L2 eukaryotic genome
Diploid = 2 genomes in a cell, slightly different
1 genome = haplotype, 2 genomes = genotype
Polyploid = more than 2 genomes in a cell (can be because multiple nuclei)
Most plants are polyploid
Chromosome:
1. DNA double helix wrapped around nucleosomes
2. Nucleosomes fold
3. Chain folds
“The human genome” is a reference genome -> hgX = human genome number X
Differences between human genomes:
- Structural differences
- Different bases
- Certain pieces that others don’t have at all
Future: graph genome
Karyotype = chromosome count and what they look like (= length, banding pattern, centromere
position), under light microscope for certain organism
Banding pattern = Giesma banding = G-banding
- AT gives dark region -> gene arm
- GC gives light region -> open chromatin -> transcriptionally active
Locus = where on banding pattern -> long arm = q, short arm = p; GC bands are numbered
Gene name: chromosome number, arm, region, band, ., subband
Cell lines: not very trustworthy, because old and manipulated
HeLa cell line: very old + fucked up
Simple sequence repeats = SSRs = almost perfect repeats of short sequences, mostly located in
centromeres, can be involved in disease
Jumping genes = transposable elements = TE;
move around in gene, important in evolution
- DNA transposon = cut + paste
- Retro transposon = copy + paste,
via RNA intermediate + reverse transcriptase
Nucleotide content differs: within/between species
- GC% = GC content = number of G+C as a fraction of
the sequence length
- CpG = CG dinucleotide, C followed by G
- CpG island = region with lot of CpGs and high GC%
GC content varies across/within species
, In humans CpG less than expected -> 1% instead of expected 4%
-> because deamination (C->T) is changed to AT
Most CpGs are methylated (except in CpG islands -> usually promotor of housekeeping gene)
-> which leads to deamination
If CpG island is methylated -> gene is repressed
In bacteria, archaea and viruses: (weak) relation between gene number and complexity
-> Not for eukaryotes
Hard to decide how many genes an eukaryote has: alternative splicing etc
Gene = genomic sequence (DNA or RNA) that encodes for functional element (protein or RNA) and is
coherent. Genes might overlap.
Gene families: similar genes found in different organisms -> hox genes: body plan
Genome duplication: lead to genome evolution -> more complexity -> back to diploid
Homology
- Homologs = shared ancestry
- Ortholog = by speciation
- Paralog = by duplication
L3 Sequencing
First generation sequencing:
- Sanger
o Chain termination technique = dideoxynucleotides without 3’ hydroxyl group -> can
see where chain ends with which base + radio-/fluorlabeling
o 800-1000 nucleotides
o Very accurate but low throughput
- Maxam-gilbert
o Radiolabelled DNA -> chemical treatment to break
Second generation sequencing = next generation sequencing:
- Illumina
o Bridge amplification
o Single end read = one way on the bridge
paired end read = from both ways on the bridge
- Ion Torrent
o Ion semiconductor sequencing
Third generation sequencing: long reads
- Pacific biosciences
o Single molecule, real time sequencing = SMRT
- Oxford nanopore
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 lisavddries. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €5,49. Je zit daarna nergens aan vast.