Discover how Intricate the Cell's Machinery

1. CELL STRUCTURES AND
FUNCTIONS
Jayson I. Gula
Faculty, Hua Siong College of iloilo

2. Fundamental Parts of a Cell
Plasma membrane
Regulates the passage of
materials into and out of the
cell.
Cytoplasm
Central Genetic Region
A gel-like structure making-up
the cell’s internal environment.
Region containing the genetic material in
the form of DNA that provides instructions
to make proteins, regulate activities, and
enables cells to reproduce its kind.

3. Prokaryotic cells Eukaryotic cells
Bacteria
Archaea
Protist
Fungi
Plant
Animal

4. Differences between Prokaryotic and
Eukaryotic
Prokaryotic
pro (before), karyon (nut)
Eukaryotic
eu (true), karyon (nut)

5. Differences between Prokaryotic
and Eukaryotic

6. Differences between Prokaryotic
and Eukaryotic
• Eukaryotic cells are
generally much larger
than prokaryotic cells.
– smallest bacteria –
mycoplasmas (0.1µm –
1.0µm)
– Eukaryotic cells are typically
10-100 µm in diameter.

9. The Cell’s Intricate
Machinery
1. Protection
2. Genetic Control
3. Manufacturing, Storage, Distribution and
Breakdown
4. Energy-Processing
5. Structural Support, Movement, and
Communication Between Cells

10. Cell Structure for Protection
• Plasma Membrane
– a thin barrier that forms a
boundary separating an
individual cell from
external environment.
– acts as a gatekeeper
– consists of double layer
of phospholipids

11. Cell Structure for Protection
• Plasma Membrane
– Each phospholipid is composed of
• Charged phosphate group
• Glycerol
• Two fatty acid chains
– Polar Head (hydrophilic), Non-polar Tail
(hydrophobic)

12. Cell Structure for Protection
• Plasma Membrane
– Cholesterol – molecules
help strengthen the cell
membrane making it
more flexible but less
fluid, making permeable
to water soluble
substances such as ions
or simple sugars.

13. Cell Structure for Protection
• Plasma Membrane
– Membrane proteins
• Transport proteins
• Channel proteins
• Cell recognition proteins
• Enzymatic proteins
• Cytoskeleton proteins
• Junction proteins
• Receptor proteins

14. Cell Structure for Protection
• Plasma Membrane
– Carbohydrates – attached
to membrane proteins
that serve as
identification tags,
enabling cells to
distinguish one type of
cell from one another.

15. Cell Structure for Protection
• Cell Wall of Plants
– The wall protects the
plant cell, maintains its
shape, and prevents
excessive uptake of
water.
– Prokaryotes, some
protists and fungi have
cell walls as well.

16. Cell Structure for Protection
• Cell Wall of Plants
– Plants and algae –
polysaccharide cellulose.
– Fungi – chitin
– Bacteria – peptidoglycan

17. Cell Structure for Protection
• Cytoplasm
– Fills the space between the
nucleus and the cell
membrane.
– Cytosol – fluid portion
consisting mainly of water
excluding organelles in it.

18. Cell Structure for Protection
•Plasma Membrane
•Cell Wall
•Cytoplasm

19. Genetic Control Organelles
• Nucleus
– contains most of the genes in
the eukaryotic cell.
– DNA – Deoxyribonucleic
acid.
– The nuclear envelope
encloses the nucleus
separating its contents from
the cytoplasm.

20. Genetic Control Organelles
• Nucleus
– Nuclear Pore - regulates
the entry and exit of most
proteins and RNAs, as
well as large complexes
of macromolecules.

21. Genetic Control Organelles
• Nucleus
– Within the nucleus, the DNA
is organized into discrete units
called chromosomes,
structures that carry the
genetic information.
– Each chromosome is made up
of a material called
chromatin, a complex of
proteins and DNA.

22. Genetic Control Organelles
• Nucleus
– Nucleolus – dense region
where ribosomes, a small
organelles essential for
making proteins are
assembled.

23. Endomembrane System
• synthesis of proteins and
their transport into
membranes and organelles
or out of the cell,
metabolism and
movement of lipids, and
detoxification of poisons.

24. Endomembrane System
• The Endoplasmic Reticulum:
Biosynthetic Factory
– Smooth ER
– Rough ER
• an extensive network of
membranes that it accounts for
more than half the total membrane
in many eukaryotic cells.
• Endoplasmic – (within the
cytoplasm), reticulum – (little net)

25. Endomembrane System
• The Endoplasmic Reticulum:
Biosynthetic Factory
– The ER consists of a network of
membranous tubules and sacs
called cisternae.
– ER lumen (cavity) or
cisternal space - internal
compartment of the ER.
• Production of lipids and
proteins.

