Cell Structure and Function

1. Cell Structure and Function Basic Unit of Life…

2. Objectives • The learner will be able to: • Tell what cells are. • State the cell theory and identify the components of the cell theory. • Identify the role of the cell wall and the cell membrane in the cell. • Describe the functions of the cell. • Explain how cells are organized in many-celled organisms. • Describe diffusion, osmosis, active transport, and facilitated diffusion.

3. BEFORE ACTIVITY Active Art • Go to phschool.com • Type the code cbp-3072 • Follow directions and take the quiz at the end.

4. BEFORE ACTIVITY • Cells • Eukaryotes • Prokaryotes • Unicellular • Multicellular • Microscopic • Organelles • Nucleus • DNA • Organisms Possible Sentences

5. History of the Cell • The invention of the microscope made it possible to discover and study cells. • The scientists who contributed to the microscope are: • Hans and Zacharias Janssen • Robert Hooke • Anton Von Leeuwenhoek

6. History of the Cell • Who discovered the cell and gave it its name? • Robert Hooke • When did he discover the cell? • 1663 • How did he discover the cell? • Using his version of the Compound Microscope. • He was viewing a piece of cork.

7. History of the Cell (cont.) Robert Hooke’s Compound Microscope Robert Hooke

8. Cells are the basic unit of structure and function in ALL living things. • Cell form parts of the organs and perform all functions for the organ. • All cells are surrounded by a cell membrane. • All cells contain DNA at some point in their life. • Most cells are made up of tiny structures called organelles. • One square centimeter of your skin is made up of more than 100,000 cells. Cell Overview

9. Development of the Cell Theory • 3 German Scientists made important contributions to our knowledge of the cell. • Matthias Schleiden • Theodore Schwann • Rudolf Virchow discovered all cells come from cells. • They developed the first two points of the cell theory, but did not explain where cells come from.

10. Cell Theory • All living things are composed of cells. • Cells are the basic units of structure and function in living things. • All cells are produced from other cells.

11. Prokaryotes vs. Eukaryotes • All cells fall into two categories (eukaryotes and prokaryotes) depending on whether they have a nucleus or not. • Karyon means “kernel” or “nucleus” • Prokaryotes • Cells that do not contain nuclei. • pro- means before • Genetic material is not contained in a nucleus. • They have all the characteristics of life such as reproduction, responding to the environment, and growing. • Ex. Bacteria • Eukaryotes • Cells that contain nuclei. • Eu- means true • Contains dozens of structures that are highly specialized • Genetic material is contained in the nucleus away from everything else. • Ex. Plants, Animals, Fungi, and Protists

12. Cyt- : [cell] Ex. Cytoplasm fluid (cytosol) • Endo-: [within] Ex. Endoplasmic reticulum (membranous structure within the cell • Hyper-: [above] Ex. Hypertonic solutions have greater osmotic pressure than body fluids. • Hypo- : [below] Ex. Hypotonic solutions have lower osmotic pressure than the body fluids. • Inter-: [between] Ex. Interphase is the stage between divisions of a cell. • Iso- [equal] Ex. Isotonic solutions have the same osmotic pressure as body fluids. • Mit- [thread] Ex. Mitosis is cell division when thread-like chromosomes become visible. • Phag- [to eat] Ex. Phagocytosis takes place when a cells takes in solid particles. • Pino- [to drink] Ex. Pinocytosis takes place when a cell takes in tiny drops of liquid. • -som [body] Ex. Ribosomes are tiny structures that consist of protein and RNA. Keys to Understanding CellsAnatomy Students need these!!!

14. Looking Inside The Cell • Nucleus • Contains nearly all of the cell’s DNA, which controls the cell’s activities. • Enclosed in a double-layered (lipid) membrane called the nuclear envelope. • Nuclear pores allow materials to move in and out. • Chromatin is found in nucleus. • Consists of DNA and proteins. • Condenses into chromosomes during cell division (i.e. mitosis, meiosis) • Nucleolus • dense region found inside the nucleus • Ribosomes are made in the nucleolus and leave through the nuclear pores into the cytoplasm Looking Inside The Cell

15. Cytoplasm: clear, thick, gel-like fluid between the cell membrane and the nucleus; it is constantly moving • It contains networks of membranes and organelles suspended in a clear liquid called cytosol • Cytoskeleton: a network of protein filaments (rods and tubules) that help the cell maintain its shape. • In animal cells, the microfilaments form centrioles (used during cell division) Looking Inside The Cell

16. Check Point • What structure separates the nuclear contents from the cytoplasm? • What is produced in the nucleolus? • What is chromatin? • What structures are produced by the cytoskeleton?

