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Cells
Unit 4
Chapter 7
Cellular Structure and Function
7.1 Cell Discovery and Theory
The Cell Theory
 All organisms are composed of one or
more cells.
 The cell is the basic unit of structure and
organization of organisms.
 All cells come from preexisting cells.
Chapter 7
Cellular Structure and Function
7.1 Cell Discovery and Theory
Light Microscopes
 Utilizes a series of
glass lenses and
visible light to
magnify an image
 Magnifies images
up to 1,000 times
the actual size
Chapter 7
Cellular Structure and Function
7.1 Cell Discovery and Theory
Electron Microscopes
 Utilizes magnets to aim a beam of electrons
to produce
an image
 Magnifies
images up to
500,000 times
the actual size
9560x
Chapter 7
Cellular Structure and Function
7.1 Cell Discovery and Theory
Prokaryotic Cell
 Simple structure
 Contains a plasma
membrane
 Does not contain
membrane-bound
organelles
11,000x
Chapter 7
Cellular Structure and Function
7.1 Cell Discovery and Theory
Eukaryotic Cell
 More complex
structure
 Contains a plasma
membrane
 Contains membranebound organelles
400x
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Plasma (Cell) Membrane
 Thin, flexible boundary between the
cell and its environment
 Allows nutrients into the cell
 Allows waste to leave the cell
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Selective Permeability
 The plasma membrane controls the movement of
substances into
and out of the cell.
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
 The plasma membrane is composed of the
phospholipid bilayer.
 A phospholipid means:
a glycerol backbone
two fatty acid chains
a phosphate group.
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Fluid Mosaic Model
 The phospholipid
bilayer allows other
molecules to “float”
in the membrane.
Other Components
 Proteins
 Cholesterol
 Carbohydrates
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Proteins
 Transmit signals inside the cell
 Act as a support structure
 Provide pathways for larger substances to enter
and leave the cell
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Cholesterol
 Prevents fatty acid tails from sticking
together
Chapter 7
Cellular Structure and Function
7.2 The Plasma Membrane
Carbohydrates
 Identify chemical signals
Chapter 7
Cellular Structure and Function
7.3 Structures and Organelles
Chapter 7
Cellular Structure and Function
7.3 Structures and Organelles
Chapter 7
Cellular Structure and Function
7.3 Structures and Organelles
Cilia
 Short, numerous
projections that look
like hairs
400x
Flagella
 Longer and less
numerous than cilia
 Create movement
with a whiplike
motion
26,367x
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Passive Transport
 Movement of particles across the cell
membrane without using energy
Three Modes of Passive Transport
 Diffusion
 Facilitated Diffusion
 Osmosis
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Diffusion
 Movement of particles from an area of high
concentration to an area of lower
concentration
Diffusion
Initial Conditions
Low
High
High
Low
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
 Diffusion is controlled by
 Temperature
 Pressure
 Concentration
Dynamic Equilibrium
 When diffusion of material into the cell
equals diffusion of material out of the cell
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Diffusion in a Cell
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Facilitated Diffusion
 Movement of materials across the plasma
membrane using proteins
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Channel Proteins
Carrier Proteins
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Osmosis
 Diffusion of water across a selectively
permeable membrane
Three Types of Solutions
 Isotonic
 Hypotonic
 Hypertonic
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Isotonic Solution
 Water and dissolved substances diffuse
into and out of the cell at the same rate.
Plant Cell
Blood Cell
11,397x
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Hypotonic Solution
 Solute concentration is higher inside the
cell.
 Water diffuses into the cell.
 BLOWS UP the cell.
Plant Cell
Blood Cell
13,000x
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Hypertonic Solution
 Solute concentration is higher outside the
cell.
 Water diffuses out of the cell.
 SHRINKS the cell.
