YEAR 11 BIOLOGY – MODULE 1 NOTES
Cells as the Basis of Life
, TOPIC 1: CELL STRUCTURE
Microscopes
Eukaryotic and Prokaryotic Cells LIGHT MICROSCOPE:
Prokaryotic Cells: - Light source passes through condenser
lens then through specimen
- Don’t have a nucleus or membrane bound - Beam of light passes through convex lens
organelles and is then magnified and viewed through
- Found in single celled organisms the eyepiece
- Ribosomes are only organelles - Magnification 1500x, resolution 200nm
- Cell wall, vacuoles, cytoplasm,
chloroplast, nucleus and membrane can be
seen using a LM
FLOURESCENCE MICROSCOPE:
- Magnification 2000x, resolution 200nm
- Sample labelled with fluorescent
substance, illuminated with high-intensity
source causing substance to emit light
Eukaryotic Cells: - Light directed through filters, areas with
fluorescent substances can be seen
- Does have a nucleus, membrane bound
organelles ELECTRON MICROSCOPE:
- Found in multicellular organisms
- Uses electron beam instead of light,
electromagnets instead of glass lenses
- Electrons provide greater magnification
- Living tissue cannot be viewed.
- Very expensive
o TEM (Transmission Electron
Microscope):
• Electron beam passes through specimen
which produces 2D images.
Both cells have membrane, DNA, ribosomes, and • Magnification 1,500,000x, 2nm resolution
cytoplasm.
Calculating Microscope Magnification o SEM (Scanning Electron Microscope):
• Magnification 30000x, 10nm resolution
- Multiply objective lens by eyepiece • Bombards surface of specimen with
beams of electrons, creates 3D images
Example: if the eyepiece was 10x and the objective
lens was 10x, the total magnification would be
10*10 = 100x magnification
CONFOCAL MICROSCOPY:
- Low magnification (65x) and low
resolution (500nm)
- Uses laser beams to make images of
layers, combined to a 3D model.
- Expensive, but can obtain high-quality
images of thin sections of a specimen
, Golgi Body Layers of Packs cellular
membrane products into
which are vesicles,
not transported
connected inside or secreted
outside the cell
Mitochondria Double Cellular
membrane, respiration,
inner combines sugar
membrane with oxygen to
folded, make ATP as an
contains energy source for
DNA the cell
Chloroplast Double Site of
membrane, photosynthesis,
contains double
DNA and membrane
thylakoid
sacks
Calculating Cell Size Vacuole Membrane Provides
bound, structural
field of view
Size of cell diameter =
estimation of cells needed to cross diameter
fluid-filled support, contains
vesicle dissolved
CONVERSIONS: chemicals
1cm = 10mm (millimetres) Cell Wall External Provides
structure structural support
1mm = 1000µm (micrometres) surrounding and helps prevent
membrane, cell expansion
1µm = 1000nm (nanometres)
made of
Organelle Structure/Function cellulose
Cytoplasm Liquid with Structural
Organelle Structure Function dissolved support
Nucleus Double Contains genetic salts and
membrane, material (DNA) enzymes
contains
DNA
Ribosome Made of Converts DNA to
proteins, no proteins for cell
membrane structure/function
Endoplasmic Layers of Transports
Reticulum membrane materials
with throughout the
binding cell
ribosomes
(rough) or
without
(smooth)
Lysosomes Vesicle Digests cellular
containing waste/breaks
digestive down compounds
enzymes to be reused
, The Fluid Mosaic Model
- Representation of cell membrane (When temperature increases, fluidity increases –
- Accepted because it accounts for phospholipids become less closely packed and
behaviour of membranes, and surface move around more)
area.
