CELL BIOLOGY

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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
The NIH of USA(1988) What is popular in
research today? ? 3 kinds of diseases
? cancer ? cardiovascular
diseases ? infectious
diseasesAIDS,hepatitis ? 5 research fields
? cell cycle control ? cell
apoptosis ? cellular senescence ?
signal transduction ? DNA damage and
repair.
What? Forwhy? How to study?
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.
3.All cells arise only from preexisting cells by
division.
Schleiden(18041834)
Schwann(18101882)
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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

• 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
• Diameter
• Measured in units of
• micrometers 1µm10-6 meter
• nanometers 1nm10-9 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
• Subkingdom Bacteria
• Most Bacteria and Archaea have 1000-4000 genes
• The smallest known cells
• ---the Mycoplasma
• 0.10.3µm
• smallest genome 482 genes,
• minimal essential gene256

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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 double- stranded 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 LondonGarland
publishing,Inc. 1998 Alberts B et al. Molecuar
Biology of the Cell, 3rd ed. New York and
LondonGarland 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 Biologyconcepts and experiments,2nd
Edition. Published by John Wiley Sons,Inc.
1999 Gerald Karp. Cell and Molecular
Biologyconcepts 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
Unlike eukaryotes, prokaryotes lack A. a plasma
membrane. B. DNA. C. ribosomes. D. nuclei. E.
molecular motors
Eukaryotic cells usually contain A. a nucleus. B.
mitochondria. C. ribosomes. D. microtubules. E.
all of the above.
D. Eukaryotes have all of these, but prokaryotes
do not have nuclei. Rather, the DNA is free in
the cytoplasm
E. These are all typical features of eukaryotic
cells.
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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.