Cell Theory The CELL THEORY states: all organisms are composed of similar units of organization, called cells. The concept was formally written in 1839 by Schleiden & Schwann and remains as the foundation of modern biology.

Cell Theory All known living things are made up of cells. 2. The cell is structural & functional unit of all living things. 3. All cells come from pre-existing cells by division.            

4. Cells contains hereditary information 4. Cells contains hereditary information which is passed from cell to cell during cell division. 5. All cells are basically the same in chemical composition. 6. All energy flow (metabolism & biochemistry) of life occurs within cells.       

Robert Hooke In 1663 an English scientist, Robert Hooke, discovered cells in a piece of cork, which he examined under his primitive microscope. Hooke only observed cell walls because cork cells are dead and without cytoplasmic contents. Hooke drew the cells he saw and also coined the word CELL.

Anton van Leeuwenhoek Ten years later Anton van Leeuwenhoek (1632-1723), a Dutch businessman used his own (single lens) monocular microscopes and was the first person to observe bacteria and protozoa

The Similarities and Differences Between Plant and Animal Cells

Animal Cells Can not make their own food so they have to eat food Do not go through photosynthesis Animal cells are more round shaped Animal cells have lysosomes Animal cells can not make sugar Animal cells use mitochondria to release energy

Animal cells cont. Animal cells do not have a cell wall We are all made of animal cells Animal cells have lysosomes where plant cells have plastids Animal cells do not have a large vacuole Animal cell DO NOT have chloroplasts

Plant Cells Plant cells HAVE: … a cell wall ...a large vacuole unlike the animal cell … Plastids instead of lysosomes. Plant cells are in the shape of a rectangle Plant cells go through photosynthesis – using the organelle called the chloroplast go

Plant Cells cont. Plant cells have chloroplast Plant cells use chloroplast to store energy They also have cell membranes

Similarities of Animal and Plant Cells They both HAVE: …a nucleus … many of the same organelles …ribosome's that make protein …Golgi bodies (apparatus) …cytoplasm …vacuoles that store food, water and waste products. …cell (plasma) membranes

Cell Membrane (Transport) Notes Cell Membrane and Cell Wall: ALL cells have a cell membrane made of proteins and lipids Cell Membrane lipid bilayer protein channel protein pump Layer 1 Layer 2 SOME cells have cell membranes and cell walls – ex: plants, fungi and bacteria Cell Membrane Cell Wall

Plant cells have a cell wall made of cellulose – that cellulose is fiber in our diet Bacteria and fungi also have cell walls, but they do not contain cellulose Cell membranes and cell walls are porous allowing water, carbon dioxide, oxygen and nutrients to pass through easily

Function of the Cell Membrane: Cell membrane separates the components of a cell from its environment—surrounds the cell “Gatekeeper” of the cell—regulates the flow of materials into and out of cell—selectively permeable Cell membrane helps cells maintain homeostasis—stable internal balance

Passive Transport A process that does not require energy to move molecules from a HIGH to LOW concentration Diffusion Facilitated Diffusion Osmosis

Diffusion is the movement of small particles across a selectively permeable membrane like the cell membrane until equilibrium is reached. These particles move from an area of high concentration to an area of low concentration. outside of cell inside of cell

HIGH to LOW concentration Diffusion HIGH to LOW concentration

Semi-permeable membrane is permeable to water, but not to sugar Osmosis is the diffusion of water through a selectively permeable membrane like the cell membrane Water diffuses across a membrane from an area of high concentration to an area of low concentration. Semi-permeable membrane is permeable to water, but not to sugar

Proteins that form channels (pores) are called protein channels Facilitated Diffusion is the movement of larger molecules like glucose through the cell membrane – larger molecules must be “helped” Proteins in the cell membrane form channels for large molecules to pass through Proteins that form channels (pores) are called protein channels outside of cell inside of cell Glucose molecules

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Hypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. Hypotonic Solutions: contain a low concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode. Isotonic Solutions: contain the same concentration of solute as another solution (e.g. the cell's cytoplasm). When a cell is placed in an isotonic solution, the water diffuses into and out of the cell at the same rate. The fluid that surrounds the body cells is isotonic.

Interactive Red Blood Cell Click

Active Transport Active transport is the movement of molecules from LOW to HIGH concentration. Energy is required as molecules must be pumped against the concentration gradient. Proteins that work as pumps are called protein pumps. Ex: Body cells must pump carbon dioxide out into the surrounding blood vessels to be carried to the lungs for exhale. Blood vessels are high in carbon dioxide compared to the cells, so energy is required to move the carbon dioxide across the cell membrane from LOW to HIGH concentration. outside of cell inside of cell Carbon Dioxide molecules

Endocytosis and Exocytosis is the mechanism by which very large molecules (such as food and wastes) get into and out of the cell Food is moved into the cell by Endocytosis Wastes are moved out of the cell by Exocytosis

Ex: White Blood Cells, which are part of the immune system, surround and engulf bacteria by endocytosis.

Osmosis—Elodea Leaf