Title: Are All Cells Alike?
1Are All Cells Alike?
Section 7-1
- All living things are made up of cells. Some
organisms are composed of only one cell. Other
organisms are made up of many cells. - 1. What are the advantages of a one-celled
organism? - 2. What are the advantages of an organism that
is made up of many cells?
2Section Outline
Section 7-1
- 71 Life Is Cellular
- A. The Discovery of the Cell
- 1. Microscopes
- 2. The Cell Theory
- B. Exploring the Cell
- C. Prokaryotes and Eukaryotes
- 1. Prokaryotes
- 2. Eukaryotes
3Section 7-1
- Discovery of the Cell
- Robert Hooke 1665 named cell
- Leeuwenhoek 1674 observed living
microorganisms - Schleiden 1838 all plants made of cells
- Schwann 1839 all animals made of cells
- Virchow 1855 - all cells come from cells
4Section 7-1
- Exploring the Cell
- Microscopy
- - the history of cytology is tied to the
development of the microscope. - Light microscopes - pass light through the
specimen - - can magnify up to about 1200x
- - easy to prepare specimens and can look at
living specimens.
5Section 7-1
2. Transmission Electron Microscope - send a
beam of electrons through the specimen -
focused with magnets - resolving power up to
100,000()x - specimens have to be prepared and
cant be alive
6Section 7-1
3. Scanning Electron Microscope - bounce
electrons off the surface of the specimen -
gives detailed three-dimensional images of the
surface of the specimen
7Section 7-1
- Cell Theory
- Cells are the basic structural and functional
units of life - Under the conditions present on Earth today all
cells come from other cells. - All living things are composed of cells
8Section 7-1
Prokaryotes-cells that have genetic material that
is not contained in the nucleus. Generally
smaller and more simple than eukaryotes. Bacteria
are prokaryotes.
Eukaryotes-contains a nucleus in which their
genetic material is separated from the rest of
the cell. Plants, animals, fungi, and protists
are Eukaryotes.
9Prokaryotic and Eukaryotic Cells
Section 7-1
Prokaryotic Cell
Nucleus
Eukaryotic Cell
Organelles
10Venn Diagram
Section 7-1
11Division of Labor
Section 7-2
- A cell is made up of many parts with different
functions that work together. Similarly, the
parts of a computer work together to carry out
different functions. - Working with a partner, answer the following
questions. - 1. What are some of the different parts of a
computer? What are the functions of these
computer parts? - 2. How do the functions of these computer parts
correspond to the functions of certain cell
parts?
12Section Outline
Section 7-2
- 72 Eukaryotic Cell Structure
- A. Comparing the Cell to a Factory
- B. Nucleus
- C. Ribosomes
- D. Endoplasmic Reticulum
- E. Golgi Apparatus
- F. Lysosomes
- G. Vacuoles
- H. Mitochondria and Chloroplasts
- 1. Mitochondria
- 2. Chloroplasts
- 3. Organelle DNA
- I. Cytoskeleton
13Section 7-2
- Nucleus
- control center of the cell
- Contains the chromosomes on which the genes are
located - Fine threads called chromatin in nondividing
cells - Condense into visible chromosomes during cell
division - Nuclear membrane has two parallel membranes with
nuclear pores penetrating them - Nuclear pores allow mRNA to leave the nucleus to
go to the cytoplasm - Also contains the nucleolus where ribosomal
subunits are produced
14Section 7-2
Ribosomes - sites of protein synthesis where
amino acids are joined - many are attached to
Rough ER others are free in the cytoplasm -
composed of RNA and protein - attached ribosomes
make proteins for export - free ribosomes make
proteins for intracellular use
15Section 7-2
Endoplasmic Reticulum - membranous-walled canals
and flat sacs that extend from the plasma
membrane to the nucleus - important in the
synthesis, modification, and movement of
materials within the cell
A. Rough Endoplasmic Reticulum - has ribosomes
attached to its surface - ribosomes make
proteins which move into the cisternae of the
ER and are transported toward the Golgi
apparatus
16Section 7-2
B. Smooth Endoplasmic Reticulum - lacks
ribosomes - transports, synthesizes, and
chemically modifies small molecules -
synthesizes certain lipids and carbohydrates and
creates membranes for use throughout the cell
17Section 7-2
Golgi Apparatus - series of flattened
membranous sacs that modify protein products of
the rough endoplasmic reticulum - final
products are packaged in vesicles which can then
be moved to the cell membrane for export - some
of these vesicles remain in the cell as
lysosomes - can also give rise to new
membrane structures for the cell
18Section 7-2
- Lysosomes
- - digestive system of the cell
- - membranous sacs which pinch off the Golgi
apparatus - - contain hydrolytic enzymes which digest
particles or large molecules that enter them - - also responsible for digesting unneeded or
