100% tevredenheidsgarantie Direct beschikbaar na betaling Zowel online als in PDF Je zit nergens aan vast
logo-home
Samenvatting Introduction to Cell Biology €3,49   In winkelwagen

Samenvatting

Samenvatting Introduction to Cell Biology

2 beoordelingen
 58 keer bekeken  4 keer verkocht

Samenvatting van colleges, alle tutorials (ICT modules) en cases. Colleges van week 5 & 6 ontbreken.

Laatste update van het document: 3 jaar geleden

Voorbeeld 4 van de 82  pagina's

  • Nee
  • Onbekend
  • 23 december 2020
  • 23 december 2020
  • 82
  • 2018/2019
  • Samenvatting
book image

Titel boek:

Auteur(s):

  • Uitgave:
  • ISBN:
  • Druk:
Alle documenten voor dit vak (1)

2  beoordelingen

review-writer-avatar

Door: nikascholte • 2 jaar geleden

review-writer-avatar

Door: annaremmerswaal4 • 1 jaar geleden

avatar-seller
michouweimar
lOMoARcPSD|2392027




Week 1
Lecture Chapter 1: Cells, The Fundamental Units of Life
Cell theory

1. All living organisms are composed of one or more cells
2. Cells are the fundamental units/building block that provide structure and organization to
organisms.
3. All cells arise from pre-existing cells by growth and division (evolution). They do not arise
spontaneously.


Cells are diverse, but their chemistry is remarkably similar:

o DNA (genetic information), RNA (transcription) and protein (translation) synthesis
o Building blocks & enzymes are very similar.
Evidence -> swapping genes between organisms



Model systems = Organisms of which we exploit the similarity between cell types

o Requirements:
 Replicate quick
 Easy to maintain
 Can be modified or has other properties that make them easy to study (e.g. translucent)
o E.coli = fundamental mechanisms of life, e.g. transcription (DNA -> RNA) and translation
(RNA -> protein)
o Single cells: Yeast and mammalian cell lines (internal organization and cell cycle control)
o Arabidopsis, Drosophila, C.elegans: mechanisms of development of multicellular organisms
o Not just chemistry is conserved but also organizing mechanisms (e.g. growing microtubules
push nuclei into position)



Microscopes

o Observing cell division provided evidence for the cell theory
o Electron microscopes (EM)
 Highest resolution/resolving power
 Shows features that are < 200 nm apart
 Very expensive

Light microscopes (LM)

0,61∙ λ 0.61∙ λ
 Resolution = d = =
N.A n sin α
λ = wavelength in nm
n = refractive index of medium
N.A = numerical aperture (≈ 1)




Gedownload door Michou Weimar (michoumelody@live.nl)

, lOMoARcPSD|2392027




 EM LM
1. Absorption and scattering of electrons 1. Absorption and scattering of photons
(light)
2. Cells in vacuum (fixated) 2. Cells in liquid (live cell imaging)
3. Contrasting agents (e.g OSO 4) 3. Dynamic processes visualized
6
4. High magnification (×10 ) 4. ×10 3
5. Magnetic lenses 5. Glass lenses
 Low image contrast because of limited absorption and light scattering
Histological stains improve contrast, but are often incompatible with live cells (I 2KI stains
starch blue)
 Techniques that rely on differences in refractive index between cell compartments
increase contrast for live cells
 Microscopy methods:
1. Scanning EM (surface)
2. Transmission EM (inside of 50 nm thin-section)
3. Fluorescent LM (translucent)
4. Confocal fluorescence (virtual thinsectioning)
o Nobel prizes microscopy, do we need to know these???



