3. Cells
⚫ ALL organisms are made up of cells
⚫ Simplest collection of LIVING matter
⚫ Cell structure correlate to their functions
⚫ All cells are related to earlier cells that they descend
from
5. Microscopy
⚫ Microscope is an instrument that magnifies objects
too small to be seen, producing an image that
appears larger.
⚫ Photographs/ pictures of cells derived from the
microscope - Micrographs
6. Magnification
⚫ A measure how much larger a microscope can
cause an object to appear
⚫ The Ratio of the object to its actual size
(Magnification = measured length[of image]/ actual
length of object)
7.
8.
9. Resolution
⚫ A measure of clarity – the smallest distance by
which two points can be distinguished in an image.
⚫ Limited by the physical properties of light
10. Light Microscope
⚫ Commonly used
⚫ Visible light passes through
the specimen
⚫ Bent through the lens system
– producing magnified image
⚫ X1000 magnification
⚫ Uses blue light – 400 nm
⚫ Lowest Resolution = 200nm
13. Light Colors
⚫ Light with the largest wavelength is red = 700 nm
⚫ Light with smallest wavelength is blue = 400 nm
⚫ With the magnification, resolution is actually half the
wavelength
⚫ Light microscope uses blue – 200 nm resolution
14. Electron microscope
⚫ Uses electron – has a
shorter wavelength
⚫ X-ray is hard to control –
electron can be controlled
using magnets
⚫ Electron can only function
in vacuum – oxygen
molecules may cause the
electron to be knocked
around
⚫ False-coloring by computer
15. SEM
⚫ Scanning Electron
microscope
⚫ Electron bounce back
and forth across
specimen’s surface
⚫ Creating a detailed 3D
image
⚫ Resolution smaller that
TEM
17. Light Vs. Electron
Similarities
⚫ Both uses
Lens
Differences
⚫ One uses visible light, another uses electron molecule
(electron vs. photon)
⚫ Resolution, one is 200, the other is 0.5
⚫ With SEM – 3D image is possible
⚫ Electron is more expensive
⚫ One focuses light with lens, the other focuses light by
electromagnetic control
⚫ One uses electron gun, the other uses low voltage
bulb
⚫ On magnifies up to 1500, the other up to 500000
⚫ One uses air as medium, another uses vacumm
18. Cell Fractionation
⚫ Takes cell apart and separates organelles
⚫ Cells are centrifuged where the heavier components
will sink to the bottom
⚫ Ultracentrifuges – fractionates them into
components
23. Prokaryotic
⚫ Prokaryote – a simple organism e.g. Bacteria
⚫ No nucleus
⚫ No membrane-bound organelles
⚫ Has Cell Walls
⚫ Has Circular chromosomes
⚫ Common cell structures: Plasma membrane,
Cytoplasm, DNA, Ribosomes
27. Animal Cell Structure
⚫ Nucleus: Contains chromosomes/ DNA – code for the
synthesis of proteins that control the function of the cell –
hence the nucleus commands the cell
⚫ Cell Surface membrane: Holds the cell content, controls
the ins/outs, structural forms, cell recognition, adhesion,
signaling, transport of substances, endo/exocytosis
⚫ Cytoplasm: the liquid where all the cell metabolic
activities take place
⚫ Mitochondria: Produces energy in the form of ATP
through respiration
28. Animal Cell Structure
⚫ Ribosomes: Receiving mRNA coded for Protein
synthesis
⚫ Lysosome: Engulfs materials and destroy them with
enzymes
⚫ Rough ER: Has ribosomes on it – involved in protein
synthesis – transport network for protein
⚫ Smooth ER: Synthesis of lipid – involved in cell
detoxification
⚫ Golgi bodies: Process the finished proteins
29. Nucleus
⚫ Double nuclear envelope –
encloses/ protect DNA
⚫ Nuclear pore – received
substances for DNA
Replication(extra phosphate),
exits for mRNA
⚫ small molecules pass through
by diffusion, large ones get in
actively
⚫ in micrographs – RNA/protein
complex can be seen
plucking the pore
30. Nucleus
⚫ Nucleoplasm – contains
chromatin granules,
DNA/associated proteins:
during cell division, they
condense to form
chromosomes
⚫ Nucleolus – produces rRNA
part of ribosomes, proteins,
coenzymes, enzymes for
nucleic acid synthesis, RNA
⚫ Outer membrane continuous
with ER – easier transport
31. Endoplasmic Reticulum
⚫ A system of hollow tubes/ sacs – transportation
purpose
nucleus
Rough
Endoplasmic
Reticulum
Smooth
Endoplasmic
Reticulum
32. Rough ER
⚫ Covered with ribosomes
⚫ Interconnected system of
flattened sacs
⚫ Ribosomes on surface
synthesize proteins which are
then transported through the
interconnected system
⚫ RER is abundant in cells which
needed to produce a lot of
proteins for exports e.g.
