1. CELL BIOLOGY:
AN INTRODUCTION
Department of Natural Sciences
University of St. La Salle
Bacolod City

2. 1. Introduction to Cells
2. Chemical Foundations - Biochemistry
3. Methods of Studying Cells
a. Investigating Cells
b. Visualizing Biomolecules CELL BIOLOGY:
c. Visualizing Nucleic Acids COURSE OUTLINE
4. Genetic Mechanisms
a. DNA and Chromosomes
b. Anatomy of a Gene
c. Replication, Transcription, Translation
d. Regulating Gene Expression
e. Genetic Techniques and Genomics - Biotechnology
f. Molecular Basis of Inheritance - Genetics
5. Cell Signaling
6. Cell Membranes and Cell Architecture
a. Plasma Membrane and Transport
b. Organelles - Histology
c. Cytoskeleton
7. Energetics – Biochemistry
8. Cellular Traffic
9. Cell Birth, Lineage and Death
10. Molecular Basis of Cancer

3. GRADING SYSTEM
Quizzes/ Exams: 50% Seminar Presentation: 50%
1. A long exam will be given after each seminar topic,
with a 60% cut-off for the passing grade.
2. Prelim, Midterm and Endterm exams will cover only
the last topic covered for the period.
3. The PP lessons prepared by the instructor will be
the basis of the scope of the content material for
the seminar topics. The use of such materials is
allowed for all presentors.
4. However, you are free to design the kind of
presentations you will give your audience within 1-2
hours. The objective is they will understand the
topic in accordance with the limits their
intelligence genes would allow.

4. 5. A copy of the presentation must be provided to the
instructor at least 2 days before the scheduled event.
6. No appearance during the scheduled presentation will
automatically result to a grade of 60 for the presentor.
No excuses will be entertained.
7. Swapping of schedules is not allowed without previous
notice.
8. For additional points, invite at least one faculty of the
Dept. of Natural Sciences/or a person of authority to
evaluate your presentation. She/ He may attend during
the final presentation and/or submit a written evaluation
of the presentation on or before the scheduled event.
9. Your presentation will be graded as follows:
 Comprehensiveness of content material – 20%
 Mastery of topic – 60%
 Audience impact- 10%
 Faculty Evaluation – 10%

5. Cell Biology
in a
nutshell…
(Basic Concepts)

6. All living organisms are constructed from cells.

7. All cells are prokaryotic or eukaryotic

9. General Structure Of The Cell
1.Shape – depends upon:
 Functional adaptations
 Surface tension & viscosity of the protoplasm,
e.g., leukocytes in circulating blood are
spherical but emit pseudopods and become
irregular in shape extravascularly.
 Mechanical action exerted by adjoining cells
 Rigidity of the cell membrane
 Presence of cytoplasmic microtubules
2.Size – variations are due to:
 adaptations to perform a specific function
 withstand mechanical stresses & pressures
 environmental and genetic factors

11. All organisms from simple
bacteria to complex
mammals probably evolved
from a common, single-
celled progenitor.
DNA and protein sequences
were examined for assigning
relationships, which agree
with fossil records. Although
prokaryotes, Archaea are
more similar to eukaryotes
than to
Eubacteria, e.g., archaean
and eukaryotic genomes
encode homologous histone
proteins, which associate
with DNA; bacteria lack
histones. RNA and protein
components of Archaean
ribosomes are more like
those in eukaryotes than
those in bacteria.

12. MECHANISMS OF EVOLUTION Intragenic mutation:
an existing gene can be
modified by mutations
in its DNA sequence.
Gene duplication:
an existing gene can be
duplicated so as to
create a pair of closely
related genes within a
single cell.
Segment shuffling:
two or more existing
genes can be broken
and rejoined to make a
hybrid gene consisting
of DNA segments that
originally belonged to
separate genes.
Horizontal transfer:
a piece of DNA can be
transferred from the
genome of one cell to
that of another.

13. We develop from a single cell
 Fertilization of an egg by a sperm cell
yields a zygote, a cell about 200 μm
in diameter.
 A zygote houses all the necessary
instructions for building the human
body with 100 trillion (1014) cells.
 It generates hundreds of different
kinds of cells that differ in
contents, shape, size, color, mobility,
and surface composition.
 Genes and signals control cell
diversification
 Our current knowledge lead to stem
cell, cloning, and related techniques
that offer exciting possibilities but
raise some concerns

14. The Molecules of a Cell
1. Small molecules carry energy, transmit
signals, and are linked into macromolecules.
Neurotransmitters
Hor-
mones
Monomers to polymers
Adenosine triphoshate (ATP)

15. 2. Proteins give cells structure and perform most
cellular tasks
 Each protein has a defined 3D conformation that is
stabilized by numerous chemical interactions.
 Proteins below include enzymes, an antibody, a
hormone, and the blood’s oxygen carrier. Models of a
DNA segment and the lipid bilayer that forms cellular
membranes demonstrate the relative width of these
structures compared with typical proteins.

16. 3. Nucleic acids carry coded information for making
proteins at the right time and place.
Step 1 : Transcription factors bind to the
regulatory regions of the specific genes
they control and activate them.
Step 2 : Following assembly of a
multiprotein initiation complex bound to
the DNA, RNA polymerase begins
transcription of an activated gene at a
specific location, the start site. The
polymerase moves along the DNA
linking nucleotides into a single-
stranded pre-mRNA transcript using
one of the DNA strands as a template.
Step 3: The transcript is processed to
remove noncoding sequences.
Step 4: In a eukaryotic cell, the mature
messenger RNA (mRNA) moves to the
cytoplasm, where it is bound by
ribosomes that read its sequence and
assemble a protein by chemically linking
amino acids into a linear chain.

