CH. 7 – CELLS. I. CELLS A. What is a cell? 1. Cell – the smallest unit of matter that can carry on all the processes of life.

CH. 7 –

CELLS

I. CELLSA. What is a cell?

1. Cell – the smallest unit of matter that can carry on all the processes of life

I. CELLSB. Who first discovered the cell?

1. Anton van Leeuwenhoek – first to observe cells

2. Robert Hooke – used the light microscope to observe cork

a. First person to call the shapes inside of organisms “cells”

I. CELLS3. Rudolph Virchow – studied cell reproduction and discovered that all cells come from other pre-existing cells.

http://www.youtube.com/watch?v=5fg3Q-hbSsI

I. CELLS4. Mathias Schleiden – studied plants and discovered that all plants are made of cells 5. Theodor Schwann – studied animals and discovered that all animals are made of cells

I. CELLSC. What is the cell theory?

1. The cell theory was developed by theories of Hooke, Virchow, Schleiden, and Schwann.

a. The cell is the basic unit of organization for organisms.

b. All organisms are made of one or more cells.

c. All cells come from other pre-existing cells.

I. CELLS2. With better microscopes, scientists observed that cells contained specialized structures.

a. Organelles – cells parts that perform a specific job or function for the cell

I. CELLSD. Cell Diversity!

1. Your body alone contains 200 different cell types!2. Cells Organisms can be classified by the number of cells they are made up of.

a. Unicellular Organism – single celled organismExample: bacteria, yeast

b. Multicellular Organism – organism made up of many cells

Example: plants, animals

I. CELLSE. How are cells classified based upon the presence/absence of

organelles?

1. Eukaryotic Cells – cells with a membrane-bound nucleus and organelles

a. Examples: plant and animal cells

4. Cell membrane

1. Nucleus

2. Nucleolus

3. Chromatin

5. Organelles

I. CELLS2. Prokaryotic Cells – cells with no membrane-bound nucleus or organelles (except ribosomes)

a. Examples: bacteria

1. Ribosomes

2. DNA 3. Cell membrane

4. Cell wall

I. CELLS

Left: Colorized micrograph of a prokaryotic cell of the bacterium.

Right: Colorized micrograph of a eukaryotic cell of the green algae.

I. CELLS

Cell Type Nucleus? Organelles? Uni or Multicellular?

Prokaryotic  

Eukaryotic  

3. Review:

II. CELL BOUNDARIESPlasma (Cell) MembraneFunction:

Surrounds cellAllows things in and out (homeostasis)

Fact: Selectively permeable – allows water and nutrients in and

waste outMade of phospholipids

Found in: ProkaryotesEukaryotes

Cell WallFunction:

Surrounds cell membrane to provide extra support and protection

Fact: Made of cellulose in plants

Found in: ProkaryotesEukaryotes (plants)

1. Cell membrane

2. Cell wall

II. CELL BOUNDARIES

NucleusFunction:

