DNA and RNA Structure Flashcards
What is the major difference between the structure of an RNA and that of a DNA nucleotide?
The sugar. There is an hydroxyl group on the 2’ carbon of an RNA nucleotide above from only on the 3’ in DNA. This makes the sugar ribose instead of deoxyribose.
What are the constituents of a strand of DNA?
Chained polynucleotides. There are the sugar-phosphate backbone and go from 3’ to 5’ linkage.
How do you identify which is the end of a strand of DNA or RNA?
The end that has a phosphate group is the 5’ end and the one with a sugar (hydroxyl) is the 3’ end.
How do nucleobases bind together?
Through hydrogen bonds. (Either 2 or 3)
What type of linkage is there between the phosphate group and the hydroxyl group of two nucleotides?
It is a phosphodiester linkage.
Why are some bases complementary?
To keep a common distance of 34 nm between the strands, there needs to be 3 rings. Thus, purines which have 2-ringed nucleobases bind with the pyrimidines with 1 ring.
Which link is the strongest between the nuclear bases?
It is the C-G linkage because they make 3 H bonds whereas A-T or A-U make 2 H bonds
What does it mean for the strands of DNA to be antiparallel?
It means that one strand goes from 3’ to 5’ and the other from 5’ to 3’.
Why are the strands of DNA antiparallel?
So that the phosphate group of a nucleotide can be aligned with the hydroxyl group of another one to make a phosphodiester link.
What do genes do?
They specify genetic information for regulation (control other genes) and make RNA in a process called transcription
What are 3 main types of RNA? What do they each do?
rRNA (ribosomal): It combines with ribosomal proteins to make the ribosomes, the organelle that synthesizes proteins. It is the last set of genes to be turned off before division and it exists in many copies.
tRNA (transfer): Brings the amino acids to the ribosome to synthesize proteins
mRNA (messenger): It is the recipe to make the good proteins. Codons are 3 nucleotides that indicate which amino acid is needed for the tRNA to bring the right one.
What are types of proteins?
Transport proteins, enzymes to catalyze cell rxns, structural proteins, storage proteins to store nutrients, regulatory proteins, motile proteins (microtubules), protective proteins (antibodies)
