General Biology 1 - Lesson 1: Cell (structure,function, and theory)

General Biology1: SubjectDescription
This subject is designed to enhance the
understanding of the principles and
concepts in the study of biology,
particularly life processes at the cellular
and molecular levels. It also covers the
transformation of energy in organisms.

CONTENT
I. CELL
a. Cell Theory
b. Cell Structure and Functions
c. Prokaryotic vs. Eukaryotic Cells
d. Cell Types
e. Cell Modifications
f. Cell Cycle: Mitosis/Meiosis
g. Transport Mechanism
1. Simple Diffusion
2. Facilitated Diffusion
3. Active Transport
4. Bulk/Vesicular
Transport

CONTENT
ii. Biological molecules
 Structure and Functions of Biological Molecules
a. Carbohydrates
b. Lipids
c. Proteins
d. Enzymes
e. Nucleic Acid

CONTENT
ii. ENERGY TRANSFORMATION
A. ATP-ADP Cycle
B. Photosynthesis
C. Cellular Respiration

LESSON 1: THE CELL
(Theory, Structure and Functions)
General Biology 1

OOTD: Objectives of the day!
At the end of the lesson, I should be able to:
Recite the postulates of cell theory and explain the roles of a cell in an
organism, particularly in the levels of organization of an organism;
Describe the structure and functions of major and subcellular
organelles;
Determine the role of each cellular organelle and explain how it relates
to the functions of other organelles.

History ofcell
 In 1665, British scientist Robert
Hooke examined a piece of cork and
found little structures in it which he
compared to cellulae.
 He named these structures “cells”.
Later it was discovered that the cell
he had found in the cork were
actually outer walls of former plant
cell.

HISTORY OFCELL
 In the late 1600’s, Dutch scientist
Anton van Leeuwenhoek examined
different subjects , using a refined
microscope than that of Hooke.
 Leuwenhoek found moving protist
and sperm, which he collectively
termed “animalcules”

CellTheory: Definition
The Cell Theory, developed in the mid-1800’s as a result of
various discoveries about cells, it is one of the basic principles of
biology.
1. The cell is the basic unit of life;
2. All living organisms are composed of cell; and
3. New cells are created from pre-existing cell

First Postulate:Cellis thebasic unit of life
In order that an organism may be
considered living, it must have a cell.
One proof that an organism is alive
just by looking at its cell is the
movement of the organelles inside it.

First Postulate:Cellis thebasic unit of life
In the cork that Hooke examined, the
protoplasm of the cell had already dissipated,
indicating the cell’s death.
When Leeuwenhooek observed his teeth
scrapings, he found animalcules shooting and
spinning inside the cell.

Second Postulate:
ALLLIVINGORGANISMSARECOMPOSED OF CELL
In 1838, German botanist Mattthias Jacob
Schleiden established that the small
compartments in his plant specimens are
cells.
In 1839, a German zoologist named
Theodore Schwann after doing microscopic
studies of animal cells, instituted that all
animals are also composed of cells.

Third Postulate:
new cells arecreatedfrompre-existingcells
German scientist Rudolf
Virchow introduced the third
tenet of the cell theory: Omnis
cellula e cellula which means
“Cells come from pre-existing
cell”.

Development of Cell Theory
1590 – Zacharias Janssen
invented a primitive microscope
with the help of his father Hans.
1663-1665 – Robert Hooke
viewed a thin slice of cork

1665-1676 Marcello Malpighi
and Nehemiah Grew conducted
separated investigations on plant
cell. They determined the
presence of organelles within its
cells .

1670-1683 Anton van Leeuwenhoek upgraded
Janssen’s microscope and produced his lens. With
this invention, he discovered mobile organelles in
many subjects, which he called animalcules.

1831- Robert Brown made a series of discoveries
about cell organelles and ultimately discovered
the nucleus. This became a major breakthrough in
the history of biology.

1838 Matthias Schleiden microscopically examine
plants and recognized that plant parts come from
cells. In his writings in Contribution in
Phytogenesis, he proposed that the different
structures of a plant are all composed of cells.

1839 Theodore Schwann declared that animals
are likewise composed of cells. This put an end to
the debates – whether or not plants and animals
are different in structural origin and composition.

1840 Albrecht von Roelliker stated that sperm and
egg are composed of cells and that all humans are
configured from cells.
1849 Louis Pasteur was developing fermentation, a
process to kill bacteria, he proved that bacteria are
able to multiply and that bacterial cells come from
other bacterial cells.

1858 Rudolf Virchow declared, “Omnis cellula e
cellula” which he meant that cells come from pre-
existing cells. With this conclusion, the cell theory
was completed.

Question!
If life were to be found in other planets,
would you expect it to form cells? Why or
why not?

ASTROBIOLOGY
Our space exploration has been
continually searching for life in outer
space. On the space probes sent to
other planets (especially Mars), these
are equipped to look after life.
However, very high resolution are still
not possible on-site.

