Chapter 7 Cell Structure and Function

Chapter 7Cell Structure and Function +7.1 Life is Cellular Whats the smallest part of any living thing that still counts as being alive?

Cell!

+What is this?

+Discovering the CellWhat was invented to observe cells?MicroscopeIn 1665, Englishman Robert Hooke used a compound microscope to observe a then slice of cork (dead). Under the microscope the cork looked like it was made up of tiny chambers he called cells.

+Advancing the Microscope Anton Van Leeuwenoek further advanced the microscope and saw the first living cells he observed in pond water.

+Cell:Basic unit of structure and function. Matthias Schleiden and Theodor Schwann concluded that both animals and plants are made of cells.Cell theory:1. All living things are made of cells.2. Cells are the basic unit of structure and function in living things.3. New cells are produced from existing cells. +What are some types of cells in our body?Blood cells

Skin cells

Hair cells

Nail cells

+Exploring the CellLight microscopes uses lenses to magnify the image of an object by focusing on light or electrons.Magnify objects up to 1000x. If most cells are transparent, how can we figure out if the cell has any structures?Stain cells to reveal certain compounds of structures.

+Electron microscope:Use beams of electrons that are focused by magnetic fields. Much higher resolution than light microscopes.

+Q1: What are some things that can pass through a window screen?

Q2: What are some things that cannot pass through a window screen?

Q3: Why is it important to keep these things from moving through the screen?

+The cell (plasma) membrane separates the interior of a living cell from its surroundings.So thin that you would have to stack 8,000 of them to equal thickness of a piece of paper. What is the function of the plasma membrane?Regular traffic of chemicals into and out of the cell.

+What is a prokaryote and a eukaryote?Which type of organisms are unicellular?Bacteria and protists

Which type of organisms are multicellular?Animals, plants, fungi+What is the control center of the cell?Nucleus Nucleus:Large membrane-enclosed structure that contains genetic information (DNA) and controls many of the cells activities.

+Prokaryotes and Eukaryotes Prokaryotes:Pro rhymes with noNo nucleus Examples would be bacteria. Think of small organisms.Eukaryotes:Eu-YOU Has a nucleus Examples would be plants, animals, and fungi. Think of complex organisms.

+Two classes of cellsProkaryoteEukaryoteNucleus and membrane bound organelles NoYesHow many cellsUnicellularMulticellularExamplesBacteriaPlants, animals, fungiWhen did they appear in fossil recordEarlierLaterSizeSmall. 1-10 micrometersBigger. 10-100 micometers+What are these?

Cells are also made up of different organelles.+7.2 Cell StructureAll cells are also made of organs called organelles.Organelles:Tiny specialized organs. Our stomach, heart, and brain have specific jobs much like organelles do.

+CytoplasmThe entire region of the cell between the nucleus and the plasma membrane is the cytoplasm.Cytoplasm:Consists of various organelles suspended in a fluid.

+NucleusSTRUCTUREThe nucleus contains most of the cells DNAIt is surrounded by a pair of membranes called the nuclear envelope.FUNCTIONThe information stored in DNA directs the activities of the cell.

+Organelles That Store, Clean Up, and SupportVacuoles

Lysosomes

Cytoskeleton +VacuolesSTRUCTURELarge, membrane-bound sacsFUNCTIONStore undigested nutrientsLarge Central vacuole found in plant cells; stores chemicals such as salt and contributes to plant growth by absorbing water and causing cells to expand

+LysosomeSTRUCTUREMembrane-bound sacsFUNCTIONContain digestive enzymes that can break down such macromolecules as proteins, nucleic acids and polysaccharides.

+CytoskeletonCytoskeleton - network of fibers extending throughout the cytoplasmMaintains the internal structure of the cell by keeping organelles in place, giving the cell its shape, and enabling the cell to moveMicrotubules:Straight hollow tubes of proteins that give rigidity and shape.Microfilaments:Thinner, solid rods of proteins. Centrioles:Help organize cell division

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Cell membraneEndoplasmicreticulumMicrotubuleMicrofilamentRibosomesMitochondrionOrganelles That Build ProteinsRibosomes

Endoplasmic Reticulum

Golgi Apparatus +RibosomesSTRUCTURESmall particles of RNA and protein.Found floating in cytoplasm or attached to Rough ERFUNCTIONConstruct proteins using instructions in the cells DNAMade in the nucleolus

+Rough Endoplasmic ReticulumSTRUCTUREExtensive network of membranesHas bound ribosomes that dot the outside of the ER membraneFUNCTIONRibosomes on the Rough ER produce proteins that are inserted right into the ER membrane.Produce proteins that are packaged in vesicles by the ER and later secreted by the cell

+Smooth Endoplasmic ReticulumSTRUCTUREExtensive network of membranesLacks ribosomes FUNCTIONContains a number of different enzymes.Build lipid molecules.

