honors biology i semester one chapter 3: cell structure and function
TRANSCRIPT
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