Central Dogma of Molecular Biology Flashcards
What is a gene ?
The recipe to make a protein
Where are genes found ?
They are found in DNA
What is a chromosome ?
A full length DNA molecule
What is a chromatid ?
DNA stored in a highly compact state
What is a species’ genome ?
The complete set of all its chromosomes
What are “house-keeping genes” ?
Genes that encode proteins needed in all cells (such as actin and tubulin)
What are histones ?
Sphere-like, positively charged proteins found in the nucleus
What is the role of histones ?
To help sort out DNA
To maintain an organised structure
Where are proteins produced ?
In the cytosol
On the rougth ER
What concepts form the Central Dogma of Molecular BIology ?
Transcription
Translation
Replication
What is transcription ?
The production of mRNA by using a DNA template
What is mRNA ?
An intermidiate copy of a gene that can be taken out of the nucleus
What is RNA polymerase ?
An enzyme that catalyses the formation of phosphodiester bonds between nucleotides
In what direction are phosphodiester bonds formed ?
Only in a 5’-to-3’ direction
In what direction does RNA plolymerase move along the template strand ?
In a 3’-to-5’ direction
What is the template strand ?
The DNA strand on which the RNA polymerase attaches
What is the terminator region ?
The transcription end site, where RNA polymerase will stop transcription
What is the promoter region ?
A part of a DNA molecule that allows RNA polymerase to arrive and begin transcription more quickly
What is the enhancer and repressor regions ?
Regions in the DNA that help or deter the recruitment of RNA polymerase
What changes does the mRNA must undergo before being allowed to leave the nucleus ?
The addition of a 5’ cap and a 3’ polyA tail
Splicing
What is splicing ?
The removal of introns
What are introns ?
Unnecessary regions of the mRNA (consistuted of non-coding nucleotides)
What is alternative splicing ?
When an intron is left behind
When some of the coding part of the mRNA is removed
What is the consequence of alternative splicing ?
Different mRNA are produced from the same gene, which leads to different proteins being made
What is a mature mRNA ?
A mRNA that is ready to leave the nucleus
What is translation ?
The process of changing from nucleotide “langage” to amino acid “langage”
What is a codon ?
A set of three nucleotides that is translated into a single amino aicd
What is one of the challenges of translation ?
There are only four nucleotides, but 20 amino acids
What is the redundancy or degeneracy of the genetic code ?
The fact that different codons can code for the same amino acid
What does the tRNA (transfer RNA) ?
It is responsible for linking a specific codon to the corresponding amino acid
What is a charged tRNA ?
A tRNA attached to the right amino acid
What does aminoacyl tRNA synthesase ?
It attaches the amino acid to the tRNA
What does the ribosome during translation ?
It catalyses the formation of peptide bonds
It regulates when translation of a specific mRNA is needed
It determines where on the RNA translation must take place
Of what is made the ribosome ?
Proteins Ribosomal RNA (rRNA)
What are the three steps of translation ?
Initiation
Elongation
Termination
What is initiation?
THe step at which translation is the mos carefully reviewed and regulated (Happens BEFORE translation starts)
What is elongation ?
The systematic occurance of translation (the actual process)
What sites does the ribosome have ?
The A-site (amino acid site)
THe P-site (polypeptide site)
THe E-site (exit)
WHat is the A-site ?
The site where the charged tRNA arrives
What is the P-site ?
The site where a tRNA with a full chain of the polypeptide “rests”
What is the E-site ?
The site where the empty tRNA is ejected
What is termination ?
The recruitment a of release factor to end translation
WHat is a release factor ?
A protein that is similar to tRNA that is recruited when a codon for “stop” is read.
What are the differences between prokaryotes and Eukarytoes for those two processes ?
In prokaryotes:
Transcription and translation take place in the cytosol
No changes made to the mRNA after transcription
Polycistronic
What does polycistronic mean ?
A mRNA that has more than one gene on it. (by comparison, eukaryotes are monocistronic)
What is replication ?
The process during which DNA produces a complete copy of itself
What is DNA polymerase ?
The enzyme that catalyses the formation of a new copy of DNA
In what direction does DNA polymerase move ?
In a 3’-to- 5’ direction
Why is replication called a “semi-conservative model” ?
Because after the passage of DNA polymerase, the two DNA strands won’t reattach. They both will be paired up with a new strand (daugther strand)
What is the replication fork ?
The point at which the two DNA stands separate
What is the leading strand ?
The continuous “round “ of replication
What is the lagging strand ?
The discontinuous “round “ of replication
