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The use of microscopy to observe and investigate different types of cell and cell structure in a range of eukaryotic
organisms
To include an appreciation for the images produced by a range of microscopes: light microscope, transmission
electron microscope, scanning electron microscope and laser scanning confocal microscope
...
A
smaller wavelength means a higher resolution
...

Dry mount – Solid specimens are sectioned or viewed whole and placed on the centre of the slide with a cover slip over the
sample
...

Wet mount – Specimens suspended in a liquid and cover slip placed at an angle
...

Squash slides – Wet mount prepared and specimen is squashed
...

Smear slides – Specimen smeared using edge of slide and cover slip placed on top
...

The use of staining in light microscopy
Coloured stains bind to chemicals on or in the specimen, allowing specimens to be seen
...
Staining increases contrast allowing us to identify
organelles in parts of cells that make up molecules or compounds
...

An eyepiece scale can be fitted to the eyepiece, which has a scale of 1 to 100
...
The relative size
of the divisions increases with the magnification
...
1 division = 10μm and 100 divisions = 1mm
The use and manipulation of the magnification formula
nm
μm
mm
cm

nm
x1
÷1 000
÷1 000 000
÷10 000 000

μm
x1 000
x1
÷1 000
÷10 000

mm
X1 000 000
x1 000
x1
÷10

cm
X10 000 000
X10 000
X10
x1

The total magnification is objective lens magnification x eyepiece lens magnification
...

Magnification is the degree to which the size of the image is larger than the object itself
...

Light microscopes have a magnification of x1 500 and a resolution of 200nm (when the objects have a much smaller than
the wavelength being used, they don’t interrupt the waves, so aren’t detected)
...
2nm (electrons have a shorter
wavelength than light)
...

The ultrastructure of eukaryotic cells and the functions of the different cellular components
To include the following cellular components and an outline of their functions: nucleus, nucleolus, nuclear
envelope, rough and smooth endoplasmic reticulum (ER), Golgi apparatus, ribosomes, mitochondria, lysosomes,
chloroplasts, plasma membrane, centrioles, cell wall, flagella and cilia
...

Nucleolus
Within the nucleus and composed of proteins
Produces RNA and ribosomes
1µm
and RNA
...

Contains nuclear pores, which
0
...
04µm
allow the transport of proteins
into the nucleus
Rough endoplasmic
Consists of a series of flattened, membraneTransports proteins synthesised
0
...

Smooth endoplasmic
Consists of cisternae and no ribosomes
...
1µm
reticulum (SER)
Golgi apparatus
Formed of cisternae and no ribosomes
Modifies, processes and
2
...
025µm
RER
...

Mitochondria
Have a double membrane: inner is highly
Releases energy through
3µm
folded forming cristae and fluid interior is
aerobic respiration
called the matrix
...

Contains mitochondrial (mt)DNA
...
5-1
...

for intercellular digestion
...

Chloroplasts
Two membranes separated by fluid-filled
Contains chlorophyll for
6µm
space
...
A stack of thylakoids is called a
granum (plural: grana)
...
Also contain DNA and
ribosomes
...
006µm
with protein channels, glycoproteins etc)
substances in and out of the cell
Centrioles
Composed of microtubules (small tubes of
Helps make spindle fibres for
0
...
Two associated centrioles form
cell division
the centrosome
...

Made of cellulose fibres which
1-2 µm
provide strength and supports
cell
Flagella
Made up of a cylinder that contains nine
Used for cell movement
20µm
microtubules arranged in a circle
...

Cilia
Similar structure to flagella but smaller and in
Used to move fluids
less than 10µm
larger numbers
...

The sweeping movements of mobile cilia move substances such as mucus across the surface of the cells
...
g
...

Undulipodia and cilia can move because the microtubules can use energy from ATP
...

To include interpretation of transmission and scanning electron microscope images
...
TEM will be able to magnify further and show more details due to its
high magnification and resolution so it’s more likely to see smaller organelles
...


The interrelationship between the organelles involved in the production and secretion of proteins
No detail of protein synthesis is required
...
The newly synthesised proteins are
transported by vesicles to the Golgi apparatus
...
The vesicles fuse to the plasma membrane, releasing their contents by exocytosis
...

The cytoskeleton provides stability and mechanical strength to the whole cell, aids in the movement of the cilia and flagella
to move the cell, aids in changing the shape of the cell in processes like cytokinesis, muscle contraction and phagocytosis
and helps in the movement of chromosomes
...

Microtubules are hollow rod-like cylinders made of the protein tubulin
...
Proteins present on microtubules called microtubule motors move organelles: Movement of transport vesicles from
RER to Golgi apparatus and movement of chromosomes during mitosis
...

Intermediate filaments are fibres which give mechanical strength to the cell and help maintain cell integrity
...
They are responsible for cell movement and allow
contraction during cytokinesis
...

Microfilaments and microtubules are involved in the movement of cells but intermediate filaments aren’t because
microfilaments composed of actin, are contractile and microtubules, composed of tubulin, polymerises
...
Intermediate filaments have a
fixed length for stability
...
5 to 5μm
20-40μm
Examples
Bacteria and cyanobacteria
Protists, plants, fungi and animals
Nucleus
Not present
Present
DNA
Single circular chromosome
Multiple linear chromosomes
DNA organisation
Proteins fold and condense DNA
Associated with proteins called histones
Extra chromosomal DNA
Circular DNA in plasmids
...
g
...

Location of genetic material ‘naked’ DNA found in cytosol/nucleoid
DNA and protein in nucleus, enclosed in the
nuclear envelope
Cell division
Binary fission
Meiosis and mitosis
Reproduction
Asexual
Asexual or Sexual
Organelles
Few, non-membrane bound
Many, membrane and non-membrane bound
Cell Wall
Made of peptidoglycan
Made of cellulose (sometimes present)
Ribosomes
Small, 18nm
Large, 22nm
Cytoplasm
Present
Present
Cytoskeleton
Present
Present and more complex
Cell surface membrane
Present
Present
Mitochondria
Absent
Present
Centrosomes
Absent
Present
Lysosomes
Absent
Present
Golgi apparatus
Absent
Present
ER
Absent
Present



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