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Tutorial 1. Biology background for the course. Genome sizes and number of genes. Orthologs vs. Paralogs. Orthologs – Genes in different genomes with a common origin Paralogs – Genes in the same genome with a common origin.
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Tutorial 1 Biology background for the course
Orthologs vs. Paralogs Orthologs – Genes in different genomes with a common origin Paralogs – Genes in the same genome with a common origin http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2010/Rydberg/Orthologs.html
The Central Dogma http://www.labgrab.com/users/labgrab/blog/central-dogma-genetics-incomplete_id%3D904 Transcription Translation Replication Single stranded (SS) RNA Double stranded (DS) DNA Amin Acids Nucleic Acids
Prokaryotes vs. Eukaryotes • Smaller cells • Single-celled organisms • Ancient • Multi-cellular organisms • Has a nucleus http://www.phschool.com/science/biology_place/biocoach/cells/common.html
RNA splicing in Eukaryotes Only exons form the final mRNA that the protein will be translated from. Exons << Introns http://en.wikipedia.org/wiki/File:Pre-mRNA_to_mRNA.svg
Alternative splicing ~100,000 proteins and only ~20,000 genes. How can that be? Gene != Protein Protein 1 Transcript 1 Protein 2 Gene Transcript 2 Nucleic Acids Amino Acids The different mRNA molecules created by alternative splicing are called transcripts or isoforms. Transcript 3 Protein 3
Alternative Splicing in Eukaryotes Prokaryotes usually have smaller and more compact genomes. Eukaryotes “can afford” to have alternative splicing. http://commons.wikimedia.org/wiki/File:DNA_alternative_splicing.gif
What are proteins? Biological molecules with a variety of functions: • Chemical and metabolic reactions Enzymes in the gut, replication of DNA • Signal transductions Receptors on cells • Structural proteins For example collagen and keratin in hair, nails and feathers • Binding ligands Antibodies that bind foreign antigens
Amino acids form proteins Each AA has traits that are reflected in the protein’s folding and function Neutral, Non polar Neutral, polar Basic Example: trans-membrane protein Acidic https://www.mun.ca/biology/scarr/iGen3_06-02.html http://bio1151b.nicerweb.com/Locked/media/ch07/transmembrane.html
Amino Acids G A S T C V L I M P F Y W D E N Q H K R Nucleic Acids A G T C http://www.biogem.org/blog/rna-to-protein-translation-in-perl/
Regulation • If all the cells in our body have the same DNA code – why is a brain cell, a muscle cell and a skin cell different from one another? • Chimps and humans share 98.5% of the DNA sequence – why are they so different?
Regulation • Only ~1% of the DNA sequence encodes for proteins. Some of the rest is used for regulation of gene expression. The DNA sequence to which a protein binds is called a binding site. Regulation can both activate or repress expression.
Brain cell Muscle cell Gene transcription start site Repressor binding sites Activator binding sites
Real life is a lot more complex… E. Davidson, Current Opinion in Genetics & Development, 2009
Notes for CS students • The challenge in this course is not in algorithms or mathematical proofs, but in understanding the biological questions and applying appropriate computational methodologies to solve them. • Most of the topics we will talk about is under constant research.