Flashcards in Chapters 11-13 Deck (107)
the turning on and off of genes
-gene being turned on: being transcribed into mRNA and translated into specific protein molecules
-can help organisms respond to environmental changes.
the overall process by which genetic information flows from genes to proteins (from genotype to phenotype)
a control sequence at a site where the transcription enzyme, RNA polymerase, attaches and initiates transcription
between the promoter and the enzyme genes
-DNA control sequence that acts as a switch
-determines whether RNA polymerase can attach to the promoter and start transcribing the genes
a cluster of genes with related functions and the control sequences
What is the key advantage to the grouping of related genes into operons?
A single "on-off switch" can control the whole cluster.
How is transcription turned off?
a protein called a repressor binds to the operator and physically blocks the attachment of RNA polymerase to the promoter.
-located outside the operon
-codes for the repressor
-expressed continually, so the cell always has a small supply of repressor molecules
proteins that turn operons on by binding to DNA and stimulating gene transcription
what individual cells must undergo to become specialized in structure and function, with each type of cell fulfilling a distinct role.
A chromosome contains DNA wound around clusters of small proteins
-account for about half of the mass of eukaryotic chromosomes
"bead" that consists of DNA wound twice around a protein core of eight histone molecules
inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence
x chromosome inactivation
-a specific gene on the X chromosomes ensures that only one of the chromosomes will be inactivated
-initiated early in embryonic development when one of the two X chromosomes in each cell is inactivated at random
inactive X in each cell of a female condenses into a compact object
alternative RNA splicing
an organism can produce more than one type of polypeptide from a single gene
-may generate two or more types of mRNA from the same transcript.
opportunities for regulation of gene expression
-breakdown of mRNA
-initiation of translation
small single-stranded RNA molecules
-can bind to complementary sequences on mRNA molecules
small interfering RNAs
-similar in size and function to miRNAs
blocking of gene expression by siRNAs
master control gene that regulates groups of other genes that determine the anatomy of parts of the body.
nucleic acid hybridization
the base pairing of one strand of a nucleic acid to a complementary sequence on another strand
consists of tiny amounts of a large number of different single-stranded DNA fragments
signal transduction pathway
series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell.
capable of producing every kind of specialized cell in the organism
the regrowth of lost body parts
DNA from a donor cell is inserted into a nucleus-free host egg, resulting in a clone of the DNA donor.
therapeutic cloning goal
produce ES cells to treat disease
a gene that can cause cancer when present in a single copy in the cell