Gen Bio 1 - Q1 - W1 - Las 1 PDF

General Biology 1 Quarter 1 Week 1
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THE CELL THEORY
Learning Competency: Explain the postulates of the Cell Theory
Specific Objectives:
1. State the three postulates of the original Cell Theory;
2. Explain the three postulates of the original Cell Theory.
Writer: Jodison A. Tanutan
Editor:
What I Need to Do
In your previous grade levels, you have learned about the characteristics of a
cell – its parts and the functions of each part. In this lesson, we will learn how
cells were first discovered, how the cell theory was developed, and the main
components of the cell theory. To enhance learning, you will be doing
activities around cell theory for deeper understanding of this lesson.
Gearing Up
Anton Van Leeuwenhoek, a Dutch shopkeeper, discovered the microscope in

the 1600. This paved way to the discovery of bacteria and protozoa. In his
experiments, he observed the box – like structures when viewing cork tissue
through his lens, in which he coined the term “cell”. Developments in 17th
century in the field of microscopy and staining techniques enabled other
scientist to view some components inside the cells.
The unified theory was proposed by botanist Matthias Schleiden and zoologist
Theodor Schwann who were both studying tissues in the late 1930’s. The
unified cell theory states that: all living things are composed of one or
more cells; the cell is the basic unit of life; and new cells arise from
existing cells. Rudolf Virchow later made important contributions to this
theory.
Later, spontaneous generation as a method for cell origination – abiogenesis
was proposed by Schleiden and Schwann but was disproven. Furthermore,
Rudolf Virchow proposed that - “All cells only arise from pre-existing cells”.
These observations made by Hooke, Leeuwenhoek, Schleiden, Schwann,

Virchow, and others made an important hallmark for the development of the
cell theory. The cell theory is a widely accepted explanation of the relationship
between cells and living things. The cell theory states: (1) All living things or
organisms are made of cells; (2) New cells are created by old cells dividing into
two and; and, (3) Cells are the basic building units of life.
The cell theory proves that cells are common to all living things and the best
source of information about life. And because cells come from other cell, it is
possible for scientists to study growth and reproduction and all other
functions of living things.
THE THREE POSTULATES OF THE CELL THEORY
1. The cell is the basic unit of life.
The cell is considered as the building blocks of all living things. It is the
smallest unit of a living thing. It is the smallest part of the organism that
retains characteristics of the entire organism. For example, a cell can take in
fuel, convert it to energy, and eliminate metabolic wastes, just like the
organism as a whole can. But, the structures inside the cell cannot perform
these functions on their own, so the cell is considered the lowest level.
Each cell is capable of converting fuel to useable energy. Therefore, cells not
only make up living things; they are living things. Cells are found in all plants,
animals, and bacteria. Many of the basic structures found inside all types of
cells, as well as the way those structures work, fundamentally are very
similar, so the cell is said to be the fundamental unit of life.
2. All living things are made up of one or more cells.
A living thing, whether made of one cell (like bacteria) or many cells (like a
human), is called an organism. Several cells of one kind that interconnect
with each other and perform a shared function form tissues; several tissues
combine to form an organ (your stomach, heart, or brain); and several organs
make up an organ system (such as the digestive system, circulatory system,
or nervous system). Several systems that function together form an organism
(like a human being). There are many types of cells all grouped into one of
two broad categories: prokaryotic and eukaryotic. For example, both animal
and plant cells are classified as eukaryotic cells, whereas bacterial cells are
classified as prokaryotic.
Reference: https://resources.saylor.org/wwwresources/archived/site/wp-content/uploads/2010/11/Wiki-Cell-Theory.pdf
Creative Commons Attribution-Share Alike 3.0 Unported
http://creativecommons.org/licenses/by-sa/3.0/
Increasingly more complex organisms are made up of increasingly more
groups of cells and the organisms survive based on products that the cells
make. For example, cells in the pancreas make insulin, which is necessary to
ensure that the blood glucose level does not rise steeply. Without insulin, the
blood glucose can reach a level that is lethal. So, without that cellular
product, a person would die.
3. All cells come from pre-existing cells (omni cellulae e cellula).
In the mid-1800s, the long-standing myth which claims the "spontaneous

generation" of life from inanimate matter was dispelled. This happened when
Rudolf Virchow observed that cells divide to produce more cells. It became
clear that all life must arise from pre-existing life — via a process of
reproduction. If cells are the fundamental units of life, they too must have a
reproductive mechanism that maintains the proper chromosome number in
each cell.
Hence, the most important characteristic of a cell is that it can reproduce by

dividing. If cells did not reproduce, any living thing would not continue to live.
Cell division is the process by which cells duplicate and replace themselves.
If a person did not replace his/ her red blood cells, for example, he/ she would
have a life span only as long as that of red blood cells — a mere 120 days.
Exceptions
1. Viruses are considered alive by some, yet they are not made up of cells.
Viruses have many features of life, but by definition of the cell theory, they
are not alive.
2. The first cell did not originate from a pre-existing cell. There was no exact
first cell since the origin of cell is imprecise.
3. Mitochondria and chloroplasts have their own genetic material and
reproduce independently from the rest of the cell.
B. ONLINE VIDEO LESSONS FOR DEEPER UNDERSTANDING
The supplemental video links below will help you better understand the
following: (1) how cells were first discovered, (2) how the cell theory was
developed, and (3) main components of the cell theory.
After watching the video answer the guide questions that follow.
https://www.texasgateway.org/resource/its-all-about-cell-theory
https://www.youtube.com/watch?v=4OpBylwH9DU
Guide Questions:
1. What caused scientists to discover the existence of cells?
2. What discovery is van Leeuwenhoek noted for?
3. What are the three parts of the cell theory?
Getting Better
Activity 1. Going Back in Time
Direction: Read the storyboard below and complete the graphic organizer.
1590 1665 1674
Zacharias made the first compound

microscope allowing scientists to
explore what they cannot see with
the naked eye
All organisms
are made of
one or
more cells.
1831 1838/ 1839 1858
Source: https://www.storyboardthat.com/fr/storyboards/s162169/bio-comic-strip
In this graphic organizer, (1) indicate the contribution of each scientist in
their respective box, (2) state the three postulates of the Cell Theory, and (3)
explain how the invention of the compound microscope contributed to the
development of the Cell Theory.
Robert Hooke Anton van What are the main points of the Cell Theory?
Leeuwenhoek 1.
2.
3.
1665 1674
How did the invention of the

1838 1839 1855
microscope contribute to the
formation of the Cell Theory?
Matthias Theodor Rudolf
Schleiden Schwann Virchow
Activity 2. Find My Match!

Direction: Match the postulate in Column A with its corresponding
Explanation in Column B. Write your answer in the space below.
Column A Column B
1. All cells come from pre- I. All organs are made up of tissues. Tissues
existing Cells are made up of cells. Each type of cell has
a different, specialized role.
2. The cell is the basic unit II. All current life on Earth is descended
of life. from the very first cells. Cells have been
replicating themselves continuously ever
since.
3. All living things are III. The cells are capable of performing
made up of one or more metabolic processes which are vital to an
cells. organism such as respiration, protein
synthesis, and secretion / excretion of
metabolic wastes.
Answer:
1. __________ 2. __________ 3. __________
Gaining Mastery
Activity 3. Guess that Picture!

Direction: Each picture below represents a postulate of the cell theory. Study
each picture and identify and explain the postulate of Cell Theory it
represents.
Postulate:
Explanation:
Source: commons.wikimedia.org
Creative Commons Attribution 2.5 Generic
Postulate:
Explanation:
Creative Commons Attribution 2.0 Generic
Postulate:
Explanation:
Creative Commons Attribution-Share Alike 3.0
Unported
Activity 4. Cell Comics

Direction: Read the text below. Choose one new tenet from the Modern Cell
Theory (e.g. Energy flows within cells.) and create a short comic strip
illustrating and explaining the chosen tenet. The comics can be funny, but
must also be clear, accurate, and explanatory in nature.
All three postulates of the Cell Theory are equally important – the postulates
support the theory that the functions necessary for life occur in the cell. Findings
since the time of the original Cell Theory have enabled scientists to "modernize"
the theory, including points related to biochemistry and molecular biology. The
modern version of the Cell Theory includes:
• All known living things are made up of one or more cells.

• All living cells arise from pre-existing cells by division.
• The cell is the fundamental unit of structure and function in all living
organisms.
• The activity of an organism depends on the total activity of
independent cells.
• Energy flow (metabolism and biochemistry) occurs within cells.
• Cells contain hereditary information (DNA) which is passed from
cell to cell during cell division.
• All cells are basically the same in chemical composition in
organisms of similar species.
The Cell Theory is one of the main principles of biology. The points of the theory
have been found to be true for all life. It has withstood intense examination
of cells by modern powerful microscopes and other instruments.
Note: You may use the template below or use a storyboard creator online in
making your comic strips.
Activity 5. Cell-ious Misconceptions
The statements below are serious misconceptions or alternative conceptions

about the cell. Refute these statements by providing a correct explanation
using the postulates of the Cell Theory.
1. One cell alone cannot conduct the basic processes associated with life.
2. There are only two types of cell – plant cell and animal cell.
3. Living things can descend from non-living things (e.g. rotting garbage turn
into maggots, which are fly larvae that will later grow into adult flies).
What I Need to Remember
• The postulates of the original Cell Theory are the following:

