Structures
Adenine - Thymine
Guanine - Cytosine
Number of strands created and how much it is conserved.
It is semi-conserved and 2 new strands are synthesized (1/2 is new and 1/2 is old)
3 stages of protein synthesis
Transcription, Modification, Translation
How does the modified mRNA leave the nucleus
Through nuclear pores (channels). Not active or passive transport because there isn't a concentration.
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Bases of RNA
Adenine - Uracil
Guanine - Cytosine
What direction is DNA synthesized and where can those two carbons be found?
5' - 3'. 5' carbon is the one that is closest to phosphate group while 3' is the one with the single oxygen.
Transcription
RNA primase starts at promoter and unzip the DNA RNA nucleotides start to build using 3’-5’ strand as template, so it builds 5’3 prime complementary until it reaches termination sequence.
How many bases is each codon/anticodon
3 bases.
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Structure of DNA and RNA. What are the three components? Which way is it built? What are the bonds called?
Made up of phosphate group, sugar, and a base. It is built from the 5' - 3' direction.
Bond between the phosphates are called phosphodiester bonds (covalent) while bonds between nucleotides are hydrogen bonds (easier to break).
What are the two fragments called + a fragment that starts with O.
Leading and lagging strands. The lagging strand is made of Okazaki Fragments.
What two things are added during modification?
modified guanine cap to the 5' end and a poly-adenine tail to the 3' end.
Translation
It reaches an rRNA and starts at the AUG codon. A tRNA carrying the anti-codon enters the a-site carrying methionine, the start amino acid.
Then the mRNA, carrying the tRNA moves on to the p-site and new tRNA carrying appropriate amino acid enters a-site. A peptide bond forms between the two amino acids.
The mRNA moves again and the tRNA leaves from e-site to pick up a methionine.
When it hits a stop sequence, the chain folds up so that it can’t add anymore and it leaves. To form protein, many polypeptides join.
What is the start codon?
AUG - methionine
2 differences between DNA and RNA
DNA is double stranded and doesn't have an oxygen in the 3rd hydroxyl group.
RNA is single stranded and has an oxygen in the 3rd hydroxyl group
When does DNA replication happen.
The S phase during mitosis or meiosis.
What happens during modification?
Spliceosomes cut out the introns that don't code for anything. It also takes out exons that aren't needed for a certain protein. It modifies the end.
How many amino acids are needed to form a protein?
There isn't a set amount. However, you need many polypeptides to create a protein.
What would cause a protein to not work?
A mistake in translation could cause the protein to not bend properly, rendering it useless.
Types of RNA and Function
ribosomal RNA - translates mRNA and links together the tRNA to form polypeptides.
transport RNA - Bottom as anti-codons, which pair with codons on mRNA and top carries amino acids, which link together to form polypeptides
messenger RNA - Transcribes genetic information from DNA to RNA, becomes processed, goes to rRNA, where it will be translated to polypeptides.
The enzymes responsible and their function.
Helicase - unzips the DNA
RNA primer - lays down RNA nucleotides where replication is supposed to start on lagging strand.
DNA polymerase - lays down DNA nucleotides
DNA ligase - connects the two fragments together.
Do mistakes in replication in introns affect the human?
No, the introns aren't translated so mutated introns aren't harmful.
How do they stop adding more codons?
The protein chain folds up so that more codon's can't be added.
4 types of mutations and describe them.
Silent Mutations - Single base is changed but the new codon codes for the same amino acid
Nonsense Mutations - changes to stop codon, protein is damaged
Missense Mutations - different amino acid is produced and protein is damaged
Frameshift Mutations - Base is either deleted or inserted, resulting in the wrong amino acid.