Download Type of Cells

The Cell Theory
• All organisms are made of cells
• The cell is the simplest collection of matter
that can live
• All cells come from other cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
What are cells made of?
Cells are mostly water.
The rest of the molecules present are:
• protein
• nucleic acid
• carbohydrate
• lipid
• others
By elements, a cell is composed of:
• 60% hydrogen
• 25% oxygen
• 10% carbon
• 5% nitrogen
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2
• Cell structure is correlated to cellular function
Figure 6.1
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10 µm
Microscopy
• To study cells, biologists use microscopes and
the tools of biochemistry
• Scientists use microscopes to visualize cells
too small to see with the naked eye
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Types of microscopes
• Light microscopes (LMs)
– Pass visible light through a specimen
– Magnify cellular structures with lenses
• Electron microscopes (EMs)
– Focus a beam of electrons through a specimen
(TEM) or onto its surface (SEM)
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Unaided eye
• Different types of microscopes
– Can be used to visualize different sized
cellular structures
10 m
0.1 m
Human height
Length of some
nerve and
muscle cells
Chicken egg
1 cm
Light microscope
1m
10 µ m
1µm
100 nm
Most plant
and Animal
cells
Nucleus
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
10 nm
Ribosomes
Proteins
1 nm
Lipids
Small molecules
Figure 6.2
0.1 nm
Atoms
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Electron microscope
100 µm
Electron microscope
Frog egg
1 mm
Measurements
1 centimeter (cm) = 102 meter (m) = 0.4 inch
1 millimeter (mm) = 10–3 m
1 micrometer (µm) = 10–3 mm = 10–6 m
1 nanometer (nm) = 10–3 mm = 10–9 m
– Use different methods for enhancing
visualization of cellular structures
TECHNIQUE
RESULT
(a) Brightfield (unstained specimen).
Passes light directly through specimen.
Unless cell is naturally pigmented or
artificially stained, image has little
contrast. [Parts (a)–(d) show a
human cheek epithelial cell.]
50 µm
(b) Brightfield (stained specimen).
Staining with various dyes enhances
contrast, but most staining procedures
require that cells be fixed (preserved).
(c) Phase-contrast. Enhances contrast
in unstained cells by amplifying
variations in density within specimen;
especially useful for examining living,
unpigmented cells.
Figure 6.3
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Types of electron microscopes
• The scanning electron microscope (SEM)
– Provides for detailed study of the surface of a
specimen
TECHNIQUE
RESULTS
1 µm
Cilia
(a) Scanning electron microscopy (SEM). Micrographs taken
with a scanning electron microscope show a 3D image of the
surface of a specimen. This SEM
shows the surface of a cell from a
rabbit trachea (windpipe) covered
with motile organelles called cilia.
Beating of the cilia helps move
inhaled debris upward toward
the throat.
Figure 6.4 (a)
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Types of electron microscopes
• The transmission electron microscope (TEM)
– Provides for detailed study of the internal
ultrastructure of cells
Longitudinal
section of
cilium
(b) Transmission electron microscopy (TEM). A transmission electron
microscope profiles a thin section of a
specimen. Here we see a section through
a tracheal cell, revealing its ultrastructure.
In preparing the TEM, some cilia were cut
along their lengths, creating longitudinal
sections, while other cilia were cut straight
across, creating cross sections.
Figure 6.4 (b)
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Cross section
of cilium
1 µm
Types of Cells
 Fungi
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Characteristics of ALL cells
• All cells have several basic features in common
– They are bounded by a plasma membrane
– They contain a semifluid substance called the
cytosol
– They contain chromosomes
– They all have ribosomes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Prokaryotic cells
• Prokaryotic cells
– Unicellular
– Do not contain a nucleus or membrane bound
organelles
– Has circular DNA
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Example Prokaryotic cells
Pili: attachment structures on
the surface of some prokaryotes
Nucleoid: region where the
cell’s DNA is located (not
enclosed by a membrane)
Ribosomes: organelles that
synthesize proteins
Plasma membrane: controls
entry and exit of substances
Cell wall: rigid structure outside
the plasma membrane that protects cell
From damage and maintains shape
Bacterial
chromosome
(a) A typical
rod-shaped bacterium
Capsule: jelly-like outer coating
of many prokaryotes
Flagella: locomotion
organelles of
some bacteria
0.5 µm
(b) A thin section through the
bacterium Bacillus coagulans
(TEM)
Cytoplasm: Fluid component which contains the enzymes needed for all
metabolic reactions
Figure 6.6 A, B
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Live in enormous numbers
Soil, rock, oceans and arctic
Causes disease or illness
Asexual reproduction: where one individual produces
offspring that are genetically identical to itself=clones
No fusion of gametes and no mixing of genetic info.
http://www.livescience.com/51641-bacteria.html
http://www.encyclopedia.com/topic/bacteria.aspx
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Mesophiles-act best at moderate temps.
Extremophiles-thrives best in extreme
environments
http://www.ucmp.berkeley.edu/archaea/archaea.html
http://eol.org/info/457
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•
The Domain Archaea wasn't recognized as a major domain of life until quite recently. Until the 20th century, most
biologists considered all living things to be classifiable as either a plant or an animal. But in the 1950s and 1960s, most
biologists came to the realization that this system failed to accomodate the fungi, protists, and bacteria. By the 1970s,
a system of Five Kingdoms had come to be accepted as the model by which all living things could be classified. At a
more fundamental level, a distinction was made between the prokaryotic bacteria and the four eukaryotic kingdoms
(plants, animals, fungi, & protists). The distinction recognizes the common traits that eukaryotic organisms share, such
as nuclei, cytoskeletons, and internal membranes.
