chapter 11 Biology
Terms
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- clone
- an individual created by asexual reproduction and thus genetically identical to a single parent
- gene expression
- the overall process by which genetic information flows from genes to proteins (genotype to phenotype)
- Escherichia coli
- scientific name for E. coli, can change its metabolic activities in response to changes in its environment
- control sequences
- short sections of DNA that help control the enzyme genes
- promoter
- a site where the transcription enzyme (RNA polymerase) attaches and initiates transcription
- operator
- a DNA segment that acts as a switch between the promoter and the enzymes genes
- operon
- a cluster of genes with related functions, along with a promoter and an operator (exists in prokaryotes)
- repressor
- turns off transcription, a protein that functions by binding to the operator and physically blocking the attachment of RNA polymerase to the promoter
- regulatory gene
- located outside the operon, codes for the repressor (expressed continually)
- lac operon
- the repressor is active when alone and inactive when bound to lactose
- activators
- type of operon, proteins that turn operons on by binding to DNA, act by making it easier for RNA polymerase to bind to the promoter
- trp operon
- operon allows bacteria to stop making certain essential molecules when the molecules are already present in the environment: saving materials and energy for the cell
- differentiation
- during the repeated cell divisions that lead from a zygote to a multicellular adult, individual cells must become specialized in structure and function, results from the selective gene expression (turning on and off of genes)
- regeneration
- the regrowth of lost body parts
- histones
- association of the DNA with small proteins (account for about half the mass of eukaryotic chromosomes)
- nucleosome
- consists of DNA wound around a protein core of eight histone molecules
- X chromosome inactivation
- initiated early in embryonic development, when one of the two X chromosomes in each cell is inactivated at random
- transcription factors
- proteins that assist eukaryotic RNA polymerase
- enhancers
- usually far away from the gene they help regulate and may be on either side of the gene, leads to bending of the DNA
- alternative RNA splicing
- an organism can get more than one type of polypeptide from a single gene
- nuclear transplantation
- involves replacing the nucleus of an egg cell or a zygote with the nucleus of an adult somatic cell (allows animal cloning)
- reproductive cloning
- if the animal to be cloned is a mammal, further development requires implanting the blastocyst into the uterus of a surrogate mother
- embryonic stem cells
- give rise to all the different kinds of specialized cells of the body
- therapeutic cloning
- the process that aims to produce embryonic stem cells for therapeutic treatments
- adult stem cells
- cells present in adult tissues that generate replacements for nondividing differentiated cells
- Drosphila melanogaster
- fruit fly
- homeotic gene
- master control gene that regulates batteries of other genes that actually determine the anatomy of parts of the body
- signal transduction pathway
- a series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell
- homeoboxes
- nucleotide sequences that are each translated into a segment (60 amino acids long) of the protein product of the homeotic gene