26. Endomembrane System
• The Endoplasmic
Reticulum: Biosynthetic
Factory
– proteins enter the lumen where
it is modified further with
addition of sugars chains
adding to stability.
– Proteins made in ER is secreted
to the areas where body needs
them.

27. Endomembrane System
• The Endoplasmic Reticulum:
Biosynthetic Factory
– Smooth Endoplasmic
Reticulum – lack of
ribosomes.
– Rough Endoplasmic
Reticulum - has ribosomes
on the outer surface of the
membrane.

28. Endomembrane System
• The Endoplasmic Reticulum:
Biosynthetic Factory
– Functions of Smooth
Endoplasmic Reticulum –
synthesis of lipids,
metabolism of
carbohydrates, and
detoxification of drugs,
alcohols and poisons.

29. Endomembrane System
• The Endoplasmic
Reticulum: Biosynthetic
Factory
– Functions of Rough
Endoplasmic Reticulum –
Many types of cells secrete
proteins produced by
ribosomes attached to
rough ER.

30. Endomembrane System
• Vesicles
– cellular organelles that are
composed of a lipid bilayer
used to transport materials from
one place to another.
– Categorized as; storage
vesicles, transport vesicles, or
secretory vesicles.

31. Endomembrane System
• Golgi Apparatus
– layered stacks of membrane –
enclosed spaces where proteins
from ER are processed, sorted,
and delivered.
– Presence of enzymes modify
the proteins from ER.

32. Vacuoles
• fluid-filled sac for the
storage of materials
needed by the cell, which
includes water, food
molecules, inorganic ions
and enzymes.

33. Lysosomes
• Round-shaped, membrane-
bound structures
containing chemicals that
can break down materials
in the cell.
– Lyzozyme – enzymes that
can defend the cell from
invading bacteria and
viruses.

34. Phagocytosis

35. Peroxisomes
• Surrounded by single
membrane containing
digestive enzymes for
breaking down toxic
materials.
• They carry enzyme that
require oxygen (oxidative
enzymes)
• They also help in breaking
down alcohols.

37. Energy-Processing Organelles
Mitochondria - sites of
cellular respiration, the
metabolic process that
generates ATP by
extracting energy from
sugars, fats, and other
fuels with the help of
oxygen.

38. Plastids (Chloroplast)
• contain the green
pigment chlorophyll,
along with enzymes and
other molecules that
function in the
photosynthetic
production of sugar.

39. Organelles for Structural Support, Movement, and
Communication Between Cells
• In animal cells, microtubules
grow out from a centrosome, a
region that is often located near
the nucleus and is considered a
“microtubule-organizing center.”
• Within the centrosome are a pair
of centrioles, each composed of
nine sets of triplet microtubules
arranged in a ring.

40. Organelles for Structural Support, Movement, and
Communication Between Cells
Cilia and Flagella
– Two locomotory projections in
eukaryotes.
– They allow the cell to move like an oar
or a whip.
– Cilia look like little hairs with much
shorter length.
– Flagella look like a whip or tail.
– For cells anchored in tissue, ciliary
motion sweeps liquid across the cell.

41. Organelles for Structural Support, Movement, and
Communication Between Cells
• Cytoskeleton
– Made up of a small
protein subunit forming
long threads or fibers that
can crisscross the entire
cell, thus providing
sturdy mechanical
support.

42. Types of Cytoskeleton
• Microtubules
– Long and thickest filaments.
– Stiff, hollow tubes that give the cell
shape and serve as anchorage for the
membrane-bound organelles and other
cell parts.
– Tracks for the movements of vesicles
and other cell components.
– Microtublues form spindle fibers that
pull half of DNA into a new cell.
– Form permanent structures such as
flagellum that propels the sperm
towards the egg.

43. Types of Cytoskeleton
• Intermediate filaments
– smaller than microtubules and rope-
like in appearance.
– give the cell tensile strength and
ability to stretch without breaking
apart.
– Prominently present in the skin
cells and other body sites subject to
mechanical stress.
– Important in ensuring the strength
of claws, hairs, and feathers of
animals.

44. Types of Cytoskeleton
• Microfilaments
– Thinnest among cytoskeletons and
are also known as actin filaments.
– Tiny flexible filaments that provide
protective meshwork found
underside of the plasma membrane.
– Important particularly to cell
movement as they allow muscles to
contract and relax.

45. Plasmodesmata
• Cytoplasmic strands passing
through openings in some
plant cell walls and forming
connections with adjacent
cells.
• Play an important role in
sharing of water, nutrients
and chemical messages
among plants.