HONORS BIOLOGY ISEMESTER ONE

Chapter 3: Cell Structure and Function

Robert Hooke

Mid-1600s: First to describe cells

Used a compound microscope Two lenses

Actually looking at dead cork cells

Anton van Leeuwenhoek

Made many microscopes (single lens)

Describes several types of cells

First to study living, moving organisms (from pond water) with microscope

Fig. 3.2 – page 71

Cell Theory

The cell theory is a fundamental concept of biology!

It states: All living things are composed of cells. Cells are the basic units of structure and function in

living things. New cells are produced from existing cells.

Compound Microscope

Staph bacteria under a compound microscope

Electron Microscope

Transmission (TEM) Specimen cut into very thin slices Beam of electrons pass through

Scanning (SEM) Samples are dehydrated, put in a vacuum, and

sometimes coated in materials like gold Electrons are bounced off the surface Produces 3-D images of the surface

Electron Microscope

Staph bacteria under an electron microscope

Other EM Images

Clockwise from top left: spider, bacteria,

microorganism (probably bacteria)

Classifying Cells – RA Activity

Read the hand out of page 72 and talk to the text.

Construct and color code a Double Bubble Map comparing and contrasting prokaryotic and eukaryotic cells.

Be prepared to share with your partner, and then with the class!

Classifying Cells

Prokaryotes Lack organized structures Circular loop of nucleic acid (DNA) No nucleus Examples: bacteria and blue-green algae

Eukaryotes Organized structures called organelles DNA in nucleus Examples: animal, plant, fungi, and protists

"Cells: Basic Units of Life" Video

Eukaryotic Cells

Three regions Cell membrane Nucleus Cytoplasm

Cell Membrane

Cell Membrane

Function Regulates what comes in and out of cell

Selective permeability – read on page 83! Communication Protection and Support

Phospholipid bilayer Double layer of phospholipids

Fluid Mosaic – read about on page 82! Phospholipid molecules with other molecules (proteins

and carbohydrates) embedded The membrane is in constant movement

Phospholipids - Revisited

Polar Head (phosphate) Hydrophilic Attracted to water

Non-polar Tail (fatty acid) Hydrophobic Doesn’t want to be

near the water

Membrane Proteins

Allow larger molecules to pass through the membrane

Can regulate what comes in or out (is the cell’s bodyguard!)

Other Molecules

Cholesterol Stabilizes the membrane Keeps non-polar tails from sticking to each other

Carbohydrate chains Identification markers: cell communication

Cell Wall

Plants onlyRigid outer layer

covering the cell membrane

Allow plants to support heavy structures like flowers

Contains cellulose and various proteins

Movement Across Membranes

Passive Transport Diffusion (Simple and Facilitated) Osmosis

Active Transport Protein Pump Endocytosis and Exocytosis

Movement is controlled by concentrations

Concentration

Amount of solute (dissolved substance) in a volume of solution

Expressed as mass/volumeAmount of mass is proportional to the

concentrationVolume is inversely proportional to the

concentration

Passive Transport

Movement from an area of high concentration to an area of low concentration (down the concentration gradient)

Requires NO energy Examples: Diffusion (simple and facilitated)

and Osmosis

Diffusion

Movement of solute from high to low concentrations

Requires no energy

Continues until equilibrium is reached

Facilitated Diffusion

Solute cannot simply cross cell membrane because it is semi-permeable

Solute diffuses through membrane proteinsAllows diffusion of molecules that are too

large to diffuse through the membrane using simple diffusion

Osmosis

Movement of water from an area of high concentration to low concentration

Requires no energySolutions surrounding cells can be…(read on

page 86!) Hypertonic – solution has high [solute]* compared to

the inside of the cell Isotonic – solution has the same [solute] as the inside of

the cell Hypotonic – solution has a low [solute] compared to the

inside of the cell *[solute] = solute concentration

Active Transport

Movement of solute from an area of low concentration to high concentration (across or up the concentration gradient)

Requires energy (using ATP)Examples: Protein pumps, endocytosis, and

exocytosis

Protein Pumps

Membrane protein pumps solute across cell membrane

Solute moving from low to high concentration

Requires ATP energy

Endocytosis and Exocytosis

BOTH: Movement of large materials across the cell membrane

Read and take your own notes about each type – pages 90 and 91

Endocytosis Movement into cell Pocket of membrane pinches off to form vesicle (membrane

circle surrounding material) Two types

Phagocytosis – solid material Pinocytosis – dissolved material

Exocytosis Movement out of cell

Phagocytosis and Pinocytosis

Exocytosis

Cytoplasm

The cytoplasm includes everything INSIDE the cell membrane except the nucleus

Also includes the fluid cytosol

Where do Organelles Come From?

