Cells are the basic unit of structure and function in human bodies. They contain specialized structures called organelles that perform specific functions. The cell membrane controls what enters and exits the cell. Movement across the membrane occurs through diffusion, osmosis, and active/passive transport. The nucleus houses DNA and controls cell activities. Other organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and ribosomes help synthesize proteins and carry out metabolic functions. Cells reproduce through mitosis and differentiate during development. Aging and death are normal cellular processes.

1. CELL
STRUCTURE AND
FUNCTIONS

2. CELL STRUCTURE
CELLS
• Determine the form and functions
of the human body.
• Basic living unit of all organisms.
• Are complex living structures.
• Are specialized to perform
specific functions.

3. CELL STRUCTURE
ORGANELLES
- Specialized structures
within cells.
- Perform specific
functions.

4. CELL MEMBRANE CYTOPLASM
NUCLEAR
ENVELOPE
NUCLEOLUS
NUCLEUS
LYSOSOME
PHAGOCYTIC
VESICLE
CENTROSOME
CENTRIOLES
PEROXISOME
MICROTUBULE
MICROVILICILIA
SECRETORY VESICLE
GOLGI
APPARATUS
SMOOTH
ENDOPLASMIC
RETICULUM
ROUGH
ENDOPLASMIC
RETICULUM
RIBOSOME
MITOCHONDRION

5. CELL STRUCTURE
CELL MEMBRANE
- selectively permeable to ions and organic molecules and
controls the movement of substances in and out of cells.
CYTOPLASM
- The living material surrounding the nucleus.
NUCLEUS
- Contains genetic material of cell (DNA) and nucleoli; site
of RNA synthesis and ribosomal subunit assembly.
LYSOSOME
- Contains enzymes that digest material taken into the cell.

6. CELL STRUCTURE
PHAGOCYTIC VESICLE
- Contains materials produced outside the cell; secreted
by endocytosis.
CENTRIOLES
- Facilitate the movement of the chromosomes during cell
division.
MICROTUBULE
- Supports cytoplasm; assists in cell division and forms
components of cilia and flagella.
MICROVILLI
- Increase surface area of certain cells.

7. CELL STRUCTURE
CILIA
- Move substances over surfaces of the certain cells.
SECRETORY VESICLES
- Contains materials produced in the cell; formed by the
Golgi apparatus; secreted by exocytosis.
GOLGI APPARATUS
- Modifies protein structure and packages protein in
secretory vesicles.
SMOOTH ENDOPLASMIC RETICULUM
(SER)
- Site of lipid synthesis; participates in detoxification.

8. CELL STRUCTURE
ROUGH ENDOPLASMIC RETICULUM
(ROR)
- Has many ribosomes attached; site of the protein
synthesis.
RIBOSOME
- Site of protein synthesis
MITOCHONDRION
- Site of aerobic respiration and the major site of ATP
synthesis.

9. CELL FUNCTIONS
1. Cell metabolism and energy use.
2. Synthesis of molecules.
3. Communication.
4. Reproduction and inheritance.

10. CELL MEMBRANE
- Is the outermost component of the
cell.
- Made up of phospholipids and
proteins.
EXTRACELLULAR Substances
- Substances outside the cell.
INTRACELLULAR Substances
- Substances inside the cell.
FLUID-MOSAIC MODEL

11. CELL MEMBRANE

12. MOVEMENT THROUGH THE
CELL MEMBRANE
DIFFUSION
Movement of ions or molecules from higher
concentration to lower concentration of that same
solute in solution.
CONCENTRATION GRADIENT
- Difference in the concentration of a solute in a
solvent between two points divided by the
distance between the two points.

13. MOVEMENT THROUGH THE
CELL MEMBRANE

14. MOVEMENT THROUGH THE
CELL MEMBRANE
CELL MEMBRANE CHANNELS
- Consist of large protein molecules that extend
one surface of cell membranes to the other.
1. Leak Channels- constantly allow ions to
pass through.
2. Gated Channels- limit the movement of
ions across the membrane by opening and closing.

