Ch. 7 Cellular Structure and Function

p. 180 -207

7.1 Cell Discovery and Theory

p. 182-186

Big Idea

Cells are the structural and functional units of

all living organisms

7.1 Cell Discovery and Theory

p. 182-186

Essential Question

What are the differences between prokaryotic and

eukaryotic cells?

Main Idea

•  The invention of the microscope led to the discovery of cells.

Robert Hooke

•  Made a simple microscope •  Observed small, box-shaped structures in a

piece of cork •  Most scientists observed tiny organisms

using the first microscopes

Cell

•  The basic structural and functional unit of all living organisms

Anton van Leeuwenhock

•  Designed a microscope that allowed him to see living organisms in pond water, milk, and various other substances

Cell Theory

1.  All living organisms are composed of one or more cells

2.  Cells are the basic unit of structure and organization of all living organisms

3.  Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cell

Microscopes

•  Compound light microscope - Utilizes a series of glass lenses and visible light to magnify an image

•  Magnifies up to 1000 times

• 

Microscopes

•  Electron Microscopes uses magnets to aim a beam of electrons at an object to produce an image

•  Magnifies up to 500,000 times

Pollen

• 

Plasma Membrane

•  A special boundary that helps control what enters and leaves the cell

Eukaryotic cells

•  Contain a nucleus and other organelles that are bound by membranes

Prokaryotic cells •  Cells without a nucleus or other membrane-

bound oragnaelles

Comparison of Eukaryotic and Prokaryotic cells

•  Eukaryotic Cells –  True nucleus –  Membrane-bound

organelles –  Usually larger in size –  Example: cells that

make up a human

•  Prokaryotic Cells –  No true nucleus –  No membrane-bound

organelles –  Smaller in size –  Example: bacteria

End of 7.1

7.2 The Plasma Membrane

p. 187-190

Main Idea

•  The plasma membrane helps to maintain a cell’s homeostasis

Essential Question What is the plasma membrane and what

is its function?

Homeostasis

•  Is maintaining balance in an organism’s internal environment

Plasma Membrane

•  Responsible for maintaining homeostasis in a cell

•  A thin flexible boundary between a cell and its environment

•  Allows nutrients into the cell and allows waste and other products to leave the cell

Selective permeability

•  When a membrane allows some substances to pass through while keeping others out

p. 187, fig 7.5 (right)

•  What substances are allowed into the cell by the plasma membrane?

•  What substances are allowed out of the cell by the plasma membrane?

•  What is selective permeability?

p. 187, fig 7.5 (right)

•  What substances are allowed into the cell by the plasma membrane? –  Water, oxygen and glucose

•  What substances are allowed out of the cell by the plasma membrane? –  Water, wastes and carbon dioxide

•  What is selective permeability? –  When a membrane allows some substances to pass

through, and keeps others out

Phospholipid bilayer

•  2 layers of phospholipids arranged tail-to-tail

•  This arrangement allows the membrane to exist in watery environments

Phospholipid

•  Polar head – faces the watery environment –  Is attracted to the water

•  Nonpolar tail – faces each other

Find the polar head, and nonpolar tail

Phospholipid bilayer

•  Functions to separate the environment inside the cell from the environment outside of the cell

Transport Proteins

•  Move substances or waste materials through the plasma membrane

Proteins •  Transmit signals inside the cell •  Act as a support structure •  Provide pathways for substances to enter

and leave

Cholesterols

•  Prevent fatty acid tails from sticking together

Carbohydrates

•  Identify chemical signals

Fluid mosaic model

  The phospholipid bilayer allows other molecules to “float” in the membrane.

End of 7.2

7.3 Structure and Organelles

p. 191 - 200

Main Idea

•  Eukaryotic cells contain organelles that allow the specialization and the separation of functions within the cell

Essential Question What are the component parts of a cell and what

are their functions?

Cytoplasm

•  The environment inside the plasma membrane that is a semifluid material

Cytoskeleton

•  A supporting network of long, thin protein fibers that form a framework for the cell and provide an anchor for the organelles inside the cell

•  Made up of microfilaments and microtubules

Nucleus

•  “manages” the cell •  Contains DNA that stores genetic

information

•  Nucleolus – where ribosomes are made

Nuclear Membrane

•  Double membrane that surrounds the nucleus

•  Nuclear pore –opening that allows larger-sized substances to move in and out of the nucleus

Ribosome

•  Help manufacture proteins •  Made up of RNA and protein

Endoplasmic Reticulum

•  Aka ER •  A membrane system of folded sacs and

interconnected channels that serves as the site for protein and lipid synthesis

•  Rough ER – area of ER where ribosomes are attached

•  Smooth ER – area of the ER where there are no ribosomes attached

Golgi Apparatus

•  A flattened stack of membranes that modifies, sorts, and packages proteins for distribution into and outside of the cell

Vacuole

•  A sac used to store food, enzymes, and other materials needed by a cell

•  Mostly found in plant cells

Lysosomes

•  Vesicles that contain substances that digest excess or worn-out organelles and food particles

Centrioles

•  Groups of microtubules •  Function during cell division •  We will learn more about these in ch. 9

Mitochondria

•  “energy generators” that convert fuel particles (sugars) into usable energy

•  Aka “powerhouse” of the cell

Chloroplast

•  Organelles that capture light energy and convert it to chemical energy through a process called photosynthesis

•  Only found in plant cells

Cell Wall

•  Thick, rigid mesh of fibers that surrounds the outside of the plasma membrane, protecting the cell and giving it support

•  Only in plant cells

Cilia and Flagella

•  Structures that project outside the plasma membrane

•  Cilia – short, numerous projections that look like hairs

•  Flagella – long, less numerous projections that move in a whiplike motion

End of 7.3

7.4 Cellular Transport

p. 201 - 207

Main Idea

•  Cellular transport moves substances within the cell and moves substances into and out of the cell

Essential Question How are substances moved

into and out of a cell?

Diffusion

•  The net movement of particles from an area where there are many particles of the substance to an area where there are fewer particles of the substance

•  Example: a drop of ink in water

Dynamic equilibrium

•  The condition in which there is continuous movement but no overall change

•  Example: ink that has been dropped in water last hour

Facilitated Diffusion

•  Substances move into the cell through a water-filled transport protein called a channel

•  The protein is “facilitating” the diffusion of the water

Osmosis

•  Diffusion of water across a selectively permeable membrane

•  Look at fig 7.22 pg. 203

Isotonic solution

•  A solution that has the same concentration of water and solutes (ions, sugars, proteins) –  Iso means same

Hypotonic solution

•  A solution that has a lower concentration of solute – There is more water outside the cell than in it – Cell swells

Hypertonic solution

•  The concentration of the solute outside of the cell is higher than inside – Cell shrivels

Active Transport

•  The movement of substances across the plasma membrane against a concentration gradient

•  Requires energy •  Example: sodium-potassium ATPase pump

Endocytosis

•  The cell engulfs an object •  Example: cellular eating in unicellular

organisms

Exocytosis

•  The secretion of materials at the plasma membrane

•  Example: to expel waste from a cell

End of 7.4

End of ch. 7