Chapter 11: DNA Replication and Recombination Flashcards
This is the chemical affinity between nitrogenous bases as a result of hydrogen bonding.
Complementarity
Cytosine is a ______.
pyrimidine
Guanine is a ______.
purine
Thymine is a ______.
pyrimidine
Adenine is a ______.
purine
Why isn’t A-G bonding possible?
The double helix must be three rings across. A-G bonding would require four, because both are purines and have two rings each. That would make the DNA too big.
Why isn’t C-T bonding possible?
The double helix must be three rings across. C-T bonding would require two, because both are pyrimidines and have only one ring. That would make the DNA too small.
Why isn’t C-A or G-T bonding possible?
Though it’s purine-pyrimidine, the charges on the molecules would repel each other, and no hydrogen bonding could happen.
What’s the total diameter of a DNA strand?
20 Å
How does the cell know when the wrong base pair has been put in?
The DNA is too wide or too narrow.
This type of DNA makes up the majority of DNA in the body and is the original structure determined by Watson and Crick. It is a right-handed corkscrew.
B-DNA
This type of DNA is a right-handed corkscrew but is twisted a bit tighter and is found only in solution, not in living cells.
A-DNA
This type of DNA is a left handed corkscrew and is twisted a bit looser (12 base pairs per turn). It is found in the body.
Z-DNA
What type of sugar does DNA have?
deoxyribose
What type of sugar does RNA have?
ribose
Which base pairs differ between RNA and DNA?
RNA has uracil instead of DNA’s thymine.
Is RNA single stranded or double stranded?
It’s single stranded except for in some viruses, but it can hydrogen bond with itself to form shapes that are critical to its function.
This type of RNA is never translated into protein, but is an important structural component of ribosomes.
rRNA (ribosomal RNA)
This type of RNA carries information from DNA to the ribosomes, where translation occurs.
mRNA (messenger RNA)
This type of RNA carries amino acids to the ribosome during translation.
tRNA (transfer RNA)
This type of RNA helps process mRNA by getting rid of introns and splice exons.
snRNA (small nuclear RNA)
This type of RNA is involved in DNA replication and is an enzyme RNA that places the telomere on the end of the chromosome.
telomerase RNA
This type of RNA is a short strand that can base pair with an mRNA sequence to prevent expression of that particular gene.
antisense RNA
What does “semiconservative replication” mean?
It means each time DNA is replicated, each of the two original strands gets a new pair strand, so the new DNA molecule has one old strand and one new.