17. 4. The genome is packaged into chromosomes and
replicated during cell division.
A normal human has 23 pairs of morphologically distinct chromosomes; one
member of each pair is inherited from the mother and the other member
from the father. Chromosomes from the preparation on the left arranged in
pairs in descending order of size, an array called a karyotype. The presence
of X and Y chromosomes identifies the sex of the individual as male.

18. 5. Mutations May Be Good, Bad, or Indifferent
 Mutations are mistakes that occasionally occur
spontaneously during DNA replication, causing
changes in the sequence of nucleotides. Such
changes can arise from radiation, chemical poisons
(e.g., cigarette smoke, alcohol).
 Mutations come in various forms: a simple swap of
one nucleotide for another; the deletion, insertion, or
inversion of one to millions of nucleotides in the DNA
of one chromosome; and translocation of a stretch of
DNA from one chromosome to another.
 “Indifferent” mutations in nonfunctional DNA have
been a major player in evolution, leading to creation
of new genes or new regulatory sequences for
controlling already existing genes. Some of our own
copies of genomes are genetic residues of
infections acquired by our ancestors.

19. CELL FUNCTIONS
1. Cells build and degrade numerous molecules and
structures.
ATP is formed from ADP and inorganic phosphate (Pi) by
photosynthesis in plants and by the breakdown of sugars and
fats in most cells. The energy released by the splitting
(hydrolysis) of Pi from ATP drives many cellular processes.

21. 2.Cells can be powered by a
variety of free energy sources
a. Organotrophic -
animals, fungi, and the
bacteria that live in the
human gut, get it by feeding
on other living things or the
organic chemicals they
produce. These organisms
could not exist without
primary energy converters:
b. Phototrophic - those that
harvest the energy of Living organisms at a hot
hydrothermal vent
sunlight At temperatures up to about 150°C,
c. Lithotrophic - those that lithotrophic species of bacteria live,
fuelled by geochemical energy. A little
capture their energy from further away are the giant (2-m) tube
worms, which live in symbiosis with
energy-rich systems of huge numbers of symbiotic sulfur-
inorganic chemicals in the oxidizing bacteria.

22. 3. Animal cells produce their own external
environment and glues.
Animal cells produce and secrete an extracellular matrix that
cushions, lubricates, and glue cells together for exchanging
small molecules including nutrients and signals, and
facilitating coordinated functioning of the cells. The cells of
higher plants contain relatively few such molecules.

23. 4. Cells change shape and move.
 Three types of protein filaments, organized into networks and
bundles, form the cytoskeleton within animal cells.
 The cytoskeleton prevents the plasma membrane of animal
cells from relaxing into a sphere; it also functions in cell
locomotion and the intracellular transport of
vesicles, chromosomes, and macromolecules .
 The cytoskeleton can be linked through the cell surface to the
extracellular matrix or to other cells, helping to form tissues.
A cultured fibroblast in a fluorescence microscope reveals the location of
filaments bound to a particular dye-antibody preparation. All three fiber
systems contribute to the shape and movements of cells.

24. 5. Cells Sense and Send Information Binding of a
hormone or other
signaling molecule
to its specific
receptors can
trigger an
intracellular
pathway that
increases or
decreases the
activity of a
preexisting protein.
The hormone-
receptor complexes
activate
transcription of
specific target
genes. Many signals
that bind to
receptors on the cell
surface also act, by

25. 6. Cells regulate their gene expression to meet changing needs.
 Cells often respond to
changing circumstances
and to signals from other
cells by altering the amount
or types of proteins they
contain.
 Gene expression is
commonly controlled to
produce a particular mRNA
only when the encoded
protein is needed, thus
minimizing wasted energy.
 Transcriptional
activators, repressors and
other mechanisms for
controlling gene expression
determine whether such
could occur only in part of
the brain, only during
evening hours, only during
a certain stage of

26. 7. Cells Grow and Divide
During growth, eukaryotic In animals, meiosis of diploid
cells continually progress precursor cells forms gametes.
through the four stages of The male parent produces two
the cell cycle, generating types of sperm and
new daughter cells. determines the sex of the
zygote.

27. 8. Cells die from aggravated assault or an internal
program
Left, normal WBC.
Right, cell
undergoing
programmed cell
death
(apoptosis), form
numerous surface
blebs that eventually
are released. The
cell is dying because
it lacks certain
Apoptosis is important to eliminate virus-infected cells,
growth signals.
remove cells where they are not needed (like the webbing that
disappears as fingers develop), and to destroy immune system
cells that would react with our own bodies.

28. 9. Metabolic proteins, the
genetic code, and
organelle structures are
nearly universal.
(a) Hox genes serve to direct
formation of the right structures
in the right places. (b)
Development of the large
compound eyes in fruit flies
requires a gene called eyeless.
(c) Flies with inactivated eyeless
genes lack eyes. (d) Normal
human eyes require Pax6, that
corresponds to eyeless. (e)
People lacking adequate Pax6
function have the genetic
disease aniridia, a lack of irises
in the eyes. Pax6 and eyeless
encode highly related proteins
that regulate the activities of
other genes, and are descended

29. http://www.learnerstv.com/animation/animation.php?a
ni=162&cat=biology
www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/
www.cellbio.com
www.expasy.org/
www.mcb.harvard.edu/BioLinks.html
www.molbiolcell.org/
www.whfreeman.com/lodish