MAJORPARTSOF THE CELL
Plasma
Membrane
Outer covering that separates
the cell’s interior from its
surrounding environment.
Cytoplasm Consisting of a jelly-like cytosol
within the cell in which other
cellular components are found.
Nucleus Serves as the brain of the cell
and directs all of the cell’s
activity.

PlasmaMembrane
It encloses and safeguards its organelles from
possible harm that foreign materials can inflict on
them.

PlasmaMembrane
It also controls the
exchange of essential
components and obtains
chemical messages from
other cells.

PlasmaMembrane:FLUIDMOSAIC MODEL
The plasma membrane is a mosaic of components—
primarily, phospholipids, cholesterol, and proteins—that
move freely and fluidly in the plane of the membrane.

ComponentsofPlasmaMembrane
1. Phospholipids
It is a lipid made of glycerol, two fatty acid
tails, and a phosphate-linked head group.
Biological membranes usually involve two
layers of phospholipids with their tails
pointing inward, an arrangement called
a phospholipid bilayer.

2. Cholesterol
It is another lipid composed of four fused carbon rings, is found
alongside phospholipids in the core of the membrane.

3. Proteins
Proteins help move large molecules or aid in cell recognition
Peripheral proteins are attached on the surface (inner or outer)
Integral proteins are embedded completely through the
membrane

CYTOPLASM
It is the entire region of a cell between plasma
membrane and nuclear envelope.
It is composed primarily of water, proteins and salts.

CYTOPLASM
In the cytoplasm, the organelles are
suspended in a gel-like solution called cytosol,
which is composed of both organic and
inorganic compounds.
Cytosol accounts for about 70% of cellular
content. It contains a rich supply of
macromolecules and smaller organic
molecules.

CYTOPLASM
The Cytoplasm also contains enzymes that
break down waste and enable metabolic
reactions.
It allows for cellular expansion and growth.
Together with cytoskeleton, cytoplasm
determines cell shape and accommodates
movement for some cell types.

Nucleus
Discovered by Robert Brown in 1833.
It is the most vital part of the cell and
dubbed as the “control center”
It directs all of the cell’s activities and
determines how a cell should appear
and function.

Nucleus
A double layer of nuclear membrane
encloses the nucleus to keep it distinct from
other cellular components.
Nucleolus serves as the site of ribosomes
synthesis.
Nucleus holds chromosomes which carry
tightly wrapped and coined DNA.

Thecellorganelles:endomembranesystem
The endomembrane system is a
group of membranes and
organelles in eukaryotic cells that
works together to modify, package,
and transport lipids and proteins.

Thecellorganelles:endomembranesystem
This system is made up of organelles that are communally linked
by structure specific to each of them.
These organelles are:
1. Endoplasmic Reticulum 5. Lysosomes
2. Ribosomes 6. Peroxisomes
3. Vacuoles 7. Centrosomes
4. Golgi Apparatus

Endoplasmic reticulum
The Endoplasmic Reticulum (ER) is a series of
interconnected membranous sacs and tubules that
collectively modifies proteins and synthesized lipids.
These two functions are performs in separate areas of
ER; the rough endoplasmic reticulum and smooth
endoplasmic reticulum.

Endoplasmic reticulum
The hollow portion of ER tubules is
called lumen or cisternal space.
The membrane of the ER, which is a
phospholipid bilayer embedded
with proteins , is continuous with
nuclear envelope.

Rough endoplasmicreticulum
It has ribosomes on its surface.
It makes membrane proteins and proteins for
export out of cell.
Proteins are made by ribosomes on ER surface
They are then threaded into the interior of the
Rough ER to be modified and transported

smoothendoplasmicreticulum
It incorporates proteins into cisternae
and transports synthesized proteins
across the cytoplasm, thereby allowing
the synthesis of fatty acids and
phospholipids.
It is abundant in liver cell, where it
detoxifies hydrophobic chemicals. This
makes them water-soluble for excretion.

RIBOSOMES
Ribosomes are involved in providing a frame for
proteins synthesis; hence they are site of protein
production.
They are present in both prokaryotic and eukaryotic
cells.
Developing muscle cells, skin and hair cells contain
large numbers of free ribosomes.

Vacuoles
A vacuole is a fluid –filled vesicles enclosed by a membrane.
It has a selectively membrane freely allowing water passage but
retaining smaller molecules within it and stores chemicals within
the cell.
Vacuoles ability to break down large molecules makes it
comparable with lysosomes in animal cells. Likewise, both organelles
thrive in acidic environment.

lysosomes
The lysosomes serve as digestion slots for cellular materials
that are due for expiration or are no longer useful.
It is the cell’s reprocessing area, where it hacks chemical
bonds of any foreign substance it comes contact with, in
order to recycle with the raw material

lysosomes
It is dubbed as the cell’s “suicide bags”
These organelles are capable for self-destruction In order to
save the rest of the other organelles from being poisoned.
This happens through autophagy, or the natural process of
organelle destruction.