15. MOVEMENT THROUGH THE
CELL MEMBRANE

16. MOVEMENT THROUGH THE
CELL MEMBRANE
OSMOSIS
- Is the diffusion of water across a selectively
permeable membrane.
- From higher water concentration to one of lower
water concentration.
- Occurs when the cell membrane is less
permeable, selectively permeable or not
permeable to solutes and a concentration
gradient for water exists across the cell
membrane.

17. MOVEMENT THROUGH THE
CELL MEMBRANE
OSMOTIC PRESSURE
- Is the force required to prevent the movement of
water across a selectively permeable
membrane.
HYPOTONIC- Solution usually has a lower
concentration of solutes and higher concentration of water.
- Solution has less tone or osmotic pressure than cell.
- The cell will SWELL.
- The cell can rupture a process called Lysis.

18. MOVEMENT THROUGH THE
CELL MEMBRANE
ISOTONIC- the concentrations of various
solutes and water are the same on both sides of
the cell membrane.
- The cell will NEITHER SHINKS NOR SWELLS.
HYPERTONIC- A solution usually has a
higher concentration of solutes and a lower
concentration of water.
- Resulting in CELL SHRINKAGE or CRENATION.

19. MOVEMENT THROUGH THE
CELL MEMBRANE

20. MOVEMENT THROUGH THE
CELL MEMBRANE

21. MOVEMENT THROUGH THE
CELL MEMBRANE
CARRIER-MEDIATED
TRANSPORT MECHANISM
Facilitated Diffusion
Active Transport
Secondary Active Transport

22. MOVEMENT THROUGH THE
CELL MEMBRANE
FACILITATED
DIFFUSION
- Moves substances
across the cell
membrane from an
area oh higher
concentration to an
area of lower
concentration.
- ATP is NOT required.

23. MOVEMENT THROUGH THE
CELL MEMBRANE
SECONDARY
ACTIVE
TRANSPORT
- Involves active transport
of one substance such as
Na+ that establishes
concentration gradient.
COTRANSPORT- diffusing
substance moves in the
same direction as the
transported substance.
COUNTERTRANSPORT-
diffusing substance moves

24. MOVEMENT THROUGH THE
CELL MEMBRANE

25. MOVEMENT THROUGH THE
CELL MEMBRANE

26. MOVEMENT THROUGH THE
CELL MEMBRANE

27. MOVEMENT THROUGH THE
CELL MEMBRANE

28. MOVEMENT THROUGH THE
CELL MEMBRANE
ENDOCYTOSIS AND
EXOCYTOSIS
VESICLES- Membrane bound sacs.
ENDOCYTOSIS- uptake of material
through the cell membrane by the
formation of a vesicle.

29. MOVEMENT THROUGH THE
CELL MEMBRANE
RECEPTOR-
MEDIATED
ENDOCYTOSIS
- When specific
substance binds to the
receptor molecule and
the substance is
transported in the cell.

30. MOVEMENT THROUGH THE
CELL MEMBRANE

31. MOVEMENT THROUGH THE
CELL MEMBRANE
PHAGOCYTOSI
S
- A part of the cell
membrane that
extends around a
particle and fuses it
into the cell

32. MOVEMENT THROUGH THE
CELL MEMBRANE
PINOCYTOSIS
- Forms smaller
vesicles and contain
liquid rather than
particles.

33. MOVEMENT THROUGH THE
CELL MEMBRANE
SECRETORY
VESICLES
- Accumulate
materials for
release from the
cell.

34. MOVEMENT THROUGH THE
CELL MEMBRANE
EXOCYTOSIS
- Allows the
release of
materials from
the cells.

35. CELL ORGANELLES
NUCLEUS
- Large organelle that
is located near the
center of the cell.
NUCLEAR ENVELOPE
- Consist of outer and inner
membranes with space
between nucleus and nuclear
envelope.
NUCLEAR PORES
- Combination of inner and outer
membranes to which the
materials can pass in or out of the
Human cells contain
23 pairs of chromosomes.
CHROMATIN
- Chromosomes that are
loosely coiled.
NUCLEOLI
- Are diffuse bodies with no
surrounding membrane that
are found within the nucleus.
RIBOSOMAL
RIBONUCLEIC ACID
(rRNA)
- Proteins that are joined
together to form large and
small ribosomal subunits.

