Molecular Basis of Gene Expression

Study Notes

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.

Description

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.