Chapter 7
Cellular Structure and Function
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.
Advent of the Cell
• Hooke and Leeuwenhoek used early microscopes
– Hooke saw/named “cells” in dead cork
– Leeuwenhoek saw living cells in pond water
Light Microscopes
• Use 1 or more lenses and visible light
• Can view live specimens
• Max 2000x due to poor resolution
Electron Microscopes
• Uses electrons instead of light for image
• Very high power/resolution ( max 2 million X)
• Specimen prep is deadly
• SEM = Scanning, 3d surface image
• TEM = Transmission, 2d, more powerful, view slice
Microscopy Links
http://biologygmh.com/
9560x
Cell Types
Prokaryotes
Eukaryotes
• Simple (small)
• More complex (larger)
– Plasma membrane
– Plasma membrane
– Cytosol
– Cytosol
– Non-membrane bound
organelles
– Non-membrane bound
organelles
– No membrane bound
organelles
– Has membrane bound
organelles
• Nucleus
Plasma Membrane
• Cell boundary (inside vs. environment)
• Phospholipid Bilayer
• Selectively permeable
– Controls what/how much can enter or leave cell
– Allows waste out/nutrients in
Phospholipid Bilayer
• Phospholipid structure
– 2 layers, tails facing each other
– Glycerol + phosphate polar “Head”
– 2 nonpolar fatty acid tails (sat or unsat)
The Fluid Mosaic Model
• Phospholipid flow
• Other molecules float on/with lipids
– Proteins
– Carbs
– Cholesterol
Membrane Proteins
• Signal transmission
• Transport
• Support
Membrane Carbohydrates
• Attached to protein or lipid
• Convey signals/communication
Membrane Cholesterol
• Embedded into phospholipids
• Increase membrane fluidity
– Especially in low/high heat
– Unsat fat also helps with low temp
Cell Structures and Organelles
Animal Cell
Plant Cell
Cellular Pursuit
7.3 Structures and Organelles
7.3 Structures and Organelles
Outer Cell Structures
• Cell Membrane
– All cells have it
– Flexible Phospholipid bilayer w/proteins
– Selectively permeable (controls in/out)
• Cell Wall
– Not found in animal cells
– Inflexible barrier for cell protection and support
Outer Structures Cont.
• Flagella
– Long whiplike projections on some cells
– Used for movement or feeding
• Cilia
– Small numerous cell projections on some cells
– Used for movement or feeding
Some other major structures
• Nucleus
– Enclosed by double membrane nuclear envelope
– Envelope has pores for transport
– Contains DNA and nucleoli
• Ribosomes
– Protein synthesis
– Made by nucleoli
– No membrane (all cells have them)
Energy Organelles
• Mitochondria
– In all eukaryotic cells
– Site of cell respiration (ATP production, Energy!)
– Has folded inner membrane
• Chloroplast
– Only in Plant/algae cells
– Site of photosynthesis (organic molecule creation)
– Has lots of small sacs stacked inside
A Cell Framework
• Cytoskeleton
– Protein skeleton
– Provides structure, support, transport
• Centrosome/Centrioles
– microtubule production (ex. cell reproduction)
– Centrioles only in animal cells
Endomembrane System
• Endoplasmic Reticulum (ER)
– Highly folded membranes
• Smooth ER: lipid synthesis
• Rough ER (w/ribosomes): protein synthesis
• Transport and detox
• Golgi Apparatus
– Flattened stack of membranes
• Modifies, packages, export proteins
Endomembrane System II
• Vacuoles
– Membrane bound storage vesicles
– Reduced or not present in animal cells
– Very large central vacuole in plants
• Lysosomes
– Membrane bound digestive vesicle
– Contain enzymes
– Usually only in animal cells
Cellular Transport
• Passive Transport (uses no Energy)
– Diffusion
– Osmosis
– Facilitated Diffusion
Diffusion
• Move from high to low conc.
– “Down” the conc. Gradient
– Affected by temp, pressure, conc.