36. CELL ORGANELLES

37. CELL ORGANELLES

38. CELL ORGANELLES
RIBOSOMES
- Organelles where
proteins are
produces.
- Can be attached to
endoplasmic
reticulum.
- Ribosomes that are
not attached to any
organelle are called
free ribosomes.

39. CELL ORGANELLES

40. CELL ORGANELLES
ENDOPLASMIC
RETICULUM
- Is a series of membranes
forming sacs and tubules.
SMOOTH
ENDOPLASMIC
RETICULUM
- E.R without ribosomes.
- Site for lipid synthesis
and participates in
detoxification of
chemicals.
ROUGH
ENDOPLASMIC
RETICULUM
- E.R with ribosomes.
- Large amount of
Rough E.R indicates
that it is synthesizing
large amounts of
protein for export.

41. CELL ORGANELLES

42. CELL ORGANELLES
GOLGI
APPARATUS
- Consists of closely
packed stacks of
curved,
membrane-bound
sacs.
- It modifies,
packages and
distributes proteins
and lipids
SECRETORY
VESICLES
- Pinch off from the
golgi apparatus and
move to the cell
membrane.
VESICLE
- Is a small,
membrane-bound sac
that transports or
stores materials
within cells.

43. CELL ORGANELLES

44. CELL ORGANELLES
LYSOSOMES
- Are membrane-
bound vesicles
formed from the
golgi apparatus
- Contains variety of
enzymes that
function as
intracellular
digestive system.
PEROXISOMES
-Are small, membrane-
bound vesicles
containing enzymes that
break down fatty acids,
amino acids and
hydrogen peroxide
(𝐻2 𝑂2)
- Hydrogen peroxide is a by-
product of fatty acid and
amino acid breakdown and
can toxic to a cell.

45. CELL ORGANELLES

46. CELL ORGANELLES
MITOCHONDRIA
- Are small organelles
with inner and outer
membranes
separated by a space.
- Outer membranes
have a smooth
contour but the inner
membranes have
numerous folds called
cristae.
- Are the major sites of
adenosine
triphosphate (ATP)
production within
cells.
- Carry out aerobic
respiration, a series of
chemical reactions
that require 𝑂2 to
break down food
molecules to produce

47. CELL ORGANELLES

48. CELL ORGANELLES
CYTOSKELETON
- Consists of proteins that support the cell,
hold organelles in place and enable the cell
to change shape.
- These protein structures are:
Microtubules
Microfilaments
Intermediate filaments

49. CELL ORGANELLES
Microtubules
- Are hollow structures formed from protein
subunits.
FUNCTIONS:
1. Helps to support the cytoplasm of cells.
2. Assisting in cell division.
3. Forming essential components of certain
organelles such as cilia and flagella.

50. CELL ORGANELLES
Microtubules

51. CELL ORGANELLES
Microfilaments
- Are small fibrils from protein subunits that
structurally support the cytoplasm.
FUNCTIONS:
1. Some microfilaments are involved with cell
movement.

52. CELL ORGANELLES
Microfilaments

53. CELL ORGANELLES
Intermediate
Filaments
- Are fibrils formed from protein subunits that
are smaller in diameter than microtubules
but larger in diameter than microfilaments.
FUNCTIONS:
1. Provide mechanical support to the cell.

54. CELL ORGANELLES
Intermediate
Filaments

55. CELL ORGANELLES
CYTOSKELETON

56. CELL ORGANELLES
CENTRIOLES
CENTROSOME
-Is a specialized zone of cytoplasm close to the nuecleus
which microtubule formation occurs.
- It contains two centrioles which are normally oriented
perpendicular to each other.
CENTRIOLE
- Is small, cylindrical organelle composed of nine triplets;
each triplet consists of three parallel microtubules joined

57. CELL ORGANELLES
CENTRIOLES

58. CELL ORGANELLES
CILIA
- Project from the surface of
cells.
- Cylindrical structures that
extend from the cell.
- Composed of microtubules
which are enclosed by the
cell membrane.
- Numerous on the surface
cells that line the respiratory
tract.
- Their movement transport
mucus in which dust
particles are embedded,
upward and away from the
FLAGELLA
- Occur only one per cell.
MICROVILLI
- Specialized extensions of
the cell membrane that
are supported by
microfilaments.
- Abundant on the surface
of cells in which
absorption is an important
function.

