The cell is the basic unit of living organisms. The contents of the cell are described as the ultrastructure of the cell.
&
similarities
animal cell
animal cells have an irregular shape,
granular cytoplasm and a prominent nucleus.
They're bound by a cell surface membrane
The detail seen by the light microscope is limited, so the membranes in the
cell are too thin to be seen, but their positionsare marked
Differences
&
Unit Symbol Size in m
millimetre mm 10-3m
Plant cell μm
micrometre
nanometre nm Om m
Resolution → Ability to see 2 adjacent (but separate) points as distinct
entities following magnification
magnification → Ability to make small objects larger.
Electron microscope (EM)
uses electrons to procluce images. There are 2 types: Transmission electron microscope (TEM) and Scanning electron
microscope (SEM). Both do slightly different jobs and produce different images. They're both strong, powerful
microscopes which are capable of distinguisning between 2 ajacent points ie. seeing them as separate → the
resolution.
EMs can resoive points down to 0.1nm, LM can only achieve 0.2 um, or 200mm.
The magnifications of EMs are in excess of | million but LMs can only magnify things up to a few thousand bc. light
waves have a longer wavelength than electrons. electrons have a shorter wavelengen than light, which is why they
can resolve clown to a smaller amount.
/
Advantages of the LM. Disadvantages of the EM.
Portable Lots of prep → sections nave to be cut very thin
Relatively cheap using spetialised unting instruments +
Less specialist training required to prepare samples Stained to give the appropriate contrast.
Living cells can be viewed as well as dead ones → Problem?? the prep can result in artefacts being
can view biological processes produced, which are structures that esses don't
Colour can be seen in the image belong to the cell, or changes in the image as a result
Disadvantages of the LM of the prep.
lower resolution need specialist training to operate
Cell ultrastructure cant be seen very expensive.
, Transmission Electron Microscopes TEMS
M
e are passed through a very thin specimen producing an image with very high resolution and
consequently can be used for very hign magnifications.
Scanning Electron Microscopes SEMs
e are reflected off the surface of the and don't go through it. Resolution and magnification
aren't as high as in the TEM, but it gives a 3D image of surface features.
Be prepared for an essay which compares and contrasts
the light microscope, the transmission the scanning
electron microscopes could come up!!. Start
with I adv, then contrast don't keep them Seperate.
Cell Ultrastructure
Ultrastructure means The detail of a cell when viewed through an
electron microscope Eukaryotic cells are cells which possess a true nucleus
which is found in the cytoplasm and is bound by a cell surface membrane
Within the cell are organelles and a host of membrane systems.
Many chemical reactions take place on membranes. If the cell
surface membrane was the only membrane available to the cell, this may not
be enough to meet the metabolic requirements of the cell, so
having internal membrane systems is a way of getting round this
problem. How? it increases the s.a. of the membrane system per
unit volume of the cell
Having organelles bound by membrane allows for
compartmentalisation and division of labour
compartmentalisatian - sections of the cells can be separated from
each other and kept discrete
division of labour- different parts of the cell carry out different jobs;
leads to greater efficiency and control of reactions
Eukaryotic cells are the plants, animals and fungi.
Membrane systems and organelles of animal cells. Nucleus
inactive DNA that
S Largest and most obvious organelle in most cells.
Won't become
- 10-2 5pm in diameter
↑ Contains DNA and chromosomes
L protein .
-
Chromosomes are made up of DNA and special proteins called histones which help support and protect the DNA
↑ When the cell is not dividing, the chromosomes are diffuse and are not visible. They are in a form called
L
chromatin. This can be of two types, dark stained areas which is densely packed chromatin called heterochromatin
L
and less densely packed euchromatin Which appears lighter in colour Active ! Will become protein
-
Nucleolus - there may be one or several (nucleoli) within the nucleus and appear as a very dark, discrete area
within the nucleus. They are visible with the TEM and contain DNA that codes for ribosomal RNA (rRNA) and
therefore makes ribosomes which are the organelle responsible for protein synthesis The ribosomes don't stay in
the nucleus, once made they move out into the cytoplasm
S nucleus - Control centre of cell. DNA codes for the synthesis of proteins in the cytoplasm, Keeping the
chromosomes within the nucleus helps protect it from damage as there are many chemical reactions which take
place in the cytoplasm
-
The nucleus is surrounded by a double membrane or envelope known as the nuclear envelope
- The outer membrane of the nuclear envelope has got ribosomes embedded in it and is the site of the origin of
rough endoplasmic reticulom holes in the envelope.
