CH 18 Flashcards
operator
-the entire stretch of DNA that includes the operator, the promoter, and the genes that they control
repressor
-switches off the operon
regulatory gene
-created the represor
corepressor
-a molecule that cooperates with a repressor protein to switch an operon off
inducer
-inactivates the repressor to turn the lac operon on
activator
-a protein that binds to DNA and stimulates transcription of a gene
cyclic AMP (cAMP)
-a common chemical signal as a second messenger in many eukaryotic cells, and as a regulator of some bacterial operons
differential gene expression
-the expression of different genes by cells with the same genome
histone acetylation
-acetyl groups are attached to an amino acid in a histone tail
DNA methylation
-the addition of methyl groups to certain bases in DNA, is associated with reduced transcription in some species
epigenetic inheritance
-The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence
control elements
-segments of noncoding DNA that serve as binding sites for transcription factors that help regulate transcription
enhancers
-grouped Distal control elements
alternative RNA splicing
-different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
MicroRNAs (miRNAs)
-small, single-stranded RNA molecules that can bind complementary sequences in mRNA
Small interfering RNAs (siRNAs)
-similar to miRNAs in size and function
RNA interference (RNAi)
-blocking of gene expression
Long noncoding RNAs (lncRNAs)
-200 to hundreds of thousands of nucleotides in length
cell differentiation
-the process by which cells become specialized in structure and function
morphogenesis
-The physical processes that give an organism its shape
Cytoplasmic determinants
-are maternal substances in the egg that influence early development
induction
-signal molecules from embryonic cells cause changes in nearby target cells
Determination
-irreversibly commits a cell to becoming a particular cell type
-precedes differentiation
Pattern formation
-the development of a spatial organization of tissues and organs
Positional information
-the molecular cues that control pattern formation, tells a cell its location relative to the body axes and to neighboring cells
homeotic genes
-control pattern formation in the late embryo, larva, and adult stages
embryonic lethal
-mutations with phenotypes causing death at the embryonic or larva stage
Maternal effect genes
-mutant is in the mother
-results in a mutant phenotype in offspring
bicoid gene
-affects the front half of the body
-no functional Bicoid gene=no front half of body missing
morphogens
-gradients of substances
-establish an embryo’s axes and other features of its form
Oncogenes
-cancer-causing genes in some types of viruses
Proto-oncogenes
-are the corresponding normal cellular genes that are responsible for normal cell growth and division
Tumor-suppressor genes
-inhibit cell division
ras gene
-mutations can lead to production of a hyperactive Ras protein and increased cell division
p53 gene
-mutations prevent suppression of the cell cycle
