more cell 2. Cell is the basic unit of life 3. All cells come from the division of pre-existing cells Cells are divided into 2 categories: Prokaryotes (bacteria): No nucleus No membrane bound organelles Prokaryotic vs. Eukaryotic Euakryotic cells are generally one to one hundred times bigger than prokaryotic cells Eukaryotes (plants/animals): Nucleus (or nuclei) Membrane bound organelles 1

2 Anatomy of a Plant Cell Anatomy of an Animal Cell Animal Cell vs. Plant Cell Animal Cell Plant Cell 1. No chloroplasts 1. Chloroplasts 2. Cell membrane only 2. Cell membrane & cell wall 3. Centrioles 3. No centrioles 4. Small vacuoles (H 2 O and food) 4. Large central vacuole Cell Membrane Thin membrane made of lipid and protein The Fluid Mosaic Model The properties of a solid and a liquid Forms a fluid sea in which proteins, lipids, and carbohydrates are suspended or anchored at various points on its surface The mosaic part refers to the different proteins embedded in the bilayer Selectively permeable (a.k.a. semipermeable) The membrane will let some substances cross but not others of the same size 2

3 Structure Function P/A/oth Phospholipid ilayer Nucleus Mitochondria Large centrally located organelle that controls cellular functions including metabolism and reproduction. The cell s powerhouse. Where energy is produced by converting glucose into ATP via a reaction called cellular respiration. Phospholipid bilayer The cell membrane is made up of two layers of phospholipids Phospholipid molecules Phosphate head HYDROPHILIC ( water-loving ) Two Lipid (fat) tails are HYDROPHOIC ( water-fearing ) Rough ER Cell Wall Cytoplasm Ribosome Centriole Nucleolus A system of membranous tubular canals that are studded with ribosomes. This is the site of protein synthesis. Gives the cell its shape and provides protection. A gel like fluid that suspends the cell s organelles. Composed of rrna and proteins. Made up of 2 non-identical subunits. The site of protein synthesis. A barrel shaped organelle involved in cell organization and replication. Found in the centre of the nucleus. This organelle is involved in rrna synthesis. P A Cell Membrane This semi-permeable double layer is composed of phospholipids, proteins, carbohydrates, and cholesterol. Controls what enters and exits the cell. Structure Function P/A/oth Chloroplast A organelle green in colour that is involved in photosynthesis. This process involves the conversion of light energy into chemical energy. P Cell Transport Vesicle A small membrane-bound sac that stores and transports substances within the cell. Passive Transport (no energy) Active Transport (energy) Nuclear Envelope A double membrane composed of phospholipids that separate the nucleus from the rest of the cell. 1. Simple Diffusion 4. Active Transport 2. Osmosis 5. Endocytosis and Exocytosis Smooth ER A system of membranous tubular canals that lack ribosomes. Involved in lipid synthesis, storage and the detoxification of chemicals and drugs in the cell. 3. Facilitated Transport Lysosome A cellular stomach involved in digestion of bacteria, autodigestion of damaged cell components, and cell suicide. A Central Vacuole Large fluid filled organelle that stores food and wastes. Also maintains turgor pressure against the cell wall. P Golgi Apparatus An organelle involved in modification, assembly, packaging, storage and secretion of substances. 3

4 1. Simple Diffusion Law of Diffusion: molecules move from [high] to [low] i.e. along the concentration gradient Requires no energy Diffusion is a slow process To increase the rate of diffusion: Increase the temperature Increase the concentration gradient Decrease the size of the diffusing molecules 2. Osmosis (Diffusion of Water) The net movement of water molecules across a selectively permeable membrane; from an area of high water concentration to an area of low water concentration Solute: particles which are dissolved in water Solvent: liquid which dissolves the solute Solution: combination of solute and solvent 2. Osmosis (Diffusion of Water) Cells may be placed in solutions: Isotonic solution ( same strength solution): The solution contains the same number of solute molecules per volume as the cell No net movement of water across the membrane Hypertonic solution ( greater strength solution) The solution has a greater number of solute molecules per volume than the cell Net movement of water out of the cell Crenation (animals) or plasmolysis (plants): cell will shrivel up Hypotonic solution ( lesser strength solution) The solution has a lesser number of solute molecules per volume than the cell Net movement of water into the cell Lyse: cell will burst Osmosis in a blood cell Osmosis in a plant cell 4

5 3. Facilitated Transport Uses protein carriers to transport molecules Protein carriers are specific to the type of molecule Molecules move from [high] to [low] (i.e. along the concentration gradient) Requires no energy 4. Active Transport Uses protein carriers to transport molecules Moves molecules from an area of [low] to [high] (i.e. against the concentration gradient) Requires energy in the form of ATP 5. Endocytosis Shape of cell membrane changes as vesicles are formed and absorbed Requires energy in the form of ATP 2 Types: Phagocytosis Endocytosis where large particles are taken in ( eating ) Pinocytosis Endocytosis where small particles are taken in ( drinking ) 5. Exocytosis Vesicle within cell fuses with cell membrane and the vesicle contents are deposited on the outside Secretion and excretion in cells 5

6 Cell Reproduction Cell theory states that all cells come from preexisting cells Cell division is the process by which new cells are produced from one cell Chromosomes are the carriers of the genetic material that is copied and passed from generation to generation of cells This genetic material is crucial to the identity of the cell DNA 1952 Alfred Hershey and Martha Chase discovered DNA Deoxyribonucleic acid DNA is the building block of chromosomes DNA is a long chain of repeating subunits called nucleotides Made of two chains of nucleotides held together by nitrogenous bases Double helix structure (like a twisted ladder) Nucleotide A nucleotide is made up of a phosphate group, a sugar group, and a nitrogenous base Two nucleotides are joined together by their nitrogenous bases via a hydrogen bond There are 4 nitrogenous bases and are always paired in the same way: Adenine and Thymine Cytosine and Guanine reaking it down Nucleus contains chromosomes Chromosomes are made up of two sister chromatids Chromatids are tightly raveled strands of DNA DNA contains genes Genes are made up of nucleotides 6

7 Nuclear Component Analogy A Library The library represents a nucleus Inside the library are bookshelves that represent the chromosomes On the bookshelves are books that represent the DNA strand The paragraphs in the book represent the genes The letters in the words represent the nucleotides (A,T,C,G) 7