exam 3
No description yet. This curated deck is ready for daily study.
Card preview (24)
what do genes do
Genes pass down hereditary information and provide ‘instructions’ for how cells function, regulate, and form structures.
what are genes made of
DNA, which can code for amino acid sequences (proteins) or RNA (non-protein functions).
how is genetic information replicated?
DNA molecules replicate to produce two copies, distributed into each daughter cell.
what are transcription and translation
Transcription: RNA is synthesized by copying information from DNA using enzymes. Translation: RNA’s base sequence directs the creation of a polypeptide.
when was DNA discovered and by who
1869, Friedrich Miescher
what evidence showed DNA is genetic material?
Griffith’s Experiment: Showed a “transforming principle” could convert R-strain bacteria into pathogenic S-strain. Avery’s Experiment: Found DNA was the transforming substance by isolating nucleic acid from S-strain bacteria. Hershey & Chase Experiment: Confirmed DNA, not protein, was injected into bacteria by phages.
what roles do bacteriophages play in genetic studies
infect bacteria, showing how DNA or RNA is the genetic material for replication and cell function.
what is the structure of DNA
double helix, with a sugar phosphate backbone on the outside, right handed helix (B-DNA)
What did Chargaff discover about DNA?
A=T and G=C in all DNA samples, with variation among species.
how does DNA replicate
The double helix separates, and each strand serves as a template for a new complementary strand.
how is DNA packaged in eukaryotes
DNA wraps around histones to form nucleosomes. Nucleosomes coil into 30-nm chromatin fibers. Chromatin fibers further fold into loops to form chromosomes.
Positively charged proteins that stabilize negatively charged DNA and organize it into chromatin.
histones
Loosely packed, transcriptionally active DNA.
euchromatin
Highly condensed, transcriptionally inactive DNA.
heterochromatin
what are the two types of repeated DNA sequences?
Tandemly repeated DNA and Interspersed repeated DNA
how are Interspersed repeated DNA arranged
Scattered sequences like LINEs and SINEs.
how is Tandemly repeated DNA arranged
Sequences arranged in rows, such as microsatellites and minisatellites.
what are transposons
Mobile genetic elements that can move and leave copies of themselves in the genome.
What is unique about mitochondrial and chloroplast DNA
Circular DNA with no histones. Mitochondria: 16,569 bp encoding 37 genes. Chloroplasts: ~120,000 bp encoding ~120 genes.
how do organelles depend on the nuclear genome
They rely on nuclear genes for most protein synthesis while encoding some of their polypeptides.
how can DNA melting temperature indicate stability
Higher Tm reflects tighter DNA binding due to more GC content and base stacking interactions
describe nucleic acid hybridization
A method where complementary sequences bind to identify specific nucleic acids, used in FISH.
what are histone modifications
Tags like methyl or acetyl groups alter chromatin structure, affecting gene expression.
explain histone codes
The combination of histone tags that regulate DNA activity and chromatin state.