Chapter 3, Section B Key Terms - Genetics Flashcards
Gene
A sequence of DNA nucleotides containing the information that specifies the amino acid sequence of a single polypeptide chain.
Genome
The total genetic information coded in the DNA of a typical cell in an organism. The human genome contains roughly 30,000 to 40,000 genes.
Histones
A class of proteins that participate in the packaging of DNA within the nucleus; strands of DNA form coils around the histones.
Nucleosomes
Nuclear complexes of several histones and their associated coils of DNA.
Transcription
The process of transferring genetic information from DNA to RNA in the nucleus.
Translation
The process that uses the coded information in RNA to assemble a protein in the cytoplasm.
Stop Signals
Three-nucleotide sequence in mRNA that signifies the end of protein coding sequence.
Messenger RNA (mRNA)
The class of RNA molecules that specifies the amino acid sequence of a protein and carries this message from DNA to the site of protein synthesis in the cytoplasm.
RNA polymerase
Enzyme that forms RNA by joining together appropriate nucleotides after they have base-paired to DNA.
Template strand
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Promoter
Specific nucleotide sequence at beginning of gene that controls the initiation of gene transcription; determines which of the paired strands of DNA is transcribed into RNA.
Codon
A three based sequence in RNA that specifies one amino acid.
Exons
DNA gene region containing code words for a part of the amino acid sequence of a protein.
Intron
Regions of noncoding nucleotides in a gene.
Spliceosome
Protein and nuclear RNA complex that removes introns and links exons together during gene transcription.
Ribosomal RNA (rRNA)
Type of RNA used in ribosome assembly; becomes part of ribosome.
Transfer RNA (tRNA)
Type of RNA; different tRNAs combine with different amino acids and with codon on mRNA specific for that amino acid, thus arranging amino acids in sequence to form specific protein.
Anticodon
Three nucleotide sequence of tRNA able to base pair with complementary codon in mRNA during protein synthesis.
Initiation factors
A protein required for ribosomal assembly and the establishment of an initiation complex that allows new protein synthesis to begin.
Transcription factors
Proteins that act as gene switches, interacting in a variety of ways to activate or repress the initiation process that takes place at the promoter region of a particular gene.
Preinitiation complex
A group of transcription factors and accessory proteins that associate with promoter regions of specific genes; the complex is required for gene transcription to commence.
Mutation
Any alteration in the nucleotide sequence that spells out a genetic message in DNA.
Mutagens
Environmental factors that increase the rate of mutation
Natural selection
Organisms that function less effectively are less likely to produce and pass on their genes.
Ubiquitin
Small intracellular peptide that attaches to proteins and directs them to proteasomes.
Proteasome
A complex of proteins capable of denaturing (unfolding) other proteins and assisting in protein degradation.
Signal sequence
Initial portion of newly synthesized protein (if protein is destined for secretion).
Primary RNA transcript
An RNA molecule transcribed from a gene before intron removal and splicing.