Cellular structure

1. CELLS & TISSUE
DEPARTMENT OF MEDICAL LABORATORY TECHNOLOGY
NATIONAL SKILLS UNIVERSITY, ISLAMABAD, PAKISTAN
MLT 101: HUMAN ANATOMY AND PHYSIOLOGY I

2. OBJECTIVE
At the end of the session the students will be able to:
 Define cell
 Describe structure and function of cell
 List the cell organelles
 Explain the process of cell division

3. CELL
 “Cell is the basic structural and functional unit of life”.
 A cell is the smallest and basic unit that is capable of
performing life functions.

4. INTRODUCTION
 Cells vary considerable in size, shape, and function.
 The shape of cells in the body vary based on their function.
 Humans contain about 100 trillion cells.
 Most plant and animal cells are between 1 and 100 µm and
therefore are visible only under the microscope.

5. CELL HISTORY
 The cell was discovered by Robert Hooke in 1665.
 The word cell comes from the Latin cella, meaning "small
room".
 The descriptive term for cell was used by Robert Hooke
when he observed the cork cells through microscope.
HISTORY

6. CELL THEORY
 The Cell Theory is one of the basic principles of biology. It
is formulated by a german scientists Theodor Schwann,
Matthias Schleiden, and Rudolph Virchow.
The Cell Theory states:
 All living organisms are composed of cells. They may be
unicellular or multicellular.
 The cell is the basic unit of life.
 Cells arise from pre-existing cells.

7. MODERN VERSION OF THE CELL THEORY
 The modern version of the Cell Theory includes the
ideas that:
 Energy flow occurs within cells.
 Heredity information (DNA) is passed on from cell to cell.
 All cells have the same basic chemical composition.

8. COMPOSITE CELL
Because cells vary so greatly in size, shape,
content, and function, describing a “typical” cell is
impossible.
All of the structures described in the composite
cell can NOT be found in every cell regardless of
function.
The organelles are found in the cytoplasm of the
cell.

9. CELL STRUCTURE
 A cell has three main parts (plasma
membrane ,cytoplasm, and nucleus).
 Inside which there are a number of
organelles floating in a watery fluid
called cytosol.
 Organelles are small structures with
highly specialized functions. cell
growth, maintanence and
reproduction)
 Many of which are membrane
bounded.

13. CELL ORGANELLES
1. Cell Membrane
2. Cytoplasm
3. Endoplasmic reticulum
(ER)
4. Ribosomes
5. Golgi Apparatus
6. Mitochondria
7. Lysosomes
8. Peroxisomes
9. Microfilaments and
Mircotubules
10. Centrosomes
11. Cilia and flagella
12. Vesicles
13. Nucleus
14. Nuclear envelope
15. Nucleolus
16. Chromatin

14. CELL MEMBRANE
 Extremely thin and semi permeable membrane forms the
Cell‘s Outer surface.
 The cell membrane contains many kinds of proteins, each
with a special function.

15. STRUCTURE:
 The basic framework of the cell membrane consists of a
(bilayer) double layer of phospholipid, with fatty acid tails
turned in.

16. PLASMA MEMBRANE
 Phospholipids molecules have a head which is electrically
charged and hydrophilic (water loving)
 And a tail which has no charge and hydrophobic (water
hating).
 The phospholipids bilayer is arranged like a sandwich with
the head and tail.
 Forming a central water repelling layer.

17. CELL MEMEBRANE
 The Phosphate Head is HYDROPHILIC meaning
"WATER LOVING". Because of its hydrophilic nature,
the head of a Phospholipid will orient itself so that it is as
close as possible to water molecules.
 The Lipid Tails are HYDROPHOBIC meaning "WATER-
FEARING", the Hydrophobic tails will tend to orient
themselves away from water.

19. FUNCTIONS OF PLASMA MEMBRANE
 The membrane allows some substances to enter and leave the
cell but not others (selective transport)
 participates in signal transduction,
 helps cells adhere to other cells.
 forms a boundary around the cellular contents
 Branched carbohydrate molecules attached to the some
membrane protein molecules give immunological identity to the
cell.
 It plays a key role in communication among cells and between
the cell.
 Can act as specific receptors for hormones and other chemical
messenger.

21. CYTOPLASM
 Gel-like mixture
 It consist of all the cellular content between the plasma
membrane and the nucleus.
 Has two components ,cytosol (intracellular fluid portion)
and organelles

22. CYTOPLASM
 Cell activities occur mainly in the cytoplasm, where
nutrients are received, processed, and used.

23. ENDOPLASMIC RETICULUM
 ER is a network of membrane in the
Form of flattened sac Or tubules.
 It is made up of membrane-bounded flatten sacs and elongated canals.

24. ENDOPLASMIC RETICULUM
Cell contain two Distinct form of ER.
 Rough ER:
Has ribosome on its outer layer and is attached to nuclear
envelope
It synthesizes glycoproteins and phospholipids that are
transferred to cellular organelles.
its function in the synthesis and transport of PROTEIN

25. SMOOTH ER
 No ribosomes.
 it function in the transport of LIPIDS
 Smooth ER synthesize fatty acids and steriods.
 inactivate drugs.
 store and release calcium ions in muscle cell.
 ER provides a tubular transport system inside the cell.

27. RIBOSOME
 Composed of two subunits containing ribosomal RNA and
proteins.
 May be free in cytosole or attached to rough ER.
 Function is protein synthesis.

