Molecules of Life Flashcards
(22 cards)
What are nucleic acids?
They are polymers made up of nucleotides
What is the difference between DNA and RNA?
Sugar - DNA had deoxyribose and RNA has ribose
What is a nucleoside
A nucleotide lacking a phosphate
What are the pyrimidines?
Cytosine, thymidine, uracil
What are purines?
Adenine and guanine
What type of linkage is the glycosidic bond?
It is always Beta
What is the ester linkage between nucleotides?
Phosphodiester bond
How many hydrogen bonds are present between A and T?
2
How many hydrogen bonds are present between C and G?
3
What three steps is DNA replicated by?
Initiation
Elongation
Termination
Describe DNA replication.
- Unwinding the DNA
- Process is carried out by DNA Helicase which break the hydrogen bonds
- The parent strands act as a template for the synthesis of a new DNA strand
- New DNA strands are complementary to the parent strands
- DNA synthesis is catalysed by DNA polymerase
What are the precursors for the synthesis of new DNA strands?
Nucleoside triphosphates
How does RNA differ structurally from DNA?
- Sugar
- Thymine replaced by uracil in RNA
- RNA is single stranded
What is a gene?
A DNA segment that contains the information necessary for the synthesis of one protein
What is the template strand?
This is the complementary strand
What is the coding strand?
The sequence of bases along one DNA strand which provides the synthesis of proteins in an organism.
What is transcription?
The synthesis of mRNA from the DNA template
How does Gemcitabine work as an anticancer drug?
Gemcitabine has a very similar structure to 2’-deoxycytidine (a DNA molecule). It forms two metabolites; gemcitabine disphosphate and gemcitabine triphosphate. This is done by the addition of phosphate groups to Gemcitabine by kinases.
Gemcitabine disphosphate inhibits ribonulceotide reductase
Gemcitabine triphosphate causes apoptosis through inhibition of DNA elongation
How does Sofosbuvir work as a Hepatitis C drug?
The triphosphate compound inhibits the viral RNA polymerase NSSb. As a result viral (HCV) RNA synthesis is inhibited.
What amino acid does not have a chiral center?
Glycine
Which amino acid is R at the a-carbon?
Cysteine
What configuration are all naturally amino acids?
L-configuration