unhealthy cells and cell parts
19Section 7-2
20Section 7-2
- Vacuoles
- - saclike structures used for storage within the
cell - - stores water, salts, proteins, and
carbohydrates - - discerning feature in many plant cells that is
- large and liquid filled
- makes possible for plants to support heavy
- structures such as leaves and flowers
- - in many cases the vacuole is controls the
water content of the cell which maintains
homeostasis
21Section 7-2
- Mitochondria
- - power plants of cells
- - double membraned organelle with fluid between
the membranes - - lots of enzymes attached to both membranes
- - enzymes catalyze oxidation reactions of
cellular respiration and capture the energy of
sugars in the bonds of ATP - - provide 95 of the cells energy
- - contain their own ribosomes and DNA and can
replicate themselves
22Section 7-2
- Chloroplasts
- - capture the energy of the sunlight and convert
it into the chemical energy of sugar in a
process called photosynthesis - - double membraned organelle like mitochondria
- - also contain their own DNA
- - contain large stacks of membranes containing
chlorophyll
23Section 7-2
Cytoskeleton Internal support framework made up
of rigid, rodlike proteins that support the cell
and allow movement and mechanisms that can move
the cell or its parts Acts as both muscle and
skeleton for cell Cell Fibers - form a
three-dimensional support framework - support
endoplasmic reticulum, mitochondria, and free
ribosomes
24Section 7-2
- 1. Microfilaments smallest fibers
- - cellular muscles that provide for movement
- 2. Intermediate filaments form much of the
support network of the cell - 3. Microtubules maintain cell shape and move
things within the cell made up of proteins known
as tublin - 4. Tubulin is also used to make structures in
animal cells known as the centrioles. These
aid in organization during cell division
25Figure 7-11 Cytoskeleton
Section 7-2
26Figure 7-5 Plant and Animal Cells
Section 7-2
Plant Cell
27Figure 7-5 Plant and Animal Cells
Section 7-2
Animal Cell
28Venn Diagram
Section 7-2
29In or Out?
Section 7-3
- How is a window screen similar to a cell
membrane? Read on to find out. - 1. What are some things that can pass through a
window screen? - 2. What are some things that cannot pass through
a window screen? Why is it important to keep
these things from moving through the screen? - 3. The cell is surrounded by a cell membrane,
which regulates what enters and leaves the cell.
Why is it important to regulate what moves into
and out of a cell?
30Section Outline
Section 7-3
- 73 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
31Section 7-3
- Cell Membrane
- All of the membranes of the cell have similar
structure. - Plasma Membrane
- -Fluid Mosaic Model developed by Singer and
Nicolson - -Molecules are arranged in a sheet
- -Molecules are held together by chemical
attractions between them and their interactions
with water. - -Primary structure is a double layer of
phospholipid molecules - Phosphate heads are hydrophilic tails are
hydrophobic
32Section 7-3
-Cholesterol molecules within the membrane help
it function at body temperatures. -Because the
hydrophobic tails make-up most of the membrane,
water soluble materials cant pass through the
membrane. -Channel proteins which are embedded in
the membrane help control movement of materials
into and out of the cell -Glycoproteins have
carbohydrates attached and serve as cell surface
identifiers -Receptor proteins react to specific
chemicals and cause changes within the
cell. -Overall, the plasma membrane is
selectively permeable.
33Figure 7-12 The Structure of the Cell Membrane
Section 7-3
34Section 7-3
-Provide support and protection for the
cell. -Most are composed of fibers of
carbohydrate and protein -Plant cell walls are
mostly cellulose
35Passive and Active Transport
Section 7-3
36Section 7-3
- Movement Through the Cell Boundaries
- Passive Transport Processes
- -Do not require energy expenditure by the cell
- -Second Law of Thermodynamics
- Diffusion
- - movement of particles from an area of high
concentration to an area of low concentration
down a concentration gradient. - - continues until equilibrium is reached
- - membrane channels are pores through which
specific ions or small water-soluble molecules
can pass - - gases also move by diffusion
37Diffusion and Osmosis Video
Section 7-3
38Section 7-3
Passive Transport Processes cont. Osmosis -
diffusion of water through a selectively
permeable membrane - water moves down its
concentration gradient this often means it is
moving toward higher salt concentrations -
Osmotic Pressure water pressure that develops
as a result of osmosis - healthy cells are
normally in an environment where the net movement
of water is 0.
