Bio Terms Chapter 17 ;)

clairebear2018's version from 2018-04-12 04:08

Section 1

Question Answer
Gene Expressionthe process by which DNA directs protein synthesis, includes two stages: transcription and translation
Transcriptionthe synthesis of RNA using information in DNA
Translationthe synthesis of a polypeptide, using information in the mRNA
Ribosomesthe sites of translation
Ribosomes are the sites of protein synthesis
The flow of information from gene to protein is based on DNA triplet codes in the ______, a series of nonoverlapping, three-nucleotide “wordstemplet strand
The triplets of a gene are ______ into complementary nonoverlapping three-nucleotide “words” (______) of mRNAtranscribed ; codons
These codons are ______ into a sequence of amino acids, then ______ by the ribosome’s rRNA to form a polypeptide chaintranslated ; synthesized
Codonsread in the 5′ → 3′ direction
Codons must be read in the correct ______ (correct groupings) in order for the specified polypeptide to be producedreading frame
mRNA synthesis is catalyzed by RNA ______, which pries the DNA strands apart and joins together the mRNA nucleotidesRNA polymerase
The DNA sequence where RNA polymerase attaches is called thepromoter
In bacteria, the sequence signaling the end of transcription is called the terminator

Section 2

Question Answer
The stretch of DNA that is transcribed is called atranscription unit
The three stages of transcriptioninitiation, elongation, termination
Promoters signal the transcription _____ and usually extend several dozen nucleotide pairs upstream of the ____ start point
Transcription facorsmediate the binding of RNA polymerase and the initiation of transcription
The completed assembly of transcription factors and RNA polymerase II bound to a promoter is called a ______ transcription initiation complex
TATA Boxcrucial in forming the initiation complex in eukaryotes
Enzymes in the eukaryotic nucleus modify pre-mRNA (______) before the genetic messages are dispatched to the cytoplasmRNA processing
Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that lie between coding regions. These noncoding regions are called intervening sequences, or introns
The other regions are called ______ because they are eventually expressed, usually translated into amino acid sequencesexons
RNA Splicingremoves introns and joins exons, creating an mRNA molecule with a continuous coding sequence
Spliceosomesconsist of a variety of proteins and several small RNAs that recognize the splice sites
Ribozymesare catalytic RNA molecules that function as enzymes and can splice RNA
Some genes can encode more than one kind of polypeptide, depending on which segments are treated as exons during splicing. This is called alternative RNA splicing

Section 3

Question Answer
Proteins often have a modular architecture consisting of discrete regions called domains
A cell translates an mRNA message into protein with the help of transfer RNA
Flexible pairing at the third base of a codon is called _____ and allows some tRNAs to bind to more than one codonwobble
Ribosomes facilitate specific coupling of tRNA anticodons with mRNA codons in protein synthesis
The two ribosomal subunits (large and small) are made of proteins and ribosomal RNA
P Siteholds the tRNA that carries the growing polypeptide chain
A Siteholds the tRNA that carries the next amino acid to be added to the chain
E Sitethe exit site, where discharged tRNAs leave the ribosome
Mutationsare changes in the genetic information of a cell
Point Mutationsare changes in just one nucleotide pair of a gene
Nucleotide Pair Substitutionreplaces one nucleotide and its partner with another pair of nucleotides
Silent Mutationhave no effect on the amino acid produced by a codon because of redundancy in the genetic code
Missense Mutationstill code for an amino acid, but not the correct amino acid

Section 4

Question Answer
Nonsense Mutationchange an amino acid codon into a stop codon; most lead to a nonfunctional protein
_____ and _____ are additions or losses of nucleotide pairs in a geneinsertions ; deletions
Insertion or deletion of nucleotides may alter the reading frame, producing a frameshift mutation
Mutagensare physical or chemical agents that can cause mutations