Download The History of the Cell Theory

Biology 1- Chapter 7 Notes
Prentice Hall (pg. 168-193)
•
7–1
Life Is Cellular
•
A. The Discovery of the Cell
1. Early Microscopes
2. The Cell Theory
B. Exploring the Cell
C. Prokaryotes and Eukaryotes
1. Prokaryotes
2. Eukaryotes
•
7–2
A.
B.
C.
D.
E.
F.
G.
H.
Cell Boundaries
A. Cell Membrane
B. Cell Walls
C. Diffusion Through Cell Boundaries
1. Measuring Concentration
2. Diffusion
D. Osmosis
1. How Osmosis Works
2. Osmotic Pressure
E. Facilitated Diffusion
F. Active Transport
1. Molecular Transport
2. Endocytosis and Exocytosis
Eukaryotic Cell Structure
Comparing the Cell to a Factory
Nucleus
Ribosomes
Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Vacuoles
Mitochondria and Chloroplasts
1. Mitochondria
2. Chloroplasts
3. Organelle DNA
I. Cytoskeleton
7–3
•
7–4
The Diversity of Cellular Life
A. Unicellular Organisms
B. Multicellular Organisms
1. Specialized Animal Cells
2. Specialized Plant Cells
C. Levels of Organization
1. Tissues
2. Organs
3. Organ Systems
7.1: The History of the Cell Theory
• Before microscopes were invented, people
believed that diseases were caused by
curses and supernatural spirits.
• As scientists began using microscopes,
they quickly realized they were entering a
new world–one of microorganisms.
• Microscopes enabled scientists to view
and study cells, the basic units of living
organisms.
Development of Light
Microscopes
• The first person to record looking at water under a
microscope was Anton van Leeuwenhoek.
• The microscope van Leeuwenhoek used is considered a
simple light microscope because it contained one lens and
used natural light to view objects.
• Compound light microscopes use a series of lenses to
magnify objects in steps.
• These microscopes can
magnify objects up to
1500 times.
The Cell Theory
• Robert Hooke was an English scientist
who lived at the same time as van
Leeuwenhoek.
• Hooke used a compound light microscope
to study cork, the dead cells of oak bark.
• Cells are the basic building blocks of all
living things.
The cell theory is made up of three
main ideas:
• All organisms are composed of one or more cells.
• The cell is the basic unit of structure and function of
organisms.
• All cells come from preexisting cells.
Three Scientists contributed to the Cell Theory:
• 1838- Schleiden: plants are made of cells
• 1939- Schwann: animals are made of cells
• 1855- Virchow: New cells are produced from the
division of old cells
Development of Electron
Microscopes
• The electron microscope was
invented in the 1940s.
• This microscope uses a beam
of electrons to magnify
structures up to 500,000 times
their actual size.
There are two basic types of
electron microscopes.
• The scanning electron
microscope scans the surface
of cells to learn their three
dimensional shape.
• The transmission electron
microscope allows scientists to
study the structures contained
within a cell.
Scanning Probe Microscope
• Discovered in the 1990’s
• Produces images by tracing the surfaces of
samples with a fine probe
• Can observe single atoms in the air or in
solution
Natural laws limit cell size
• Large cells have a
smaller ratio of surface
area to volume than
small cells
• cells must be small
enough to have a
surface area which can
supply nutrient needs
• cells must be large
enough to hold all
required molecules and
organelles
Two Basic Cell Types
Cell membrane
Cytoplasm
Prokaryotic Cell
Cell membrane
Cytoplasm
Nucleus
Eukaryotic Cell
Organelles
Prokaryotic and Eukaryotic Cells
Prokaryotic Cells
• Cells that do not
contain internal
membrane-bound
structures and do not
have a nucleus are
called prokaryotic
cells.
Prokaryotic
Cell
• Unicellular organisms
such as bacteria are
very simple.
• They still carry out all
of life’s activities such
as respiration, cell
reproduction, growth,
etc.
Eukaryotic Cells
• Cells containing
membrane-bound
structures and a
nucleus are called
eukaryotic cells.
• Most of the multicellular plants and
animals are made up
of cells that are very
specialized and
diverse in their
structures and
functions
Eukaryotic Cell
7.2 Eukaryotic Cell Structure
Organelles
• The membrane-bound
structures within eukaryotic
cells are called organelles.
• Each “little organ” has a
specific function that
contributes to cell survival.
• Separation of organelles into
distinct compartments
benefits the eukaryotic cells.