+Golgi ApparatusSTRUCTURE

Membranes are arranged into a series of flattened sacsFUNCTIONSome products that are made in the ER travel in vesicles to the Golgi apparatus, an organelle that modifies, stores and routes proteins and other chemical products to their next destinations.

+How Proteins are Made1. Proteins are assembled on ribosomes.2. Proteins are targeted for export to the cell membrane, complete their assembly on ribosomes bound to the rough ER. 3. Newly assembled proteins are carried from the rough ER to the Golgi apparatus in vesicles.4. The Golgi apparatus further modifies proteins before sorting and packaging them in membrane bound vesicles.5. Vesicles from the Golgi apparatus are shipped to their final destination in, or out of the cell.Pg 200. +Organelles That Capture and Release Energy Chloroplast

Mitochondria +Chloroplasts (plants)STRUCTURESurrounded by two membranesFUNCTIONPhotosynthetic organelles found in some plants and algaeHarness light energy to make food (sugars)

+MitochondriaSTRUCTURESurrounded by two membranesFUNCTIONSites where cellular respiration occurs

Process the releases energy from sugars and other molecules to make ATP main energy that cells use to do work

+Not all plants and animals have the same cells.How do plants get their energy? Plant cells have chloroplast which are used for photosynthesis.What color are chloroplast?Green Plants also have cell walls to maintain its shape. Animal cells do not have cell walls.

+Cellular BoundariesA working factory needs walls and a roof to protect it from the environment outside, and also to serve as a barrier that keeps its products safe and secure until they are ready to be shipped out.The cell has a plasma (cell) membrane,Plant cells also have cell walls.Cell wall:Strong supporting layer around the membrane. Wood on trees, paper, help keep plants upright.

+Plasma (cell) MembraneRegulate the transport of substances across the boundary, allowing only certain substances to pass. Much like a window screen.Made of mostly proteins and a type of lipid called a phospholipid. Phospholipid only has 2 fatty acid chains.

+Phospholipid

+PhospholipidOne fatty acid end is the tail which is hydrophobic.The other fatty acid end is the head which is hydrophilic. Which side touches water?The head

The layer is said to be selectively (semipermeable) permeable. Selectively permeable means that some substances can move through, but other cannot.

+AnimalsBothPlantsLysosomeNucleusChloroplastNucleolusCell wallRough ERCentral vacuoleSmooth ERGolgi apparatusPlasma membraneMitochondrionCytoskeleton+7.3 Cell Transport If I spray cologne at my desk, will you be able to smell it sitting at your desks?Why?What happens when you put a drop of dye in water?The dye spreads throughout the water.

Diffusion:Particles moving from high concentration to low concentration.

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+Suppose a container of water has a membrane that separates pure water from a solution of dye. The membrane allows both the dye and water to move through the membrane which makes the membrane permeable.

The dye will eventually evenly disperse in the container to make the solutions be in equilibrium or balanced. +

+Passive transport:Diffusion across a membrane that and uses no energy. Facilitated diffusion:Transport proteins provide a pathway for certain molecules to pass.

+Passive Transport

+Osmosis Osmosis:Diffusion of water through a selectively permeable membrane. Moves from areas of high to low concentration. Aquaporins:Water channel proteins that allow water to pass right through them.

+OsmosisOsmotic pressure:Driven by the differences in solute concentration, the net movement of water out of or into a cell. Hypertonic: aboveSolution with a higher concentration of solute.Hypotonic: belowSolution with the lower solute concentration.Isotonic: equalSolutions that are equal.

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+Hypertonic Solutions

+Water balance in animal cellsWhat would happen to an animal cell that is hypotonic?Cell gains water, swells, and may pop.

What would happen to an animal cell that is hypertonic?Cell loses water, shrivels, and could die. +Water balance in plant cellsWhat do plants have that animal cells do not?Cell walls.Cell walls help keep in water. Make the plant rigid.

If plants are in a hypertonic environment the water cells will also shrivel and could die.

+Active TransportActive transport:When a cell expands energy to move molecules or ions across a membrane.Proteins pumps a solute across a membrane, usually in the opposite direction to the way it travels in diffusion.Imagine trying to swim against a current of water. You need to use energy! +Active transport

+Transport of Large MoleculesMoving large particles needs help from vesicles.Vesicles:Small membrane sacs specialized to move products into, out of and within a cell.Endocytosis:Moving particles inside the cellExocytosis:Moving particles outside the cell

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+Summary

+7.4 Homeostasis and Cells What happens to your body when its really hot out?What happens to your body when its really cold out?Your body wants to keep its temperature at a steady state.Homeostasis:Relatively constant internal physical and chemical conditions.

+Multicellular Life How do cells of multicellular organisms work together to maintain homeostasis?

The cells of multicellular organisms become specialized for particular tasks and communicate with one another to maintain homeostasis.Much like how a baseball team is made up of several positions. They must communicate to work as a team. I dislike baseball. +Levels of Organization Cells (smallest) Group of cells make tissue.Groups of tissues make an organ.Groups of organs make an organ system.

Receptor:Used for signaling molecules. (communication)

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