– Dynamic Equilibrium = no net movement
Initial Conditions
Diffusion
Low
High
High
Low
Osmosis
• Diffusion of water across membrane
– Water is bound by solutes
– More solute = less water
– Water moves from low solute to high solute
– Solutes suck
Osmosis II
• Three osmotic conditions
– Isotonic: equal solute/water, no net movement
– Hypertonic: more solute (water enters)
– Hypotonic: less solute (water leaves)
– Pay attention to frame of reference
• Ex. The aquarium fish cells are hypertonic to the
water can also be the aquarium water is hypotonic to
the fish cells
Osmosis III
• You find yourself stranded in a ship at sea. There is
no rescue in sight, and you’ve already eaten Ra (2
hours after being stranded). Should you drink the
seawater or go without water?
• The zombie invasion has begun. You avoid Luckee
(smart move, even if she’s not a zombie) by ducking
into a bathroom. Is it a good idea to sleep in the
bathtub full of water (assuming you won’t drown)?
Facilitated Diffusion
• Diffusion through a membrane protein
• Effects molecules unable to pass through
membrane without help:
– Larger and polar
– Charged (ions)
Diffusion in a Cell
Channel Proteins
Carrier Proteins
Active Transport
• All move from low to high conc.
• All use Energy (ATP)
• 3 types:
– Protein pumps
– Endocytosis
– Exocytosis
Sodium Potassium Pump
• Sample protein pump
• Pumps 3 Na+ out of cell; 2 K+ into cell
– Uses ATP, makes electrochemical gradient
• Gradient of charge and chemicals
Endo/Exocytosis
• Endocytosis:
– Ingest large molecules or small cells
– Envelope particles with cell
membrane
• Exocytosis
– Release large molecules/waste
– Merge vesicle with cell membrane
7.1 Formative
Questions
Robert Hooke and Anton van
Leeuwenhoek designed microscopes
that enabled them to see organelles
within the cells they observed.
A. true
B. false
1.
A
2.
B
7.1 Formative
Questions
Which type of electron microscope directs
electrons over the surface of a nonliving
specimen, producing a three-dimensional image?
A. transmission electron microscope
B. scanning electron microscope
C. scanning tunneling electron microscope
1.
D. atomic force microscope
A
2.
B
3.
C
4.
D
7.1 Formative
Questions
All cells, whether eukaryotic or
prokaryotic, have a plasma membrane.
A. true
B. false
1.
A
2.
B
7.1 Formative
Questions
What feature of eukaryotic cells has enabled
them to develop more specific functions than
prokaryotic cells?
A. nucleus
B. organelles
C. genetic material (DNA)
D. larger cell size
1.
A
2.
B
3.
C
4.
D
7.2 Formative
Questions
Which term describes the function of proteins
found on the outer surface of the plasma
membrane?
A. identifiers
B. receptors
C. supporters
D. transporters
1.
A
2.
B
3.
C
4.
D
7.2 Formative
Questions
Which component of the plasma membrane
contributes to the fluidity of the plasma
membrane?
A. phospholipids
B. proteins
C. carbohydrates
D. cholesterol molecules
1.
A
2.
B
3.
C
4.
D
7.2 Formative
Questions
What is the function of carbohydrates that
stick out from the outer surface of the plasma
membrane?
A. They give the cell shape and enable it to move.
B. They give the plasma membrane fluidity.
C. They help the cell identify chemical signals.
1.
A
D. They hold the cell in place.
2.
B
3.
C
4.
D
7.3 Formative
Questions
In prokaryotic cells, where does the conversion
of fuel particles into usable energy occur?
A. cytoplasm
B. DNA
C. mitochondria
D. ribosomes
1.
A
2.
B
3.
C
4.
D
7.3 Formative
Questions
Which organelle is similar to the section of a
factory that organizes, boxes, and ships the
final product?
A. chloroplast
B. endoplasmic reticulum
C. Golgi apparatus
D. mitochondrion
1.
A
2.
B
3.
C
4.
D
7.3 Formative
Questions
In which structure is light energy captured and
converted to chemical energy?
A. chloroplast
B. lysosome
C. nucleus
D. vacuole
1.
A
2.
B
3.
C
4.
D
7.4 Formative
Questions
Which type of cellular transport does not
require an input of energy?
