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CHAPTER 1
Introduction to Cell Biology
© 2013 John Wiley & Sons, Inc. All rights reserved.
What is Biology?
Biology literally means "the study of
life". Biology is such a broad field,
covering the minute workings of
chemical machines inside our cells, to
broad scale concepts of ecosystems
and global climate change.
Branches of Biology
•Anatomy - the study of form and function, in plants,
animals, and other organisms, or specifically in humans
•Biochemistry - the study of the chemical reactions required
for life to exist and function, usually a focus on the cellular
level
•Botany - the study of plants
•Cell biology - the study of the cell as a complete unit, and
the molecular and chemical interactions that occur within a
living cell.
•Ecology - the study of the interactions of living organisms
with one another and with the non-living elements of their
environment.
•Embryology - the study of the development of embryo (from
fecondation to birth). See also topobiology.
•Entomology - the study of insects
3
•Physiology - the study of the functioning of living
organisms and the organs and parts of living organisms
• Genetics - the study of genes and heredity.
•Histology - the study of cells and tissues, a microscopic
branch of anatomy.
•Microbiology - the study of microscopic organisms
(microorganisms) and their interactions with other living
things
•Molecular Biology - the study of biology and biological
functions at the molecular level, some cross over with
biochemistry
•Virology - the study of viruses and some other virus-like
agents
•Zoology - the study of animals, including classification,
physiology, development, and behavior.
Sizes of cells and
organelles (105, 107)
Bacteria
1 –5 m
Animal and Plant cells 1050 m
Nucleus
Mitochondria
Chloroplasts
5-6 m
2-3 m
5-10 m
Nerve cells
>1m
5
Feeling of scales
Cell
Most
Cells
Size
range
6
What Is Life?
Basic life processes
o
o
o
o
o


