Introduction to Bioinformatics 3

Introduction to Bioinformatics 3

• DNA acts as the hereditary material, transmitting genetic information between generations.
• Replication, transcription, and translation are the key processes.

DNA/RNA/Protein Relations

• DNA → RNA (transcription): RNA polymerase creates RNA based on DNA template.
• RNA → Protein (translation): Ribosomes synthesize proteins based on RNA.
• Proteins and some RNAs carry out biological functions.

Gene Expression

• Genes encoding proteins have two stages: transcription (creating RNA from DNA) and translation (creating proteins from RNA).
• Some genes do not code for proteins.

Chromosomes and Heredity

• Chromosomes are the physical basis of heredity.
• In 1915, Thomas Hunt Morgan proposed the chromosomal theory of heredity.
• Humans have 23 pairs of chromosomes in somatic cells.

Karyotype

• A karyotype is a visual representation of a cell's chromosomes, arranged in pairs.
• Chromosomes are studied by microscopic techniques.
• Visualisations of human chromosomes are commonly used to assess for chromosomal abnormalities
• Modern investigation of karyotypes focus on sequencing.

DNA Structure and Function

• DNA is a double helix, with the sequence of its bases carrying the genetic information.
• The bases of DNA are cytosine(C), guanine(G), adenine(A), and thymine(T).
• Specific base pairing (A-T and C-G).

Gene Expression: DNA to RNA

• Transcription produces mRNA.
• Transcription is followed by translation to produce a protein from the mRNA.

Gene Code

• Specific combinations of three bases (codons) determine amino acid sequence.
• The genetic code is universal.
• There are 20 standard amino acids.

Genetic Processes

• The processes described involve DNA transcription, RNA translation, the role of mRNA, and the concept of a "central dogma"

Central Dogma of Molecular Biology

• DNA → RNA → Protein: genetic information flows from DNA to RNA to protein.

The Central Dogma

• Information flow generally proceeds in one direction—from DNA to RNA to protein—in most organisms.
• Exceptions exist as in some viruses.
• The flow of information is not always unidirectional.

Gene Structure

• Genes usually have a regulatory region, exons, and introns.
• Exons code for a protein; introns do not.
• Pre-mRNA includes both introns and exons.

Alternative Splicing

• A process where different combinations of exons are joined together to make different proteins from a single gene.
• This allows for multiple proteins from a single DNA sequence.
• In eukaryotes, the transcription of a given gene results in the production of multiple forms of the corresponding RNA molecule.

Gene Regulation

• Control of gene expression in various ways (example: transcription, splicing).

Genome Structure in Bacteria

• Operons: Multiple genes transcribed in clusters with shared regulatory elements.
• Regulatory elements control the transcription of the operon.
• Transcription and translation can be coupled in prokaryotic cells, whereas they occur separately in eukaryotic cells.

Genome Availability

• The availability of genome data has exploded (exponential growth).
• Recent advances in genome sequencing speed up the process of collecting genomics data.
• DNA sequencing technology advancements have made sequencing faster, more efficient, and more affordable.

Genome Annotations

• Processes to annotate genomic sequences.
• Methods used to map genes within a genome.
• Strategies for identifying protein-coding genes.

Protein-Protein Interactions; Interactome

• Proteins frequently interact.
• The collection of interactions in an organism is called the "interactome".
• Proteomics studies focus on proteins.
• Tools study protein-protein interaction networks to obtain a snapshot view of cellular processes.

Gene Expression in Different Tissues

• Expression patterns vary in different tissues.
• Techniques like "gene expression profiling" identify genes actively used in different tissues.
• Gene activity differs depending on the tissue in which they are located.

This quiz covers key concepts in bioinformatics, including DNA replication, transcription, and translation processes. It also discusses gene expression, the role of chromosomes in heredity, and the significance of karyotypes. Test your understanding of these fundamental topics in molecular biology.