Controls the organellesContains DNA

Fact: “Command center” or “brain” of the cellMost prominent structure

Found in: Eukaryotes

Nucleus

NucleusIII. CELL CONTROL

III. CELL CONTROLChromatinFunction:

Condense to form chromosomes in nucleus

Fact: Strands of DNA that look like spaghetti

Found in: Eukaryotes

III. CELL CONTROLNucleolusFunction:

Makes ribosomes

Fact: Found inside the nucleus

Found in: Eukaryotes

Nucleolus

Nucleolus

III. CELL CONTROLRibosomesFunction:

Makes proteins

Fact: Made of RNACan be free or attached to ER

Found in: EukaryotesProkaryotes

Ribosomes

III. CELL CONTROLNuclear Envelope/MembraneFunction:

Controls what enters/exits the nucleus

Fact: Surrounds the nucleus

Found in: Eukaryotes

IV. CELL ASSEMBLYCytoplasmFunction:

Suspends/holds organellesSite of chemical reactions

Fact: Contains clear gel-like fluid called cytosol

Found in: EukaryotesProkaryotes

IV. CELL ASSEMBLYRough Endoplasmic Reticulum (ER)Function:

Produces proteins

Fact: Helps move molecules throughout the cell

Found in: Eukaryotes

IV. CELL ASSEMBLYSmooth Endoplasmic Reticulum (ER)Function:

Produces lipids (steroids)Detoxifies poisons

Fact: Helps move molecules throughout the cell

Found in: Eukaryotes

IV. CELL ASSEMBLYGolgi ApparatusFunction:

Processes, packs, and secretes proteins and lipids

Fact: Works closely with ERFlattened stack of membranes

Found in: Eukaryotes

Golgi

IV. CELL ASSEMBLYVacuoleFunction:

Stores food, water, waste, proteins, carbs

Fact: Helps maintain homeostasis

Found in: Eukaryotes (plants have a LARGE vacuole)

Vacuole

IV. CELL ASSEMBLYLysosomesFunction:

Uses enzymes to digest old organelles and foreign objects (bacteria, viruses)

Fact: “Suicide sacs”

Found in: Eukaryotes

Lysosome

IV. CELL ASSEMBLYEver wonder how a tadpole gets rid of its tail and

grows legs????

It’s lysosomes digest the cells in the tail, and these molecules are released to build different cells, like legs!

V. ENERGY TRANSFORMERSChloroplastFunction:

Capture light (solar energy) and convert it to chemical energy during photosynthesis

Fact: Glucose is the sugar made

Found in: Eukaryotes (plants)

Chloroplast

Mitochondria

V. ENERGY TRANSFORMERSMitochondriaFunction:

Breaks down food into ATP energy during cellular respiration

Fact: “Powerhouse” of the cell

Found in: Eukaryotes

VI. SUPPORT & LOCOMOTIONCytoskeletonFunction:

Maintains the shape & supports the cell

Fact: Made of microfilaments &

microtubulesFound throughout the cytoplasm

Found in: EukaryotesProkaryotes

VI. SUPPORT & LOCOMOTIONCiliaFunction:

Movement of cells or fluids

Fact: Short hair-like fibers

Found in: EukaryotesProkaryotes

VI. SUPPORT & LOCOMOTIONFlagellaFunction:

Movement of cells

Fact: Long hair-like fibers

Found in: EukaryotesProkaryotes

Flagella

Cilia

http://www.youtube.com/user/ecrouch7#p/a/f/0/1IqsE8CVTms

http://www.youtube.com/watch?v=rABKB5aS2Zg&feature=related

VII. LEVELS OF ORGANIZATIONA. Organization: Organelles Cells

Tissues Organs Organ systems Organisms

VIII. THE CELL MEMBRANE

A. A cell’s survival depends on the cell’s ability to maintain the necessary conditions inside itself.1. Maintaining these constant internal conditions is called homeostasis.

VIII. THE CELL MEMBRANE

B. Cell Membrane – flexible boundary between the cell and its outside environment1. Allows water and nutrients to enter the cell and wastes to leave the cell.

Water

Cell Membrane

VIII. THE CELL MEMBRANE

2. Selectively Permeable – allowing some materials to pass while keeping others out

a. Example: A spaghetti strainer allows water, but not spaghetti to pass through

VIII. THE CELL MEMBRANE

C. What is the cell membrane made up of?1. Phospholipids – diglyceride with a phosphate group attached

VIII. THE CELL MEMBRANE

a. Phospholipid Bilayer – the cell membrane is TWO layers thick

VIII. THE CELL MEMBRANE

b. Phospholipids have a polar “head” and non polar “tail”.

- Polar “heads” are attracted to water, sugars, and proteins.

VIII. THE CELL MEMBRANE

- Non-polar “tails” repel water,sugars, and proteins.- Resulting in a selectively permeable membrane.

