Download Chapter 7: Cell Structure and Function

Chapter 3: Cell Structure and
Function
MRS. WILLIAMS
FRESHMAN BIOLOGY
SEMESTER ONE
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 page 72 in your textbook.
 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
 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


Hydrophilic
Attracted to water
 Non-polar Tail


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 Wall
 Plants only
 Rigid 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/volume
 Amount of mass is proportional to the concentration
 Volume 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 movement is aided by membrane proteins
 Allows 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 energy
 Solutions 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 –
page 90
 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
What is symbiosis?!
another cell
 Called the Endosymbiotic Theory
 Evidence
 Many
organelles are surrounded by two
membranes
 Some organelles contain their own DNA
Nucleus
 Control center of the cell
 Double membrane with
many pores
 Contains DNA


Chromatin
Chromosomes
 Nucleolus


Small, dark region
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

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
debris
 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 sac
 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 membrane
 Inner membrane highly
folded
 Power house of cell
(makes ATP’s)
 Only inherited
from mother
 Contains DNA
Chloroplast
 Only in Plants
 Double membrane
 Converts sunlight
energy into
chemical energy
 Contains
chlorophyll pigment

Captures light
energy
 Contains DNA
Cytoskeleton
 Skeleton for Cell
 Helps cell maintain
shape
 Provides support and
protection
 Aids in movement
 Made 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 extension
 Move in whip-like fashion
 Moves cells
 Cells usually only have one or a few
Centrioles
 Only in animal cells
 Grouped microtubules
 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 simple
 One cell performs
all the functions of
life
 Ex: Bacteria,
protists, some fungi
Multicellular Organisms
 Organisms made of many cells
 More complex
 Cells specialize and perform certain functions (cell
differentiation)
 All cells work together to perform all the functions of
life
 Ex: animals, plants, and fungi
Levels of Organization
Levels of Organization
 Atom
 Molecule
 Macromolecule
 Cell
 Tissue- cells working together towards a common goal
 Organ- tissue working together towards a common goal
 Organ system- organ working together towards a
common goal
 Organism