Lesson 1 - cell organelles
Leasing objectives
-de ne what a cell is and to which group it can belong
-explain di erent microscopy methods and choose the best method to answer a research question
-identify the key-organelles of the cells and explain their prime function
The cell
-is the essential building block of the life on earth.
-has a limiting membrane (inside, outside and compartments)
-contains biomolecules (e.g protein, RNA, DNA)
-is an autonomous unit in performing a function
-can respond & adopt to stimuli
-can (often) reproduce herself
Despite the obvious di erences between cells, basic functions and components are highly similar.
Bacteria, archaea & eukaryotes
-Bacteria: no nucleus or other organelles
-Archaea: no nucleus, often extremophiles (survive
in places many normal cells can’t survive in)
-Eukaryotes: nucleus and other organelles,
sometimes multicellular life forms
You have di erent wavelengths in visible light
LM (light microscopy) for larger things: used for cells
Photon wavelength: 300-700 nm
EM (electron microscopy): used for organelles
Electron wavelength: 2.5 x 10-3 nm
How it works
-It uses an electron gun instead of a light bulb as a light source
-Condenser lens: turns it into a focused beam to the specimen
-Objective lens: carousel lens determines magni cation and the focus same for LM
-Fluorescent screen: falls onto into it because our own eyes cannot see electrons directly, so it
translates it into something we can observe
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, Di erence between EM & LM
-The EM is under a high/deeply vacuum because electrons are easily scattered.
-EM uses electrons
-LM uses glass lenses
-EM uses electromagnetic lenses
EM how it works
-Diverge the electrons (negatively charged) by using a positive charge so they bend away
-Positive charge: the protons in the atoms that are in the material
-Nature does not provide elements that contain enough protons
-Heavy metals are used on the preparation that contain a lot of protons: diverge the electrons, so
that you can see something
LM vs EM
-Advantage of EM over LM:
-Superior resolution (up to 0.5 nm! , atoms!)
-Visualize the whole cell, not only a uorescent probe (e.g. GFP).
-Huge magni cation range (30x-300.000x: 104)
Disadvantages of EM compared to LM:
-requires xation of cells (operates under vacuum).
-Only small pieces of tissue can be imaged.
-Time-consuming method
Summary
All life on Earth consists of cells
-A cell is a compartment containing biomolecules (DNA, RNA, protein) that are surrounded by
membrane and can react to stimuli.
-All cells have the same basic ingredients but the show a huge diversity in shapes and specialized
functions.
-To study the form-function relationships, microscopes are essential:
Light microscopy
Fluorescence microscopy
Electron microscopy
-Using these methods in combination, you can study processes in cells at a 1 000 000
magni cation range
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,Organelles
Only eukaryotic cells contain organelles, including a nucleus, which distinguishes them from
prokaryotic cells. Eukaryotic cells can form
multicellular organisms
Nucleus:
Function: store DNA and facilitate
transcription of DNA to RNA.
Structure:
-Nucleus envelope: distinguishing where the
genetic material is from the rest of the
cell: protects and isolates DNA from the
cytoplasm, allowing selective exchange via
nuclear pores.
-Nucleolus: where the RNA transcription
occur and ribosome assembly
-Chromatin: a complex of DNA and protein
that forms chromosomes
-Nuclear pores: lters that regulate
molecular tra c in and out of the nucleus
Endoplasmatic reticulum (ER):
Function: translation of RNA to protein and protein
folding.
Synthesis of most lipids; synthesis of protein for
distribution to many organelles and to the plasma.
-Some proteins are packaged in the ER lumen for
secretion.
Golgi apparatus:
Function: Post-translational modi cation and
sorting of proteins for their speci c destinations
(secretion to to another organelle).
Organization:
- Cis : where proteins come in
- Trans: where the proteins go out. The location of
the protein is decided here
Lysosomes: intracellular degradation.
Endosomes: sorting of endocytose material
Peroxisome: oxidative breaks down of toxic molecules
ffi fi fifi
, Mitochondrion:
Function: produce energy (ATP) trough cellular respiration. ATP synthesis by oxidative
phosporylation.
Features:
-2 membrane structure: inner and outer
-Inner membrane has cisternae to maximize surface area for energy production.
-Contain its own DNA, allows for some independent protein synthesis
Chloroplast (speci c to plant cell):
Function: Conducts photosynthesis, converting light energy into chemical energy (glucose).
-Plants also rely on mitochondria to metabolize glucose for energy.
Cytosol: contains many metabolic pathways.
Cytoskeleton: supportive structure, maintains cell shape and facilitate intracellular transport,
contributed to cell movement. Is a network of protein laments.
In the cytoskeleton comprise 3 types
of laments:
-Microtubules: give the core shape of
the cell (provide structural support)
-Intermediate laments: connect and
stabilise components within and
between cells
-Actin lament: mobility of the cell
Cytoplasm: A jelly-like matrix containing proteins and facilitating numerous cellular processes (cell
homeostasis)
Functions:
-transport
-protein synthesis
-protein break-down
-signal transduction
-membrane fusion
-ionic homeostasis
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fi fi fi fi
Leasing objectives
-de ne what a cell is and to which group it can belong
-explain di erent microscopy methods and choose the best method to answer a research question
-identify the key-organelles of the cells and explain their prime function
The cell
-is the essential building block of the life on earth.