Digestive enzymes/ growth
33. Smooth ER
⚫ Lacks ribosomes
⚫ A system of interconnected
tubules
⚫ Carbohydrate/ lipids metabolism
⚫ Synthesizes: triglycerides,
phospholipid, cholesterol
⚫ Modification of steroid hormones
⚫ High percentage in cells
involved with metabolism of
lipids/drugs
34. Golgi Body
⚫ Flattened cisternae
⚫ Invaginate/ fuse to form
vesicles
⚫ Internal transports by
vesicles
⚫ Vesicles protect molecules
⚫ In case of enzymes –
protect the cells
35. Cell Membrane
⚫ Fluid mosaic bilayers which surround the cell content
⚫ Control the ins/outs of the cell
⚫ Gives the cell stability during temperature changes
⚫ Endocytosis/ exocytosis
⚫ Important in cell recognition
⚫ Cell signaling
⚫ Cell adhesion
36. Cytoplasm
⚫ Makes up of liquid: Cytosol
⚫ Where the metabolism takes place
⚫ Contains water/ solution
⚫ Most organelles float here
⚫ Osmoregulation
37. Mitochondria
⚫ Double Membrane – isolate
certain reaction – high
concentration of enzymes/
substrates can be maintained
⚫ Outer membrane –
permeable to salt, sugar,
nucleotides
⚫ Inner membranes –
selectively permeable
(control chemical composition
of the matrix – optimizes
enzyme activity)
38. Mitochondria
⚫ Porins on inner membranes – entry of
oxygen/pyrovic acid – exit of ATP/ Carbon dioxide
⚫ Folded inner membrane (cristae) – increases
surface area for enzymes/ coenzymes
⚫ 70s ribosomes – protein manufacturing
⚫ Loop of circular DNA – codes for protein
⚫ Enzymes
39.
40. Endosymbiosis theory
⚫ States that mitochondria’s
ancestors were bacterial
ingested by a eukaryote
⚫ The eukaryote kept it as it is
useful for respiration
⚫ Evidences: 70s vs. 80s
ribosomes
⚫ Evidences: Own DNA
⚫ Evidences: Divides by itself
41. Ribosomes
⚫ 2 subunits
⚫ Made of rRNA/ Protein
⚫ rRNA – formed in nucleus –
moves out via pores
⚫ Protein part – assembled in
the cytoplasm
⚫ Found as dense clusters
(polysomes)
⚫ On membranes of RER
42. Lysosomes
⚫ Vesicles that contains
hydrolytic enzymes
⚫ Break down old organelles –
recycle the materials
⚫ Break down storage
molecules
⚫ Break down whole cell when
it dies
43. Cytoskeleton
⚫ Microtubules – tubulin proteins : Thickest fo the
three – around 25 nm
⚫ Microfilaments – actin proteins
⚫ Intermediate filaments
44. Microfilament
⚫ Rods of about 7nm in diameter
⚫ Made up of a twisted double chain of actin subunits
45. Microfilaments
⚫ Create tension
⚫ Support the shape of the cell
⚫ 3-D Cortex inside plasma membrane
⚫ Bundles of microfilaments indie the microvilli
48. Microtubules
⚫ 25 nm wide
⚫ Made up of tubulin proteins
⚫ Arranged in dimers (alpha tubulin/ beta tubulin)
⚫ This dimer repeat in vertical format – forming a
protofilament
⚫ 13 protofilaments arrange around a hollow core
⚫ MICROTUBULES FORM
49. Microtubules
⚫ Shapes the cell
⚫ Guide the movements of cells/ organelles – with
help of motor proteins
⚫ Make up spindles that separate chromosomes
during cell division
50. Centrosome
⚫ Contains 2 centrioles
⚫ The location for MTOC (Microtubules organizing
center)
⚫MAY have a role in regulating the cell division
51. Centrioles
⚫ Microtubules form triplets (1
complete microtubule, 2 partial
microtubules)
⚫ These triplets then arrange into a
cylinder
⚫ 200 nm in diameter, 500 nm long
⚫ Two of these line up perpendicular
to form centriole
⚫ Not sure of its function yet
⚫ Some believe it might be MTOCs
for spindles during cell division
52.
