Molecular Biology Flashcards
Messenger RNA
• RNA copies of DNA regions that code for proteins - it is a temporary information transfer molecule
Transfer RNA (tRNA):
• “transfers” amino acids to growing polypeptide
Ribosomal RNA
• specialized RNA protein complex from a ribosome involved in protein synthesis
miRNA
• microRNA, noncoding RNA that helps regulate gene expression
siRNA
• small/short interfering or silencing RNAs that are involved in post-transcriptional gene silencing
replication
synthesis of an exact duplicate DNA molecule
maintenance of the genetic information
transcription
making an RNA copy of a DNA molecule
translation
converting RNA sequence into an amino acid sequence
four different bases in DNA
A, G, C, T
A-T
G-C
Proteins can be modified in a variety of ways
after initial synthesis
List those types of modifications
– Cleavage (removal of signal sequences)
– Glycosylation (addition of oligosaccharides to amino
acid residues)
– Phosphorylation
– Addition of lipids, nucleotides
– Acetylation, methylation, hydroxylation
What does post-translational modification of proteins do?
alter function, target proteins,regulate interactions, etc.
What is cDNA?
– DNA copy of an mRNA
– Contains the protein coding domain; no introns
– When transcribed RNA requires no processing;
can be translated directly
Plasmid DNA Delivery
Advantages
- Few limitations on DNA size
- Non-infectious
- Chemically defined
- Lack of immune response
Plasmid DNA Delivery
Limitations
• Inefficient delivery • Low expression levels • Short term expression • Toxicity • Different methods for different cells
• Proteins have a variety of functions
– Catalysis of chemical reactions (enzymes)
– Structural (histones, cytoskeletal proteins)
– Regulatory (transcription factors, growth factors)
Ribonucleic Acid (RNA) differences from DNA
• Mostly single stranded; base pairs can form
within a strand
Ribonucleic Acid (RNA) functions
– Genetic material for some viruses
– mRNA: an RNA copy of a region of DNA that
codes for a protein
– Other RNA species are involved in protein
synthesis
Expression Cassettes
An expression cassette is a part of a vector DNA used for cloning and transformation
– Promoter
– cDNA (transgene)
– Termination signal (poly A site)
Replicons
• Sub-genomic constructs of pathogenic viruses
• Contain sufficient genes to study replication
process but not produce progeny virions
• Qualify as rDNA work
– Genetically modified
– Usually contain >2/3 genome
• Examples: HIV, HCV replicons