LYSOSOMES
•Cells take in food by
phagocytosis
• Lysosomes digest the food
& get rid of wastes
•Example: macrophages

peroxisomeS
•It is a small, round organelles enclosed by single
membrane, somehow resembles that of a lysosomes.
•It is responsible for self-damage and mostly
disintegrate proteins, accommodate the breakdown of
fatty acids and detoxify many poisons that enter the
body.
•It also shields the cell from serious damage caused
reactive oxygen species (ROS) molecules

GolgiAPPARATUS
Stacks of flattened sacs
Have a shipping side (cis face) & a
receiving side (trans face)
Receive proteins made by ER
Transport vesicles with modified
proteins pinch off the ends
CIS
TRANS
Transport
vesicle

GolgiAPPARATUS
•a stack of pancakes
Modify, sort, & package molecules from ER
for storage OR
transport out of cell

CENTROSOME
It comprised of two centrioles or cylindrical structures with
a central cavity surrounded by microtubules arranged side
by side.
These structure take part in the assembly of spindle fibers
at cell division and contribute to the successful outcome of
mitosis.

CENTROSOME
It is found in all eukaryotic cells, assist in arranging
microtubules (hollow tubes of proteins) to be utilized for
cell division.
They also enable the said microtubules to form part of the
cell’s microtubules to form part of the cell’s cytoskeleton.
In this way, cellular shape is maintain and the cell structure
is stabilized.

mitochondria
Mitochondria are the sites of
cellular respiration, the
metabolic process that uses
oxygen to drive the
generation of ATP by
extracting energy from
sugars, fats, and other fuels.

ADENOSINETRIPHOSPHATE
It is the major energy currency of the
cell that provides the energy for most of
the energy-consuming activities of the
cell.
Mechanism: When the third phosphate
group of ATP is removed by hydrolysis, a
substantial amount of free energy is
released.

MITOCHONDRIA
The mitochondria are oval-shaped
organelles found in most eukaryotic cells.
They are considered to be the
‘powerhouses’ of the cell.
Mitochondria are most plentiful in cells
that require significant amounts of
energy to function, such as liver and
muscle cells.

MITOCHONDRIA
 The mitochondria has two membranes that are similar in composition to
the cell membrane:
 Outer membrane—is a selectively permeable membrane that surrounds
the mitochondria.
 It is the site of attachment for the respiratory assembly of the electron
transport chain and ATP Synthase.
 It has integral proteins and pores for transporting molecules just like the
cell membrane

MITOCHONDRIA
 Inner membrane—folds inward (called cristae) to increase surfaces for
cellular metabolism.
 It contains ribosomes and the DNA of the mitochondria. The inner
membrane creates two enclosed spaces within the mitochondria:
 intermembrane space between the outer membrane and the inner
membrane; and
 matrix that is enclosed within the inner membrane.

CHLOROPLAST
Chloroplasts, which are found in plants and algae, are the
sites of photosynthesis.
This process converts solar energy to chemical energy by
absorbing sunlight and using it to drive the synthesis of
organic compounds such as sugars from carbon dioxide
and water.

CHLOROPLAST
Chloroplasts are double membrane-bound
organelles and are the sites of photosynthesis.
The chloroplast has a system of three membranes:
the outer membrane, the inner membrane, and the
thylakoid system.

Structure of chloroplast
Outer membrane—This is a semi-porous
membrane and is permeable to small
molecules and ions which diffuse easily.
The outer membrane is not permeable to
larger proteins.

Intermembrane Space—This is usually a thin
intermembrane space about 10-20
nanometers and is present between the
outer and the inner membrane of the
chloroplast.

Inner membrane—The inner membrane of
the chloroplast forms a border to the
stroma.
It regulates passage of materials in and out
of the chloroplast. In addition to the
regulation activity, fatty acids, and are
synthesized in the inner chloroplast
membrane.

Stroma—This is an alkaline, aqueous fluid
that is protein-rich and is present within the
inner membrane of the chloroplast.
It is the space outside the thylakoid space.
The chloroplast DNA, chloroplast ribosomes,
thylakoid system, starch granules, and other
proteins are found floating around the
stroma.

Thylakoid System
The thylakoid system is suspended in the
stroma. It is a collection of membranous
sacks called thylakoids.
Thylakoids are small sacks that are
interconnected.

The membranes of these thylakoids are the
sites for the light reactions of the
photosynthesis to take place. The
chlorophyll is found in the thylakoids.
 The thylakoids are arranged in stacks known
as grana. Each granum contains around 10-
20 thylakoids.

Practice:HOMEWORK
Draw and label each part of plant and animal cell in a
short bond paper.

ENRICHMENT
Why cells are generally small in size?

General Biology 1 - Lesson 1: Cell (structure,function, and theory)

More Related Content

What's hot

Similar to General Biology 1 - Lesson 1: Cell (structure,function, and theory)

More from EDUTASK PRO PH

Recently uploaded

General Biology 1 - Lesson 1: Cell (structure,function, and theory)

Editor's Notes