Chapter 7 Cell Structure and Function Section 7

Chapter 7: Cell Structure and Function Section 7 -1: Life is Cellular

The observations and conclusions of many scientists helped to develop the current understanding of the cell

The Cell Theory Robert Hooke (1665) n English physicist used primitive compound microscope to look at plant tissue (cork). n He called the chambers “cells” because they reminded him of the small rooms in a monastery

The Cell Theory Rudolph Virchow (1855) n n Proposes that all cells come from existing cells Where did the first cell come from?

THE CELL THEORY 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. New cells are produced from existing cells.

How small are cells? How much is a micrometer? n 1 micrometer (µm) = 1/1, 000 m Typical cell size = 5 to 50 µm in diameter n n In a dice that is 1 cm 3 We could fit 1, 000 cells

How small are cells?

Two categories of cells 1. Prokaryotic Cells pro = before; karyon = nucleus or kernel • • contain cell membranes and cytoplasm but no nucleus DNA is scattered through cytoplasm examples: bacteria

Two categories of cells 2. Eukaryotic Cells eu = true; karyon = nucleus or kernel contain a nucleus that holds DNA and membrane bound organelles that have specific functions examples: all plants, animals, some fungi, some microorganisms

Two categories of cells Prokaryotic -No Nucleus Eukaryotic -Nucleus -Cell wall (plants and -Complex -Less complex bacteria) -Membrane bound -Smaller Ribosomes -Cell membrane organelles less complex -DNA - Ribosomes larger -Cytoplasm and complex -DNA is circular -Ribosomes -DNA is linear

History of the microscope Twig video

Plant Cell - Eukaryotic Prokaryotic Animal Cell - Eukaryotic

Page 173 n Q 1, 2, 4, 5

7 -2 Cell Structures n Organelle – a specialized structure that performs a specific function inside a cell

7 -2 Cell Structures Cytoplasm n Found – between the nucleus and cell membrane n Structure – a clear jelly-like fluid n Function – supports the organelles

The Nucleus Found – In cytoplasm near middle of cell Structure – contains DNA Function: instructs making of protein and cell activities. DNA Nucleus Nuclear Envelope

Ribosomes n n n Found: In the cytoplasm Structure: Small and grain-like Function: make proteins from directions given by DNA

Endoplasmic Reticulum n n Found: just outside the nucleus Structure: a maze of membranes Smooth ER: make lipids Rough ER: produces and transports proteins.

Golgi Apparatus n n n Found: In the cytoplasm Structure: A stack of membranes Function: to modify, sort and package materials from the ER for storage or transportation.

Vesicles n n n Found: In the cytoplasm Structure: membrane bounded sac Function: transports and/or stores cellular products

Lysosomes “The Cells Clean-up Crew” n Found: In the cytoplasm n Structure: Small enzyme filled organelles n Function: Breakdown large organic molecules, and old nonfunctioning organelles

Vacuoles n n Found: In the cytoplasm Structure: Saclike n n n Very large in plant cells Smaller in animal cells Function: Storage (water proteins, carbs, salts) Contractile vacuole Vacuole

Mitochondria “Powerhouse of the Cell” Found: In the cytoplasm Structure: Rod-shaped with a folded double membrane Function: Provide the cell with energy. Mitochondrion

Chloroplast Found: In the cytoplasm of plant cells Structure: Stack of membranes that contain photosynthetic pigments (chlorophyll) Function: Use energy from the sun to make food (photosynthesis)

Cytoskeleton Found: Throughout the cell Structure: A network of protein n Microtubules (25 nm) n Microfilaments (7 nm) Function: Helps support the cell & maintain shape n Involved in several types of movement

Cell Membrane Found: Located around the perimeter of the cell Structure: Made of a phospholipid bilayer Function: Regulates what leaves and enters the cell and provides protection and support

Cell Wall Found: Located outside the cell membrane Structure: Fibers of carbohydrate, cellulose in plant cells Function: Provide support and protection for the cell

In your notebook construct a Venn diagram that compares and contrasts prokaryotic and eukaryotic cells Prokaryotic Eukaryotic

2. 1. 3.

Centrioles Found: Within the cytoplasm only in animal cells Structure: Made of a microtubules (tubulin) Function: Help organize the cell during division. Centrioles - Miosis

7. 3 Cell Boundaries

Cell Membrane • Regulates what enters and leaves a cell • Is made from a double layer of lipids (lipid bilayer)

Fluid mosaic model - many things are imbedded in the membrane and it flows like a fluid 1. Channels (Doorways) 2. Pumps 3. Markers

Cell Walls • Provides support and protection for plants, fungus, algae, and some bacteria. • Porous to allow O 2, H 2 O, CO 2, food and waste in and out. • Plant cell walls made of cellulose • Membrane inside cell wall

Diffusion Random movement of molecules from a high concentration to a little low concentration– no energy required. example: Ink in water or why your whole house smells like dinner when it’s cooking!

Diffusion in cells Random movement of molecules from a high concentration to a little low concentration– no energy required.

Diffusion Movement of particles will continue until equilibrium is reached

Osmosis Diffusion of water through a selectively permeable membrane from high to low concentration

Osmosis • Water moves because there is a difference in solute concentration

Osmosis in cells

Isotonic solution (equal strength)- When the concentration of water is the same inside and outside the cell

Hypertonic solution (too strong)– When the water leaves the cell

Hypotonic Solution (under strength) – water moves into a cell because there is not enough inside

Facilitated Diffusion Protein channels/doorways “help” larger molecules in and out of the cell. Ex. Sugar Still occurs from high to low concentration and does not require energy.

Both diffusion and facilitated diffusion are called passive transport No energy is needed!

Active Transport Molecules are moved in and out of a cell against the concentration Requires energy

– small molecules are “pumped” in or out of the cell by the protein pumps in the cell membrane

Hypertonic solution

Active transport Exocytosis • pushing molecules out Endocytosis • taking molecules in

Endocytosis 2 kinds of endocytosis a. Phagocytosis – “cell eating” used to take in solids b. Pinocytosis – “to drink” used to take in liquids

• animations http: //www. pearsonsuccessnet. com/snpapp/i. Text/products/0 -13 -1811185/bm/vadiffus. html na. edu/~phys 215/lecture/lecnotes/lecgraphics/diffusion. gif/~phys 215/lecture/lecnotes/lecgra

Osmotic/Turgor Pressure A. Pressure of water inside a cell B. Causes plants to stand up straight C. Can cause cells to burst (cytolysis) D. Cell wall and contractile vacuoles prevent this E. This is how penicillin kills bacteria.

• http: //www. youtube. com/watch? v=JShw. X BWGMy. Y&feature=related • https: //www. youtube. com/watch? v=Ia. Z 8 Mt F 3 C 6 M