Samenvatting
Summary Genetics chapters 14,15,16,17
- Vak
- Genetics
- Instelling
- Vrije Universiteit Amsterdam (VU)
Chapters 14,15,16,17 genetics vu biomedical sciences
[Meer zien]Voorbeeld 2 van de 12 pagina's
Voorbeeld 2 van de 12 pagina's
In winkelwagengesponsord bericht van onze partner
Verkoper
Volgen
Voorbeeld van de inhoud
CHAPTER 17Some genes do not encode polypeptides but are transcribed into non-coding
RNAs (ncRNAs). In most cell types, ncRNAs are more abundant than mRNAs.
In a typical human cell, only about 20% of transcription involves the production
of mRNAs, whereas 80% of it is associated with making ncRNAs (Mainly rRNAs and
tRNAs).
17.1 OVERVIEW OF NON-CODING RNAs
ncRNAs can bind to different types of molecules, which is why they can perform
so many functions.
RNA molecules can form stem-loop structures, which may bind to pockets on
the surface of proteins. The binding of ncRNAs to DNA, RNA allows ncRNAs to affect
transcription and translation.
FUNCTIONS
Scaffold: ncRNA binds a group pf proteins.
Guide: ncRNA binds to a protein and guides it to a specific site in the cell.
Alteration of Protein Function or Stability: ncRNA binds to a protein and alters that
protein's structure
the ability of the protein to act as a catalyst
the ability of the protein to bind to another molecule
the stability of the protein
Ribozyme: RNA molecules with catalytic function.
Blocker: ncRNA physically prevents or blocks a cellular process from happening.
Decoy: ncRNA recognizes another ncRNA and sequesters it.
ncRNAs are broadly categorized according to their length
• Long non-coding RNAs (lncRNAs) are longer than 200 nucleotides.
• small regulatory RNAs (also called short ncRNAs) are shorter than 200 nucleotides.
MicroRNAs fall into this category, usually 20-25 nucleotides.
The Emergence of Living Cells May Have Been Preceded by an RNA World
Researchers propose that living cells arose from more primitive structures.
1
CAROLINA SANZ HERNÁNDEZ
, A protobiont is the term for a precursor to living cells which consisted of an
aggregate of molecules and macromolecules that acquired a boundary, such as a lipid
bilayer. It was able to maintain an internal chemical environment distinct from that of
its surroundings.
Characteristics that make Protobionts possible precursors of living cells:
• A boundary that separated the internal contents of the protobiont from the
external environment.
• Polymers inside the protobiont that contained information.
• Polymers inside the protobiont that had catalytic functions => simple
metabolism.
• The precursors developed the capability of self-replication.
Scientists favor the idea that RNA was the first macromolecule found in
protobionts.
RNA world refers to a period on Earth in which RNA molecules, but not DNA or
proteins, were found within protobionts.
RNA would have carried out three key functions:
1. Information storage in its nucleotide base sequence
2. Self-replication by functioning as a ribozyme and using RNA as a template to make
complementary RNA molecules
3. Catalytic activity such as the synthesis of polypeptides and other kinds of organic
molecules.
17.3 NON-CODING RNAs
ncRNAs can exert their effects on RNA molecules that are already made. ncRNAs affect
the ability of mRNAs to be translated or degraded.
Experiment 17A – mRNA silencing
Researchers had used antisense RNA to inhibit mRNA translation – complementary to
target mRNA.
• Oddly, researchers also introduced sense RNA, which also inhibited mRNA expression
• The effects of antisense RNA often persisted for a very long time (longer than
predicted based on stability of the RNA used).
Led Fire and Mello to investigate how the introduction of RNA into cells inhibits
mRNA.
THE GOAL: understand how the experimental injection of RNA was responsible for the
silencing of particular mRNAs.
Andrew Fire and Craig Mello: used the nematode worm Caenorhabditis elegans
• Easy to inject with RNA.
• The expression of many of its genes had already been established.
2
CAROLINA SANZ HERNÁNDEZ
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
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
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
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 carolinasanzhernandez. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €6,49. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 52510 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen