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Chapter 1 Our Biological Heritage and Cell
主讲人
黄 文 英
It is assumed that our solar system was created
some 4,600 million years ago. At that time the
atmosphere surrounding our planet did not contain
oxygen. This was a prerequisite for the evolution of life
from nonliving organic matter, for without atmospheric
oxygen and thus without high-altitude ozone, the
ultraviolet radiation from the sun could reach the
surface of the earth.
Content
Section 1
Section 2
Section 3
Development
of Primitive
Organisms
Mammals
The Cell and
its Regulatory
Mechanisms
Section 1 Development of Primitive Organisms
A new milestone in biological
evolution occurred about 1,500
million years ago, when the
unicellular organism with a
nucleus (the eukaryote)
developed (Vidal 1984).
Section 2 Mammals
1
Microcosmic
Mechanism of
Animal
Evolution
2
Appearance
of Mammals
3
 Emergence
of Primates
4
Modern
Human
Evolution
Microcosmic Mechanism of Animal Evolution
Evolution was then ready for the next major step, the development of larger
animals, probably beginning some 700 million years ago (Valentine 1978) the
evolution of larger organisms .
In the evolution of larger animals, the individual cell retained its original size,
that is, the same size as the unicellular organism living more than 1,000 million
years ago. However, more of these single cells were piled together as a means of
increasing the size of the organism. Special structures in the cell, the genes,
were encoded with detailed instructions about the proliferation of the cell mass,
guiding specialization in shape, structure, and function.
Appearance of Mammals
In the course of diversification of multicellular organisms that took place
over the last 700 million years, new types of organisms appeared and
divergence occurred within already established groups. The earliest fossil
traces of animal life are burrows that begin to appear in rocks younger than
700 million years (Valentine 1978).
Evolution is a consequence of the gradual accumulation of genetic
difference due to point mutation and rearrangements in the chromosomes.
Emergence of Primates
Maybe only 10 million
or as much as 20
million years ago, the
family tree of primates
developed a branch
called the hominids,
which finally resulted in
Homo sapiens sapiens,
the only surviving
hominid.
Somewhere along the
line a prototypic
anthropoid ape
abandoned life in the
trees and started to
forge and hunt on the
ground. A species
related to these
creatures may have
been Ramapithecus.
Modern Human Evolution
1
2
Most likely, a human being
living 50,000 years ago had
the same potential for
physical and intellectual
performance, such as
playing a piano or
constructing a computer, as
anyone living today.
Humans, like all higher
animals, are basically
designed for mobility.
Consequently, our
locomotive apparatus and
service organs constitute the
majority of our total body
mass.
SECTION 3 The Cell and its Regulatory Mechanisms
1
2
The Structure of Cell
The Regulatory Mechanism of Cell Activity
The Cell Membrane
 The Structure of Cell Membrane
The structural framework of the cell membrane, approximately
5 nm thick, is a double layer of lipid molecules. The individual lipid
molecule has a head and two tails. Polar (i.e., hydrophilic, or
soluble in water) heads form the outer and inner membrane
surfaces, while apolar (i.e., hydrophobic, or insoluble in water) tails
meet in the membrane interior. This structure serves as an anchor
for other components of the membrane, such as proteins and
glycoproteins (figure 1.4).
The Cell Membrane
 Transport Mechanisms Through the Cell Membrane
 The Active Transport and Pssive Transport
Transport through cell membranes can be active or passive,
depending on whether it consumes energy or not (figure 1.6).
 Exocytosis and Endocytosis
The Intracellular Structure
3
Cytoplasmic Vesicles
3
The Endoplasmic Reticulum
3
The Intracellular Vesicle
3
The Mitochondria
3
The Nucleus and Enzymes
Summary
The cell interior consists of organelles, small structures of
different shapes and functions, suspended in the cytosol.
The cytosol is a viscous solution of proteins,
carbohydrates, ions, and nutrients suspended in water.
The various organelles serve different functions in the cell,
much like the different organs in our body.
The Regulatory Mechanism of Cell Activity
1
2
3
4
The Intracellular Signal Conduction and Communication
Sensitivity of the Cell Adapts to the Level of the Stimulus
Common Cellular Strategies for Adaptation to New Demands
Control of Gene Expression
Summary
 The purpose of this brief review of our biological heritage is to
provide some basic facts that may be useful in understanding the
complicated interplay between all the biological processes that form the
basis for our existence and performance. Humans are made to be
physically active.
 This chapter also provides an overview of cell biology as a basis for
understanding how cells and organs of the body react to different
challenges in connection with work and physical activity.