Biology Flashcards
(27 cards)
What are the components of a nucleotide ?
a pentose, aromatic base and phosphates
What is the point mutation that creates a STOP codon?
Nonsense
How many types of RNA polymerases are used by eukaryotic cells?
Three
Where is the START codon bound in a ribosome ?
P site
What is the formula for determining ATP equivalents for amino acids ? Example how many ATP equivalents for 100 amino acids ?
ATP equivalents = number of amino acids x 4
ex: if have 100 aa X 4= 400 ATP equivalents
What are similarities and differences for prokaryotes and eukaryotes for transcription ?
Similarites:
-both prokaryotic and eukaryotic RNA Polymerases require template
-
differences:
-transcription occurs in cytoplasm for prokaryotes, nucleus for eukaryotes
-only prokaryotes use shine-Dalgarno sequence to initiate translation
-Eukaryotes undergo post-translational modification (splicing, adding cap, poly A tails), prokaryotes don’t
what are the three types of RNA polymerase that humans use? What are their roles ?
The three types of RNA polymerase in humans are RNA Polymerase I, II, and III
- RNA polymerase I is responsible for the transcription of most rRNA
-RNA polymerase II synthesizes mRNA, as well as snRNA (RNA polymerase III synthesizes mostly tRNA, some snRNA, and miRNA
what is genetic penetrance?
when a certain genotype has the potential to lead to a phenotype
What happens during Sanger sequencing ?
Sanger sequencing involves performing four different DNA replication reactions on one sample of DNA, where each reaction contains a different modified nucleotide that arrests synthesis on a certain template
What are the different forms of DNA repair ?
Connecting broken ends of chromosomes, reversing UV damage, and removing defective bases are all forms of DNA repair.
What are some features of prokaryotic translation? Which ribosome subunits are used?
In prokaryotes, the 30S and 50S subunits of the ribosome must come together for translation to occur but when they do they make a 70S ribosome. The Shine-Dalgarno sequence is the ribosome binding site in prokaryotes and without this the gene product cannot be translated.
fMet (formylmethionine) is a modified methionine used as the first amino acid in all prokaryotic proteins.
What is the energy source used in prokaryotic transcription ?
GTP is used in prokaryotic transcription
What is the role of DNA gyrase? Which kind of organisms is it seen in?
Gyrase is an enzyme specific to prokaryotes that maintains bacterial DNA in its supercoiled helical state.
Which polymerases produce of stand od DNA in 5’ to 3’ direction ?
All three polymerases (polymerase I, III and Reverse transcriptase listed use a template strand to create a new strand of DNA. They do so by adding new nucleotides to the 3’ end of the new strand (hence, the strand grows in the 5’ to 3’ direction).
How does reverse transcriptase differ from DNA polymerase?
Revere transcriptase differs from the DNA polymerase’s only that RNA template is made (instead of DNA template). but it too adds nucleotides in 5’ to 3’ direction
What is the role of topoisomerase ?
Topoisomerase creates controlled cuts in DNA strands to manage the increased tension created by expanding replication bubbles
What is the role of DNA ligase
RNA polymerase is used by eukaryotes and can be eliminated.and ligase links together the Okazaki fragments of the lagging strands
What occurs in alternative splicing? which lab techniques would be useful?
Alternative splicing creates different mRNA sequences leading to different proteins, thus any technique that detects changes in mRNA transcripts or final protein products could be useful. Northern blotting is used to detect RNA and both Western blotting and ELISAs can be used to detect proteins. However, Southern blotting is used to detect DNA, and a if it says that genomes are the same (their is least useful technique).
what are the chain of events that occur in the synthesis of a polypeptide?
DNA generates mRNA; mRNA moves to the ribosomes, where a tRNA anticodon binds to an mRNA codon, causing amino acids to join together in their appropriate order.
When do translocations happen?
Translocations happen when recombination occurs between non-homologous chromosomes and previously unrelated genes are now placed together.
What does a complex transposon contain?
A complex transposon contains an IS element (the transposase and its accompanying inverted repeat sequences) and one or more genes.
what occurs in RNA splicing?
During RNA splicing, introns are removed and exons are connected together. This process occurs in the nucleus, and can be variable
What is direct reversal ?
Direct reversal : a form of DNA repair , where visible light can trigger repair enzymes via photo reactivation when pyrimidine dimers appear (due to UV light)
How do Eukaryotes and prokaryotes differ during translation ?
Eukaryotic and prokaryotic translation differ in the mechanism by which ribosomes recognize the 5’ end of mRNA.
Prokaryotic mRNA is recognized by the ribosome using the Shine-Dalgarno sequence (-10) while eukaryotic mRNA is recognized via the 5’ cap that is added during post-transcriptional modification.