• Lysosomes
• Nucleus
• Plasma Membrane
• Endoplasmic Reticulum
• Mitochondrion
Biologists divide the cell into
two major parts
• The nucleus is the central
membrane-bound organelle that
manages cellular functions.
• Everything between the cell
membrane and the nucleus is
called the cytoplasm.
Nucleus
- Nuclear envelope – double layered membrane surrounding nucleus;
contains small pores
- Nuclear pores- allow transport of materials in and out of nucleus
- Chromatin-granular material visible within the nucleus; consists of
DNA tightly coiled around proteins
- Chromosomes – threadlike
Nucleolus
Chromatin
structure within the nucleus
containing the genetic
information that is passed
from one generation of cells
to the next (chromosomes are
formed when chromatin
condenses during cell division)
Nuclear
- Nucleolus – dense material
Envelope
in nucleus; makes
ribosomes which make
proteins
Nuclear Pore
Ribosomes
• Ribosomes are made in
the nucleolus.
• They travel in and out
of the nucleus throught
he nuclear pores.
Ribosomes
• Ribosomes are small
particles within the cell
on which proteins are
assembled; made of
RNA and protein
• They can be free (in the
cytoplasm)
• They are also attached
to the rough endoplasm
reticulum
Endoplasmic reticulum
• The endoplasmic reticulum
(ER) is responsible for
assembly, transport, and
storage of molecules within
cell.
• There are two types
• Rough ER- contains
ribosomes and makes
proteins
• Smooth ER- lacks
ribosomes; has enzymes
that make membrane lipids
and detoxifies drugs
• Liver cells contain many
smooth ER for
detoxification
Golgi Apparatus
• Stacks of membranes
in the cell that
modifies, sorts, and
packages proteins
from the endoplasmic
reticulum
• The Golgi apparatus
is like a customization
shop where finishing
touches are added to
proteins.
Lysosomes
• Lysosomes are organelles that contain
digestive enzymes. They digest excess or
worn out organelles, food particles, and
engulfed viruses or bacteria.
• The lysosomes are the clean-up crew of the
cell
• Tay-Sachs disease is caused by excess lipid
accumulation on the brain. The cause of this
disease has been traced to lysosomes that
failed to function properly
Vacuoles
• Vacuoles are membrane-bound spaces used for
temporary storage of materials (such as water,
salts, proteins, and carbohydrates)
• Notice the difference between vacuoles in plant
and animal cells.
Plant
Vacuole
Animal
Cell
Cell
• Paramecium have a contractile vacuole that pumps
excess water out of the cell, which aids with
homeostasis
Mitochondria
• Mitochondria are
• Cellular respiration is the
membrane-bound
process that converts
organelles in plant and
chemical energy stored in
animal cells that transform
food into ATP energy for
energy for the cell.
cells to use.
• A mitochondria, like the
• Muscles cells (needed for
endoplasmic reticulum,
has a highly folded inner
movement) contain a large
membrane.
number of mitochondria for
• The folds increase the
energy production
surface area of the
mitochondrion in order to
make more energy (ATP)
• Cellular Respiration takes
place in the mitochondria
of cells
Chloroplasts
• Chloroplasts are found in
cells of plants and some
other organisms
• Chloroplasts are organelles
that capture light energy
and produce food to store
for a later time.
• Photosynthesis takes place
in the chloroplasts
• Chloroplasts contain green
pigment called chlorophyll.
• Chlorophyll traps light
energy and gives leaves
and stems their green
color.
• Chloroplasts acts like a
solar power plant
Cytoskeleton
• Cells have a support structure called the
cytoskeleton within the cytoplasm.
• It is a network of proteins that help
maintain cellular shape and movement
• The cytoskeleton is composed of
microtubules and microfilaments.
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Mitochondrion
• Microtubules are
thin, hollow
cylinders made of
protein that
maintain cell
shape
• Microfilaments
are thin solid
protein fibers
that help cells
move (amoeba)
Centrioles
• Made of microtubules
• one of two tiny structures located in the cytoplasm of
animal cells near the nuclear envelope
• help to organize cell division (helps cells split into two)
• only found in animal cells
Cilia and Flagella
Cilia
• Some cell surfaces have cilia and
flagella, which are structures that
aid in locomotion or feeding. Cilia
and flagella can be distinguished by
their structure and by the nature of
their action.
• Cilia are short, numerous, hair-like
projections that move in a wavelike
motion.
• Flagella are long projections that
move in a whip-like motion. Flagella
and cilia are the major means of
locomotion in unicellular organisms. Flagella
The Plasma Membrane
•
All living cells must maintain a balance
regardless of internal and external
conditions. Survival depends on the
cell’s ability to maintain the proper
conditions within itself.
