Biology Chapter 11 Flashcards

Genetic Terms and Definitions

• A site: Ribosomal site occupied by ammoniacal-tRNA, crucial for protein synthesis.
• Allolactose: Inducer molecule derived from lactose that activates the lactose operon, facilitating gene expression for lactose metabolism.
• Aminoacyl-tRNA synthetase: Enzyme that catalyzes the attachment of specific amino acids to their corresponding tRNA, essential for translation.
• Anticodon loop: Portion of tRNA that pairs with the mRNA codon, ensuring the correct amino acid is added during protein synthesis.
• Bacteriophage: Viruses specifically targeting bacteria, instrumental in genetic studies and biotechnology.

Core Concepts in Genetics

• Codon: Triplet of nucleotides in mRNA that specifies a particular amino acid during translation.
• Conjugation: Mechanism of genetic exchange between bacteria, utilizing a pilus in Gram-negative or direct adhesion in Gram-positive bacteria.
• Constitutive gene: Genes that are consistently active and produce proteins, unlike inducible or repressible genes that are regulated.
• Degenerate genetic code: Characteristic of the genetic code allowing multiple codons to encode the same amino acid, providing redundancy in protein translation.
• Deoxyribose: The sugar component in DNA, forming part of the nucleotide structure.

DNA Structure and Replication

• Dissimilation plasmid: Extrachromosomal DNA conferring resistance to environmental stressors.
• DNA ligase: Enzyme facilitating the joining of DNA fragments by sealing gaps, especially relevant on the lagging strand during replication.
• DNA polymerase: Key enzyme that matches and links complementary bases during DNA replication.
• E site: Ribosomal site where tRNA releases its amino acid after peptide formation.
• Frameshift mutation: Genetic alteration resulting from the insertion or deletion of nucleotides, shifting the reading frame of the genetic code.

Gene Regulation and Transcription

• Gene expression: Encompasses transcription and translation processes that transform DNA into functional proteins.
• Generalized transduction: Process by which bacterial DNA fragments are transferred from one bacterium to another via a virus.
• Genetic code: Defined relationship between mRNA codons and their corresponding amino acids, foundational for translation.
• Helicase: Enzyme that unwinds the DNA helix during replication, allowing separation of the strands.
• Hfr (high frequency of recombination) cell: A bacterial cell with an F plasmid integrated into its chromosome, facilitating efficient gene transfer during conjugation.

mRNA and Protein Synthesis

• Initiation codon: The first codon in mRNA that signals the start of translation.
• Initiator protein: Binds to the replicator sequence to initiate transcription.
• Lac operon: Genetic system that regulates lactose utilization, incorporating structural and regulatory genes.
• Lagging strand: DNA strand synthesized in short pieces (Okazaki fragments) due to the opposite orientation relative to the replication fork.
• Leading strand: DNA strand synthesized continuously in the direction of the replication fork.

RNA and Mutations

• Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes for protein synthesis.
• Mutagen: Agents that cause DNA mutations, potentially leading to genetic diversity or diseases.
• Nucleotide excision: DNA repair mechanism that excises damaged sections of DNA.
• Okazaki fragments: Short DNA fragments synthesized on the lagging strand during replication.
• Open reading frame: The segment of mRNA that is translated into a protein, starting from the initiation codon.

Genetic Processes and Repair

• Operator site on DNA: Regulatory sequence where repressor proteins bind to inhibit transcription.
• Operon: Cluster of genes controlled by a single regulatory element, allowing coordinated expression.
• Origin of replication: DNA sequence where replication begins, marked by specific nucleotide arrangements.
• P site: Ribosomal site that holds the growing polypeptide chain.
• Peptidyl transferase reaction: Chemical process linking amino acids during protein formation, critical for polypeptide assembly.

DNA Damage and Repair Mechanisms

• Photoreactivation: Light-dependent repair mechanism that corrects thymine dimers in DNA using photolyase enzyme.
• Point mutation: Substitution of a single nucleotide, often leading to altered protein function.
• Polycistronic: Referring to prokaryotic mRNA that encodes multiple proteins from a single transcript.
• Polyribosome: Complex of multiple ribosomes translating a single mRNA molecule simultaneously.
• Primase: Enzyme that synthesizes RNA primers necessary for initiating DNA replication.

Additional Genetic Concepts

• Primer:template junction: The connection between the RNA primer and the DNA template, critical for DNA replication initiation.
• Promoter site on DNA: Region where RNA polymerase and associated transcription factors bind to initiate transcription.
• Prophage: A bacteriophage's DNA integrated into a bacterial genome, playing a role in horizontal gene transfer.
• Purines: Nitrogenous bases adenine and guanine, fundamental components of nucleic acids.
• Pyrimidines: Nitrogenous bases thymine and cytosine, essential for DNA structure.

Reading Frames and Recombination

• Reading frame: The way nucleotides are divided into codons for translation, critical for accurate protein synthesis.
• Recombination: The exchange of genetic material between molecules, leading to new genetic configurations.
• Replication fork: The Y-shaped structure where DNA unwinding and synthesis occur during replication.
• Replicator sequence: AAT-rich area of DNA that facilitates the opening of strands for replication.
• Ribosomal RNA: Essential RNA component of ribosomes, contributing to the structural and functional roles in protein synthesis.

RNA Processing and Genetic Mobility

• RNAase H: Enzyme that removes RNA primers from DNA during lagging strand synthesis.
• Specialized transduction: Genetic transfer involving specific genes adjacent to viral DNA integration.
• Spontaneous mutation: Naturally occurring changes in DNA sequence without external mutagenic agents.
• Stop codon: Codon signaling termination of protein synthesis, releasing the newly formed polypeptide chain.
• Supercoiling of DNA: Tight coiling of the DNA helix, impacting replication and gene expression.

Mutation Dynamics

• Suppressor mutations: Mutations that counteract the effects of previous mutations, restoring the original phenotype.
• Topoisomerase: Enzyme that alleviates DNA supercoiling by cutting, unwinding, and resealing DNA strands.
• Transfer RNA: The adaptor molecule that carries amino acids to the ribosome for incorporation into proteins.
• Transformation: Uptake and incorporation of free DNA from the environment by a bacterial cell.
• Translation: The process of synthesizing proteins based on mRNA templates, central to gene expression.

Genetic Mobility and Theoretical Concepts

• Transposition: Mobility of genetic sequences within or between genomes, contributing to genetic variation.
• Transposon: Mobile genetic element that carries genes for its own transposition and additional genes that may confer advantages.
• Wobble hypothesis: Concept suggesting that flexibility in base pairing at the third codon position allows for some mutations without adverse effects on the protein.

Test your knowledge with flashcards from Biology Chapter 11, focusing on key terms such as ribosomes, operons, and tRNA. This quiz includes definitions and important concepts related to molecular biology and genetics. Perfect for students seeking to reinforce their understanding of these topics.