(31)
Metabolism
Movement
Responsiveness
Homeostasis
Differentiation
Reproduction and heredity
Growth and development
7
The Cell Theory :
(91)
is one of the foundations of modern biology. It
stats that :
•All living things are composed of one or more cells;
•The chemical reactions of living cells take place within
cells;
•All cells originate from pre-existing cells; and
•Cells contain hereditary information, which is passed
from one generation to another
© 2013 John Wiley & Sons, Inc. All rights reserved.
(1.1) The Discovery of Cells (90)
Hooke: double lens microscope
• The discovery of
cells followed from
the invention of the
microscope by
Robert Hooke, and
its refinement by
Anton Leewenhoek.
Leewenhoek: single lens
microscope
• Cell theory was articulated in the mid-1800s by Schleiden,
Schwann and Virchow.
– All organisms are composed or one or more cell.
– The cell is the structural unit of life.
– Cells arise from pre-existing cells by division.
© 2013 John Wiley & Sons, Inc. All rights reserved.
(1.2) Basic Properties of Cells (91)
• Life is the most basic
property of cells.
• Cells can grow and
reproduce in culture
for extended periods.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Basic Properties
of Cells
1- Cells Are Highly
Complex and
Organized
– Cellular processes
are highly regulated.
– Cells from different
species share
similar structure,
composition and
metabolic features
that have been
conserved
throughout
evolution.
Levels of cellular and molecular organization
© 2013 John Wiley & Sons, Inc. All rights reserved.
Organization in living organisms (28-30)
• Atoms:
– are the smallest chemical units
• Molecules:
– are a group of atoms working together
• Organelles:
– are a group of molecules working together
• Cells:
– are a group of organelles working together
• Tissues:
– are a group of similar cells working together
• Organs:
– are a group of different tissues working together
• Organ systems:
– are a group of organs working together
• Organism:
– is an individual
© 2013 John Wiley & Sons, Inc. All rights reserved.
Basic Properties
of Cells
2- Cells Possess a
Genetic Program
and the Means to
Use It
– Genes encode
information to build
each cell, and the
organism.
– Genes encode
information for
cellular
reproduction,
activity, and
structure.
Levels of cellular and molecular organization
© 2013 John Wiley & Sons, Inc. All rights reserved.
Basic Properties of Cells
3- Cells Are Capable of
Producing More of
Themselves
– Cells reproduce, and
each daughter cells
receives a complete set
of genetic instructions.
Mammalian oocyte after unequal cell
division to produce polar body (arrow)
© 2013 John Wiley & Sons, Inc. All rights reserved.
Basic Properties of Cells
4- Cells Acquire and Utilize Energy
– Photosynthesis provides fuel for all living organisms.
– Animal cells derive energy from the products of photosynthesis,
mainly in the form of glucose.
– Cell can convert glucose into ATP—a substance with readily available
energy.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Basic Properties of Cells
5- Cells Carry Out a Variety of
Chemical Reactions
6- Cells Engage in Mechanical
Activities
7- Cells Are Able to Respond
to Stimuli
8- Cells Are Capable of SelfRegulation
9- Cells Evolve
Spirogyra: alga with ribbon-like
chloroplast for photosynthesis
© 2013 John Wiley & Sons, Inc. All rights reserved.
Cells: the basic unit of life
17
(99)
.
The Cell
Cellulae (Small room)
The Organism’s Basic Unit of Structure and Function
‫بدائية‬
Types
of cells
‫متقدمة‬
Prokaryotic
Eukaryotic
Micro-organisms
All other forms
of life
‫الكائنات الدقيقة‬
19
Types of Prokaryotes
Prokaryotes
Bacteria
- Exist in most
environments
Archaea
- Exist in extreme environments
‫( البيئات القاسية‬hot and salty)
They are differing in some other structural,
biochemical and physiological characteristics ‫صفات‬
Page 526
‫المادة الوراثية‬
‫الريبوسومات‬
‫غشاء الخلية‬
‫جدار الخلية‬
‫محفظة‬
‫اسواط‬
‫بكتيريا عصوية تحت‬
‫المجهر االلكتروني‬
‫تركيب الخلية بدائية النواة‬
‫نموذج تركيب البكتيريا‬
‫العصوية‬
‫‪ Prokaryotes‬تركيب الخاليا بدائية النواة‬
‫‪21‬‬
Typical prokaryotic structures
Working from the outside in…
22
Generalized
Nucleoid DNA
Prokaryote
Plasmid DNA
Cytosol
Flagellum
Capsule
Plasma
Membrane
Cell Wall
23
Typical shapes of bacteria
Most bacteria retain a particular shape; a few
are pleiomorphic
24
Characteristic grouping (or not grouping)
25
Bacterial Shape and
Arrangement
26
A) the bacterial capsule
•
Many prokaryotes (bacteria)
secrete a sticky
called
the cell wall, which has the
following functions ‫وظائف‬:
1.
2.
3.
4.
protective layer
capsule outside
Adhere ‫ تثبيت‬bacteria cells to their substratum ‫السطح‬.
Increase bacteria resistance ‫ المقاومة‬to host defenses ‫مناعة العائل‬.
Stick )‫ )تلصق‬bacterial cells together when live as colonies.
Protect ‫ تحمى‬bacterial cell.
Fig. 27.6
B) The bacterial cell wall
•
In all prokaryotes, the functions of the cell wall are as following:
1. maintains ‫ تحافط‬the shape of the cell,
2. affords physical protection ‫توفر الحماية الطبيعية‬
3. prevents the cell from bursting (‫ )إنفجار‬in a hypotonic
environment ‫البيئة ذات الضغط األسموزى المنخفض‬.
•
Most bacterial cell walls contain peptidoglycan
(a polymer of modified sugars cross-linked by short polypeptides).
• The walls of Archaea lack (‫ )تـفـتـقـد‬peptidoglycan.
The Gram’s stain: ‫صبغة جرام‬
• It is a tool for identifying ‫ تعريف‬specific bacteria, based on differences in
their cell walls.
• A)- Gram-positive (Gram +ve) bacteria:
• Their cell walls have large amounts ‫ كمية كبيرة‬of peptidoglycans that react
with Gram’s stain (appear violet-stained ‫)تـُصبغ بنفسجيا‬.
Fig. 27.5a
Page 529
The Gram’s stain: ‫صبغة جرام‬
• B)- Gram-negative (Gram -ve) bacteria:
• their cell walls have no or small amount of peptidoglycan. So, do
not react or very weakly react with Gram’s stain (do not appear stained ‫ال‬
‫)تظهر الصبغة‬
Fig. 27.5b Page 529
Gram Staining of Bacteria
• Gram +ve bacteria: have Large amount of peptidoglycan that stained
violet (non-pathogenic ‫)غير ممرضة‬.
• Gram –ve bacteria: Have small amount or no peptidoglycan (no
staining) (pathogenic ‫)ممرضة‬.

