honors biology 9 saavas chapter 12 and 13

transformation

process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria

bacteriophage

kind of virus that infects bacteria

base pairing

principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine

replication

process of copying DNA prior to cell division

DNA polymerase

principle enzyme involved in DNA replication

telomeres

repetitive DNA at the end of a eukaryotic chromosome

RNA

single-stranded nucleic acid that contains the sugar ribose

messenger RNA

type of RNA that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell

ribosomal RNA

type of RNA that combines with proteins to form ribosomes

transfer RNA

type of RNA that carries each amino acid to a ribosome during protein synthesis

transcription

synthesis of an RNA molecule from a DNA template

RNA polymerase

enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template

promoters

specific region of a gene where RNA polymerase can bind and begin transcription

introns

sequence of DNA that is not involved in coding for a protein

exton

expressed sequence of DNA; codes for a protein

polypeptides

long chain of amino acids that makes proteins

genetic code

collection of codons of mRNA, each of which directs the incorporation of a particular amino acid into a protein during protein synthesis

codon

group of three nucleotide bases in mRNA that specify a particular amino acid to be incorporated into a protein

translation

process by which the sequence of bases of an mRNA is converted into the sequence of amino acids of a protein

gene expression

process by which a gene produces its product and the product carries out its function

mutations

changes in the genetic material

point mutations

gene mutation in which a single base pair in DNA has been changed

frameshift mutations

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

mutagens

s chemical or physical agent that interacts with DNA and causes a mutation.

polyploidy

condition in which an organism has extra sets of chromosomes

operon

in prokaryotes, a group of adjacent genes that share a common operator and promoter and are transcribed into a single mRNA

operator

short DNA region, adjacent to the promoter of a prokaryotic operon, that binds repressor proteins responsible for controlling the rate of transcription of the operon

RNA interference

introduction of double-stranded RNA into a cell to inhibit gene expression

differentiation

process in which cells become specialized in structure and function

homeotic genes

a class of regulatory genes that determine the identity of body parts and regions in an animal embryo. Mutations in these genes can transform one body part into another

homeobox genes

genes that code for transcription factors that activate other genes that are important in cell development and differentiation

hox genes

a group of homeotic genes clustered together that determine the head to tail identity of body parts in animals. All hox genes contain the homeobox DNA sequence.