I
Nuclear pores are present in the nuclear envelope, which allow materials such as DNA (genetic code) to pass
L
through the nuclear pore into the cytoplasm
&
similarities
animal cell
animal cells have an irregular shape,
granular cytoplasm and a prominent nucleus.
They're bound by a cell surface membrane
The detail seen by the light microscope is limited, so the membranes in the
cell are too thin to be seen, but their positionsare marked
Differences
&
Unit Symbol Size in m
millimetre mm 10-3m
Plant cell μm
micrometre
nanometre nm Om m
Resolution → Ability to see 2 adjacent (but separate) points as distinct
entities following magnification
magnification → Ability to make small objects larger.
Electron microscope (EM)
uses electrons to procluce images. There are 2 types: Transmission electron microscope (TEM) and Scanning electron
microscope (SEM). Both do slightly different jobs and produce different images. They're both strong, powerful
microscopes which are capable of distinguisning between 2 ajacent points ie. seeing them as separate → the
resolution.
EMs can resoive points down to 0.1nm, LM can only achieve 0.2 um, or 200mm.
The magnifications of EMs are in excess of | million but LMs can only magnify things up to a few thousand bc. light
waves have a longer wavelength than electrons. electrons have a shorter wavelengen than light, which is why they
can resolve clown to a smaller amount.
/
Advantages of the LM. Disadvantages of the EM.
Portable Lots of prep → sections nave to be cut very thin
Relatively cheap using spetialised unting instruments +
Less specialist training required to prepare samples Stained to give the appropriate contrast.
Living cells can be viewed as well as dead ones → Problem?? the prep can result in artefacts being
can view biological processes produced, which are structures that esses don't
Colour can be seen in the image belong to the cell, or changes in the image as a result
Disadvantages of the LM of the prep.
lower resolution need specialist training to operate
Cell ultrastructure cant be seen very expensive.
, Transmission Electron Microscopes TEMS
M
e are passed through a very thin specimen producing an image with very high resolution and
consequently can be used for very hign magnifications.
Scanning Electron Microscopes SEMs
e are reflected off the surface of the and don't go through it. Resolution and magnification
aren't as high as in the TEM, but it gives a 3D image of surface features.
Be prepared for an essay which compares and contrasts
the light microscope, the transmission the scanning
electron microscopes could come up!!. Start
with I adv, then contrast don't keep them Seperate.
Cell Ultrastructure
Ultrastructure means The detail of a cell when viewed through an
electron microscope Eukaryotic cells are cells which possess a true nucleus
which is found in the cytoplasm and is bound by a cell surface membrane
Within the cell are organelles and a host of membrane systems.
Many chemical reactions take place on membranes. If the cell
surface membrane was the only membrane available to the cell, this may not
be enough to meet the metabolic requirements of the cell, so
having internal membrane systems is a way of getting round this
problem. How? it increases the s.a. of the membrane system per
unit volume of the cell
Having organelles bound by membrane allows for
compartmentalisation and division of labour
compartmentalisatian - sections of the cells can be separated from
each other and kept discrete
division of labour- different parts of the cell carry out different jobs;
leads to greater efficiency and control of reactions
Eukaryotic cells are the plants, animals and fungi.
Membrane systems and organelles of animal cells. Nucleus
inactive DNA that
S Largest and most obvious organelle in most cells.
Won't become
- 10-2 5pm in diameter
↑ Contains DNA and chromosomes
L protein .
-
Chromosomes are made up of DNA and special proteins called histones which help support and protect the DNA
↑ When the cell is not dividing, the chromosomes are diffuse and are not visible. They are in a form called
L
chromatin. This can be of two types, dark stained areas which is densely packed chromatin called heterochromatin
L
and less densely packed euchromatin Which appears lighter in colour Active ! Will become protein
-
Nucleolus - there may be one or several (nucleoli) within the nucleus and appear as a very dark, discrete area
within the nucleus. They are visible with the TEM and contain DNA that codes for ribosomal RNA (rRNA) and
therefore makes ribosomes which are the organelle responsible for protein synthesis The ribosomes don't stay in
the nucleus, once made they move out into the cytoplasm
S nucleus - Control centre of cell. DNA codes for the synthesis of proteins in the cytoplasm, Keeping the
chromosomes within the nucleus helps protect it from damage as there are many chemical reactions which take
place in the cytoplasm
-
The nucleus is surrounded by a double membrane or envelope known as the nuclear envelope
- The outer membrane of the nuclear envelope has got ribosomes embedded in it and is the site of the origin of
rough endoplasmic reticulom holes in the envelope.
I
Nuclear pores are present in the nuclear envelope, which allow materials such as DNA (genetic code) to pass
L
through the nuclear pore into the cytoplasm
