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
