MCB 121- Lecture 1

MCB 121- Lecture 1 - MCB 121 Lecture 1 I Introduction to...

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MCB 121 - Lecture 1 I. Introduction to Course II. Organization and Content of Genomes III. Genome Sequencing Exam: 2 midterms (30%) + comprehensive final (40%) OH: wed 10-11 am/ Thur 12-1:30 3061 SLB + professor's office Required: Molecular Biology of the Gene, Watson et al. 6th edition Benjamin Cummings (2008) Final exam 03/16/10 8am - 10am Human genome: 3.2 x 10^9 nucleotides or base pairs of DNA * this is the number of haploid complement of the genome * For diploid: 3.2 x 10^9 x 2 bp x 0.34nm/bp = 2M of DNA per cell Number of cells in our body is about 10^13 (ten trillions) cells/body * 10^13 cells/body x 2M = 50 round trips to the sun and back from earth Genome comprises both coding and noncoding region Genome size doesn't necessarily coordinate with the number of genes. ex. organism genome size # of genes Mycoplasma 0.58 Mb 500 Ecoli 4.6 Mb 4400 Yeast 12 Mb 5800 (Worm) C.elegans 103 Mb 14000 Human 3200Mb 20000 Arabidopsis (plant) 120Mb 27000 => MORE THAN WE HAVE * plants in general have more genes than animals What is a gene? 1. Basic unit of heredity 2. Information that is required to form an RNA transcript (siRNA, tRNA, mRNA, miRNA) * region of DNA codes for protein = this only consider the coding region open reading from of the gene. Gene contains coding regions and noncoding region - coding region: ~2% codes for proteins - nocoding region: contains sequences which promote transcription = can have promoters (sequences that will not be translated) = or intron (will be transcribed but removed prior to translation) and UTR Noncoding region contributes to the majority of the sequenced genome
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Important roles: 1. Functional DNA sequences: elements of eukaryotic chromosomes that are essential for replication of maintenance (chromosome maintenance) - centromere (length varies in species) - origins of replication - telomeres 2. Functional RNA: have very conserved structure (folds upon themselves by base pair interaction) - includes rRNA, tRNA, snRNA, miRNA - some have catalytic activities - these RNA thought to be relics of RNA world . ( earliest life form on the planet would be RNA molecule) 3. Gene relics - mutated duplicated genes = often times during evolution, the entire genome may duplicate itself which cause multiple copies of same genes. The extra copy of the gene can be mutated and become non-functional but also it gives the opportunity of the extra copy of the gene to have new role in the cell - pseudogene: recognizable, resemble as a mature RNA sequence, typically non-functional * Pseudogenes are defunct relatives of known genes that have lost their protein -coding ability or are otherwise no longer expressed in the cell
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MCB 121- Lecture 1 - MCB 121 Lecture 1 I Introduction to...

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