9. Transcription and Translation - What is a Gene? Flashcards
What is a gene?
Stretch of DNA chromosomal locus.
What are the two chromatin structures?
Heterochromatin - solenoid and euchromatin - beads on a string.
What is the product of transcription?
mRNA.
What are the five types of RNA?
mRNA, rRNA, tRNA, miRNA (microRNA) and noncoding RNA.
What is needed when making a polynucleotide or polypeptide?
An enzyme, activated substrate, a template and a three stage process:initiation, elongation and termination.
What is needed to make DNA?
Enzyme DNA polymerase, activated substrates dNTPs (deoxynucleoside triphosphate) and the template DNA.
What is needed to make a polypeptide?
Enzyme ribosome, activated substrate amino acids and the template mRNA.
What are the three stages of transcription in DNA replication?
Initiation, elongation and termination.
Describe the process of initiation in DNA replication, transcription.
A transcription factor (RNA polymerase) attaches to the promoter region. It reads downstream (5’ to 3’). The promoter region is the TATA box in eukaryotes and is a Pribnow box at -10 prokaryotes.
Describe the process of elongation in DNA replication, transcription.
The DNA template strand, aka non coding strand, is the template for the mRNA strand. It’s read 3’ to 5’ so the mRNA produced is 5’ to 3’.
How is pre-mRNA processes to mature mRNA?
Capping (at the 5’ end:5’ cap) which protects against degradation. Taking or polyadenylation (at 3’ end: polyA tail) which protected against degradation. Splicing (in the middle: removes introns) this is sequence dependent.
What do endonucleases and exonucleases do?
Endonucleases break the polynucleotide, can be specific or non specific. Exonucleases degrade the polynucleotide from end, 5’ specific or 3’ specific.
Where is the site of transcription?
The nucleus.
