Molecular Basis of Gene Expression

Molecular Basis of Gene Expression

• Gene expression is the process of using gene information to synthesize a functional gene product, typically a protein.
• Two main stages are transcription and translation.
• Transcription converts a gene's DNA sequence into a complementary RNA molecule (mRNA).
• Translation uses the mRNA sequence to create a polypeptide chain, which folds into a functional protein.
• Regulation controls gene expression timing and location, responding to cellular needs.

Splicing

• Splicing is critical for gene expression, especially in eukaryotes.
• Pre-mRNA molecules undergo splicing to remove non-coding introns.
• Exons (coding regions) are joined, forming mature mRNA.
• Alternative splicing allows one gene to create multiple protein isoforms by selectively including exons. This increases protein diversity.
• The spliceosome, a complex of snRNPs and proteins, facilitates splicing.
• Splicing errors can cause diseases.

Plasmids

• Plasmids are small, circular DNA molecules, separate from chromosomal DNA in bacteria and some other organisms.
• They replicate independently.
• Plasmids offer advantageous traits to host cells, like antibiotic resistance or unusual substance metabolism.
• Plasmids are vectors in recombinant DNA technology.
• Foreign genes can be inserted into plasmids to create recombinant DNA.
• These plasmids are introduced into host cells for expressing the foreign gene.
• Plasmids typically contain an origin of replication (ori), selectable markers (e.g., antibiotic resistance genes), and cloning sites (polylinkers) for foreign DNA.

PCR (Polymerase Chain Reaction)

• PCR is an in vitro method for amplifying specific DNA segments.
• It uses repeated cycles of denaturation, annealing, and extension.
• Denaturation separates double-stranded DNA into single strands (template DNA is exposed).
• Annealing allows primers to bind to complementary sequences, initiating replication.
• Extension enables DNA polymerase to synthesize complementary DNA strands using the template and primers.
• This cycle exponentially amplifies the target DNA.
• PCR components include DNA sample, primers, DNA polymerase, and nucleotides.
• PCR is crucial for analyzing minute DNA quantities in forensics, diagnostics, and research.

Transcriptome

• The transcriptome represents all RNA transcripts in a cell or tissue at a specific time and condition.
• It contains mRNA, tRNA, rRNA, and other non-coding RNAs.
• The transcriptome shows which genes are active.
• Studying the transcriptome gives insights into gene expression patterns and cellular processes.
• Changes in the transcriptome can indicate disease.
• Techniques like RNA sequencing (RNA-Seq), microarrays, and quantitative PCR measure RNA species abundance.

Explore the essential processes of gene expression, focusing on transcription and translation. Discover how splicing modifies pre-mRNA and the role of regulatory mechanisms in protein synthesis. This quiz covers key concepts in molecular biology regarding gene function.