Thought to originally be prokaryotes that formed a symbiotic relationship with another cell

Called the Endosymbiotic TheoryEvidence

Many organelles are surrounded by two membranes

Some organelles contain their own DNA

What is symbiosis?!

Nucleus

Control center of the cellDouble membrane with

many poresContains DNA

Directions to make proteins

Two forms: Chromatin Chromosomes

Nucleolus Small, dark region in

nucleus Makes ribosomes

Ribosomes

Site of protein synthesis Link amino acids

together to form proteins

Two subunits made of RNA and protein

Found free floating in cytoplasm or attached to rough ER

Endoplasmic Reticulum

Series of membrane bound canals

Two Types Rough

Studded w/ ribosomes Produces and

transports proteins Smooth

No ribosomes Produces and

transports lipids Detoxifies your blood

in liver cells

Golgi Apparatus

Stack of flattened pancake-like membranes

Modifies, packages, and ships out lipids and proteins

Lysosome

Vesicle filled w/ digestive enzymes

Breaks down cellular waste, bacteria and viruses

Aids in programmed cell death (apoptosis)

Vacuole

Animals Many small membrane

bound sacs Storage compartments for

water, food molecules, inorganic ions, and enzymes

Plants Usually one large central

vacuole Used for storage of water,

toxins, waste products, and pigments that give color (like in flower petals)

Water storage helps establish turgor pressure to keep plant upright

Mitochondria

Double membraneInner membrane

highly foldedPowerhouse of cell

(makes ATP’s)Only inherited

from motherContains DNA

Chloroplast

Only in PlantsDouble membraneConverts sunlight

energy into chemical energy

Contains chlorophyll pigment Captures light

energyContains DNA

Cytoskeleton

Skeleton for CellHelps cell maintain

shapeProvides support and

protectionAids in movementMade of microtubules

and microfilaments

Cilia

Short, hair-like microtubule extensions

Move in oar-like motion

Move cell or move materials on the surface of cells

Cells usually have many

Flagella

Long, whip-like microtubule extensionMove in whip-like fashionMoves cellsCells usually only have one or a few

Centrioles

Only in animal cellsGrouped

microtubulesCan form cillia or

flagella in multicellular or single-celled organisms

Aids in cell division Moves chromosomes

with spindle fibers

Animal Vs. Plant Cells

Organelle Animal Plant

Nucleus YES YES

Cytoplasm YES YES

Cell membrane YES YES

Cell wall NO YES

Lysosome YES YES

Ribosome YES YES

ER YES YES

Mitochondria YES YES

Animal Vs. Plant Cell Continued

Organelle Animal Plant

Golgi YES YES

DNA YES YES

Vacuole YES (small, several, only in a few animal cells)

YES (large, single)

Cytoskeleton YES YES

Chloroplast NO YES

Centriole YES NO

Flagella YES (some) NO

Cilia YES (some) NO

Cell Thinking Map!

Make a brace map of all the parts of the cell and how they fit together.

Skill: Whole to Part Relationship

Unicellular Organisms

Organism made of a single cell

Very simpleOne cell

performs all the functions of life

Ex: Bacteria, protists, some fungi

Multicellular Organisms

Organisms made of many cellsMore complexCells specialize and perform certain functions

(cell differentiation or cell specialization)All cells work together to perform all the

functions of lifeEx: animals, plants, and fungi

Levels of Organization

Levels of Organization

AtomMoleculeMacromoleculeCellTissue- specialized cells working together

towards a common goalOrgan- tissue working together towards a

common goalOrgan system- organ working together towards a

common goalOrganism