Samenvatting

Evolutionary Genetics - Summary (VU pre-master/minor/bachelor)

0 keer verkocht

Vak
Evolutionary Genetics

Instelling
Vrije Universiteit Amsterdam (VU)

This is an English summary for the course Evolutionary Genetics at the VU Amsterdam (given during the pre-master, minor, and bachelor). I used A LOT of images as visual support (for my visual learners).

[Meer zien]

Voorbeeld 4 van de 49 pagina's

Bekijk voorbeeld

Geupload op 6 februari 2024
Aantal pagina's 49
Geschreven in 2023/2024
Type Samenvatting

genetics
pcr
dna
virus
rna
variation
sequencing
transposons
transposable elements
phylogenetics
horizontal gene transfer
rna world
sexual selection

Volgen

Gonzo420 Lid sinds 3 jaar 27 documenten verkocht

€5,89

In winkelwagen

Opslaan

100% tevredenheidsgarantie
Direct beschikbaar na je betaling
Lees online óf als PDF
Geen vaste maandelijkse kosten

Summary Evolutionary Genetics

Lecture 1 – Introduction

Evolutionary Genetics
1. Molecular evolution
2. Phylogeny
3. Evolution mechanisms & population genetics

What are genes?
- DNA sequences that can produce RNA → genes not always result in protein

- Coding DNA → transcription leads to pre-mRNA → mature mRNA (processed) → translation leads
to protein

Pre-processing:
- Splicing
- 5’cap addition
- Poly-A tail addition
- Transport (from nucleus to cytoplasm)

- 5’cap: modified guanine nucleotide that has been added to the ‘front’ / 5’ end of mRNA → this is
critical for recognition by ribosome and protection from enzyme RNases
- 3’ poly-A tail: protect mRNA from degradation by exonucleases. This
‘tail’ is a long sequence of adenine nucleotides (several 100), and also
facilitates the export from the nucleus.

Non-coding RNA’s

1. rRNA (ribosomal RNA)
- A molecule is cells that forms part of the protein-synthesizing organelle
known as a ribosome. Helps translate the information in messenger RNA
(mRNA) into a protein.
- Small subunit → contains an mRNA binding site
- Large subunit → contains 3 tRNA binding sites (A, P and E site)
- Ribosomes can be found either floating free in cytosol OR bound to
rough ER (in eukaryotes)
- Ribosomes differ in size in prokaryotes (70S) and eukaryotes (80S).
- Small subunit: 16S in prokaryotes and 18S in eukaryotes

,2. tRNA (transfer RNA)
- Helps decode a mRNA sequence (codon / 3 nucleotides) into a protein (translation).

3. LncRNA (long non-coding RNA)
- There are many genes that give rise to distinct
transcripts (more than 28.000 in humans)
- We only know the function of very few of them
- LncRNA are longer than 200 nucleotides
- They’re not translated into a protein because
they lack long open reading frames
- E.g. Xist (X-inactive specific transcript) →
inactivation of 1 of the 2 X-chromosomes in
female mammals → a lncRNA binds to one the X-
chromosomes to inactivate it → monoallelic
expression

4. Small ncRNA (microRNA / miRNA)
- Play an important role in in post-transcriptional gene regulation → miRNA’s regulate their targets by
translational inhibition or induction of degradation
- Small ncRNA is shorter than 200 nucleotides

5. siRNA (short interfering RNA)
- Interferes with the expression of specific genes with complementary nucleotide sequences by
degrading mRNA after transcription → thus preventing translation

6. piRNA → DNA methylation → preventing transcription

What are mutations
- Changes in the DNA → can be good/bad (affecting fitness), neutral or nearly neutral
- Selection: is an allele maintained or removed form population

Types of proteins
- Antibodies
- Enzymes
- Hormonal proteins
- Structural proteins
- Storage proteins
- Transport proteins

,Protein folding
- Primary structure: sequence of amino acid chain (polypeptide)
- Secondary structure: local folding of polypeptide chain into α -helix (spiral) or β-sheet (sheet)
- Tertiary structure: 3D folding pattern of a protein due to amino acids that are not laying next to
each other, such as hydrogen bonds or hydrophobic interactions.
- Quaternary structure: protein consisting of more than one amino acid chain

Active site: the region of an enzyme where substrate molecules bind and undergo a chemical
reaction → the amino acids here form a temporary bond with the substrate

Types of mutations
1. Silent: change of a single nucleotide does not affect the sequence of amino acid chain
2. Missense: change of a single nucleotide does affect the sequence of amino acid chain
3. Nonsense: point mutation that results in a premature stop codon or a nonsense codon

Nucleotides
- Purines (two ring structure): Adenine, Guanine → are larger
- Pyrimidines (one ring structure): Cytosine, Thymine (DNA), Uracil (RNA)

A. Point mutations (SNP’s): Transitions are (twice) more likely to happen than transversions
- Transitions: Purine → purines OR pyrimidines → pyrimidines
- Transversions: Purine → pyrimidines
B. Insertion: insertion of a nucleotide in the DNA sequence
C. Deletion: deletion of a nucleotide in the DNA sequence

, Origin of genes
- Ribozymes (RNA enzyms): RNA-molecules that function as
protein enzymes → first genes may have encoded for just RNA
- After building a small collection of genes, the following things
happened:
- Mutations
- Polyploidy (di-, tri-, tetraploid)
- Duplication (e.g. alleles of hemoglobin)

Polyploidy (or ploidy) allows for mutation accumulation → if the
mutation is beneficial in the population, it’ll become fixed
- Also, more genetic diversity

Genome structure: Prokaryotes vs. Archaea vs. Eukaryotes

Eukaryotes
- Intro-exon structure (huge variation among eukaryotes)
- DNA divided over chromosomes (vary in size)
- Chromosomes located inside nucleus
- Chromosomal DNA that is packaged by 8 histones is called a
nucleosome (plays a role in epigenetic regulation)
- Eukaryotes with mainly diploid or haploid stage
- ‘Single gene’ transcription units (few exceptions)

Bacteria
- No introns (few exceptions)
- Circular chromosomes and circular plasmids
- Several operon type transcription units

Archaea
- Some introns (different proportions from eukaryotic introns)
- TATA box-like binding sites (like eukaryotes, unlike bacteria)
- Circular chromosomes and circular plasmids
- DNA associated with histone-like proteins (also bind to the DNA)
- Several operon type transcription units

TATA box → continued sequence of T’s and A’s.

Dit zijn jouw voordelen als je samenvattingen koopt bij Stuvia:

Bewezen kwaliteit door reviews

Studenten hebben al meer dan 850.000 samenvattingen beoordeeld. Zo weet jij zeker dat je de beste keuze maakt!

In een paar klikken geregeld

Geen gedoe — betaal gewoon eenmalig met iDeal, creditcard of je Stuvia-tegoed en je bent klaar. Geen abonnement nodig.

Direct to-the-point

Studenten maken samenvattingen voor studenten. Dat betekent: actuele inhoud waar jij écht wat aan hebt. Geen overbodige details!

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.