UPDATED LESSON 1 GENERAL BIOLOGY 1 STEM

1. GENERAL BIOLOGY 1
SENIOR HIGH SCHOOL – STEM

2. LESSON 1: THE CELL

3. 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; and
• determine the role of each cellular organelle and explain
how it relates to the functions of other organelles.

4. THINK & SHARE
WHAT MAKES SOMETHING ALIVE?
LIST 2–3 CHARACTERISTICS

5. NASAL SINUS CELL

6. ONION CELL

7. HUMAN CHEEK CELL

8. VIBRIO TASMANIENSIS BACTERIAL
CELL

10. INTRODUCTION
Cells are the
fundamental building
blocks of life, enabling
various activities like
studying, playing, and
traveling.
Your body consists of
countless cells of diverse
shapes and sizes, each
organized and
equipped with
specialized parts for
specific tasks.

11. INTRODUCTION
• The concept of cells was unknown
to scientists until the invention of
the microscope in the 16th
century, which unlocked our
understanding of their existence
and functions.

13. THE EARLY MICROSCOPE
• The microscope's invention enabled
the finding of cells. Initially, lenses
were used in late 1500s Europe by
merchants to assess cloth quality
based on thread and weave precision.
• These lenses formed the foundation
for assembling more complex
combinations of lenses.

14. THE EARLY MICROSCOPE
• Dutch spectacle-maker Zacharias
Janssen invented the primitive
microscope with the help of his
father Hans Janssen.
• This microscope would later be used
by Marcello Malpighi and Robert
Hooke

15. DISCOVERY OF CELLS
• In 1665, English physicist Robert
Hooke used of the first light
microscopes to look at cork.

16. DISCOVERY OF CELLS
• Under the microscope, cork seemed to
be made of thousands of tiny chambers.
• Hooke called these chambers “cells”
because they reminded him of a
monastery’s tiny rooms, which were also
known as cells.

17. DISCOVERY OF CELLS
• In 1674, Dutch businessman Anton Van
Leeuwenhoek became one of the first
person to use a microscope to study nature.
• Using only a single powerful lens, Van
Leeuwenhoek crafted instruments that
could produce magnified images of very
small objects.
• He was the first person to see tiny living
organisms in a drop of water.

25. • The postulates of cell theory served
to be the strong foundation of cells
as the basic unit of life that
undergo several biological
processes like cell divisions and
cellular processes.

26. DEVELOPMENT
OF CELL THEORY
• In 1837, while having a meal with
his friend, a zoologist named
Theodore Schwann, Matthias
Schleiden announced that the plants
organized into cells having
independent processes.
• Likewise, Schwann also reported that
he had also seen the same
observations in the animal cells.

27. DEVELOPMENT OF CELL
THEORY
• In 1855, Rudolph Virchow, a German
Physician, discovered that cells came
from pre-existing cells after he worked
on how diseases affect living organisms.

28. POSTULATES OF CELL THEORY
ALL LIVING THINGS ARE MADE
UP OF ONE OR MORE CELLS.
CELL IS THE BASIC UNIT OF LIFE. ALL CELLS COME FROM PRE-
EXISTING CELLS

29. MODERN CELL THEORY
• 1900s onward: modern cell theory expands
• With advances in biochemistry, genetics, and electron
microscopy, the cell theory evolved:
• Discovery of organelles (nucleus, mitochondria, ER) and cell
membranes.
• Understanding of dna as the hereditary material (watson & crick,
1953).
• Realization that cells are biochemically similar, regardless of organism.

30. MODERN CELL THEORY
 All living organisms are made of one or more cells.
 The cell is the basic unit of life.
 All cells arise from pre-existing cells.
 Cells contain hereditary information (DNA) passed
from cell to cell.
 All cells have similar biochemical composition and
metabolic processes.

31. CELL STRUCTURES & FUNCTIONS

32. GROUP
ACTIVITY
Paper
• On a sheet of colored cartolina, clearly draw and
label the assigned organelle’s key features (e.g.,
membranes, internal structures).
Write
• Beneath or beside the drawing write its name, a
concise 1–2 sentence description, 2–3 bullet points
of its primary functions, and a brief note on how it
interacts with or depends on another organelle.
Prepare
• Prepare to present your poster in class in 3–5
minutes by pointing out the structure, summarizing its
function, and explaining its role in the cell’s overall
workings.

33. GROUP ACTIVITY
PLASMA
MEMBRANE
NUCLEUS CYTOPLASM
ENDOPLASMIC
RETICULUM
RIBOSOMES
VACUOLES
GOLGI
APPARATUS
LYSOSOMES &
PEROXISOMES
VESICLES
CENTROSOME /
CENTRIOLES
MITOCHONDRIA CHLOROPLAST
CELL WALL

