Proteins 1 Flashcards
The Central Dogma
a scheme that underlies information processing at the level of gene expression
the flow defines the relation between the seq. of bases in DNA and the seq. of amino acids in a protein
DNA—–>RNA—–> Protein
Flaws in the Central Dogma
- It states that such information cannot be transferred back from protein to either protein or nucleic acid
- The basic tenets of the scheme are correct but it is an oversimplification
The Genome
all genetic information of an organism,
nucleotide sequences of DNA (or RNA in RNA viruses)
-includes both the genes (the coding regions) and the noncoding DNA, as well as mitochondrial DNA and chloroplast DNA
Genomics
The study of the genome
The Proteome
entire set of proteins that is, or can be expressed by a genome, cell, tissue or organism, at a given time, under defined conditions
The functional representation of the genome
Proteomics
The study of the proteome
Compare the size and complexity of the proteome with the genome
The proteome is much larger and more complex because there are various transcription pathways (alternative splicing of pre-mRNA) and post-translational modifications
Examples of post-translational modifications
proteolytic cleavage, glycosylation and phosphorylation
What does the proteome vary with?
- cell type
- developmental stage
- environmental conditions
It is NOT a fixed characteristic of the cell
The function of a protein depends on what?
It’s 3D structure
amino acid seq. —-> 3D structure —-> function
What is the C-value?
The amount of DNA per haploid genome
The C-value paradox
There is no real correlation between genome size and complexity of the organism
Why is there no correlation between genome size and complexity?
- the proportion of non-coding DNA varies with organism
- repetitive DNA
- genome duplication
Polyploidy
The organism has more than 2 sets of chromosomes in its cells
Ploidy
The mutation caused by the change in the no. of chromosomes in an organism
Autopolyploidy
polyploids produced by the multiplication of chromosome sets that are initially from a single species (often sterile)
Allopolyploidy
polyploids produced from 2 different species
Causes of polyploidy
failure of cell division (by abnormal meiosis):
- fusion of a diploid and haploid gamete to form a triploid organism
- fusion of 2 diploid gametes to produce a tetraploid
What does the C-value correlate with?
- cell size
- cell division rate
- body size
- metabolic rate
- developmental rate
- organ complexity
- geographical distribution
- extinction risk
Non-coding RNA
referred to as the dark matter of the genome
- small non-coding RNA
- large non-coding RNA
What makes analysing and investigating the proteome difficult?
proteins do not exist in isolation, they often interact with each other to form complexes with specific functional properties
