*BIOLOGY LECTURE EXAM 3* Flashcards
What is the forth type of biological molecule and what does DNA stand for?
Nucleic Acid
Deoxyribose Nucleic Acid
Draw and label a nucleotide.
ON NOTES!
What did Rosalind Franklin do to contribute to the discovery of DNA structure?
Took photo 51 that showed that DNA was double helix
What components make up chromatin?
DNA & histone proteins
Draw and label the two classes and four type of nitrogenous bases in DNA?
ON NOTES!
Draw and label a small section of DNA with four different base pairs?
ON NOTES!
Whose rules are you following when your paring up these nitrogenous bases?
Chargaff
Why does DNA replication occur?
Cell is about to divide, so both cells have the same amount of DNA
What are the three stages of DNA replication?
Initiation, Elongation, & Termination
Where do origin of replication occur along the double helix and why?
Areas that are rich in adenine and thymine because they require less energy to break apart
What enzyme unwinds the DNA and what does it need to work?
Helicase & ATP
What enzyme cuts, repairs, and alleviates the stress of supercoils?
Topoisomerase
Why are these enzymes (Topoisomerase) important from a medicinal perspective?
Because antibiotics target topoisomerase
What does DNA polymerase type III need to synthesize new DNA? What is the only direction that it can do this in?
It needs a 3’ OH of RNA primer; 5’ to 3’
Describe the initial difference between the leading strand and the lagging strand of the DNA replication fork?
The leading strand is made up of one RNA primer and a continuous new strand of DNA; the lagging strand is made up of RNA primers and DNA stretches called Okazaki fragments.
What enzyme cuts out RNA primers and inserts new DNA nucleotides in their place?
DNA Polymerase Type I
What enzyme seals the newly synthesized DNA strands together?
Ligase
Where does termination of DNA replication occur?
Where replication forks merge and telomeres
Replicated DNA is made up one old or parental strand of DNA and one new one what is this model of replication called?
Semi-conservative
What does RNA stand for and how is it different structurally than DNA?
Ribonucleic Acid & it’s single stranded versus DNA which is double stranded
How is the genetic code for the DNA expressed in a living organism?
RNA & proteins
What are the tree essential roles that proteins fulfill?
Metabolic, Structure & Transport
Does all DNA code for proteins?
No
Where does transcription occur?
In the nucleus
What is the first stage of transcription of mRNA and what happens in this stage?
Initiation
-RNA polymerase II attaches on to a PROMOTOR sequence on the DNA
What is the second stage of transcription and what happens in this stage?
Elongation
-RNA polymerase II opens the DNA reads the template strand in a 3’- 5’ direction and attaches RNA nucleotides in the 5’- 3’ direction
What is different about RNA nitrogenous bases?
Uracil instead of Thymine
What is the third stage of transcription and what happens in this stage?
Termination
-RNA polymerase II synthesizes a poly adenylation signal (AAUAAA), and enzymes move in to cut the hnRNA strand
What modifications does this hnRNA need to become mRNA?
- Guanosine cap added to the 5’ end
- SNRP’s cut out the introns that do not code for amino acids, leaving only the exons, that will code for amino acids
- Poly A tail added to the 3’ end
What happens next to this mRNA?
Leaves the nucleus to go get translated on the ribosomes
What are codons?
How many are their?
How many code for amino acids?
Which ones don’t code for amino acids?
Triplets of nucleotides
64
61
Stop codons
What are anticodons and where are they?
Triplets of nucleotides complementary to codons & on the tRNA
What does it mean to charge a tRNA?
Add an amino acid to 3’ end
What is a ribosome made of?
rRNA & proteins
What is the first stage of translation and what happens in this stage?
Initiation:
- Small ribosomal subunit binds to AUG, the start codon.
- The first tRNA, charged with the amino acid, methionine, binds its anticodon (UAC) with the start codon.
- Large ribosomal subunit binds to small ribosomal subunit, with the first charged tRNA in the P site.
What is the second stage of translation and what happens in this stage?
Elongation:
- A second charged tRNA is bonded to the codon in the A site.
- The amino acid (methionine) on the first tRNA in the P site is added to the amino acid on the second tRNA in the A site.
- The first, now uncharged, P site tRNA moves to the E site, where it is expelled from the ribosome.
- The second A site tRNA moves to the P site, and a third charged tRNA is bonded to the next codon in the A site.
- The two amino acids on the second tRNA in the P site are added to the amino acid on the third tRNA in the A site.
- The same process repeats until the stop codon is reached.
What are we initially building in this stage?
Polypeptide
What is the third stage of translation and what happens in this stage?
Termination:
- A stop codon (UGA, UAA, UAG) enters the A site.
- The Release Factor binds to the stop codon and cuts off the polypeptide.
What are the four structures of proteins which one is the most complex and why?
Primary, Secondary, Tertiary, Quaternary
Quaternary because it’s a combination of all four
Describe SARS-CoV-2 pathophysiology?
Spike proteins bond with ACE2 proteins in our alveoli this allows for the virus to enter the cell, Type II pneumocyte, and replicate itself using our cells ribosomes eventually collapsing the alveoli
Describe how covid-19 mRNA vaccines work?
Small sections of the viruses mRNA are incased within phospholipids and enter our cells there the mRNA uses our cells ribosomes to translate ONLY the spike protein our immune system discovers these foreign proteins and produce antibodies that will bond to them and to real spike proteins that are connected to an actual Covid virion inhibiting it from entering our cells and replicating
What is the specific bacterial immune system called that we are using to perfect gene editing that will possibly eliminate diseases such as blood disorders, cancer, aids, and will change the future of medicine, agricultural, and humanity as we know it?
CRISPR Cas9 technology