AH Biology: Unit 1 Proteomics and Protein Structure 1

Proteonomics LOs: The proteome is larger than the genome due to RNA splicing and post-transitional modification. As a result of gene expression not all genes are expressed as proteins in a particular cell. The proteome is the entire set of proteins expressed by a genome. While DNA sequencing and microarray technology allow the routine analysis of the genome and transcriptome, the analysis of the proteome is far more complex.

Think What is the proteome? What codes for the proteome? How will we figure out how the proteome works? Why is it important that we understand the proteome? What are the applications of this technology to mankind in the future? Think about these questions as you study proteins in this section. Knowing the genome of an organism forms only the known words of the genetic language, but does not show you the sentences and paragraphs that correspond to the function of the proteins produced and how they interact. Also see the PowerPoint presentation in Scientific Method 1 for more information on the human genome and proteomics.

Think back to higher…… What is the genome? The genome of an organism is the entire hereditary information encoded in DNA. It is made up of genes and other DNA sequences that do not code for proteins (i.e. introns and exons).

Proteomics Activation and inactivation of genes The proteome is the entire set of proteins expressed by a genome. It is larger than the genome due to RNA splicing and post-transitional modification. Activation and inactivation of genes Transcription animation Translation animation To understand proteomics you need to understand transcription and translation first. You then need to understand the function of the rough endoplasmic reticulum and golgi apparatus in relation to protein modification.

RNA splicing

RNA splicing (revision) When mRNA is transcribed in eukaryotic cells it is composed of introns and exons. Introns are the non-coding sequence of the mRNA and will not be expressed in the protein molecule. They are spliced out (removed) from the mRNA. Exons are the coding sequence and will be expressed in the protein molecule. RNA splicing in detail. Transcription still happens in the same way using RNA polymerase.

Post-translational modification (revision) Post-translational modification is the alteration of the protein after translation Post-translational modification occurs in the rough endoplasmic reticulum, Golgi apparatus and target site of the protein. Post-translational modification can involve 1. the addition of chemical groups 2. the covalent cleavage of the polypeptide

Post-translational modification These modifications give the proteins specific functions and target the proteins to specific areas within the cell and the whole organism.

RNA splicing and post-translational modification RNA splicing and post-translational modification results in the proteome being larger than the genome. One gene may code for many proteins. The proteome may be as many as three orders of magnitude (103) larger than the genome. Human genome = 30,000 genes. Human proteome > 100,000 proteins.

Analysis of the genome While DNA sequencing and microarray technology allow the routine analysis of the genome and transcriptome, the analysis of the proteome is far more complex. Genome analysis involves the following techniques: Sanger sequencing in detail gel electrophoresis cycle sequencing microarray in detail.

The Transcriptome A transcriptome is the full range of messenger RNA, or mRNA, molecules expressed by an organism. While the genome is stable, the transcriptome actively changes. In fact, an organism's transcriptome varies depending on many factors, including stage of development and environmental conditions.

Analysis of the proteome This is a complex process as the proteins expressed differ from cell to cell and within the life cycle of the cell. In a multicellular organism all the different cell types throughout the lifetime of the organism would have to be sampled in order to determine all the possible proteins expressed. Proteomics technologies and cancer. See Proteomics tutorial 2 about the parasite Trypanosoma brucei and Trypanosoma evansi and the proteins identified in its life cycle.

Think What is the proteome? What codes for the proteome? How will we figure out how the proteome works? Why is it important that we understand the proteome? What are the applications of this technology to mankind in the future? Think about these questions again and answer them as part of a discussion in class based on what you have learned in this section. Also see the PowerPoint presentation in Scientific Method 1 for more information on the human genome and proteomics.

Proteonomics Key Concepts: The ____________ is larger than the genome due to RNA splicing and post-transitional modification. As a result of gene expression not all genes are expressed as __________ in a particular cell. The proteome is the entire set of __________ expressed by a genome. While DNA sequencing and microarray technology allow the routine analysis of the ____________ and ___________, the analysis of the proteome is far more complex.

Proteonomics Key Concepts: The proteome is larger than the genome due to RNA splicing and post-transitional modification. As a result of gene expression not all genes are expressed as proteins in a particular cell. The proteome is the entire set of proteins expressed by a genome. While DNA sequencing and microarray technology allow the routine analysis of the genome and transcriptome, the analysis of the proteome is far more complex.