Nucleic Acids Flashcards
(23 cards)
What are the two proposed models of DNA replication?
The conservative model.
The semi-conservative model.
What bacterium did Meselson and Stahn culture?
E-coli
What does a nucleotide consist of?
A pentose sugar - deoxyribose or ribose.
A nitrogenous base - from adenine, guanine cytosine and thymine or uracil.
A phosphate group. (Attached to the carbon 5 of the sugar).
What bond joins two nucleotides together?
Phosphodiester bonds
What is the shape of DNA?
A 3D double helix shape with anti parallel strands.
What model is achieves self replication?
Semi conservative mechanism.
What are the sequence of events in DNA replication?
The enzyme DNA helicase breaks the hydrogen bonds holding the base pairs together and unzips part of the DNA double helix
The enzyme DNA polymerase moves along each strand, which acts as a template for the synthesis of a new strand.
DNA polymerase catalyses the joining of free deoxyribonucleotides to each of the exposed original strands, according to base pairing rules, so that new complementary strands form.
The process of unzipping and joining new nucleotides continues along the whole length of the DNA molecule.
What was used to separate he heavier nitrogen to the lighter nitrogen
.
Density-gradient centrifugation
What does a nucleotide consist of?
A pentose sugar - deoxyribose or ribose.
A nitrogenous base - from adenine, guanine cytosine and thymine or uracil.
A phosphate group. (Attached to the carbon 5 of the sugar).
What bond joins two nucleotides together?
Phosphodiester bonds
What is the shape of DNA?
A 3D double helix shape with anti parallel strands.
What model is achieves self replication?
Semi conservative mechanism.
What are the sequence of events in DNA replication?
The enzyme DNA helicase breaks the hydrogen bonds holding the base pairs together and unzips part of the DNA double helix
The enzyme DNA polymerase moves along each strand, which acts as a template for the synthesis of a new strand.
DNA polymerase catalyses the joining of free deoxyribonucleotides to each of the exposed original strands, according to base pairing rules, so that new complementary strands form.
The process of unzipping and joining new nucleotides continues along the whole length of the DNA molecule.
What was used to separate he heavier nitrogen to the lighter nitrogen
.
Density-gradient centrifugation
Name all the types of Nucleic acid.
Deoxyribonucleic acid
Ribonucleic acid
What is a chain of nucleotides?
Polynucleotide
What does the base pairing ensure that (which bases attach to each other)?
Adenine only pairs with thymine (by two hydrogen bonds)
Guanine only pairs with cytosine (by three hydrogen bonds)
How many base pairs are there for each complete turn of the helix?
Ten
Describe the differences between RNA and DNA.
RNA has the sugar ribose, DNA has deoxyribose.
RNA molecules are single stranded, DNA are double.
RNA is much shorter than DNA.
In RNA the base uracil replaces thymine.
Name the three types of RNA.
Messenger
Transfer
Ribosomal
How many bases code for an amino acid?
3
How did Meselson and Stahl culture the heavy nitrogen isotope?
They cultured e.coli using N15. This was incorporated into the bases of the DNA in the bacterium over time, as older bacteria died and were replaced.
Explain Meselson and Stahls results.
After one generation - the intermediate position of DNA can be explained by all the DNA containing one strand that has bases containing N15 and one strand having bases N14.
After two - about half of the DNA consisted of mixed DNA of both N14 and N15 but the other was DNA that only contained N14.