Plant Cell
Blood Cell
13,000x
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Active Transport
 Movement of particles across the cell
membrane using energy
Active Transport Using Carrier Proteins
Chapter 7
Cellular Structure and Function
7.4 Cellular Transport
Endocytosis
 Process by which the
cell surrounds and
takes particles into the
cell
Exocytosis
 Secretion of material
out of the plasma
membrane
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Transformation of Energy
 Energy is the ability to do work.
 Thermodynamics is the study of the flow
and transformation of energy in the
universe.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
 All of the chemical reactions in a cell
 Photosynthesis—light energy from the Sun
is converted to chemical energy for use by
the cell
 Cellular respiration—organic molecules are
broken down to release energy for use by
the cell
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
 ATP releases energy
when the bond between
the second and third
phosphate groups is
broken.
Chapter 8
Cellular Energy
8.2 Photosynthesis
Overview of Photosynthesis
 Photosynthesis occurs in two phases.
 Light-dependent reactions
 Light-independent reactions
Light and pigments
• Photosynthesis requires light and the
pigment chlorophyll
• The green pigment is the wavelength
reflected rather than absorbed, by plants
the most – so plants are green and other
colors are absorbed
Chapter 8
Cellular Energy
8.2 Photosynthesis
Phase One: Light Reactions
 The absorption of light is the first step in
photosynthesis.
 Chloroplasts capture light energy.
Reactions of Photosynthesis
Light dependent reactions
• Grana are stacks of thylakoids in the
chloroplast that contain the chlorophyll
which captures sunlight
• Light dependent reactions take place in
the thylakoids
Chapter 8
Cellular Energy
8.2 Photosynthesis
Phase Two: The Calvin Cycle (Light-Independent)
 In the second
phase of
photosynthesis,
called the
Calvin cycle,
energy is
stored in
organic
molecules such
as glucose.
Light independent reactions
The Calvin Cycle
• The Calvin cycle or light independent
reactions take place in the stroma
• Uses ATP and NADPH from light dep.
Reactions to produce high energy sugars
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Overview of Cellular Respiration
 Organisms obtain energy in a process
called cellular respiration.
 The equation for cellular respiration is the
opposite of the equation for
photosynthesis.
(Glucose) + (oxygen)---->(carbon dioxide) + (water) + energy* (ATP)
Overview of Cellular Respiration
Mitochondrion
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Krebs
Cycle
Electrons
carried in
NADH and
FADH2
Electron
Transport
Chain
Mitochondrion
Cytoplasm
Chapter 8
Cellular Energy
8.3 Cellular Respiration
 Cellular respiration occurs in 3 parts.
 Glycolysis
 Kreb’s Cycle
 Electron Transport Chain
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Step 1: Glycolysis
 Glucose is broken down in the cytoplasm by
glycolysis (splitting glucose).
 Occurs in the cytoplasm
 Forms 2 pyruvate from 1 glucose
 2 molecules of ATP and 2 molecules of NADH
are formed for each molecule of glucose that is
broken down.
 Takes 2 ATP to start
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Step 2: Krebs Cycle
 Glycolysis has a net result of two ATP and
two pyruvate.
 The series of reactions in which pyruvate is
broken down into carbon dioxide is called
the Krebs cycle.
 Occurs in the mitochondria
Chapter 8
Cellular Energy
8.3 Cellular Respiration
 The net yield from
the Krebs cycle is
6 CO2 molecules
2 ATP
8 NADH
2 FADH2.
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Step 3: Electron Transport
 Final step in the breakdown of glucose
 Point at which ATP is produced
 Produces 24 ATP
Section 9-2
Summary Flowchart
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
Cellular Energy
8.3 Cellular Respiration
Anaerobic Respiration
 The anaerobic pathway that follows
glycolysis
 Two main types:
 Lactic acid fermentation
 Alcohol fermentation
Section 9-1
Chemical Pathways
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
Fermentation
• A process in the absence of oxygen (anaerobic)
• Lactic acid fermentation – NADH is converted
back to NAD producing lactic acid
• Occurs when body can’t supply enough oxygen
to the muscles during exercise = soreness,
burning, fatigue