DNA + REPLICATION Flashcards
What is a phosphodiester bond? (1)
the covalent bond between two nucleotides.
what are the pyrimidines of RNA? (2)
-cytosine
-uracil
what are the purines? (2)
-adenine
-guanine
what is the structure of a purine? (1)
double ringed
what is a nucleotide? (1)
the monomer from which nucleic acids are formed.
what is the structure of a pyrimidine? (1)
single ringed.
what are the nitrogenous bases? (2)
-purine
-pyrimidine
what pentose sugar is found in DNA? (1)
deoxyribose
what pentose sugar is found in RNA? (1)
ribose
what does a nucleotide consist of? (3)
-nitrogenous bases
-pentose sugar
-a phosphoric acid
what are the pyrimidines in DNA? (2)
-cytosine
-thymine
what is semi-conservative replication? (2)
the process by which two copies of a DNA molecule are made and in which both ‘parent’ strands remain intact and act as templates for the formation of new complementary strands.
what bases fit together? (2)
-cytosine and guanine
-adenine and thymine (uracil)
why is complementary base pairing important? (3)
-the stability of the double helix (hydrogen bonds are strong when there are many of them)
-the way in which genetic information can be transferred from DNA to RNA (mRNA)
-the way amino acids are assembled into polypeptides in the cytoplasm.
what is the 1st stage of DNA replication? (1)
DNA molecule unwinds and unzips (by DNA helicase) when the hydrogen bonds break. the bases on both strands are exposed.
what is the 2nd stage of DNA replication? (1)
single strands act as templates for the new strands with complimentary sequence of nucleotide bases.
what is the 3rd stage of DNA replication? (1)
free nucleotides with complimentary bases slot into place, line up, and are held in place by hydrogen bonds (DNA ligase)
what is the 4th stage of DNA replication? (1)
sugar-phosphate ‘back bone’ is formed by condensation reactions.
what is the 5th stage of DNA replication? (1)
replicated (daughter) DNA molecules each rewind into a double helix.
what is the shape of a DNA molecule? (2)
-double stranded, double helix which are held together by hydrogen bonds.
what does rRNA stand for? (1)
ribosomal RNA
what is DNA polymerase? (1)
the enzyme that catalyses the formation of a phosphodiester bond between two nucleotides.
what is meant by complementary base pairing? (1)
a key feature of DNA molecules is which two anti-parallel polynucleotide chains are held together by hydrogen bonds between the bases adenine and thymine or the bases cytosine and guanine.
what does mRNA stand for? (1)
messenger RNA
