Chapter 13 & 14: DNA Structure, Function, and RNA Synthesis

Digital flashcards created for study purposes, summarizing key concepts and definitions from Chapter 13 and 14 on DNA Structure, Function, and RNA Synthesis.

What did Griffith discover?

Bacterial transformation: dead harmful bacteria can transfer genes to harmless bacteria, making them deadly.

Avery's experiment

Proved that DNA is the transforming factor, not proteins or other molecules.

Hershey and Chase's experiment

Demonstrated that DNA, not protein, carries genetic information using bacteriophages.

3 Functions of DNA

Storing information, copying information, and gene expression.

Building block of DNA

Nucleotides, composed of sugar, phosphate, and nitrogenous base.

4 Nitrogenous bases in DNA

Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

Chargaff’s rule

States that A = T and C = G, indicating base-pairing.

Rosalind Franklin

Contributed to DNA discovery through Photo 51, which showed DNA is a double helix.

Watson and Crick

Developed the double-helix model of DNA using Franklin’s research.

Hydrogen bonds in DNA

What holds the two strands of DNA together between nitrogenous bases.

Antiparallel strands of DNA

Refers to DNA strands running in opposite directions.

S phase of interphase

The phase where DNA replication occurs.

DNA polymerase

The enzyme that adds new nucleotides during DNA replication.

Telomerase

An enzyme that protects the ends of DNA strands

DNA replication in prokaryotes vs eukaryotes

Prokaryotic replication starts at one point, while eukaryotic replication has many origins.

RNA vs DNA

RNA is single-stranded, contains ribose sugar, and uses uracil (U) instead of thymine (T).

Types of RNA

mRNA (messenger)carries code from DNA, tRNA (transfer)brings amino acids, rRNA (ribosomal)part of ribosome.

Transcription

The process of copying DNA into mRNA using RNA polymerase.

Promoters

Regions of DNA where RNA polymerase binds to initiate transcription.

RNA editing

The process of removing introns and retaining exons from pre-mRNA.

Three-base codons

There are 64 possible codons that correspond to amino acids.

Start and stop codons

Start: AUG (methionine) signals the start of translation; stop codons (UAA, UAG, UGA) signal the end of translation.

Steps of translation

1. Initiation - Ribosome binds to mRNA. 2. Elongation - tRNA brings amino acids. 3. Termination - Stop codon ends translation.

Lac operon

Controls the breakdown of lactose in bacteria, involved in gene regulation.

Transcription factors

Proteins that help regulate gene expression in eukaryotic cells.

Homeotic genes

Genes that regulate body development, such as Hox genes.

Epigenetics

Changes in gene expression caused by environmental factors, not mutations.

Point mutation

A change in a single base pair in DNA.

Types of point mutations

Silent (no change), Missense (changes one amino acid), Nonsense (creates a stop codon).

Frameshift mutation

An insertion or deletion that shifts the entire reading frame of the DNA sequence.

Chromosomal mutations

Mutations that involve large segments of DNA, including deletions, duplications, inversions, and translocations.

Mutagens

Agents that cause mutations, such as radiation and chemicals.

Helpful mutations

Some mutations can lead to beneficial traits, like antibiotic resistance in bacteria.