Molecular Genetics Flashcards
(36 cards)
What does DNA stand for?
Deoxyribonucleic Acid
Is DNA anti-parellell?
DNA is antiparallel: one strand runs 5’ → 3’, the other 3’ → 5’.
Explain DNA’s backbone, shape, and nitrogenous base pairs?
- Backbone: Made of phosphate groups and deoxyribose sugars.
- Shape: Double helix
- Base Pairs: Adenine (A) pairs with Thymine (T)
Cytosine (C) pairs with Guanine (G)
Where do hydrogen bonds occour in DNA?
They hold the base pairs together (2 bonds between A-T, 3 bonds between G-C).
What is DNA replications purpose, location and what part it happens in the cell cycle?
Purpose: To make an exact copy of DNA before cell division (mitosis or meiosis).
Location: Nucleus
Cell Cycle: During the S phase
Explain the step by step process of DNA replicaiton
- Initiation:
Helicase enzyme unzips the double helix by breaking hydrogen bonds between base pairs. - Elongation:
Primase lays down a short RNA primer.
DNA polymerase III adds complementary DNA nucleotides to the 3’ end.
The leading strand is built continuously.
The lagging strand is built in fragments (called Okazaki fragments) because it goes in the opposite direction. - Termination:
DNA polymerase I removes RNA primers and replaces them with DNA.
Ligase joins Okazaki fragments on the lagging strand to create a continuous strand.
What is the result of DNA replication?
End Result: 2 identical double-stranded DNA molecules (each with one old and one new strand — called semi-conservative replication).
What is the central dogma of molecular biology?
DNA → RNA → Protein
What enzyme performs transcription?
RNA polymerase.
What is transcription?
Copying DNA into mRNA in the nucleus.
What happens after mRNA is made?
It leaves the nucleus and goes to a ribosome.
What is translation?
Using mRNA to build a protein at the ribosome.
What does tRNA do during translation?
Brings amino acids and matches codons with anticodons.
What reads the mRNA codons during translation?
Ribosomes.
What are codons and anticodons?
Codons = 3 mRNA bases; Anticodons = 3 complementary tRNA bases.
What sugar is in DNA vs RNA?
DNA = deoxyribose, RNA = ribose.
What bases are in DNA vs RNA?
DNA: A, T, C, G — RNA: A, U, C, G (U replaces T).
How many strands in DNA vs RNA?
DNA is double-stranded, RNA is single-stranded.
Where is DNA vs RNA located?
DNA: nucleus only. RNA: nucleus and cytoplasm.
What is the function of DNA vs RNA?
DNA stores genetic info; RNA helps make proteins.
What is an operon?
A group of genes controlled together in prokaryotes.
What is the lac operon?
An inducible operon that digests lactose; normally OFF.
What turns on the lac operon?
The presence of lactose, which inactivates the repressor.
What is the trp operon?
A repressible operon that makes tryptophan; normally ON.