VIII. THE CELL MEMBRANE

2. Proteins are embedded in the cell membrane to recognize substances that can enter and exit the cell.

VIII. THE CELL MEMBRANE

3. Cholesterol stabilizes the membrane by preventing lipids from sticking together.

VIII. THE CELL MEMBRANE

D. Fluid Mosaic Model - describes how phospholipids can move around like a fluid and the proteins make a pattern

VIIII. CELL TRANSPORT

A. What types of materials need to cross the cells membrane? Water, nutrients, oxygen, waste

B. In cells, particles always move to reach equal concentrations.1. Concentration Gradient – unequal distribution of particles

VIIII. CELL TRANSPORTC. Types of Transport

1. Passive Transport – movement of any substance across a membrane WITHOUT the use of chemical energy.

a. Occurs from high to low concentration, with the concentration gradient.

VIIII. CELL TRANSPORT

b. Types of Passive Transport- Diffusion – movement of molecules across a selectively permeable

membrane; occurs from high to low concentration, with the concentration gradient.

VIIII. CELL TRANSPORT

- Example: Oxygen diffuses into the bloodstream because of a high pressure in the lungs.

VIIII. CELL TRANSPORT

- Osmosis – movement of water across a selectively permeable membrane; occurs from high to low concentration, with the

concentration gradient.

VIIII. CELL TRANSPORTc. How are larger and strongly charged molecules, such as

glucose, able to pass through the cell membrane more quickly than they should?

- Facilitated diffusion – passive transport of large particles across a membrane with the help of

proteins; occurs from a high to low concentration, with the concentration gradient

- Example: Sugars, Amino Acids

Glucosemolecules

LowConcentration

CellMembrane

HighConcentration

Proteinchannel

VIIII. CELL TRANSPORT

VIIII. CELL TRANSPORT2. Types of Solution – How does the water “know” which way to move?

a. Hypertonic Solution – (high solute concentration) more water on the inside of the cell than the outside of the cell.

- Water moves OUT of the cell.- Size of the cell = shrinks (plasmolysis)

H2O + NaCl Solution

VIIII. CELL TRANSPORTb. Hypotonic Solution – (low solute concentration) more

water on the outside of the cell than the inside of the cell.

- Water moves INTO the cell.

- Size of the cell = swells

- Cytolysis = animal cells burst

- Turgor Pressure = water pushes against cell wall in plants

H2O + NaCl Solution

VIIII. CELL TRANSPORTc. Isotonic Solution – equal concentration of water and solute inside and outside the cell

- Water moves in and out of cell equally.- Size of cell = stays the same

H2O + NaCl Solution

VIIII. CELL TRANSPORT

Criteria Inside Cell

Outside Cell

Where is there more solvent (water)?

hypertonic

hypotonic

Where is there more solute (salts, dissolved substances)?

hypotonic hypertonic

CELL TRANSPORT

VIIII. CELL TRANSPORT3. Diffusion is a powerful process, however, sometimes cells need to move materials in the opposite direction.

a. Active Transport – proteins are used to move ions or molecules against the concentration gradient, using ATP energy.

- Occurs from areas of low to high concentrations.

- Examples: minerals, nutrients

VIIII. CELL TRANSPORT4. Types of Active Transport

a. Endocytosis – process when a cell surrounds and takes in materials from the environment

- Example: White blood cell engulfing a bacterium.

VIIII. CELL TRANSPORT- Two types of Endocytosis

- Pinocytosis – movement of liquids into a cell

- Phagocytosis – movement of solids in a cell

VIIII. CELL TRANSPORTb. Exocytosis – the explusion (exit) or secretion of

material out a cell - Example: Cell getting rid of waste.

VIIII. CELL TRANSPORTc. Although endocytosis and exocytosis are different, the two processes often work TOGETHER.

http://www.youtube.com/watch?v=dPKvHrD1eS4