Chapters 11-13 Flashcards
Gene regulation
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.
gene expression
the overall process by which genetic information flows from genes to proteins (from genotype to phenotype)
Prometer
a control sequence at a site where the transcription enzyme, RNA polymerase, attaches and initiates transcription
operator
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
operon
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.
regulatory gene
- located outside the operon
- codes for the repressor
- expressed continually, so the cell always has a small supply of repressor molecules
activators
proteins that turn operons on by binding to DNA and stimulating gene transcription
differentiation
what individual cells must undergo to become specialized in structure and function, with each type of cell fulfilling a distinct role.
histones
A chromosome contains DNA wound around clusters of small proteins
-account for about half of the mass of eukaryotic chromosomes
nucleosome
“bead” that consists of DNA wound twice around a protein core of eight histone molecules
epigenetic inheritance
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
Barr body
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
- protein processing
microRNAs
small single-stranded RNA molecules
-can bind to complementary sequences on mRNA molecules
small interfering RNAs
-similar in size and function to miRNAs
RNA interference
blocking of gene expression by siRNAs
homeotic gene
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
DNA microarray
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.
totipotent
capable of producing every kind of specialized cell in the organism
regeneration
the regrowth of lost body parts
nuclear transplantation
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
oncogene
a gene that can cause cancer when present in a single copy in the cell
proto-oncogene
a normal cellular gene that helps control cell division that has the potential to become an oncogene
tumor-suppressor genes
genes whose normal products inhibit cell division
carcinogens
agents that alter DNA and make cells cancerous
transcription factors
proteins that promote the binding of RNA polymerase to a gene.
reproductive cloning
If the animal being cloned is a mammal, the blastocyst is then implanted into the uterus of a surrogate mother.
adult stem cells
both perpetuate themselves in culture and give rise to differentiated cells.
-normally give rise to only a limited range of cell types.
biotechnology
manipulation of organisms or their components to makes useful products
DNA technology
modern laboratory techniques for studying and manipulating genetic material
how is recombinant DNA formed?
when scientists combine pieces of DNA from two different sources to form a single DNA molecule
what does genetic engineering use?
recombinant DNA technology
plasmids
small, circular DNA molecules that replicate separately from the larger bacterial chromosome
DNA cloning
the production of many identical copies of a target segment of DNA
vector
gene carrier