53. Cilia/ Flagella
⚫ Long structures projecting out of a cell membrane
⚫ A core of microtubules sheathed by the plasma
⚫ Flagellum – longer and for movement of cell
⚫ Cilia – shorter – usually to beat up things
56. Cell Wall
⚫ Cellulose fiber embedded in
other polysaccharides/
proteins
⚫ Pectin and cellulose fiber
(strong)
⚫ Permeable
⚫ Space between cells above
the wall: middle lamella
⚫ Things like wood may have
secondary cell wall
57. Cell Wall
⚫ The osmotic pressure vs. the pressure from cell wall
gives the plant its structure
⚫ Structure of Cellulose – resistant to degradation and
enzymes – only cellulase – Protects the cell
⚫ Prevent bursting
58. Cell Wall
⚫ May have multiple layers
1. Primary Cell Wall – thin and flexible
2. Middle lamella – a thin layer between primary walls
and adjacent cells
3. Secondary cell wall (only found in certain cells) :
between plasma membrane and primary cell wall –
on the inside where it grows
59.
60. Cell Wall
⚫ Tunnels between cells: Plasmodesmata
⚫ Protoplast:A plant, bacterial or fungal cell with its
cell wall removed
61. Vacuoles
⚫ Enclosed membrane
compartments – filled with water
content/ enzymes/ proteins etc.
⚫ Storage for waste, harmful
materials
⚫ Storage for water
⚫ Hydrostatic pressure controlled
⚫ Work with cell wall to maintain
turgidity
⚫ The membrane around it:
Tonoplast
62. Chloroplasts
⚫ Plant organelles specialized in conducting
photosynthesis
⚫ Larger than mitochondria
⚫ Double membrane
⚫ Has its own DNA
⚫ Endosymbiosis theory applied to it as well
63.
64. Chloroplast
⚫ Inner/ Outer membrane
⚫ Stroma: The liquid inside the inner membrane
⚫ Grana: Made up of stacks of thylakoid
⚫ Thylakoid: Has chlorophyll on the surface
65. Virus
⚫ Size: 20 – 750 nm
⚫ We are not sure if virus
is considered an
organism
⚫ As it is unable to fully
function without a host
⚫ Nevertheless, virus is a
fascinating component
to Biology worthy of
studies
66. Virus Structure
⚫ Consists of an RNA molecule
protected by a protective
protein coat called capsid
⚫ Capsid made up of proteins
called capsomere
⚫ On the outside a protein
envelope gives it another
layer of protection
⚫ Glycoproteins/lipids stuck out
from the envelope
67. Plant Cell Vs. Animal Cell
Common
⚫ Nucleus
⚫ ERs/ Golgi body
⚫ Plasma membranes
⚫ Phospholipid bilayer
⚫ Mitochondria
⚫ Gap between cells (gap junction/
Plasmodesmata)
⚫ Both have cytoskeleton
⚫ Peroxisomes
Differences
⚫ Cell Wall
⚫ Cell membrane: Glycolipid/
Glycoprotein
⚫ Centrioles
⚫ Central vacuoles
⚫ Chloroplasts
