W1 Flashcards
(67 cards)
Bacteriophages
Viruses that infect bacteria, used in the Hershey-Chase experiment to demonstrate DNA is the genetic material by labeling DNA with radioactive phosphorus.
Chargaff’s Rules
DNA has equal amounts of adenine and thymine, and equal amounts of cytosine and guanine, suggesting complementary base pairing.
DNA Structure
Watson and Crick proposed a double helix model with two antiparallel strands held by hydrogen bonds between base pairs (A-T, G-C).
Base Pairing Rules
Adenine pairs with Thymine (2 hydrogen bonds), Guanine pairs with Cytosine (3 hydrogen bonds), ensuring a uniform helical structure.
DNA Polymerase
Enzyme responsible for synthesizing new DNA strands by adding nucleotides in the 5’ to 3’ direction, requiring an RNA primer to start replication.
Leading vs. Lagging Strand
Leading strand is synthesized continuously, while the lagging strand is synthesized in short Okazaki fragments that are later joined by DNA ligase.
Replication Fork
Y-shaped region where DNA unwinds for replication, with helicase breaking hydrogen bonds and topoisomerase preventing supercoiling.
Telomeres & Telomerase
Telomeres are repetitive sequences at chromosome ends that protect DNA; telomerase extends them in germ cells to prevent degradation.
Nucleosome
The basic unit of chromatin, consisting of DNA wrapped around histone proteins, allowing for DNA packaging inside the nucleus.
Heterochromatin vs. Euchromatin
Heterochromatin is tightly packed and transcriptionally inactive, while euchromatin is loosely packed and active in gene expression.
Transcription
Synthesis of RNA from a DNA template by RNA polymerase, producing a complementary mRNA strand.
RNA Processing
Eukaryotic mRNA undergoes splicing (removing introns), 5’ capping, and 3’ polyadenylation before translation.
Translation
Conversion of mRNA codons into an amino acid sequence at the ribosome, facilitated by tRNA and rRNA.
Codon and Anticodon
Codons are three-nucleotide sequences in mRNA specifying amino acids, while anticodons on tRNA pair with them to ensure correct protein synthesis.
tRNA Function
Transfers specific amino acids to the ribosome during translation, ensuring correct protein synthesis based on mRNA codons.
Genetic Code Redundancy
The genetic code is degenerate, meaning multiple codons can specify the same amino acid, reducing the effect of mutations.
Post-Translational Modification
Chemical modifications like phosphorylation, glycosylation, and proteolytic cleavage alter protein function after translation.
Whole-Genome Shotgun Sequencing
A rapid sequencing technique that randomly fragments DNA, sequences the pieces, and assembles them computationally.
Bioinformatics
The application of computational tools to analyze biological data, including genome sequencing and functional annotation.
Gene Annotation
the plotting of genes onto genome assemblies, and indexing their genomic coordinates
Proteomics
the study of proteins
what they do and sht
Genome Size and Gene Density
Larger eukaryotic genomes have lower gene density and contain more noncoding DNA, including introns and regulatory elements.
Multigene Families
Groups of closely related genes arising from duplication, which can evolve new functions (e.g., hemoglobin gene family).
similar genes in different species coming from common ancestor
Transposable Elements
Mobile DNA sequences (like LINEs and SINEs) that can relocate within the genome, influencing gene regulation and evolution.