34. Criteria Excellent (3) Satisfactory (2) Needs Improvement (1)
Diagram & Labeling
Drawing clearly shows key
structural features; all labels
are accurate, legible, and
correctly placed.
Drawing shows most main
features with generally
correct labels; minor
omissions or slight labeling
issues.
Drawing is missing or
inaccurate for key features;
labels unclear, incorrect, or
missing.
Description & Functions
Description (1–2 sentences) is
concise and fully accurate;
2–3 primary functions are
clearly stated and precise.
Description is mostly
accurate but may be vague
or omit a detail; functions
listed but may lack full
clarity.
Description vague or
incorrect; primary functions
missing or inaccurate.
Interaction/Context Note
Provides a clear, relevant
link to another organelle or
overall cell process, showing
understanding of
interdependence.
Mentions a connection but
with limited detail or minor
imprecision about how
organelles interact.
No interaction/context noted
or the stated linkage is
incorrect or unclear.
Presentation Delivery
Speaks clearly, stays within
3–5 minutes, uses poster
effectively (points, gestures),
and engages audience (eye
contact, pace).
Speech generally clear but
may slightly exceed or fall
short of time; refers to
poster but with limited
engagement.
Speech unclear or too
brief/long; reads without
context; minimal use of
poster or engagement.

35. THREE MAJOR PARTS OF 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.

36. PLASMA MEMBRANE
• It encloses and safeguards its
organelles from possible harm
that foreign materials can inflict
on them.

37. PLASMA MEMBRANE
• It also controls the exchange
of essential components and
obtains chemical messages
from other cells.

38. PLASMA MEMBRANE: FLUID MOSAIC
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.

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

41. CYTOPLASM
• In the cytoplasm, the organelles are
suspended in a gel-like solution called
cytosol, which is composed of both
organic and inorganic compounds.
• It contains a rich supply of
macromolecules and smaller organic
molecules.

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

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

44. 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 that carry
tightly wrapped and coined DNA.

45. THE CELL ORGANELLES: ENDOMEMBRANE
SYSTEM
• The endomembrane system is a group
of membranes and organelles in
eukaryotic cells that works together to
modify, package, and transport lipids
and proteins.

46. THE CELL ORGANELLES: ENDOMEMBRANE
SYSTEM
• This system is made up of organelles that are communally linked by
a structure specific to each of them, these organelles are:
1. Endoplasmic reticulum 5. Lysosomes
2. Ribosomes 6. Peroxisomes
3. Vacuoles
4. Golgi apparatus

47. ENDOPLASMIC RETICULUM

48. 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 perform in separate areas of ER; the rough
endoplasmic reticulum and smooth endoplasmic reticulum.

49. ROUGH
ENDOPLASMIC
RETICULUM
• It has ribosomes on its surface.
• It makes membrane proteins and proteins
for export out of the 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

50. SMOOTH
ENDOPLASMIC
RETICULUM
• 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 cells, where it
detoxifies hydrophobic chemicals. This
makes them water-soluble for excretion.

51. RIBOSOMES

52. RIBOSOMES
• Ribosomes are involved in providing a frame for protein synthesis;
hence they are the 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.

53. VACUOLES

54. VACUOLES
• A vacuole is a fluid – filled vesicle enclosed by a membrane.
• It has a selective membrane freely allowing water passage but
retaining smaller molecules within it and stores chemicals within the cell.
• Vacuole's ability to break down large molecules makes it comparable
with lysosomes in animal cells. Likewise, both organelles thrive in acidic
environments.

55. LYSOSOMES

56. 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 meets, in order to recycle with the
raw material

57. LYSOSOMES
• It is dubbed as the cell’s “suicide bags”
• These organelles are capable of 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.

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

59. MICROBODIES - PEROXISOME

60. PEROXISOME
• It is a small, round organelle enclosed by a single membrane,
somehow resembling that of a Lysosomes.
• It is responsible for self-damage and mostly disintegrate proteins,
accommodates the breakdown of fatty acids, and detoxifies
many poisons that enter the body.
• It also shields the cell from serious damage caused by reactive
oxygen species (ROS) molecules

61. GOLGI APPARATUS

62. GOLGI APPARATUS
•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

63. GOLGI APPARATUS
• Modify, sort, & package molecules from er
for storage or transport out of a cell.

64. CENTROSOME

65. CENTROSOME
• It is found in all eukaryotic cells (animal cell), and assists 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 cytoskeleton.
• In this way, the cellular shape is maintained, and the cell
structure is stabilized.

66. MITOCHONDRIA

67. 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.

68. MITOCHONDRIA
• The mitochondria are oval-shaped
organelles found in most eukaryotic cells.
They are the ‘powerhouses’ of the cell.

69. MITOCHONDRIA
• Mitochondria are most plentiful in cells
that require significant amounts of energy
to function, such as liver and muscle cells.

70. PLASTIDS
• Plastids are large, membrane-bound organelles that contain
pigments. Based on the type of pigments, plastids are of
three types:
a. Chloroplast
b. Chromoplast
c. Leucoplast

71. CHLOROPLAST

72. 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.

73. CHROMOPLAST & LEUCOPLAST
• Chromoplasts – the chromoplasts include fat-soluble, carotenoid
pigments like xanthophylls, carotene, etc. Which provide the plants
with their characteristic color – yellow, orange, red, etc.
• Leucoplasts – leucoplasts are colorless plastids that store nutrients.
Amyloplasts store carbohydrates (like starch in potatoes),
aleuroplasts store proteins, and elaioplasts store oils and fats.