• A component of the cell theory is that all living things are composed of
one or more cells.
• A component of the cell theory is that the cell is the basic unit of life.
• A component of the cell theory is that all cells come from pre-existing
cells.
Additional Activity
Direction: The material below is taken from the DepEd ADM Module on
Cell Theory. Read the material below and answer the questions that follow.
The Spontaneous Generation Theory

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded
scholars to articulate the theory of spontaneous generation, the notion that life can
arise from nonliving matter. Aristotle proposed that life arose from nonliving material
if the material contained pneuma (“vital heat”). As evidence, he noted several instances
of the appearance of animals from environments previously devoid of such animals, such
as the seemingly sudden appearance of fish in a new puddle of water.
This theory persisted into the seventeenth century, when scientists undertook
additional experimentation to support or disprove it. By this time, the proponents of the
theory cited how frogs simply seem to appear along the muddy banks of the Nile River in
Egypt during the annual flooding. Others observed that mice simply appeared among
grain stored in barns with thatched roofs. When the roof leaked and the grain molded,
mice appeared. Jan Baptista van Helmont, a seventeenth century Flemish scientist,
proposed that mice could arise from rags and wheat kernels left in an open container for
3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse
populations to flourish.
However, one of van Helmont’s contemporaries, Italian physician Francesco Redi
(1626–1697), performed an experiment in 1668 that was one of the first to refute the idea
that maggots (the larvae of flies) spontaneously generate on meat left out in the open air.
He predicted that preventing flies from having direct contact with the meat would also
prevent the appearance of maggots. Redi left meat in each of six containers (Figure 1).
Two were open to the air, two were covered with gauze, and two were tightly sealed. His
hypothesis was supported when maggots developed in the uncovered jars, but no maggots
appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots
could only form when flies were allowed to lay eggs in the meat, and that the maggots
were the offspring of flies, not the product of spontaneous generation.
Figure 1. Francesco Redi’s experimental setup consisted of an open container, a

container sealed with a cork top, and a container covered in mesh that let in air but not
flies. Maggots only appeared on the meat in the open container. However, maggots were
also found on the gauze of the gauze-covered container.
In 1745, John Needham (1713–1781) published a report of his own experiments,
in which he briefly boiled broth infused with plant or animal matter, hoping to kill all
preexisting microbes. He then sealed the flasks. After a few days, Needham observed that
the broth had become cloudy and a single drop contained numerous microscopic
creatures. He argued that the new microbes must have arisen spontaneously. In reality,
however, he likely did not boil the broth enough to kill all preexisting microbes.
Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions,

however, and performed hundreds of carefully executed experiments using heated
broth. As in Needham’s experiment, broth in sealed jars and unsealed jars was infused
with plant and animal matter. Spallanzani’s results contradicted the findings of
Needham: Heated but sealed flasks remained clear, without any signs of spontaneous
growth, unless the flasks were subsequently opened to the air. This suggested that
microbes were introduced into these flasks from the air. In response to Spallanzani’s
findings, Needham argued that life originates from a “life force” that was destroyed during
Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new
life force from entering and causing spontaneous generation (Figure 2).
Figure 2. (a) Francesco Redi, who demonstrated that maggots were the offspring of flies,
not products of spontaneous generation. (b) John Needham, who argued that microbes
arose spontaneously in broth from a “life force.” (c) Lazzaro Spallanzani, whose
experiments with broth aimed to disprove those of Needham.
The debate over spontaneous generation continued well into the nineteenth century,
with scientists serving as proponents of both sides. To settle the debate, the Paris Academy
of Sciences offered a prize for resolution of the problem. Louis Pasteur, a prominent French
chemist who had been studying microbial fermentation and the causes of wine spoilage,
accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon
microscopic examination of the cotton, found it full of microorganisms, suggesting that the
exposure of a broth to air was not introducing a “life force” to the broth but rather airborne
microorganisms.
Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks),
in which he boiled broth to sterilize it (Figure 3). His design allowed air inside the flasks to
be exchanged with air from the outside, but prevented the introduction of any airborne
microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life
force besides the airborne microorganisms were responsible for microbial growth within the
sterilized flasks, it would have access to the broth, whereas the microorganisms would not.
He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as
long as the swan necks remained intact. However, should the necks be broken,
microorganisms would be introduced, contaminating the flasks and allowing microbial
growth within the broth.
Pasteur’s set of experiments irrefutably disproved the theory of spontaneous
generation and earned him the prestigious Alhumbert Prize from the Paris Academy of
Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “Omne vivum ex vivo”
(“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask
experiment, stating that “life is a germ and a germ is life. Never will the doctrine of
spontaneous generation recover from the mortal blow of this simple experiment.
To Pasteur’s credit, it never has. See the details of his experiment below:
Figure 3. (a) French scientist Louis Pasteur, who definitively refuted the long-disputed
theory of spontaneous generation. (b) The unique swan-neck feature of the flasks used in
Pasteur’s experiment allowed air to enter the flask but prevented the entry of bacterial and
fungal spores. (c) Pasteur’s experiment consisted of two parts. In the first part, the broth in
the flask was boiled to sterilize it. When this broth was cooled, it remained free of
contamination. In the second part of the experiment, the flask was boiled and then the neck
was broken off. The broth in this flask became contaminated. Wikimedia Commons
Guide Questions:
1. In 1864, Pasteur articulated this phrase in his lecture: “Omne vivum

