Nucleic Acid Structure Flashcards
(12 cards)
What is the central dogma of molecular biology?
a theory stating that genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein
Describe the structure and organization of DNA
- made of two linked strands that wind around each other to resemble a twisted ladder — a shape known as a double helix.
- Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups.
- Attached to each sugar is one of four bases: adenine (A), cytosine (C), guanine (G) or thymine (T)
Compare and contrast the structures of DNA and RNA
- DNA is double-stranded, forming a double helix, while RNA is usually single-stranded.
- The sugar in DNA is deoxyribose, whereas RNA contains ribose.
- DNA uses the bases adenine, thymine, cytosine, and guanine, while RNA uses adenine, uracil, cytosine, and guanine.
How does gel electrophoresis separate nucleic acid fragments based on size?
The larger ones are slow to move to the bottom so they stay at the top while the smaller ones move faster and easier, so they’re at the bottom
Describe how Southern blots allow specific genes or DNA sequences to be visualized on a gel
Southern Blotting is a technique for identifying specific DNA sequences in a complex mixture. It involves cutting DNA into fragments, separating them by size through gel electrophoresis, transferring them onto a filter, and exposing them to a radio-labeled DNA probe.
What is the difference between southern and northern blots?
Southern blots analyze DNA, while Northern blots analyze RNA
What holds DNA strands together?
Hydrogen bonds
Which of the base pairings are stronger and which is weaker? Why?
Stronger: C and G because of 3 hydrogen bonds
Weaker: A and T because of 2 hydrogen bonds
What does it mean for the nucleic acids to be complementary and anti-parallel?
- Means the two strands run in opposite directions:
One strand goes 5’ → 3’ (top strand)
The other runs 3’ → 5’ (bottom strand)
- Means the bases on each strand match up like puzzle pieces:
A (Adenine) always pairs with T (Thymine) [or U in RNA]
C (Cytosine) always pairs with G (Guanine)
Assess the impact of changes in the nucleotide composition of DNA on temperature stability
- More G-C content = higher T
- More A-T content = lower T
- longer DNA = higher T
- shorter DNA = lower T
How can you tell if two nucleic acid molecules will hybridize based on their sequences?
Two nucleic acid molecules will hybridize, meaning they will bind together to form a double-stranded molecule, if their sequences are complementary.
DNA: A-T, C-G
RNA: A-U, C-G
In which direction does DNA move for gel electrophoresis?
To the positive side
