Cell Boundaries Notes

Cell Boundaries NotesBiology ICopyright Pearson Prentice Hall7-3Cell BoundariesAll cells are surrounded by a thin, flexible barrier known as the cell membrane. Many cells also produce a strong supporting layer around the membrane known as a cell wall.2Cell Membrane: a bilipid structure that is the outermost portion of the cellFunctions include: A boundary between the cells contents and the environment which regulates what enters and exits the cell.Communicates with other cell within an organism or unicellular organismsCopyright Pearson Prentice HallFunctions include: C) Contains proteins that identify the cellD) It serves as an attachment site for some organelles and near-by cells.Copyright Pearson Prentice HallCopyright Pearson Prentice HallCell Membrane

Outside of cellCell membraneInside of cell (cytoplasm)Protein channelProteinsLipid bilayerCarbohydrate chains5The cell membrane regulates what enters and leaves the cell. Cell Wall- A tough, supportive and protective covering of plants (of cellulose), fungi, most bacteria and some protists.

Copyright Pearson Prentice HallCopyright Pearson Prentice HallCell WallsCell WallThe cell wall lies outside the cell membrane. Most cell walls are porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily.7Prokaryotes vs. EukaryotesProkaryotesEx. BacteriaCell WallPresent in all prokaryotesNo NucleusContain RibosomesNo membrane bound organellesEukaryotesEx. Protists, fungi, plants, animalsCell WallPresent in Fungi and plants ONLYHas NucleusContain RibsomesMembrane bound organellesCopyright Pearson Prentice HallMeasuring ConcentrationSolution: a mixture of two or more substancesThe substance dissolved in the solutions are called solutesConcentration: of the solution is the mass of the solute in a given volume of solution or mass/volumeMass of Solute/Volume of Solvent=ConcentrationMeasuring ConcentrationSolvent: the liquid into which the solute is poured and dissolvedSolute: substance that is dissolved or put into the solvent

MembranesPermeable=substance is able to pass through membraneSelectively permeable=some substances can pass through membrane and others cannot

DiffusionIn solution particles move CONSTANTLYDiffusion: particles move from an area of HIGH concentration to an area of LOW concentration

DiffusionEquilibrium: Concentration of the solute is the same throughout a system.

Copyright Pearson Prentice HallDiffusion Through Cell Boundaries

14Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy.Copyright Pearson Prentice Hall

There is a higher concentration of solute on one side of the membrane as compared to the other side of the membrane.15Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy.Copyright Pearson Prentice Hall

Solute particles move from the side of the membrane with a higher concentration of solute to the side of the membrane with a lower concentration of solute. The solute particles will continue to diffuse across the membrane until equilibrium is reached.16Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy.Copyright Pearson Prentice Hall

When equilibrium is reached, solute particles continue to diffuse across the membrane in both directions.17Diffusion is the process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Diffusion does not require the cell to use energy.

DiffusionDiffusion depends on: Random particle movementsDiffuse across membrane WITHOUT ENERGY!!!!!Passive TransportOsmosisOsmosis: the diffusion of water through a selectively permeable membrane

Osmosis**Water tends to diffuse from a HIGH concentrated region to a LESS concentrated region.

membranewatersugar solutionThere are as many water molecules on the right as there are on the left but many of them are attached to sugar molecules and are not free to move.6Because there are more freely moving water molecules onthe left, more diffuse through the pores of the membrane from left to right than from right to left.7Molecular movement23Sugar molecules can pass through the membrane but, being surrounded by a cloud of water molecules, they move more slowly.

There is a greater concentration of free water molecules outside the cell than insideso water diffuses into the cellby osmosisand the cell swells up

Osmosis in animal cells11

cell wallcytoplasm and cell membranevacuoleThe cell absorbs waterby osmosis ........but the cell wall stops the cell expanding any morePlant cells1825A useful analogy is the bicycle tyre. The outer casing represents the cell wall; the inner tube represents the cytoplasm and the air inside represents the vacuole. When the tyre is pumped up, the air pressure pushes the inner tube against the outer casing. The outer casing cannot expand and so the pressure in the tube builds up until the tyre is firmOsmosis in CellsWhen comparing two solutions: The more concentrated solution is hypertonicAbove StrengthThe more dilute solution is hypotonicBelow StrengthWhen the concentrations are equal it is isotonicSame Strength

Cellulose in cell wallOsmosis in Living Cells

29Bell Ringer 3/28/12What is the difference between diffusion and osmosis?If a cell shrinks after putting it into a unknown solution.what type of solution would it be?What does the concentration have to be for the cell to swell? (what type of solution is it?)What are the two types of transports?

