Chapter 7 Cell Structure and Function Lab Biology CP

Chapter 7: cell structure & function 7.1 Life is Cellular 7.2 Cell Structure 7.3 Cell Transport 7.4 Homeostasis and Cells

7.1 life is cellular

The Cell Theory by Rudolf Virchow, Theodor Schwann, and Matthias Schleiden 1.) All organisms are made up of one or more cells. 2.) The cell is the basic unit of life. 3.) All cells come from pre-existing cells.

Other Contributors Robert Hooke: –1 st to view cells under the microscope (1665) –viewed cork cells (plant cells) Matthias Schleiden –Used a microscope to study that all plants are made of cells (1830’s)

Microscope History Anton von Leeuwenhoek –Made the 1 st simple microscope –Looked at pond water –Magnified 270x

Leeuwenhoek Microscope A subject was placed on the needle and could be positioned with the adjusting screw.

Types of Microscopes Leeuwenhoek microscope (270x) Fluorescence microscope (1500x) Phase contrast microscope (1500x) Brightfield/Darkfield microscope (2000x) Transmission electron microscope (100,000x) Scanning electron microscope (200,000x)

Electron Microscopes Scanning Electron Microscope –A beam of electrons is scanned over the surface of the specimen –Produces 3-D images Transmission Election Microscope –Make it possible to explore cell structures and large protein molecules –Electrons can only pass through thin samples, so cells and tissues must be cut thin

Microscope Parts Ocular Lens/Eyepiece – what you look through Body tube – supports the ocular lens/eyepiece Nose piece – where the objectives are located Arm and Base- what you carry the microscope by Stage- where the slide is placed Adjustments: –Course adjustment- lowers the stage up and down –Fine adjustment - focusing Light- provides a light source to view your slide Diaphragm- controls how much light is let in Stage Clips – holds the slide in place

View through a microscope Upside down and inverted w98KA8UqU

Cells

Some different types of cells

Common Cell Traits (All cells have these) 1.) Cell Membrane: –Outer covering Plant Cells have a Cell Wall also 2.) Cytoplasm: –Gel-like material inside of the cell

Cell Types Eukaryotes (Eukaryotic): –Have membrane-bound structures in their cells and a nucleus –Nucleus: brain of the cell; genetic info here –Organelles: membrane-bound structures –Animal and Plant Cells Prokaryotes (Prokaryotic): –Do not have membrane-bound structures in their cells –Bacteria and pond scum

Eukaryotes ( have membrane-bound organelles)

Prokaryotes (Do NOT have membrane-bound organelles)

7.2 cell structure

Outer Coverings of Cells Cell Membrane –Found in ALL cells –Made of a protein, lipid bi-layer –Semi-permeable –Fluid-Mosaic Model Cell Wall –Found in plants only –Tough outer covering –Made up of cellulose Also made up of pectin and lignin

Cell Membrane Structure

Cell Wall Structure

Cell Membrane and Cell Wall Comparison

Organelles (membrane bound organelles in inside of the cell) Nucleus Mitochondria Endoplasmic Reticulum –Smooth and Rough Ribosomes Golgi Bodies Lysosomes Cytoskeleton Chloroplasts (plant cells only)

Nucleus Center of cell Brain of the cell Directs all the cell’s activities DNA located here

DNA Deoxyribonucleic Acid A Nucleic Acid Organized into chromosomes DNA segments that carry genetic information are called genes genes

Chromosomes long pieces of DNA found in the center (nucleus) of cells come in pairs Normally, each cell in the human body has 23 pairs of chromosomes (46 total). –half come from the mother –the other half come from the father

Mitochondria Powerhouse of the cell Provides energy for the cell Where Cellular Respiration takes place

Endoplasmic Reticulum (ER) Transports materials around the cell 2 Types: –Rough ER: contains ribosomes –Smooth ER: does NOT contain ribosomes

Ribosomes Make proteins Located in 2 places –On Endoplasmic Reticulum –Free-floating in the cytoplasm

Golgi Bodies (a.k.a. Golgi Apparatus) Stacked flattened membranes Sort and package proteins and other substances into vesicles Deliver substances to other parts of the cell “Post Office”

Lysosomes Digests wastes inside of the cell Like a “garbage disposal”

Cytoskeleton Maintains cell shape Moves cell parts Helps cell move Made up of microfilaments and microtubules

Microfilaments & Microtubules Microfilaments: threadlike structures made up of protein called actin responsible for movement Microtubules: Hollow structures made up of protein called tubulins Maintain cell shape Important in cell division Formed from Centrioles

Microfilaments & Microtubules

Vacuoles In Plant Cells 1 Large Central Vacuole Largest portion of the cell Store water, salts and proteins In Animal Cells Vacuoles: Controls water content Vesicles: move materials between cell organelles

What Plants Cells HAVE that Animal Cells Don’t 1.) Cell Wall 2.) Chloroplasts –Make chlorophyll (green pigment) –Involved in photosynthesis 3.) Central Vacuole

Animal Cell (eukaryotic)

Plant Cell (eukaryotic)

What do cells make? Cells  Tissues  Organs  Organ systems  Organisms

7.3 cell transport

Passive Transport How the cell regulates the movement of molecules from one side of the cell membrane to the other WITHOUT ENERGY 3 Types: –1.) Diffusion –2.) Facilitated Diffusion –3.) Osmosis

Diffusion When particles move from an area of high concentration to low concentration Depends on random particle movement

Facilitated Diffusion Process in which large molecules that can’t directly diffuse across a cell membrane, cross at certain protein channels instead Some cells have certain proteins that act as channels or carriers and allow for quicker, easier movement of large molecules across a cell membrane

Osmosis An example of facilitated diffusion How water passes a selectively permeable cell membrane Aquaporins: water channel proteins that allow the passing of water across the membrane

How Osmosis Works Isotonic –When the solution concentration is the same both inside and outside of the cell Hypertonic –When comparing 2 solutions, the solution with the greater concentration of solutes Hypotonic –When comparing 2 solutions, the solution with the lesser concentration of solutes

Osmotic Pressure Pressure that must be applied to prevent osmotic movement across a selectively permeable membrane Can cause an animal cell in a hypertonic solution to shrink Cells can also burst

The Effects of Osmosis on Cells

Active Transport The movement of materials against a concentration difference Requires ENERGY Types: –Molecular Transport (small molecules) –Bulk Transport (large molecules)

Bulk Transport Endocytosis: –Process of taking materials into a cell by means of infoldings, or pockets, of the cell membrane Exocytosis: –When the membrane of the vacuole surrounding the materials fuses with the cell membranes, forcing the contents out of the cell

7.4 homeostasis and cells

Homeostasis How organisms grow, respond to the environment, transform energy and reproduce If homeostasis is not maintained, the organism will die Multicellular organisms become specialized to maintain homeostasis

Cell Specialization Each cell has a different role Example: –Blood cell

Cell Communication Cells communicate by means of chemical signals that are passed from one cell to another. Cells must have receptors to accept the signal