Samenvatting Celbiologie

Celbiologie
BSc Biomedische Wetenschappen jaar 2 UvA (2023 -2024)




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,Inhoud
Celbiologie................................................................................................................ 3
Lecture 1 ................................................................................................................ 3
Lecture 2 .............................................................................................................. 16
Lecture 3 .............................................................................................................. 31
Lecture 4 .............................................................................................................. 48
Signal transduction................................................................................................. 62
Lecture 1 .............................................................................................................. 62
Lecture 2 .............................................................................................................. 72
Lecture 3 .............................................................................................................. 86
Lecture 4 .............................................................................................................. 97
References .............................................................................................................114




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,Celbiologie
Lecture 1

Some cell compartments have endo-membranes. They all have a variety of
functions and requires different sets of proteins



Compartment Main Function
Cytosol Contains many metabolic pathways;
protein synthesis
Nucleus Contains main genome; DNA and
RNA synthesis
Endoplasmic reticulum (ER) Synthesis of most lipids; synthesis of
proteins for distribution to many
organelles and to the plasma
membrane
Golgi apparatus Modification, sorting and packaging
of proteins and lipids for either
secretion or delivery to another
organelle
Lysosomes Intracellular degradation
Endosomes Sorting of endocytosed material
Mitochondria ATP synthesis by oxidative
phosphorylation
Chloroplasts ATP synthesis and carbon fixation by
photosynthesis
Peroxisomes Oxidation of toxic molecules




Cells have different compartments. Membranes enclose these departments.
There is an external and internal membrane. The external membrane creates
a barrier between the inside and the outside of the cell. The molecules
outside the cell are different from the molecules inside the cell. It is because
of these differences that gradients are formed. The inside of the cell contains
another compartment, the nucleus. The nucleus has the internal membrane
surrounding it. This separates the molecules inside the cell and inside the
nucleus.




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, Membranes have different functions.

- Separate cell-environment
o Small molecules, ions and big molecules
- Separate organelles
- Generate / control gradients
- Generate / control potentials
- Matrix for proteins

However, there are some needed qualities for membranes.

- Enclosing
- Selective permeable (dynamical)
- Functional in watery environment
- Stretchable



A membrane is selective permeable, which means that
the size and hydrophilic qualities decide how efficient a
molecule can diffuse through a plasma membrane. The
easiest molecules that can diffuse through the plasma
membrane are hydrophobic molecules, such as O2,
CO2, N2 and benzene. Small uncharged polar
molecules are fairly efficient for diffusion as well, like
H2O, urea and glycerol. Large uncharged polar
molecules are somewhat harder to diffuse through the
plasma membrane (glucose and sucrose). Ions cannot
diffuse at all because of their charge.

Plasma membranes consist of phospholipids. They are constructed out of a
phosphate, glycerol, OH-group and two long fatty acid chains. The
amphipatic qualities of phospholipids can keep hydrophilic molecules out
and make it easy to diffuse hydrophobic molecules into the cell. It is also
because of this quality that phospholipids can create a lipid bilayer. The
hydrophobic fatty acid tails are angled towards one another while the
hydrophilic head remains on the outside of the plasma membrane. The lipid
bilayer is not the only form that can come from combining phospholipids. A
sphere can be created when the hydrophobic tails of numerous
phospholipids point towards the center, and around that are the hydrophilic
heads. This creates a lipid micelle. Inside a lipid bilayer are membrane
proteins that can be integrates inside the plasma membrane.




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