LIPID COMPONENT:
Fluid part of membrane – consists of a bilayer of
phospholipids in which:
Hydrophobic heads pointed inwards
Hydrophobic tails pointed outwards
PROTEIN COMPONENT:
Proteins scattered throughout lipid bilayer
Some proteins function as pores, or active carrier
systems, or recognition markers
OTHER COMPONENTS:
- Carbohydrates: Attach to surface of cell
membrane, plays role in cell recognition
- Microtubules: Used in cell production,
attaches to inner surface of cell membrane
Cells as the Basis of Life
, TOPIC 1: CELL STRUCTURE
Microscopes
Eukaryotic and Prokaryotic Cells LIGHT MICROSCOPE:
Prokaryotic Cells: - Light source passes through condenser
lens then through specimen
- Don’t have a nucleus or membrane bound - Beam of light passes through convex lens
organelles and is then magnified and viewed through
- Found in single celled organisms the eyepiece
- Ribosomes are only organelles - Magnification 1500x, resolution 200nm
- Cell wall, vacuoles, cytoplasm,
chloroplast, nucleus and membrane can be
seen using a LM
FLOURESCENCE MICROSCOPE:
- Magnification 2000x, resolution 200nm
- Sample labelled with fluorescent
substance, illuminated with high-intensity
source causing substance to emit light
Eukaryotic Cells: - Light directed through filters, areas with
fluorescent substances can be seen
- Does have a nucleus, membrane bound
organelles ELECTRON MICROSCOPE:
- Found in multicellular organisms
- Uses electron beam instead of light,
electromagnets instead of glass lenses
- Electrons provide greater magnification
- Living tissue cannot be viewed.
- Very expensive
o TEM (Transmission Electron
Microscope):
• Electron beam passes through specimen
which produces 2D images.
Both cells have membrane, DNA, ribosomes, and • Magnification 1,500,000x, 2nm resolution
cytoplasm.
Calculating Microscope Magnification o SEM (Scanning Electron Microscope):
• Magnification 30000x, 10nm resolution
- Multiply objective lens by eyepiece • Bombards surface of specimen with
beams of electrons, creates 3D images
Example: if the eyepiece was 10x and the objective
lens was 10x, the total magnification would be
10*10 = 100x magnification
CONFOCAL MICROSCOPY:
- Low magnification (65x) and low
resolution (500nm)
- Uses laser beams to make images of
layers, combined to a 3D model.
- Expensive, but can obtain high-quality
images of thin sections of a specimen
, Golgi Body Layers of Packs cellular
membrane products into
which are vesicles,
not transported
connected inside or secreted
outside the cell
Mitochondria Double Cellular
membrane, respiration,
inner combines sugar
membrane with oxygen to
folded, make ATP as an
contains energy source for
DNA the cell
Chloroplast Double Site of
membrane, photosynthesis,
contains double
DNA and membrane
thylakoid
sacks
Calculating Cell Size Vacuole Membrane Provides
bound, structural
field of view
Size of cell diameter =
estimation of cells needed to cross diameter
fluid-filled support, contains
vesicle dissolved
CONVERSIONS: chemicals
1cm = 10mm (millimetres) Cell Wall External Provides
structure structural support
1mm = 1000µm (micrometres) surrounding and helps prevent
membrane, cell expansion
1µm = 1000nm (nanometres)
made of
Organelle Structure/Function cellulose
Cytoplasm Liquid with Structural
Organelle Structure Function dissolved support
Nucleus Double Contains genetic salts and
membrane, material (DNA) enzymes
contains
DNA
Ribosome Made of Converts DNA to
proteins, no proteins for cell
membrane structure/function
Endoplasmic Layers of Transports
Reticulum membrane materials
with throughout the
binding cell
ribosomes
(rough) or
without
(smooth)
Lysosomes Vesicle Digests cellular
containing waste/breaks
digestive down compounds
enzymes to be reused
, The Fluid Mosaic Model
- Representation of cell membrane (When temperature increases, fluidity increases –
- Accepted because it accounts for phospholipids become less closely packed and
behaviour of membranes, and surface move around more)
area.
LIPID COMPONENT:
Fluid part of membrane – consists of a bilayer of
phospholipids in which:
Hydrophobic heads pointed inwards
Hydrophobic tails pointed outwards
PROTEIN COMPONENT:
Proteins scattered throughout lipid bilayer
Some proteins function as pores, or active carrier
systems, or recognition markers
OTHER COMPONENTS:
- Carbohydrates: Attach to surface of cell
membrane, plays role in cell recognition
- Microtubules: Used in cell production,
attaches to inner surface of cell membrane