•
The scientific community was understandably shocked in the late 1970s by the discovery of an entirely new group of
organisms -- the Archaea. Dr. Carl Woese and his colleagues at the University of Illinois were studying relationships
among the prokaryotes using DNA sequences, and found that there were two distinctly different groups. Those
"bacteria" that lived at high temperatures or produced methane clustered together as a group well away from the usual
bacteria and the eukaryotes. Because of this vast difference in genetic makeup, Woese proposed that life be divided
into three domains: Eukaryota, Eubacteria, and Archaebacteria. He later decided that the term Archaebacteria was a
misnomer, and shortened it to Archaea. The three domains are shown in the illustration above at right, which illustrates
also that each group is very different from the others.
•
Further work has revealed additional surprises, which you can read about on the other pages of this exhibit. It is true
that most archaeans don't look that different from bacteria under the microscope, and that the extreme conditions
under which many species live has made them difficult to culture, so their unique place among living organisms long
went unrecognized. However, biochemically and genetically, they are as different from bacteria as you are. Although
many books and articles still refer to them as "Archaebacteria", that term has been abandoned because they aren't
bacteria -- they're Archaea
.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Eukaryotic cells
• Eukaryotic cells have internal membranes that
compartmentalise their functions. They
– Contain a true nucleus, bounded by a
membranous nuclear envelope
– Are generally quite a bit bigger than
prokaryotic cells
– Have extensive and elaborately arranged
internal membranes, which form organelles
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Types of Eukaryotic cells
•
•
•
•
•
Can be unicellular (protists)
Or multicellular (fungi, plants & animals)
Have a membrane bound nucleus
Contain organelles
Have linear DNA
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Unicellular eukaryotes that are not animals, plants or fungi.
There are 4 subgroups.
http://www.microbeworld.org/types-of-microbes/protista
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Can be unicellular (eg. Yeasts) or multicellular (mushrooms)
Different organisms living together usually
benefiting both
Sexual reproduction- when gametes(sex cells) from
each parent join and genetic info. mixes to produce
offspring with different chromosomes
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Sexual or asexual reproduction
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• A plant cell
NUCLEUS
Centrosome
Rough
endoplasmic
reticulum
Smooth
endoplasmic
reticulum
Ribosomes (small brwon dots)
Golgi apparatus
Mitochondrion
Plasma membrane
Chloroplast
Cell wall
Wall of adjacent cell
Figure 6.9
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In plant cells but not animal cells:
Chloroplasts
Central vacuole and tonoplast
Cell wall
Plasmodesmata
Most are multicellular.
Unicellular eg is amoeba
Asexual and sexual reproduction
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• A animal cell
ENDOPLASMIC RETICULUM (ER)
NUCLEUS
Rough ER
Smooth ER
Flagellum
Plasma membrane
Centrosome
Ribosomes
Golgi apparatus
Figure 6.9
Mitochondrion
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Lysosome
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
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Non-living
• Can only reproduce when inside a
host cell
• Use the host cell’s metabolism
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The Cell: A Living Unit Greater Than the Sum of Its Parts
5 µm
• Cells rely on the integration of structures and
organelles in order to function
Figure 6.32
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Cell organelle table
• http://utahscience.oremjr.alpine.k12.ut.us/scibe
r00/7th/cells/sciber/orgtable.htm
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Degrade and digest
pathogens and
cellular components
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Energy converting Organelles
• Mitochondria and chloroplasts change energy
from one form to another
• Mitochondria
– Are found in nearly all eukaryotic cells
– Are the sites of cellular respiration
• Chloroplasts
– Found only in plants, are the sites of
photosynthesis
– Contains the green compound, chlorophyll
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Mitochondria
• Mitochondria are enclosed by two membranes
– A smooth outer membrane
– An inner membrane folded into cristae
Mitochondrion
Intermembrane space
Outer
membrane
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
Matrix
Figure 6.17
Mitochondrial
DNA
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100 µm
Chloroplasts
– Are found in leaves and other green organs of
plants and in algae
Chloroplast
Ribosomes
Stroma
Chloroplast
DNA
Inner and outer
membranes
Granum
1 µm
Figure 6.18
Thylakoid
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Cilia and Flagella
• Cilia and flagella
– Contain specialized arrangements of microtubules
– Are locomotor appendages of some cells
Flagella on sperm cells
1 µm
Cilia on protozoan cell
15 µm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Different classification Systems
List the 6 groups that we have classified organisms so far.
Go to http://sciencelearn.org.nz/Contexts/HiddenTaonga/Science-Ideas-and-Concepts/Classification-system
1. Who published a system for classifying living things in the
18th Century?
2. What did this system show?
3. List this naming structure
4. Why do some scientists say there are 5 kingdoms?
5. What is a possible 7th group? What is the argument
against this?
6. Are these groups going to remain like this? Why?
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Questions
1. What does the following equation represent?
Glucose + oxygen------- carbon dioxide + water + energy (ATP)
2. Where does the above reaction occur?
3. Write out the word equation for photosynthesis. Where does
this occur?
4. Explain the difference between prokaryotes and eukaryotes.
5. Draw a diagram of a prokaryote cell.
6. Outline the differences between a plant and animal cell.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings