Bio Ch 13 Flashcards
Operon
model that explains gene regulation in prokaryotes
Structural genes
genes for a metabolic pathway; grouped on a chromosome and subsequently transcribed at the same time; code for the enzymes and proteins that are involved in the metabolic pathway of the operon; transcribed as a unit
Regulator gene
normally located outside the operon; codes for a DNA-binding protein that acts as a repressor
Repressor
controls whether the operon is active or not
Promoter
short sequence of DNA where RNA polymerase 1st attaches to begin transcription of the grouped genes; signals the start of the operon and the location where transcription begins
Operator
short portion of DNA where an active repressor binds
Corepressor
molecule that binds to a repressor, allowing the repressor to bind to an operator in a repressible operon
Inducer
molecule that brings about activity of an operon by joining with a repressor and preventing it from binding to the operator
Epigenetic inheritance
an inheritance pattern in which a nuclear gene has been modified but the changed expression of the gene is not permanent over many generations the transmission of genetic information by means that are not based on the coding sequences of a gene
Chromatin
stringy material that makes up DNA in eukaryotes; most evident in nucleus during interphase
Barr body
small, darkly staining mass of condensed chromatin adhering to the inner edge of the nuclear membrane is an inactive X chromosome
Transcriptional control
control of gene expression by the use of transcription factors, and other proteins, that regulate either the initiation of transcription or the rate at which it occurs
Transcription factors
proteins that help regulate transcription by assisting the binding of the RNA polymerase to the promoter
Transcription activator
DNA-binding protein; transcription cannot begin without this
Enhancers
DNA sequence that acts as a regulatory element to increase the level of transcription when regulatory proteins, such as transcription activator bind to it
Posttranscriptional control
occurs in the nucleus and includes alternative mRNA splicing and controlling the speed with which mRNA leaves the nucleus
MicroRNAs (miRNAs)
small snippets of RNA that can bind to and dampen the translation of mRNA in the cytoplasm
Small-interfacing RNAs (siRNAs)
join with an enzyme (an RNA-induced silencing complex, or RISC) to form an active silencing complex
RNA Interference
cellular process that utilizes miRNA and siRNA molecules to reduce or inhibit the expression of specific genes
Translational control
begins when the processed mRNA molecule reaches the cytoplasm and before there is a protein product
Posttranslational control
begins once a protein has been synthesized and has become active
Proteases
enzymes that breakdown proteins
Proteasomes
to protect the cell, proteases are typically confined to the lysosomes or special structures called these
Gene mutation
permanent change in the sequence of bases in DNA
Spontaneous mutations
arise as a result of abnormalities in normal biological processes
Induced mutations
may result from exposure to toxic chemicals or radiation, which cause changes in the base sequence of DNA
Mutagens
environmental factors that can alter the base composition of DNA; cause induced mutations
Carcinogens
cancer-causing mutagens
DNA Repair Enzymes
constantly monitor DNA and fix any irregularities
Point mutations
involve a change in a single DNA nucleotide and therefore a possible change in a specific amino acid
Frameshift mutations
occur most often when one or more nucleotides are either inserted or deleted from DNA