Fluorophore

o Fluorescent molecules absorb photons of a specific color (= excitation) and produces
photons with a longer wavelength/less energy (emission)
o To observe the fluorophore only, we use a color filter
o Select fluorophores bind to specific cellular structures (DAPI to DNA and DIOC 6 to lipid
membranes)
o In the inside of the cell there is constant stirring: Brownian motion and active processes (e.g.
DNA replication)

GFP

o Green Fluorescent Protein -> a DNA construct that codes for a fusion protein can be inserted
in cells
o Cells express their own fluorophore
o Used to investigate dynamic interactions between cellular components
o The organization of cells is remodeled continuously




Gedownload door Michou Weimar (michoumelody@live.nl)

, lOMoARcPSD|2392027




Prokaryotes (bacteria and archaea)




o Simple internal organization: no nucleus, no membrane-bound organelles
o The plasma membrane forms a barrier between the cytosol and external space
o DNA concentrated in the nucleoid (nucleus in eukaryotes), which lacks a nuclear membrane
and is irregularly shaped
o Ribosomes perform protein synthesis in the cytosol and on the plasma membrane
o Cyanobacteria make complex organic molecules and O 2 from water and CO2 by
photosynthesis (Carbon fixation):
6CO2 + 6H2O + light  C6H12O6 + 6O2
carbon dioxide water glucose oxygen

o There are also nitrogen fixing bacteria (such as cyanobacteria) which covert N 2 to NH3
(ammonia). Ammonia is needed for the biosynthesis of the basic building blocks of many
organisms, such as DNA, RNA and proteins.
o Some bacteria can survive on air, water and inorganic minerals alone


Eukaryotes

o Evolved from prokaryotes (endosymbiosis)
o Have a nucleus with a nuclear envelope which consists of a double membrane: inner and
outer membrane
 DNA is compacted by proteins to fit in nucleus
 Chromatin  complex of DNA and proteins in the nucleus
 Euchromatin  a lightly packed form of chromatin that is enriched on genes
Is often under active transcription (active)
Heterochromatin  a tightly packed form of DNA that plays a role in gene expression
(inactive)




Gedownload door Michou Weimar (michoumelody@live.nl)

, lOMoARcPSD|2392027




o They also contain other membranes (e.g. ER), these membranes are probably evolved by
folding of the plasma membrane
o The nucleus enables complex gene regulation
o RNA processing (5’ cap and poly-A-tail) and RNA splicing (removing introns) in nucleus
provides differential control over protein function enabling e.g. cell differentiation
o The nucleolus is the largest substructure inside the nucleus. In the nucleolus, the first step of
ribosome synthesis occurs by combining ribosomal proteins and transcribed rRNA
o The internal membranes create distinct environments that enable different chemical
processes:
1. Peroxisomes ( containment of H2O2 )
2. Lysosomes ( acidic  specialized vesicles that digest large molecules with the aid of
hydrolytic enzymes)
3. Cytoplasm (= everything a cell consists of, except the nucleus, cell membrane and cell
wall )
4. Cytosol ( cytoplasm without the organelles )




o Having compartments with different conditions optimizes cellular processes and elongates
life, but much energy is needed to prevent disorder
o ER (endoplasmic reticulum)




Gedownload door Michou Weimar (michoumelody@live.nl)

Voordelen van het kopen van samenvattingen bij Stuvia op een rij:

Verzekerd van kwaliteit door reviews

Verzekerd van kwaliteit door reviews

Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!

Snel en makkelijk kopen

Snel en makkelijk kopen

Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.

Focus op de essentie

Focus op de essentie

Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!

Veelgestelde vragen

Wat krijg ik als ik dit document koop?

Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.

Tevredenheidsgarantie: hoe werkt dat?

Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.

Van wie koop ik deze samenvatting?

Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper michouweimar. Stuvia faciliteert de betaling aan de verkoper.

Zit ik meteen vast aan een abonnement?

Nee, je koopt alleen deze samenvatting voor €3,49. Je zit daarna nergens aan vast.

Is Stuvia te vertrouwen?

4,6 sterren op Google & Trustpilot (+1000 reviews)

Afgelopen 30 dagen zijn er 67096 samenvattingen verkocht

Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen

Start met verkopen
€3,49  4x  verkocht
  • (2)
  Kopen