17. Looking Inside The Cell • Ribosome: “factories” to produce proteins; some are attached to Endoplasmic Reticulum and other float in the cytoplasm • Endoplasmic Reticulum:passageways that carry proteins and other materials from one part of the cell to another; similar to hallways of a building • Lipid components of the cell are assembled here

18. Looking Inside The Cell • Mitochondria: the “powerhouse” of the cell; converts nutrients in food to energy for the cell. • Surrounded by two membranes • GolgiApparatus: the cell’s “mail room” • receive proteins from the endoplasmic reticulum and it modifies, sorts, and packages them for storage or secretion • Lysosomes: the “clean up crew” of the cell • small, round structures containing enzymes that break down lipids, carbohydrates, and proteins into small molecules to be used by the cell. • Breaks down old organelles

19. Looking Inside The Cell • Vacuoles: water filled sac that stores food and other nutrients needed by the cell. • Plants have one large Central Vacuole • Some animal cells have them and others don’t • Chloroplasts: (only in a plant cell) large green structures that capture energy from the sun and covert it into chemical energy (food for the plant) in a process called photosynthesis. • Surrounded by two membranes • Contains the green pigment chlorophyll

20. Cell Boundaries • Cell Membrane: controls what substances enters and leaves the cell; nutrients enter here and wastes leave here. • Provides protection and support • It is a double layered sheet called lipid bilayer • Also has proteins embedded in lipids • Selectively permeable (semipermeable) meaning it only allows certain substances to enter or leave the cell. • Cell Wall (only in plant cells): rigid layer of nonliving material that surrounds the cell; it provides support and protection • Composed mainly of cellulose, a tough carbohydrate fiber.

21. Movement Through Cell Boundaries • Diffusion • Particles move from an area of high concentration to an area of low concentration. • When the concentration of a solute is the sameonbothsides of the membrane, the system(organism) has reached equilibrium.

22. Movement Through Cell Boundaries • Osmosis • The diffusion of water across a semipermeable membrane. • Water moves across membranes until equilibrium is reached. • When equilibrium is reached (samestrengthinside and outside the cell) the solution is isotonic (samestrength). • When the solution ononeside of membrane is more concentrated (stronger) otherside , it is hypertonic. • When the solution ononeside of the membrane is lessconcentratedthan the otherside, it is hypotonic.

23. Movement Through Cell Boundaries • Osmotic Pressure • Osmosis exerts pressure on the hypertonic side of the permeable membrane. • Cells are filled with salts, sugars, proteins, etc.; so, they would always be hypertonic when placed in fresh water. • Cells are never in fresh water because body fluids like blood have the same concentrations of dissolved materials. They are ISOTONIC! • Plant cells and Bacteria come in contact with fresh water, but the cell walls protect the membranes from bursting.

24. Facilitated Diffusion • The cell membrane has protein channels that allow certain molecule to pass into and out of the cell. • These channels are selective. • Ex. Only glucose (sugar) can pass through a channel made for glucose. • They are not “one-size-fits-all” Movement Through Cell Boundaries

25. Active Transport • Requires energy • Movement against the concentration • Accomplished by protein “pumps” in the cell membrane. • Endocytosis: the process of taking material into the cell by means of pockets on the cell membrane. • The pocket that is formed during endocytosis breaks away from the membrane and forms a vacuole. Movement Through Cell Boundaries

26. Phagocytosis • Extensions of cytoplasm surround a particle and package it within a food vacuole. • The cell engulfs it. • The vacuole breaks from the membrane. • Pinocytosis • Tiny pockets form along the membrane. • The pockets fill with liquid. • The pockets form vacuoles. • Exocytosis • The membrane of a vacuole fuses with the membrane • Contents are forced out of the cell. Movement Through Cell Boundaries

27. Unicellular Organisms • Single-celled organisms • Carry out all characteristics of life. • Reproduce • Grow • Respond to the environment • Transform energy • Ex. Yeast, Bacteria, and some Alga Cellular Organization

28. Unicellular Organsims • Organisms composed (made) of many cells • Depends specialized cells cooperating with each other. • Cells develop specialized tasks. • Examples of Specialized Cells… • Red Blood Cells transport oxygen. • Muscles Cells specialized for movement. • Pancreatic Cells produce proteins and enzymes for digestion. Cellular Organization

29. Levels of Organization