Gram-negative species are pathogenic (‫ ) ممرضة‬more threatening
(‫ )أكثر خطورة‬than gram-positive species.

Gram-negative bacteria are commonly more resistant (‫)أكثر ممانعة‬
than gram-positive species to antibiotics ‫للمضادات الحياتية‬.
Reproduction of Bacteria
‫التكاثر فى البكتريا‬

Prokaryotes reproduce (‫ )تـتـكاثر‬only asexually (‫)ال جنسيا‬
by binary fission (‫)اإلنقسـام الثـنائى البسيط‬.

A single cell produce
a colony of offspring.
Fig. 27.9 Page 531
Nutrition of Prokaryotes
‫التغذية فى األحياء الدقيقة‬

Nutrition refers to how an organism obtains
energy and a carbon source from the environment
to build the organic molecules of its cells.
• Prokaryotes are grouped (‫صنٍفـَت‬
ُ ) into four
categories (‫ )أنواع‬according to how they obtain
energy and carbon
Nutrition of Prokaryotes
‫التغذية فى األحياء الدقيقة‬

Phototrophs (‫)ضوئية التغذية‬:

Chemotrophs (‫)كيميائية التغذية‬:
Organisms that obtain energy from light.
Organisms that obtain energy from
chemicals in their environment.

Autotrophs (‫)ذاتية التغذية‬:

