DNA Replication
What are the steps of replication?
initiation, elongation, terimination
What do initiated proteins do?
What are the three processes of transcription?
Initiation, enlongation, termination
What is the importance of ribosomes and subunits in translation?
Ribosomes initiates the translation process. The ribosomes are made up of two subunits each. The subunits come together before translation of mRNA into a protein to provide a location for translation to be carried out to a polypeptide to reproduce.
What is DNA proofreading and mis-match repair? (DNA replication)
If a mismatch occurs, the incorrect positioning stalls in the polymerization process- the 3'-5' eco-nuclease activity removes the mismatch.
What are okazaki fragments?
Okazaki fragments are short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication
What is difference between DNA helices and DNA gyrase?
DNA helices unwinds DNA at replication fork. DNA gyrase moves ahead of the replication fork, making and resealing breaks in the double-helical DNA to release the torque that builds up as a result of unwinding at the replication fork.
Describe what happens in each stage of transcription
2. elongation: RNA polymerase moves along the DNA template in a 3' and 5' direction, unwinding the DNA and synthesizing RNA in a 5' to 3' direction
3. termination: synthesis of RNA is terminated, and the RNA molecule separates from the DNA template
What are the four steps to bacterial translation?
1. tRNA charging- amino acid reacts with ATP, aminoacyl-tRNA syntheses, produces aminocyll-AMP, amino acid transferred to the tRNA, AMP released
2. initiation- reading frame- three nucleotide coding for one amino acid, components needed: mRNA, small/large subunits of ribosome, initiation factors, mRNA binds to the small subunit of the ribosome
3. elongation- requires tRNA charged with amino acid, elongation factors, and GTP
4. Termination- protein synthesis ends when the ribosome translocates a termination codon, no tRNA for termination codons
What are the products of translation? (translation)
Proteins
What is the Direction of Replication?
Always 5' to 3'
What are single-strand-binding proteins?
They are able to attach to single-stranded DNA and prevent secondary structures from forming.
What are the promoters of transcription?
TATA, transcription factors, regulatory promoters, enhancers
What are the start and stop codons?
the start- AUG
the stop - UUA, UAG, UGA
What polyA binding proteins and nuclear cap-binding proteins? (translation)
Poly(A)-binding protein: (PAB or PABP) is a RNA-binding protein which binds to the poly(A) tail of mRNA. The poly(A) tail is located on the 3' end of mRNA and is 200-250 nucleotides long.
Nuclear cap-binding protein: complex is a RNA-binding protein which binds to the 5' cap of pre-mRNA.
Whats the difference between the leading and lagging strand and how does it effect the replication fork?
The lagging strand is a discontinuous DNA synthesis. The leading strand is a continuous DNA synthesis. During the replication fork the lagging stand loops around so that 5' and 3' can be synthesized by the okazaki fragment. DNA must from a loop so that both strands can replicate simultaneously.
DNA polymerase 1 removes RNA primers and replaces them with DNA.
DNA polymerase 3 is elongates a new nucleotide strand from the 3-OH group provided by the primer.
What are RNA polymerase in eukaryotes?
1. RNA polymerase 1- Eukaryotes, rRNA
2. RNA polymerase 2- Eukaryotes, pre-mRNA, snRNA, snoRNA, miRNA
3. RNA polymerase 3- Eukaryotes, tRNA, small rRNA, snRNA, mi RNA
4. RNA polymerase IV- plants, siRNA
5. RNA polymerase v- plants, RNA molecules that are used in heterochromatin formation
What are the 6 components of initiation and complex factors?
1. mRNA
2. small subunit
3. large subunit
4.initiation factors
5. imitator tRNA
6. guanosine triphosphate
initiation factor 3- binds to the 1 small subunit of the ribosome- allowing mRNA to bind the small subunit
What are P and A sites? (translation)
The three tRNA sites are labeled P, A, and E. The P site, called the peptidyl site, binds to the tRNA holding the growing polypeptide chain of amino acids. The A site (acceptor site), binds to the aminoacyl tRNA, which holds the new amino acid to be added to the polypeptide chain.
What are the products of DNA replication?
New DNA strands that are complimentary to the old ones.
What does DNA ligase do?
Joins Okazaki fragments by sealing breaks in the sugar-phosphate backbone of newly synthesized DNA.
mRNA, tRNA, and rRNA
What is the difference between GTP and GDP?
Their activity is regulated by factors that control their ability to bind to and hydrolyze guanosine triphosphate (GTP) to guanosine diphosphate (GDP). When they are bound to GTP, they are 'on', and, when they are bound to GDP, they are 'off'. G proteins belong to the larger group of enzymes called GTPases.
What are release factors? (translation)
A release factor is a protein that allows for the termination of translation by recognizing the termination codon or stop codon in an mRNA sequence. Prokaryotic translation termination is mediated by three prokaryotic release factors: RF1, RF2, and RF3.