2 Types of Transport 1. Passive TransportNo energy required to pass through membraneEx. Water, ionsFacilitated Diffusion: movement of molecules across cell membrane through protein channels

Protein channelGlucose molecules

2 Types of Transport2. Active TransportRequires energy to transport molecules against a concentration gradientEnergy in the form of ATP

Molecule to be carriedActive Transport

Active TransportEndocytosis and ExocytosisLarge molecules and even solid clumps of material may undergo active transport by means of the cell membrane.Endocytosis is the movement of substances into a cell by being surrounded/engulfed by the cells membrane.

Copyright Pearson Prentice Hall36Active TransportTwo examples of endocytosis are:phagocytosispinocytosis

Copyright Pearson Prentice Hall37Copyright Pearson Prentice HallActive TransportIn phagocytosis, extensions of cytoplasm surround a particle and package it within a food vacuole. The cell then engulfs it. Phagocytosis requires a considerable amount of energy.38Copyright Pearson Prentice Hall

Copyright Pearson Prentice HallActive TransportIn pinocytosis, tiny pockets form along the cell membrane, fill with liquid, and pinch off to form vacuoles within the cell.

40Active TransportExocytosisThe movement of large molecules or quantities of fluids/dissolved substances out of the cell

41Learning Goals: What is cell specialization?Why do cells need specific roles?What are the four levels of organization in multicellular organisms?Copyright Pearson Prentice HallThe Diversity of Cellular Life

43 Photo Credit: CNSI/Science Photo Library/Photo Researchers, Inc.

The differences among living things arise from the ways in which cells are specialized to perform certain tasks and the ways in which cells associate with one another to form multicellular organisms.44Unicellular OrganismsUnicellular OrganismsUnicellular organisms are made up of only one cell.Unicellular organisms dominate life on Earth.45Multicellular OrganismsMulticellular OrganismsOrganisms that are made up of many cells are called multicellular.There is a great variety among multicellular organisms.46Multicellular OrganismsWhat is cell specialization?47Multicellular OrganismsCells throughout an organism can develop in different ways to perform different tasks. This process is called cell specialization.48

Copyright Pearson Prentice HallMulticellular OrganismsRed blood cells transport oxygen.

50Photo Credit: Dr. Dennis Kunkle/PhototakeCopyright Pearson Prentice HallMulticellular OrganismsCells in the pancreas produce proteins.

51Photo Credit: Don Fawcett/Photo Researchers, Inc.Copyright Pearson Prentice HallMulticellular OrganismsMuscle cells allow movement.

52Photo Credit: Manford Kage/Peter Arnold, Inc.Multicellular OrganismsSpecialized Plant CellsPlants exchange carbon dioxide, oxygen, water vapor, and other gases through tiny openings called stomata on the undersides of leaves. Highly specialized cells, known as guard cells, regulate this exchange.53Copyright Pearson Prentice HallMulticellular OrganismsStomata enclosed by guard cells.

54Photo Credit: Ron Boardman/Getty Images, Inc-StoneLevels of OrganizationWhat are the four levels of organization in multicellular organisms?55Levels of OrganizationLevels of OrganizationThe levels of organization in a multicellular organism are:individual cellstissuesorgansorgan systems56Copyright Pearson Prentice HallLevels of OrganizationLevels of Organization

Smooth muscle tissueMuscle cellStomachDigestive system57The levels of organization in a multicellular organism are individual cells, tissues, organs, and organ systems. In this example, muscle cells make up smooth muscle tissue, which, along with other tissues, makes up the stomach, an organ. The stomach, in turn, is part of an organ system, the digestive system.Copyright Pearson Prentice Hall

In multicellular organisms, cells are the first level of organization.58Levels of OrganizationTissuesSimilar cells are grouped into units called tissues. A tissue is a group of similar cells that perform a particular function.

59Copyright Pearson Prentice HallLevels of Organization

60Copyright Pearson Prentice HallLevels of OrganizationMost animals have four main types of tissue:muscleepithelialnervousconnective61Levels of OrganizationOrgansOrgans are groups of tissues that work together to perform a specific function.62Copyright Pearson Prentice Hall

63Copyright Pearson Prentice HallLevels of OrganizationOrgan SystemsIn most cases, an organ completes a series of specialized tasks. A group of organs that work together to perform a specific function is called an organ system.64Copyright Pearson Prentice Hall

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