Transcript Introduction to the study of cell biology

CELL BIOLOGY
ZHOU Yong
Department of Biology
Xinjiang Medical University
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Chapter 1
Introduction to the cell
Learning Objectives
1.About Cell Biology
2.Look briefly at the history of cell theory;
3.Consider the basic properties of cells;
4.Compare some characteristics of two different classes of cells:
prokaryotes and eukaryotes;
5.Comprehend a special life: viruses
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Teaching Requirements
• 1. Mastering: definition of Cell and Cell Biology;
main differences of structure of prokaryocytes and
eukaryocytes.
• 2. Comprehending: cell theory and cell volume
conservation law.
• 3. Understanding: simple history of cell biology;
basic properties of the cell; main stages of the
formation and evolution of cell.
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1. About “Cell Biology”
What?
Forwhy?
How to
study?
The NIH of USA(1988):
“What is popular in research today？”
 3 kinds of diseases ：
 cancer
 cardiovascular diseases
 infectious diseases：AIDS，hepatitis
 5 research fields ：
 cell cycle control ；
 cell apoptosis；
 cellular senescence；
 signal transduction；
 DNA damage and repair.
What we know//How we know.
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2. The Cell Theory: A Brief History
The discovery of cells
followed from the invention of
the microscope
In 1665, Robert Hooke saw a
network of tiny boxlike
compartments that reminded him
of a honeycomb. He called these
little compartments “cellulae”, a
Latin term meaning little room. It
is from this word we get our
present-day term, cell.
The microscope used by Robert
Hooke and the honeycomb-like
network of “cell” he drawed in 1665
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Cell theory has three basic tenets:
1. All organisms are
composed of one or
more cells.
2.The cell is basic unit
of structure and
function for all
organisms.
Schleiden(1804~1834)
Schwann(1810~1882)
3.All cells arise only
from preexisting cells
by division.
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3. Why are cells the basic units of life?
A. The cell is the
structural unit of
life, All organisms is
make up of cells.
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B.The cell is the functional unit of organisms.
All metabolic activity is based on cells.
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C. The cell is the foundation of reproduce,
and the bridge of inheritance.
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D. The cell is the growing and developing basis of life
Human fetal development. (a)At 5 weeks, limb buds, eyes, the heart,
the liver and rudiments of all other organs have started to develop in the
embryo, which is only about 1cm long. (b)Growth and development of the
offspring, now called a fetus, continue during the second trimester. This
fetus is 14 weeks old and about 6cm long. (c)The fetus in this photograph is
20 weeks old. Now the fetus grows to about 30cm in length.
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E. Cell (nucleus) is totipotent, which can create a new
organism of the same type
As a general rule, the cells of a multicellular organism
all contain the same set of genes. For animals, the first
evidence that even highly specialized cell carry a full
complement of genes was verified by the experiment of
tadpole nuclei transplanting into unfertilized egg that had
been deprived of its own nucleus. Some can develop
swimming tadpoles. This is animal cloning.
An especially dramatic example of animal cloning was
reported in 1997. Dolly the first animal ever cloned from a
cell derived from an adult.
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Dolly and her daughter
The process of
cloning Dolly
Is there any practical value to such technology?
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4. Basic properties of cells
A. Cells are highly complex
and organized, capable
of self-regulation;
Cells acquire and utilize
energy.
B. All cells share similar
structure,
composition and
metabolic features:
Plasma membrane,
DNA/RNA, and
Ribosome.
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C. Cells are capable of producing more of themselves,
even grow and reproduce in culture for extended
periods.
HeLa cells are
cultured tumor
cells isolated
from a cancer
patient named
Henrietta Lacks
in 1951. It is the
first human cell
to be kept in
culture for long
periods of time
and is still used
today.
Johns Hopkins
univesity,in 1951
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D. Cells are able to respond to stimuli via surface
receptors that sense changes in the chemical
environment.
Cells within plant or animal respond to stimuli
less obviously than single-celled protist. But
they respond. They posses receptors that
interact with substances in the environment in
highly specific ways. For example, the receptor
on the cell surface can respond to hormones and
growth factors.
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5.The Size of Cells
a) Diameter
b) Measured in units of
micrometers: 1μm=10-6 meter
nanometers: 1nm=10-9 meter
c) Cell size is limited:
 nucleus/cytoplasm ratio;
 surface area/volume ratio;
 substances can efficiently travel
through the cytoplasm via diffusion.
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6. Two fundamentally different classes of
cells: Prokaryotes and eukaryotes
A. Prokaryotic and eukaryotic cells are
distinguished by the size and the types of
internal structures, or organelles, especially if
there is nuclear envelope.
Bacteria are prokaryotes, they arose 3.5 billion years ago;
Blue algae, fungi, plants, and animals are eukaryotes. The
first eukaryotes arose 1.5 billion years ago.
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B. Characteristics that distinguish
prokaryotic and eukaryotic cells
pp.14 Table 1-1
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7.Types of Prokaryotic Cells: Two Subkingdoms
Tree of life has three primary
branches.
A. Subkingdom Archaea
B. Subkingdom Bacteria
Most Bacteria and Archaea have
1000-4000 genes
The smallest known cells
---the Mycoplasma
0.1～0.3μm;
smallest genome: 482 genes,
minimal essential gene：256
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Bacterial Cell
• cell wall
• cell membrane
• Nucleoid
region
• ribosomes
• flagellum
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8. Viruses
1.Viruses are pathogens
first described in the
late 1800s.
2. Viral structure:
a)The genetic material:
Single- or doublestranded DNA or RNA.
b)obligatory
intracellular parasites.
Virus diversity
3.Viral infection types:
a)Lytic infection;
b)integrated infection
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9. Reference book
Alberts B et al. Essential Cell Biology. New York and London：Garland
publishing，Inc. 1998
Alberts B et al. Molecuar Biology of the Cell, 3rd ed. New York and
London：Garland Publishing，Inc. 1994; 3rd 2002.
Becker W.M. et al. The World of the Cell. Fourth Ed. The
Benjamin/Cummings Publishing Company. 2000.
Gerald Karp. Cell and Molecular Biology：concepts and experiments，
2nd Edition. Published by John Wiley & Sons,Inc. 1999
Gerald Karp. Cell and Molecular Biology：concepts and experiments，
3rd Edition. Published by John Wiley & Sons,Inc. 2002
Lodish H. et al. Molecular Cell Biology. 4th Ed. Scientific American
Books,Inc. 2000.
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REVIEW QUESTIONS
Eukaryotic cells usually
contain
Unlike eukaryotes, prokaryotes
lack
A. a nucleus.
A. a plasma membrane.
B. mitochondria.
B. DNA.
C. ribosomes.
C. ribosomes.
D. microtubules.
D. nuclei.
E. all of the above.
E. molecular motors
E. These are all typical
features of eukaryotic cells.
D. Eukaryotes have all of these,
but prokaryotes do not have
nuclei. Rather, the DNA is free
in the cytoplasm
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1,000,000 nm is equal to
A. 1 μm.
B. 10 μm.
C. 1 mm.
D. 10 mm.
E. 1 m.
C. The international system prefixes used in this book
are m for milli, meaning 10-3, μ for micro, meaning 10-6,
and n for nano meaning 10-9. Thus 1,000,000 times 10-9
is 10-3 so 1,000,000 nm is equal to 1 mm.
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