Nucleic Acids Flashcards
What is the structure of DNA nucleotides?
A deoxyribose sugar, an inorganic phosphate and nitrogenous base
What is the basic function of DNA?
Holds genetic information
What is the structure of RNA nucleotides?
Ribose sugar, inorganic phosphate and nitrogenous base
What is the basic function of RNA?
Transfer generic information from DNA to ribosomes
What are the nitrogenous base pairs in DNA?
Cytosine and guanine (3 hydrogen bonds between them)
Thymine and adenine (2 hydrogen bonds between them)
What are the nitrogenous base pairs in RNA?
Cytosine and guanine
Uracil and adenine
What bond joins nucleotides?
Phosphodiester bonds
What reaction forms a phosphodiester bond?
Condensation reaction (removal of water)
What reaction breaks phosphodiester bonds?
Hydrolysis reactions (addition of water)
Between what compounds in a nucleotide does a phosphodiester bond form?
Between the pentose sugar of one nucleotide and the phosphate group of another
What is the structure of DNA?
- double helix
- long
- strands joined by H bonds
- base pairings complimentary
- they are anti parallel
What is the function of the phosphodiester backbone?
Gives stability and protects the less stable organic bases
Compare and contrast the structure of DNA and RNA.
- both are polynucleotides
- both have pentose and phosphate e backbones
- both have nitrogenous bases (cytosine, guanine and adenine)
- both form a helix
- DNA has thymine whereas RNA has uracil
- DNA has 2 strands of polynucleotides whereas RNA only has 1
- DNA has a deoxyribose sugar whereas RNA has ribose
- RNA is shorter than DNA
- DNA has hydrogen bonds whereas RNA doesn’t
What is mRNA?
Messenger RNA
What is tRNA?
Transfer RNA
Why does DNA copy itself for mitosis?
So daughter cells can have a full set of chromosomes
What is the mechanism for DNA replication that is widely accepted?
Semi-conservative replication
What is DNA helicase?
Separates the 2 DNA strands before replication by breaking the hydrogen bonds
What is DNA ligase?
Joins together the short sections of the lagging strand
What is the single stranded binding protein?
Keeps the separated DNA strands apart during replication
What is DNA polymerase?
Catalyses the formation of a new polynucleotide strand
How does DNA polymerase work?
Is complimentary to 3’ end of original strand, moves in 5’ to 3’ due to antiparallel strands it works in opposite direction
What is the process of semiconservative DNA replication?
- DNA helicase breaks hydrogen bonds between bases of two polynucleotide strands
- each strand acts as a template
- complimentary base pairings from free nucleotides align
- DNA polymerase joins the new strand with phosphodiester bonds through condensation reactions
- each DNA molecule contains one original and one new strand
Who provided evidence for semi conservative replication?
Meselson and Stahl