-has a limiting membrane (inside, outside and compartments)
-contains biomolecules (e.g protein, RNA, DNA)
-is an autonomous unit in performing a function
-can respond & adopt to stimuli
-can (often) reproduce herself
Despite the obvious di erences between cells, basic functions and components are highly similar.
Bacteria, archaea & eukaryotes
-Bacteria: no nucleus or other organelles
-Archaea: no nucleus, often extremophiles (survive
in places many normal cells can’t survive in)
-Eukaryotes: nucleus and other organelles,
sometimes multicellular life forms
You have di erent wavelengths in visible light
LM (light microscopy) for larger things: used for cells
Photon wavelength: 300-700 nm
EM (electron microscopy): used for organelles
Electron wavelength: 2.5 x 10-3 nm
How it works
-It uses an electron gun instead of a light bulb as a light source
-Condenser lens: turns it into a focused beam to the specimen
-Objective lens: carousel lens determines magni cation and the focus same for LM
-Fluorescent screen: falls onto into it because our own eyes cannot see electrons directly, so it
translates it into something we can observe
fi ffff ff fi
, Di erence between EM & LM
-The EM is under a high/deeply vacuum because electrons are easily scattered.
-EM uses electrons
-LM uses glass lenses
-EM uses electromagnetic lenses
EM how it works
-Diverge the electrons (negatively charged) by using a positive charge so they bend away
-Positive charge: the protons in the atoms that are in the material
-Nature does not provide elements that contain enough protons
-Heavy metals are used on the preparation that contain a lot of protons: diverge the electrons, so
that you can see something
LM vs EM
-Advantage of EM over LM:
-Superior resolution (up to 0.5 nm! , atoms!)
-Visualize the whole cell, not only a uorescent probe (e.g. GFP).
-Huge magni cation range (30x-300.000x: 104)
Disadvantages of EM compared to LM:
-requires xation of cells (operates under vacuum).
-Only small pieces of tissue can be imaged.
-Time-consuming method
Summary
All life on Earth consists of cells
-A cell is a compartment containing biomolecules (DNA, RNA, protein) that are surrounded by
membrane and can react to stimuli.
-All cells have the same basic ingredients but the show a huge diversity in shapes and specialized
functions.
-To study the form-function relationships, microscopes are essential:
Light microscopy
Fluorescence microscopy
Electron microscopy
-Using these methods in combination, you can study processes in cells at a 1 000 000
magni cation range
ff fi fi fi fl
,Organelles
Only eukaryotic cells contain organelles, including a nucleus, which distinguishes them from
prokaryotic cells. Eukaryotic cells can form
multicellular organisms
Nucleus:
Function: store DNA and facilitate
transcription of DNA to RNA.
Structure:
-Nucleus envelope: distinguishing where the
genetic material is from the rest of the
cell: protects and isolates DNA from the
cytoplasm, allowing selective exchange via
nuclear pores.
-Nucleolus: where the RNA transcription
occur and ribosome assembly
-Chromatin: a complex of DNA and protein
that forms chromosomes
-Nuclear pores: lters that regulate
molecular tra c in and out of the nucleus
Endoplasmatic reticulum (ER):
Function: translation of RNA to protein and protein
folding.
Synthesis of most lipids; synthesis of protein for
distribution to many organelles and to the plasma.
-Some proteins are packaged in the ER lumen for
secretion.
Golgi apparatus:
Function: Post-translational modi cation and
sorting of proteins for their speci c destinations
(secretion to to another organelle).
Organization:
- Cis : where proteins come in
- Trans: where the proteins go out. The location of
the protein is decided here
Lysosomes: intracellular degradation.
Endosomes: sorting of endocytose material
Peroxisome: oxidative breaks down of toxic molecules
ffi fi fifi
, Mitochondrion:
Function: produce energy (ATP) trough cellular respiration. ATP synthesis by oxidative
phosporylation.
Features:
-2 membrane structure: inner and outer
-Inner membrane has cisternae to maximize surface area for energy production.
-Contain its own DNA, allows for some independent protein synthesis
Chloroplast (speci c to plant cell):
Function: Conducts photosynthesis, converting light energy into chemical energy (glucose).
-Plants also rely on mitochondria to metabolize glucose for energy.
Cytosol: contains many metabolic pathways.
Cytoskeleton: supportive structure, maintains cell shape and facilitate intracellular transport,
contributed to cell movement. Is a network of protein laments.
In the cytoskeleton comprise 3 types
of laments:
-Microtubules: give the core shape of
the cell (provide structural support)
-Intermediate laments: connect and
stabilise components within and
between cells
-Actin lament: mobility of the cell
Cytoplasm: A jelly-like matrix containing proteins and facilitating numerous cellular processes (cell
homeostasis)
Functions:
-transport
-protein synthesis
-protein break-down
-signal transduction
-membrane fusion
-ionic homeostasis
fi
fi fi fi fi
