Bioinformatics/Genome Informatics/Computational Biology
Q. What is Bioinformatics?
Bioinformatics is an interdisciplinary field bringing together biology, computer science, mathematics, statistics, and information theory to analyze biological data for interpretation and prediction. This field is also known as Computational Biology and Genome Informatics.
Q. What is the central dogma of molecular biology?
The central dogma of molecular biology states that information is contained in DNA, then it is transcribed into mRNA and finally translated into protein.
Q. What is the structure of DNA?
DNA (deoxyribo nucleic acid) consists of two long strands running in an antiparallel orientation to form a double helix. The two strands are complementary of each other and each strand consists of phosphate, deoxyribose sugar and nucleotides (adenine[A], guanine[G], cytosine[C], and thymine [T]). The nucleotides in two strands follow the base pairing rules: A pairs with T and C pairs with G.
Q. How is protein made from a DNA sequence?
- First the DNA sequence is transcribed into an mRNA sequence using the nucleotides A,G,C and U (uracil which is used in place of thymine).
- Then this RNA sequence is exported out of the nucleus (in eukaryote only) to cytoplasm for translation into a protein primary sequence.
- Then the RNA sequence is deciphered as a series of three-letter codons where each codon correspond to an amino acid.
1. DNA sequence:AGTCTCGTTACTTCTTCAAAT 2. mRNA sequence:AGUCUCGUUACUUCUUCAAAU 3. 3-letter codons: AGU CUC GUU ACU UCU UCA AAU 4. Amino acid sequence: SLVTFLNwhere S=Serine (AGC/AGU), L=Leucine (CUA/CUC/CUG/CUU/UCA/UUA/UCG/UUG), V=Valine (GUA/GUC/GUG/GUU), T=Threonine (ACA/ACC/ACG/ACU), F=Phenylalanine (UCC/UUC/UCU/UUU), N=Asparagine (AAC/AAU).
Q. What are start and stop codons?
A start codon signals the machinery of the cell the beginning of the translation of mRNA sequences into amino acids. There is only one start codon which is ATG ( or AUG in mRNA [methionine]).
Any one of the three stop codons: TGA, TAG and TAA tells the cell machinery to stop translating codes into amino acids.
Q. What is gene expression level?
Gene expression is the process by which messenger RNA (mRNA) and eventually protein is made from the DNA template of each gene. The portion of each gene that is represented as mRNA is known as coding sequence for that gene. Since mRNA is an exact copy of DNA coding regions, genomic analysis at the mRNA level is used as a measure of gene expression.
Gene expression level indicates the amount of mRNA produced in a cell during protein synthesis; and is thought to be correlated with the amount of corresponding protein made.
Q. What is the hypothesis behind gene expression based classification of patient samples?
The hypothesis behind gene expression based classification is that expression levels are affected by a large number of environmental factors, including temperature, stress, light, and other signals, that lead to change in the level of hormones and other signaling substances, and many or all human diseases may be accompanied by specific changes in gene expression levels.