d1.1 dna replication Flashcards
(25 cards)
What are purines and pyrimidines?
Purines and pyrimidines are two classes of nitrogenous bases that are fundamental building blocks of DNA and RNA.
What are purines?
Purines (adenine and guanine) have a double-ring structure.
What are pyrimidines?
Pyrimidines (cytosine, thymine, and uracil) have a single-ring structure.
What are the phases of the cell cycle?
The cell cycle goes through G1 phase, S phase (synthesis), G2 phase, and mitosis.
What is the significance of the S phase in the cell cycle?
S phase is before mitosis so the new cells get full copies of DNA.
When does DNA need to be replicated in the cell cycle?
Prior to cell division (during interphase) the DNA must be replicated to ensure the daughter cells produced have an identical copy of the DNA.
What direction does DNA polymerase go?
Two DNA polymerase go different ways to link with the anti-parallel parent DNA strands.
What enzyme creates DNA polymers?
DNA polymerase.
What does DNA replication being semi-conservative mean?
DNA replication is semi-conservative as the two DNA molecules formed contain one strand from original DNA and one new strand.
Where does DNA replication occur?
Occurs in the S phase of the cell cycle (synthesis), before the cell splits (mitosis).
What is helicase’s function?
Helicase enzyme breaks down the hydrogen bonds in parent DNA for cell division, making the bases accessible for the new DNA to connect to.
What is DNA polymerase’s function?
DNA polymerase uses the single strands that helicase separated as a template to add new complementary nucleotides and form covalent bonds to produce the sugar phosphate backbone.
What does DNA polymerase produce?
Produces two identical double strands of DNA. One strand continuously replicates (the strand that starts at 5’), and one strand has to replicate backwards (the strand that starts at 3’).
What is polymerase chain reaction (PCR) used for?
Used to amplify a small quantity of DNA to a larger quantity for various applications such as forensics and parental DNA.
What are the steps of PCR?
- Denaturation: Temperature rises to 95 degrees to break hydrogen bonds. 2. Annealing: Lower temperature to 54 degrees to allow binding of primers. 3. Elongation: Raise temperature to 72 degrees for rapid DNA replication by Taq DNA polymerase.
What is gel electrophoresis?
A process using electric current to separate molecules based on their size/different rates of movement.
What are the steps of gel electrophoresis?
- An electric current is applied to the gel. 2. The DNA sample is loaded into the wells. 3. The fragments of DNA move towards the positive electrode due to DNA’s negative charge.
What happens if DNA samples are too large from eukaryotes in gel electrophoresis?
DNA samples from eukaryotes are too large and must be cut with a specific restriction enzyme before loading into wells.
What do restriction enzymes do for gel electrophoresis?
Restriction enzymes can cut DNA at specific sequences, making the DNA into smaller fragments for easier travel through the gel.
What is DNA profiling and what can it be used for?
An application of PCR and gel electrophoresis used to identify and compare individuals via their DNA profiles.
How does DNA profiling work?
- DNA is obtained from a person/hair/blood/crime scene. 2. DNA samples may require amplification using PCR. 3. The DNA samples are digested into fragments with restriction enzymes and separated using gel electrophoresis.
What are satellite DNA and where are they found?
Satellite DNA are long stretches of DNA made up of repeating elements called short tandem repeats (STRs) found within non-coding regions of an individual’s genome.
What are short tandem repeats?
DNA sequences composed of 2-6 bases that repeat, contributing to DNA profiles as genetic markers.
How will different short tandem repeats affect individuals’ DNA profiles?
Individuals will likely have different numbers of repeats at a given satellite DNA locus, generating unique DNA profiles.
