Which three major eukaryotic model organisms were compared in the year 2000? And what was the result?
Drosophila melanogaster (fly)
C. elegans (worm)
S. cerevisiae (yeast)
& some human genes (mammalian) even when it was not fully sequenced
highest proportion of shared genes between mammals and fly with 50% of fly genes giving significant BLAST (e^-10) match to mammalian gene
35% of worm genes and 37% of yeast matched a mammalian gene
Which database can be used to look up genes associated with disease
OMIM
How did they match human disease genes with other organisms?
used disease genes from OMIM as quereis for protein BLAST searches of fly, worm & yeast
cutoff e<10^-6
What was the result when they match human disease genes with other organisms?
Of 289 human disease genes:
230 (80%) were found in the fly
212 (73%) were found in the worm
120 (42%) were found in yeast
Model organisms, especially Drosophila, can be very useful for studying human disease.
How strongly differ the genoms betweeen the 12 sequences drosophilas compared to other groups?
The sequence divergence among the species is about the same as that among mammals
What do we understand under core Drosophila genome
about 7000 genes had single copy orthologs in all 12 species and almost all of these showed evidence for expresssion and lacked transposable element insertions
How do the other 5000 homologous genes behave which do not belong to the single copy core genome?
Vorderseite: Wie verhalten sich die restlichen 5.000 homologen Gene, die nicht zum Single-Copy-Core-Genom gehören?
Rückseite: Sie bilden Multi-Genfamilien. Das bedeutet, sie liegen in den verschiedenen Spezies nicht als Einzelkopie vor, sondern haben sich durch Genduplikationen in mehrere Paraloge aufgespalten.
They grouped in multi gen families
They are not as single copies between the different species instead they split up through genduplication into parlalougs
Why is it hard to to say for the unique genes of drosophila if they are real functional genes
A lot of them do not show evidence for gene expression
What is the major model system for plant genetics
mustard weed, Arabidopsis thaliana (sequenced in 2000)
How big is Arabidopsis
125 mb with aroudn 25000 genes
How many genes do the fly, worm and human have?
fly 14000
worm 19000
human 21000
Why can we say that gene duplication has played an important role in role in plant genome evolution
there is a higher percentage of arabiopsis genes that are part of multi-gene families
Does Arabidopsis have more genes that are present as parlogs comapred to fly and worm
yes
When was rice (oryza sativa) sequenced, how big is it and what effect did it have?
2002
430 Mb with 40000-50000 genes
allowed first comperative genomic analyiss in plants
what were the result for the a comperative genomic analyiss from rice to Arabidopsis, yeast, worm or fly
80-85% of the predicted Arabidopsis genes had a homolog in rice.
Only ≈50% of the predicted rice genes had a homolog in Arabidopsis.
Of the genes shared by Arabidopsis and rice, 30.5% had a homolog in yeast, worm, or fly.
Of the rice genes with no homolog in Arabidopsis, 2.4% had a homolog in yeast, worm, or fly.
Which question can be solved with horizontal gene transfer?
Are there bacterial genes in the human genome?
Were genes transferred directly from bacteria to humans (or other vertebrates)?
When scientists found 223 genes shared only between bacteria and vertebrates, what 4 scenarios (a–d) did they propose to explain it?
Contamination: A simple lab mistake (ruled out by PCR)
Ancient Ancestry: An ancient gene shared by all, but lost in flies/yeast (The winning theory!).
Human-to-Bacteria Transfer: Vertebrates gave genes to bacteria (ruled out as too complex).
Bacteria-to-Human HGT: Bacteria directly transferred genes to vertebrates (The authors' initial favorite, but later debunked)
What two major findings caused the number of suspected bacterial HGT genes in the human genome to drop?
Broader Genome Sequencing: As more non-vertebrate eukaryote genomes were sequenced, homologs to these "missing" genes were finally found. This strongly supports the independent gene loss hypothesis. 2. Phylogenetic Analysis: If HGT had occurred, human genes should look more similar in sequence to bacterial genes than to other non-vertebrate eukaryotes. Sequence trees proved this is not the case.
How much homologs genes are between mouse and human
98%
How are the genes between human and mice arranged
On a small scale, the order of genes was well conserved, but on a larger scale, there were many chromosomal re-arrangements.
-> mouse and human genes are found in conserved blocks (same gene is same order)
-> but chromosomal locations of these blocks are not well conserved (e.g. gene blocks from mouse chrom16 spreaf over 6 different in human)
Last changed13 days ago