28. RIBOSOMES
 Each cell contains thousands.
 Make proteins
 Found on ribosomes
& floating throughout
the cell

30. GOLGI APPARATUS
 Composed of about 3-20 flattened, membranous sacs (cistea).
 Cup like shape
 Stractually and functionally divided into entry face medial
sisternae,and exit face.
 Function is to refine, package, and deliver proteins synthesized
on ribosome.
 It forms Vesicles that have a role in secretion.
 Plays a central role in the transport of molecules.

31. GOLGI APPARATUS

32. GOLGI BODIES
 Protein 'packaging
plant'
 Move materials
within the cell
 Move materials out
of the cell

33. MITOCHONDRIA
 Is the POWERHOUSE of the cell.
 It contain enzymes that catalyze reactions that release
energy in the form of ATP from glucose.
 Adenosine Triphosphate (ATP) energy.

34. MITOCHONDRIA

35. MITOCHONDRIA
 Consist of outer and
inner mitrochondrial
membrane,cristae and
mitrix.
It is the power house
Of the cell.

36. MITOCHONDRIA
 Produces energy through chemical reactions
 Controls level of water and other materials in cell
 Recycles and decomposes proteins, fats, and carbohydrates

37. LYSOSOME
 Vesicle formed from
golgi complex.
Contain digestive
Enzymes.
Digestive 'plant‘
for proteins, fats,
and carbohydrates

38. LYSOSOMES
 The "garbage disposals of the cell“
 They contain powerful enzymes to break up old cell
components and bacteria. Example white blood cells can engulf
bacteria to fight bacterial infections.

39. LYSOSOME
 Transports undigested material to cell membrane for
removal
 Cell breaks down if lysosome explodes.

40. MICROFILAMENTS AND MICROTUBULES
 Thin, threadlike processes within the cytoplasm that
function in various kinds of cell movement and that serve as
the cytoskeleton of the cell.
 Microfilaments, made of the protein actin, cause various
cellular movements.
 Mictotubules, made of the globular protein tubulin.

42. CENTROSOME
 It is a structure made up of two hollow cylinders called
centrioles.
 Function in cell reproduction.

43. CILIAAND FLAGELLA
 They are motile extensions from the cell.
 Cilia is short and move “to-and-fro”.
 Cilia function is to move fluids.
 Flagella are longer and move in an undulating wavelike
motion.
 What is the only flagellated cell in the body? SPERM

44. VESICLES
 Or vacuoles are formed by part of the cell membrane.
 They contain some liquid or solid material formerly outside
the cell.
 Golgi and ER also form vesicles.

45. NUCLEUS
 It is an oval shaped organelle.
 Every cell in the body has a nucleus.
Except mature RBC.
 it is the largest
organelle.
 It has a tiny pores
through which some
substances can pass
between the nucleus and the
cytoplasm.

46. NUCLEUS, NUCLEAR ENVELOPE
 Is bounded by a double-layered nuclear membrane (nuclear
envelope) containing relatively large nuclear pores that
allow the passage of certain substances.

47. NUCLEOLUS
 Inside the nucleus are one or more spherical bodies called
nucleoli.
 Single is nucleolus.
 That function in producing ribosomes.
 Nucleoli are quit prominent in cell that synthesize large
amounts of protein.

49. CHROMOSOMES AND GENES
‘Chroma’ color ‘soma’ bodies
 Inside the nucleus the chromatin material condense to form
chromosome.
 Human cell contain 46 chromosome arrange in pair in the
nucleus of each cell.
 Each chromosome is a long molecule of DNA that is coil together
with several proteins. the complex of DNA,protein and some RNA
is called chromatin.
GENES:
 Gene is the segment of DNA
 each chromosome carries many genes
 The site on chromosome on which a particular gene is located is
called locus
 Genome all gene possessed by one individual.

50. NUCLEUS STRUCTURE AND
FUNCTIONS
 Each nucleus is simply a cluster of protein ,DNA,and RNA.
 Nucleoli are the sites of synthesis of RNA.
 Within the nucleus are most of the cell's hereditary units,
called genes. which control cellular structure and direct
cellular activities.
 Genes are arranged with chromosomes.

51. NUCLEUS STRUCTURE AND
FUNCTIONS
 Human body cells have 46 chromosomes.23 inherited from
each parents.
 Each chromosome is a long molecule of DNA, that is coiled
together with several protein.
 Nucleoli produce ribosomes, and chromosomes consist of
gene. that control cellular structure and functions.

52. WHAT CELLS DO?
 Cells are the basic units of all living things.
 Cells make up bones, muscles, skin, and blood.
 As the organism grows, the cells must reproduce.
 Cell reproduction is called mitosis

53. PASSIVE (DIFFUSION)
 Diffusion is the process by which molecules or ions scatter
or spread spontaneously from high concentration to low
concentration.
 Oxygen and carbon dioxide can diffuse readily through the
cell membrane.
 Equilibrium is reached.

54. PASSIVE
 Substances that are not able to pass through the lipid bilayer
need the help of membrane proteins to get across, this is
called facilitated diffusion.
 Carrier molecules “revolving doors” are used to carry large
molecules (glucose) across the membrane.

55. PASSIVE
 Osmosis is the diffusion of water.
 Solutions with a higher osmotic pressure than body fluids
are called hypertonic.
 Solutions with a osmotic pressure equal to body fluids are
called isotonic.
 Solutions with a lower osmotic pressure than body fluids are
called hypotonic.

56. ACTIVE
 Active transport is a process that moves particles through
membranes from a region of low concentration to high
concentration.
 Equilibrium is never reached.

57. CELL DEATH
Apoptosis is a form of cell death
that is actually a normal part of
development, sculpting organs from
overgrown tissues.