Heterotrophs (‫)متعدد التغذية‬:
a carbon source.
Organisms that use CO2 as a carbon source.
Organisms that use organic nutrients as
There are four major modes of nutrition
 Photoautotrophs (‫)ذاتية التغذية الضوئية‬:
use
light energy as energy source, and CO2 as carbon source to synthesis (‫ )تخلق‬organic
compounds.
 Chemoautotrophs )‫)ذاتية التغذية الكيميائية‬:
use
chemical inorganic substances as energy source, and CO2 as a carbon source.
 Photoheterotrophs (‫)متعدد التغذية الضوئية‬:
as energy source, and organic substances as carbon source.
 Chemoheterotrophs (‫)متعدد التغذية الكيميائية‬:
use organic substances as a source for both energy and carbon.
use light
Prokaryotic modes of nutrition
Based on Carbon source and Energy source that can be used
by a prokaryote organism to synthesise organic compounds.
Prokaryotes
Page 532
Autotrophs
CO2 as Carbon Source
Photoautotroph
Chemoautotroph
Heterotrophs
Organic compounds as
Carbon Source
PhotoHeterotroph
ChemoHeterotroph
- Light as energy
source
- Chemicals as
energy source
- Light as
energy source
- Chemicals as
energy source
-CO2 as C source
-CO2 as C source
-Organic
compounds as
C source
- Organic
compounds as C
source
B- Eukaryotic Cell
Eu: True
Karyon: Nucleus
Animal Cell
Plant Cell
What are the functions of cell organelles ?
Compare between Animal and Plant cell?
Page 114 - 115
37
‫المادة الوراثية‬
‫النواة‬
‫الشبكة اإلندوبالزمية‬
‫نوية‬
‫الجدار النووى‬
‫سوط حركى‬
‫جسم مركزى‬
‫ريبوسوم‬
‫حهاز جولـﭽـى‬
‫غشاء بالزمى‬
‫حلمات دقيقة‬
‫ميتوكوندريا‬
‫جسم ُمحلل‬
‫‪38‬‬
‫الهيكل الخلوى‬
‫‪Fig. 7.7, Page 114‬‬
‫فجوة مركزية‬
‫بالستيدة خضراء‬
‫الجدار الخلوى‬
‫ثقوب بينية‬
‫‪39‬‬
‫‪Fig. 7.8, Page 115‬‬
1). Prokaryotic and eukaryotic cells
differ in size and complexity
Similarities ‫أوجه التشابه‬
• All cells are surrounded by a plasma membrane ‫غشاء بالزمى‬.
• The semi-fluid substance ‫ المادة النصف سائلة‬within the cell is called
“cytosol”, ‫ السيتوبالزم‬containing the cell organelles ‫ ِعضيات الخلية‬.
• All cells contain chromosomes which have genes in the form of DNA.
• All cells have tiny organelles ‫ عضيات صغيرة‬called “Ribosomes” that make
proteins.
Page 112
1). Prokaryotic and eukaryotic cells
differ in size and complexity
Differences ‫أوجه االختالف‬
• A major difference ‫ الفرق األساسى‬between prokaryotic and
eukaryotic cells is the location of chromosomes ‫موضع الصبغيات‬.
– In an eukaryotic cell, chromosomes are contained in a true nucleus (‫) النواة‬.
– In a prokaryotic cell, the DNA is concentrated in the nucleoid (‫)شـبه نواة‬
without a membrane (‫ ) بدون غـشاء‬separating it from the rest of the cell.
– In prokaryotic cell, DNA is a single strand (‫ )أحادى الشريط‬or double strand
(‫ )ثنائى الشريط‬DNA. But in eukaryotic cell, DNA is double strand.
Page 112
Basic Properties of Cells
• Characteristics that distinguish prokaryotic and eukaryotic cells
– Complexity: Prokaryotes are relatively simple; eukaryotes are more complex
in structure and function.
– Cytoplasm: Eukaryotes have membrane-bound organelles and complex
cytoskeletal proteins. Both have ribosomes but they differ in size.
– Cellular reproduction: Eukaryotes divide by mitosis; prokaryotes divide by
simple fission.
– Locomotion: Eukaryotes use both cytoplasmic movement, and cilia and
flagella; prokaryotes have flagella, but they differ in both form and
mechanism.
– Genetic material:
• Packaging: Prokaryotes have a nucleoid region whereas eukaryotes have a
membrane-bound nucleus.
• Amount: Eukaryotes have much more genetic material than prokaryotes.
• Form: Eukaryotes have many chromosomes made of both DNA and protein
whereas prokaryotes have a single, circular DNA.
© 2013 John Wiley & Sons, Inc. All rights reserved.
The structure of cells
(96)
Bacterium
© 2013 John Wiley & Sons, Inc. All rights reserved.
The structure of cells
Plant cell
© 2013 John Wiley & Sons, Inc. All rights reserved.
The structure of cells
Animal cell
© 2013 John Wiley & Sons, Inc. All rights reserved.
(97)
Cellular reproduction:
Eukaryotes and prokaryotes (100-101)
Cell division in eukaryotes
DNA (blue) and microtubules
(green) of two daughter cells.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Bacterial conjugation
Sharing of DNA through
the F pilus
Basic Properties of Cells
(104)
• Types of Eukaryotic Cells:
Cell Specialization
– Multicellular eukaryotes
have different cell types
for different functions.
• Differentiation occurs
during embryonic
development in other
multicellular organisms.
• Numbers and
arrangements of
organelles relate to the
function of the cell.
• Despite differentiation,
cells have many features
in common.
Pathways of cell differentiation
© 2013 John Wiley & Sons, Inc. All rights reserved.
Classifications of Tissues
1. Epithelium:
lines and covers surfaces
2. Connective tissue:
protect, support, and bind together
3. Muscular tissue:
produces movement
4. Nervous tissue:
receive stimuli and conduct impulses
Epithelium - Shapes:
• Squamous:
flat,thin, scale-like cells
• Cuboidal:
cells that have a basic cube shape. Typically
the cell's height and width are about equal.
• Columnar:
tall, rectangular or column shaped cells. Typically
taller than they are wide.
Epithelium - Arrangements:
• Simple:
Cells are found in a single layer attached to the basement
membrane
• Stratified:
Cells are found in 2 or more layers stacked atop each other
• Pseudostratified:
a single layer of cells that appears to be multiple layers due to
variance in height and location of the nuclei in the cells.
• Transitional:
cells are rounded and can slide across one another to allow
stretching
Connective
• 1. Connective tissue proper
– a. Loose Connective Tissue
• i. Areolar
• ii. Adipose
• iii. Reticular
– b. Dense Connective Tissue
• i. Dense regular
• ii. Dense irregular
• iii. Elastic
• 2. Cartilage
– a. Hyaline
– b. Elastic
– c. Fibrocartilage
• 3. Bone (osseous tissue)
• 4. Blood