39Section 7-3
Passive Transport Processes cont. Osmosis
cont. - Tonicity ability of a solution to move
water in/out of a cell and change its shape a.
Isotonic osmotic pressure is inside and
outside b. Hypertonic osmotic pressure is
greater than within the cell water moves out of
cell causing crenation c. Hypotonic osmotic
pressure is less than within the cell water
moves into the cell causing lysis.
40Figure 7-15 Osmosis
Section 7-3
41Figure Osmosis
Section 7-3
42Osmosis Video
Section 7-3
43Facilitated Diffusion
Section 7-3
- Facilitated Diffusion
- - movement through carrier proteins along the
concentration gradient - - rate is dependent on concentration gradient
and availability of carrier molecules
44Section 7-3
-cell uses metabolic energy to move materials
1. Molecular Transport - carrier-mediated
process that moves substances against their
concentration gradients - opposite of
diffusion - substances are moved by pumps which
use ATP to change shape and move their cargos -
carrier proteins bind to cargo, change shape, and
release the cargo
45Video 4
Active Transport
Section 7-3
46Section 7-3
2. Endocytosis and Exocytosis - allow things to
enter and leave a cell without actually passing
through the plasma membrane. A. Endocytosis
plasma membrane traps some extracellular material
and moves it to the interior in a vesicle. -
Phagocytosis large particles are engulfed
within a vesicle that then fuses with lysosomes
to digest particles - Pinocytosis fluid and
the substances dissolved in it enter the cell
47Endocytosis and Exocytosis
Section 7-3
48From Simple to More Complex
Section 7-4
- 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.
49Section 7-4
- 1. Some activities cannot be performed by only
one person, but need a team of people. What type
of activity requires a team of people to work
together in order to complete a task? - 2. What do you think are some characteristics of
a successful team? - 3. How is a multicellular organism similar to a
successful team?
50Section Outline
Section 7-4
- 74 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
51Section 7-4
- Unicellular Organisms
- Single-celled organisms that grow, respond to
the environment, transform energy, and reproduce - Multicellular Organisms
- Organisms that are made up of many cells that
are developed for different tasks through a
process called cell specialization
52Levels of Organization
Section 7-4
Levels of Organization 1. Cells 2.
Tissues 3. Organs 4. Organ Systems
53Section 1 Answers
Interest Grabber Answers
- 1. What are the advantages of a one-celled
organism? - A one-celled organism has simpler needs and can
respond immediately to its environment because
its entire cell is immersed in its environment. - 2. What are the advantages of an organism that
is made up of many cells? - In a multicellular organism, different jobs are
divided among different groups of cells that work
together. Also, a multicellular organism can
continue to survive even if it loses some of its
cells.
54Section 2 Answers
Interest Grabber Answers
- Working with a partner, answer the following
questions. - 1. What are some of the different parts of a
computer? What are the functions of these
computer parts? - Answers may include monitor (interfaces with
the computers environment), software
(instructions for how to carry out different
jobs), CPU (directs the computer's activities),
recycle bin or trash can (storage area for
wastes), and so on. - 2. How do the functions of these computer parts
correspond to the functions of certain cell
parts? - Students should try to link the functions they
described in question 1 to the functions of the
different cell structures. The cell needs a way
to interface with its environment (cell
membrane), instructions for carrying out
different jobs (DNA), and a CPU to direct the
cells activities (nucleus).
55Section 3 Answers
Interest Grabber Answers
- 1. What are some things that can pass through a
window screen? - Answers may include air, fine dust, and
rainwater. - 2. What are some things that cannot pass through
a window screen? Why is it important to keep
these things from moving through the screen? - Insects, leaves, and other matter that may fall
from trees. The screen keeps out annoying insects
and objects that may bring dirt into the home. - 3. The cell is surrounded by a cell membrane,
which regulates what enters and leaves the cell.
Why is it important to regulate what moves into
and out of a cell? - Materials such as oxygen and food that are
needed by the cell have to be able to get inside
the cell. At the same time, excess materials have
to leave the cell.
56Section 4 Answers
Interest Grabber Answers
- 1. Some activities cannot be performed by only
one person, but need a team of people. What type
of activity requires a team of people to work
together in order to complete a task? - Answers might include building a human pyramid
or constructing an arch out of blocks. - 2. What do you think are some characteristics of
a successful team? - Divide up jobs and cooperate well with one
another. - 3. How is a multicellular organism similar to a
successful team? - The functions of the organism are divided up
among its parts (organs and organ systems). All
the parts cooperate to carry out all the
functions of the whole organism.
57End of Custom Shows
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