DNA Flashcards
Is DNA chemically identical in all species?
No, most eukaryotes undergo methylation.
Is the genetic code universal?
Yes, with some mtDNA exceptions.
Why is DNA organised into chromosomes?
To condense it.
Are the chromosomes always visible?
No, only at cell division.
What is DNA wrapped around in the chromosomes?
Histones.
What is a karyotype?
A description of the compliment of chromosomes within an organism.
Do all species use DNA as the genetic material?
Yes, except some viruses.
Do all species have the same compliment of AAs?
Yes.
What are AAs joined by?
Peptide bonds.
What is the chemical structure of a peptide bond?
O=C-N-H
In what kind of reactions are AAs joined?
Condensation reactions.
In what kind of reactions are AAs separated?
Hydrolysis.
What is a nucleotide composed of?
A nitrogenous base, a pentose sugar and a triphosphate group.
A and T always bond together with how many hydrogen bonds?
2
C and G always bond together with how many hydrogen bonds?
3
Which are the pyramidine bases?
C and T
Which are the purine bases?
A and G
What direction must DNA always run in?
5’ to 3’
How are the strands aligned in double-stranded DNA?
Anti-parallel.
How does a molecule of RNA differ from a molecule of DNA?
RNA has 2 -OH groups, one on the 2’ and one on the 3’ carbon. DNA has only one -OH group on the 3’ carbon.
Why are DNA strands said to have polarity?
Because they are directional, i.e. 5’ to 3’.
How many base pairs are found in a full twist of the double helix?
10.
What bases does RNA use?
A and U (instead of T) and C and G.
DNA is usually double-stranded. Is RNA the same?
No, it is single-stranded (ss).
What are the 2 requirements for DNA replication?
- A free 3’ -OH group at the end of an existing single-stranded chain that can join to the 5’ triphosphate on the free nucleotide.
- It must always occur 5’ to 3’
What type of enzyme is needed for transcription?
A DNA dependent RNA polymerase.
What kind of RNA is used in transcription?
mRNA.
What kind of RNA is used in translation?
tRNA.
What is the universal start codon?
AUG.
What does AUG encode?
Methionine.
What AA do all proteins begin with?
Methionine.
What are the stop codons?
UAA, UAG, UGA.
By how many base pairs can DNA be sequenced at any one time?
1000bp.