A. active transport
B. endocytosis
C. exocytosis
D. facilitated diffusion
1.
A
2.
B
3.
C
4.
D
7.4 Formative
Questions
How does osmosis occur
between the two solutions
separated by the selectively
permeable membrane?
A. Sugar moves to the left.
B. Sugar moves to the right.
C. Water moves to the left.
D. Water moves to the right.
1.
A
2.
B
3.
C
4.
D
7.4 Formative
Questions
Which diagram shows a
cell in a hypotonic
solution?
A.
B.
C.
1.
A
2.
B
3.
C
Chapter 7
Cellular Structure and Function
Chapter Assessment
Questions
Compare and contrast plant and animal
cells.
Answer: Plant cells have both cell walls and
chloroplasts. Animal cells do not have
these structures. Only animal cells
contain
lysosomes. Both plant and animal cells
have plasma membranes, a nucleus,
mitochondria, vacuoles, endoplasmic
reticulum, Golgi apparatus, centrioles, a
nucleolus, ribosomes, and a
cytoskeleton.
Chapter 7
Cellular Structure and Function
Chapter Assessment
Questions
Identify the structure represented by this
image.
Answer: plasma membrane and phospholipid
bilayer
Chapter Diagnostic
Questions
If you wanted to see a detailed 3-dimensional
image of a cell, which type of microscope
would you use?
A. scanning electron microscope
B. transmission electron microscope
C. scanning tunneling microscope
D. simple light microscope
1.
A
2.
B
3.
C
4.
D
Chapter Diagnostic
Questions
Which is not a part of the cell theory?
A. Cells are the basic unit of structure and
organization of all living things.
B. All living things are composed of one or more
cells.
C. Cells arise only from previously existing cells.
D. Cells are produced spontaneously as an
1.
A
organism grows.
2.
B
3.
C
4.
D
Chapter Diagnostic
Questions
Which cell organelles are directly involved with
the production of proteins?
A. ribosomes, endoplasmic reticulum, nucleus
B. cell membrane, lysosome, Golgi apparatus
C. nucleus, centriole, vacuole
D. endoplasmic reticulum, cilia, mitochondrion
1.
A
2.
B
3.
C
4.
D
Chapter Assessment
Questions
_______ is the net movement of particles from
an area where there are many particles of the
substance to an area where there are fewer
particles of the substance.
A. Diffusion
B. Endocytosis
C. Exocytosis
D. Equilibrium
1.
A
2.
B
3.
C
4.
D
Standardized Test
Practice
What is the magnification of a compound light
microscope that uses a 10X lens in series with
a 25X lens?
A. 2.5X
B. 25X
C. 35X
D. 250X
1.
A
2.
B
3.
C
4.
D
Standardized Test
Practice
What part of the plasma membrane makes it
difficult for water-soluble substances to move
freely into and out of the cell?
A. membrane proteins
B. transport proteins
C. the nonpolar tails in the middle of the
1.
plasma membrane
D. the polar heads facing the inside and2.
3.
outside of the cell
4.
A
B
C
D
Standardized Test
Practice
Muscle cells require a great amount of energy.
Which would you expect to find in large
numbers in muscle cells?
A. centrioles
B. endoplasmic reticulum
C. mitochondria
D. ribosomes
1.
A
2.
B
3.
C
4.
D
Standardized Test
Practice
In what type of cell would you most likely
expect to find numerous lysosomes?
A. a plant cell that stores food, enzymes, or
other materials
B. a plant cell that uses light energy for
photosynthesis
1.
A
C. a single-celled organism that moves around
its environment
2.
B
D. a white blood cell that digests bacteria 3.and C
4.
D
viruses
Standardized Test
Practice
Why are the carrier proteins that move substances across
a plasma membrane from a region of higher concentration
to a region of lower concentration called pumps?
A. They require energy to move substances against a
concentration gradient.
B. They open and close to allow substances to diffuse
across the plasma membrane.
C. They help with the osmosis of water through the
1.
A
plasma membrane.
B
D. They pump water into the cell, causing the2.pressure
3.
C
within the cell to increase.
4.
D