59. CELL ORGANELLES

60. CELL ACTIVITY
GENE EXPRESSION
- DNA contains the information that directs protein synthesis.
- DNA also influences the structural and functional characteristics
of the entire organism.
- DNA molecule is consist of nucleotides joined together to form
two nucleotide strands.
- NUCLEOTIDES function as chemical “letters” that form chemical
“words”.
GENE
- Is a sequence of nucleotides that provides a chemical set of
instructions for making a specific protein.

61. CELL ACTIVITY
GENE EXPRESSION
Involves two steps:
1. Transcription
- the cell makes a copy of the gene
necessary to make a particular protein.
2. Translation
- converting the copied information
into a protein.

62. CELL ACTIVITY
GENE EXPRESSION

63. CELL ACTIVITY
FORMATION OF mRNA by
TRANSCRIPTION OF DNA

64. CELL ACTIVITY
TRANSLATION
OF mRNA TO
PRODUCE A
PROTEIN

65. CELL ACTIVITY
CELL LIFE CYCLE
Includes two major phases:
1. Non-dividing phase called
INTERPHASE
2. CELL DIVISION

66. CELL ACTIVITY
INTERPHASE
- The DNA is replicated; two strands of
DNA separate from each other and
each other serves as a template for the
production of a new strand of DNA
- At the end of interphase, a cell has two
complete sets of genetic material

67. CELL ACTIVITY
INTERPHASE

68. CELL ACTIVITY
INTERPHASE

69. CELL ACTIVITY
CELL DIVISION
- Is the formation of daughter cells from
a single parent cell.
- Growth and tissue repair are formed
through MITOSIS.
- Sex cells undergo MEIOSIS necessary
for reproduction.

70. CELL ACTIVITY
CELL DIVISION
- Body cells contains 46 chromosomes .
- Sex cells have half number of
chromosomes.
DIPLOID NUMBER
- Pertains to 46 chromosomes.
HAPLOID NUMBER
-Pertains to 23 chromosomes.

71. CELL ACTIVITY
MITOSIS
- A parent cells divides to form two
daughter cells with the same amount
and type of DNA as the parent cells.
- Is divided into four stages: Prophase,
Metaphase, Anaphase, and Telophase.

72. CELL ACTIVITY
MITOSIS
STEPS EVENTS
1.Prophase Chromatic condenses to form visible
chromosomes.
The centrioles divided and migrate to each
pole of the cells.
2.Metaphase Chromosomes align near the center of the
cells.
3.Anaphase Chromatids separate. Two sets of 46
chromosomes move to the opposite cells.
4.Telophase The chromosomes in each of the daughter
cells become organized to form two separate
nuclei.

73. CELL ACTIVITY
DIFFERENTIATION
- Process by which cells develop with
specialized structures and functions.
- Some portion of DNA are active, but
others are inactive.
- Results from the selective activation
and inactivation of segments of DNA.

74. CELL ACTIVITY
DIFFERENTIATION

75. CELL ACTIVITY
APOPTOSIS
- Programmed cell death
- Normal process by which cell numbers
within various tissues are adjusted and
controlled.
- Eliminates excess cells to maintain constant
numbers of cells within the tissue.
- Damaged or potential dangerous cells,
virus-infected cells and potential cancer

76. CELL ACTIVITY
CELLULAR ASPECTS OF
AGING
1. Cellular clock – after a certain passage of
time or a certain number of cell division,
results in the death of a given cell line.
2. Death Genes – Turn late in life or
sometimes prematurely, causing cells to
deteriorate and die.
3. DNA damage – Resulting in cell
degeneration and death.

77. CELL ACTIVITY
CELLULAR ASPECTS OF
AGING
4. Free radicals – DNA is also susceptible to
direct damage, resulting in mutations. Free
radicals are atoms and molecules with an
unpaired electron.
5. Mitochondrial damage – May results in loss
of proteins critical to mitochondrial functions.

78. “A cell is regarded as the true
biological atom?
- George Lewes