ex vivo” which means life comes from life. What does “life comes from
life” mean?
2. Which tenet/ s of the Cell Theory disproved Spontaneous Generation?
3. Can you explain how Redi's experiment disproves the theory of

spontaneous generation?
4. How important is conducting scientific investigations and working

with data in supporting or refuting claims?
Rubrics for Scoring
Written Answer Rubric

Category 4 Points 3 Points 2 Points 1 Points
Basic Applies correct Shows clear Able to state Lacks
Concepts and scientific comprehension basic scientific understanding
Principles concepts and of scientific concepts and of basic
principles concepts and principles concepts and
principles principles
Clarity and Ideas are Sequencing of Sentence Sentence
Coherence logically ideas are quite structure structure is
presented. logical. Words and/or word not evident.
Sentences are are chosen to choice interfere Sequencing of
structured and communicate with clarity. ideas make
words are clearly. Needs to reading and
chosen to improve understanding
communicate sequencing of difficult.
ideas clearly. ideas.
Comic Strip Rubrics

CATEGORY 10 Points 9-8 Points 7-6 Points 5 Points Needs
Excellent Good Satisfactory Improvement
Required Comic Strip Comic Strip Comic Strip One or more
Elements includes all includes all includes all required
required required required elements is
elements as well elements and elements. missing from the
as a few one additional comic strip.
additional element.
elements.
Content - All facts in the 99-90% of the 89-80% of the Fewer than 80%
Accuracy comic are facts in the facts in the of the facts in
conceptually comic are comic are the comic are
accurate. conceptually conceptually conceptually
accurate. accurate. accurate.
Clarity/ Comic Strip is Comic Strip is Comic Strip is Organization of
Neatness/ easy to read and easy to read and somewhat easy material is
Organization all elements are most elements to read and confusing to the
clearly written are clearly some elements reader. Comic
and drawn. All written and are clearly Strip is hard to
information is drawn. Most written and read and few
organized information is drawn. Some elements are
appropriately. organized information is clearly written
appropriately. organized and drawn.
appropriately.

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General Biology 1 Quarter 1 Week 1

THE CELL THEORY

Learning Competency: Explain the postulates of the Cell Theory

Anton Van Leeuwenhoek, a Dutch shopkeeper, discovered the microscope in

These observations made by Hooke, Leeuwenhoek, Schleiden, Schwann,

THE THREE POSTULATES OF THE CELL THEORY

1. The cell is the basic unit of life.

2. All living things are made up of one or more cells.

3. All cells come from pre-existing cells (omni cellulae e cellula).

In the mid-1800s, the long-standing myth which claims the "spontaneous

Hence, the most important characteristic of a cell is that it can reproduce by

Activity 1. Going Back in Time

1590 1665 1674

Zacharias made the first compound

1831 1838/ 1839 1858

How did the invention of the

Activity 2. Find My Match!

Activity 3. Guess that Picture!

Activity 4. Cell Comics

• All known living things are made up of one or more cells.

The statements below are serious misconceptions or alternative conceptions

What I Need to Remember

• The postulates of the original Cell Theory are the following:

The Spontaneous Generation Theory

Figure 1. Francesco Redi’s experimental setup consisted of an open container, a

Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions,

1. In 1864, Pasteur articulated this phrase in his lecture: “Omne vivum

2. Which tenet/ s of the Cell Theory disproved Spontaneous Generation?

3. Can you explain how Redi's experiment disproves the theory of

4. How important is conducting scientific investigations and working

Written Answer Rubric

Comic Strip Rubrics

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