Lecture 2 - Building Blocks: Nucleotides and Amino Acids Flashcards
What does the central dogma state?
The flow of information is from DNA to RNA to proteins.
Which process converts information from DNA to RNA?
Transcription
Which process converts information from RNA to proteins?
Translation
What are the four base pairs found in DNA? Which pairs pair to each other?
A, T, C, G (A-T, C-G)
What monomer makes up proteins?
Amino Acids
Who discovered nucleic acids? When?
Friedrich Miescher discovered nucleic acids in 1869.
How were nucleic acids discovered?
Nucleic acids were discovered by isolating an acidic compound from the nuclei of white blood cells collected from puss on discarded surgical bandages.
What does DNA stand for?
Deoxyribonucleic Acid
What does RNA stand for?
Ribonucleic Acid
How long can DNA be?
DNA can be as long as hundreds of millions of nucleotides.
How long is RNA typically?
RNA is usually hundreds to thousands of nucleotides long.
What are nucleic acids composed of?
Nucleic acids are composed of a phosphate group, pentose sugar (ribose or deoxyribose), and a nitrogenous base (A, T, C, G, U).
What are the two categories of nitrogenous bases?
Purines and Pyrimidines
How many rings do purines have?
2
How many rings do pyrimidines have?
1
Which bases are purines?
Adenine and Guanine
Which bases are pyrimidines?
Uracil, Thymine, and Cytosine
Which nitrogenous base is pictured below?
Adenine
Which nitrogenous base is pictured below?
Guanine
Which nitrogenous base is pictured below?
Uracil
Which nitrogenous base is pictured below?
Thymine
Which nitrogenous base is pictured below?
Cytosine
What is the difference between a nucleotide and a nucleoside?
Nucleosides don’t have a phosphate group.
What is the repeated phosphate-pentose chain in a sequence of nucleotides known as?
The “Backbone”
What type of bond links nucleotides together? Where are they formed?
Phosphodiester Bonds
They are formed between the 3’ hydroxyl on the pentose and the 5’ phosphate.
In which direction do we write nucleic acid sequences? Why?
Nucleic acid sequences are written in a 5’ to 3’ direction because this is the direction they are synthesized in.
Who discovered the double helix structure? Who was awarded the Nobel prize for it? Who generated the high-resolution diagrams but was not recognized due to their passing.
James Watson and Francis Crick discovered the double helix. They were awarded the Nobel prize, along with Maurice Wilkins. Rosalind Franklin generated the diagrams but passed away before the prize was awarded and was not recognized.
What information is stored in the DNA backbone?
Absolutely None
In which direction do polynucleotide chains exist in DNA double helices.
Antiparallel (to eachother)
How many hydrogen bonds exist between paired adenine and thymine?
2
How many hydrogen bonds exist between paired cytosine and guanine?
3
What is the most prevalent form of DNA found in cells?
B Form
How do the helical grooves differ in B form DNA?
In B form DNA, one groove is bigger than the other groove. These are named the major and minor grooves.
How does A-DNA compare to B-DNA?
A-DNA is shorter and wider than B-DNA.
How does Z-DNA compare to B-DNA?
B-DNA is right-handed while Z-DNA is left-handed. Z-DNA is longer and narrower.
Is A-DNA right-handed or left-handed?
Right-Handed
What happens to B-DNA (in vitro) in very low humidity?
B-DNA changes to A-DNA.
Which type of DNA can form DNA-RNA hybrids and RNA-RNA double helices in vivo.
A-DNA
When does Z-DNA form?
Z-DNA forms when short DNA molecules are in a regularly alternating purine-pyrmidine sequence, leading to the zig-zag left-handed Z-form helix.
How can Z-DNA be used as a tag for which parts of the genome are transcribed?
There is a possiblity that an RNA-DNA hybrid will form shortly after genes are transcribed. This hybrid takes on the Z-form.
What can DNA binding proteins do to the shape of the DNA helix while reading it?
DNA binding proteins can distort the shape of the DNA helix.
What causes DNA denaturation?
Heat
What is the Tm of double stranded DNA?
Tm is the temperature at which the sample is halfway denatured.
Why is Tm a function of G-C content?
Tm is a function of G-C content because they form three hydrogen bonds (instead of two like A-T) and therefore require more energy to break the bonds and be denatured.
What are the two main secondary structures of RNA? What do they look like?
What is the structure of the RNA pseudoknot?
The RNA pseudoknot is one polynucleotide chain of RNA holding on to itself in two subsequent loops
What is the importance of the RNA pseudoknot?
The RNA pseudoknot is cruicial to the function of a RNA molecule. The pase pairing holds the RNA together and the bonds cannot be disrupted without transforming RNA’s original function.