Why cells must control materials
•
The plasma membrane is the
boundary between the cell and its
environment.
It is the plasma membrane’s job to:
• allow a steady supply of glucose, amino acids, and lipids to come
into the cell no matter what the external conditions are.
• remove excess amounts of these nutrients when levels get so
high that they are harmful.
• allow waste and other products to leave the cell.
Cell membrane
•
This process of
maintaining the cell’s
environment is called
homeostasis.
•
Selective permeability is
a process used to
maintain homeostasis in
which the plasma
membrane allows some
molecules into the cell
while keeping others out.
Plasma
Membrane
Water
Structure of the Plasma Membrane
• The plasma membrane is
composed of two layers of
phospholipids back-to-back.
• Phospholipids are lipids with a
phosphate attached to them.
Phosphate
Group
Glycerol
Backbone
Two Fatty
Acid Chains
• The lipids in a plasma
membrane have a
glycerol backbone, two
fatty acid chains, and a
phosphate group.
Makeup of the phospholipid bilayer
• The phosphate group is
critical for the formation
and function of the
plasma membrane.
•
Phosphate Group
The fluid mosaic model describes the plasma membrane as
a flexible boundary of a cell. The phospholipids move within
the membrane.
Other components of the plasma
membrane:
Cholesterol
• Cholesterol plays the
important role of
preventing the fatty acid
chains of the
phospholipids from
sticking together.
Molecule
• Transport proteins allow
needed substances or waste
materials to move through the
plasma membrane.
Cellular Boundaries
•
The plasma membrane acts
as a selectively permeable
membrane.
• The cell wall is a fairly
rigid structure located
outside the plasma
membrane that provides
additional support and
protection.
Diffusion
• process by which
molecules tend to
move from an area
where they are more
concentrated to an
area where they are
less concentrated
• Equilibrium- when the
concentration of a
solute is the same
throughout the
solution
Osmosis
• diffusion of water through a selectively permeable
membrane
Hypertonic
Solution
• concentration of
solutes in solution is
higher than the
concentration of
solutes inside the cell
• causes water to
diffuse out of the cell;
may cause cell to
shrivel and shrink;
disrupts metabolism
and may kill cell
Hypotonic
Solution
• concentration of
solutes is lower than
the concentration
inside the cell
• causes water to diffuse
into the cell
• animal cells may burst
in a hypotonic solution
• plant cells do not burst
because they are
surrounded by a rigid
cell wall
Isotonic
Solution
• the concentration of
solutes equals the
concentration of solutes
inside the cell
• does not result in the net
diffusion of water into or
out of the cell
• kidneys and skin help to
maintain isotonic
conditions in your body
Facilitated Diffusion
• movement of specific
molecules across cell
membranes through
protein channels
• passive - does not
require an input of
energy
• always moves particles
down a concentration
gradient
• because these
molecules re polar they
must travel through
channels in transport
proteins; ex: glucose
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Protein
channel
Active Transport
• energy-requiring process that
moves material across a cell
membrane against a
concentration difference
• requires energy from ATP
molecules
• can move particles up a
concentration gradient (from low
to high)
• requires carrier proteins to
“pump” particles across
membrane
• ex: Na-K pumps in nerve cells,
movement of nutrients into plant
roots
Molecule to
be carried
Energy
Molecule
being carried
Endocytosis
• process by which a cell
takes material into the cell
by infolding of the cell
membrane
Two Types
• Phagocytosis-process in
which extensions of
cytoplasm surround and
engulf large particles and
take them into the cell
• Pinocytosis-process by
which a cell takes in a
liquid from the
surrounding environment
Exocytosis
• wastes and cell
products leave the
cell by fusing with
membrane;
products packaged
by Golgi apparatus
and excreted from
cell
7.4- Diversity of Cellular Life
Unicellular Organisms
• Sometimes single
cells are the organism
• Grow, respond to the
environment,
transform energy, and
reproduce
•
•
•
•
Multicellular Organisms
Made up of many cells
Very diverse
Depend on
communication and
cooperation between
specialized cells
Cell specialization
Cells throughout an
organism can develop in
different ways to perform
different tasks
Cell Specialization
Animal cells
• Red Blood Cells
• Pancreatic Cells
• Muscle Cells
Plant Cells
• Guard cells
Levels of Organization
Muscle cell
Smooth muscle tissue
Stomach
Digestive system
• Many multicellular organisms have structures called organs that
have a specific function and work with other organs.
• Working together, these organs carry out the life processes of
the entire organism.