Zellbiologie

• Adaptive immunity has more “power”
• Adaptive immunity lasts and amplifies
• Adaptive immunity “remembers” pathogens
• Adaptive immunity is effective against peptide sequences
• Adaptive immunity can recognize infected self cells

> MHC or major histocompatibility complex is a molecular marker
> All cells express MHC class I, only APC(antigene presentig cell, monozyten macrophagen) express MHC class II
> Specific for each individual: Polygenic (HLA-A, HLA-B, HLA-C) co-dominant and highly-polymorphic.
> Indicates self to immune system, or foreign pathogens
> Protects own cells from immune attack
> “Presents” self peptidic sequences

> Family of immune cells (cellular response)
> Matured in the thymus
> Two type: LT-4 or helpers, LT-8 or cytotoxic
> Specialized in fighting abnormal cells (virus infected or cancer cells)
> Recognize only sequential non-self epitopes from APC
> Activation results in cytokine release inducing clonal amplification

• Also know as lymphocytes T helpers
• Intermediary cell in the immune response, recognize “non- self antigens” on MHC-II.
• Once activated they secrete many cytokines to activate other immune cells.
• Activate and direct other cells (conductor). Work as “whistle blowers” of the immune system.
• Necessary cells (target of HIV)
• Once activated they, grow (clonal expansion) to amplify the response and produce memory cells

• Immune cells need to be controlled to avoid unnecessary activation
• Also have to be activated when needed
• Each pathogen requires a specialized response
• Immune cells excrete cytokines to attract, promote, differentiate, even toxify.

Many soluble factors:
— Interleukins (26, e.g. IL-1)
— Interferons (alpha, beta, gamma, omega,...)
— Tumor necrosis factors (TNFs)
 

• Creates a “cytokines profile” (like a barcode)

B-Lymphozyten oder kurz B-Zellen gehören zu den Leukozyten (weiße Blutkörperchen). Sie sind als einzige Zellen in der Lage, Antikörper zu bilden

Diese Proteinkomplexe finden sich auf der Oberfläche nahezu aller (kernhaltiger) Zellen des Organismus (außer Trophoblasten und Erythrozyten (kernlos)) und dienen der Antigenpräsentation für zytotoxische T-Zellen sowie dem Schutz gesunder Zellen vor einer Zerstörung durch Killerzellen (→ Missing-self-Hypothese).

Die Intensität der Immunantwort muss ständig kontrolliert werden, um einerseits die Krebszellen und Krankheitserreger zu vernichten, dabei aber Autoimmunität gegen normale Gewebe zu unterdrücken.

Bei CD4 handelt es sich um einen so genannten Corezeptor, der gemeinsam mit dem T-Zell-Rezeptor das MHC-Klasse II Molekül (siehe auch Haupthistokompatibilitätskomplex) mit dem Antigen auf anderen Körperzellen erkennt.

• Der einfachste ist die Neutralisation von Antigenen. Dadurch, dass der Antikörper das Antigen bindet, wird dieses blockiert und kann beispielsweise seine toxische Wirkung nicht mehr entfalten
• Ein weiterer ist die Opsonisierung („schmackhaft machen“), das Einhüllen von Krankheitserregern und Fremdpartikeln mit Antikörpern. Wenn ein Antikörper beispielsweise an ein Antigen bindet, das sich auf der Oberfläche eines Bakteriums befindet, markiert er damit gleichzeitig das Bakterium
• Eine dritte Wirkungsweise ist, dass Antikörper das Komplementsystem aktivieren-->Zelle schwillt an und platzt.
• Dadurch, dass ein Antikörper zwei Antigenbindungsstellen aufweist, kann es zur Agglutination(verklumpung) kommen.

Precursors (e.g. glucose, amino acids, fatty acids, bases) are “transformed” into complex molecules
(e.g. carbohydrates, proteins, lipids, DNA, RNA) by using the energy received from catabolism.

Catabolism (from Greek κάτω kato, "downward" and βάλλειν ballein, "to throw") is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy

Kilocalorie: (kcal or Cal) is 1000 cal or the amount of energy to elevate the temperature of 1 kg of water of 1°C

KiloJoule: (kJ) is roughly 4.2 kcal

oxydation of high energy bond to low ones

phosphoanhydride bonds
Water can be added to ATP to form ADP
Delta G⁰ = -30.5KJ/mol
 

• > Important carrier molecules
• > Oxydation/reduction reaction require protons/electrons
• > Proton carriers accept temporarily protons (H + ) and high energy electrons (e - )
• > NADPH, NAD+ and FAD

Energetically unfavourable reactions (ΔG > 0 edergonic) can only occur if they are coupled to an
energetically favourable (exergonic) reaction and the net free-energy change for the pair of coupled reactions
is less than zero.

• Carbohydrates: Starch is hydrolysed by α-amylase (produced by pancreas) to disaccharides. The disaccharides are hydrolysed to monosaccharaides which can be absorbed from the intestine
• Lipids: Must be emulgated by bile from the liver. Then they are hydrolysed by lipases to fatty acids and glycerol and taken up into the cells
• Proteins: Are first denatured in the stomach by acids and shaking. In the next steps they are hydrolysed to polypeptides by pepsin and t

The glycolysis can be divided into three parts:

• In the first step, energy (2 ATP) is invested to make one molecule of fructose 1,6-biphosphat out of one molecule of glucose
• In the second step, the six-carbon sugar is cleaved to two molecules of glyceraldehyde-3-phosphate (three-carbon-sugars)
• In third step, energy is generated (4 ATP) by making two pyruvate molecules out of the two glyceraldehyde-3-phosphates.