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38 Cards in this Set

  • Front
  • Back
Synthesis of RNA under the direction of DNA; copied from one molecule to another; DNA serves as a template for the RNA nucleotides
Carries the message from the DNA to the ribosome
Messenger RNA (mRNA)
Synthesis of a polypeptide, occuring under the direction of mRNA
Yields the finished mRNA - primary transcript
RNA processing
Genetic instructions for a polypeptide chain are written in the DNA as a series of three-nucleotide words
Triplet Code
DNA strand; provides the template for ordering the sequence of nucleotides in a RNA transcript
Template strand
mRNA base triplets; read in 5' - 3' direction; number of nucleotides making up a genetic message much be three times the number of amino acids
Groupings that help us read the genetic messages
Reading Frame
Pries the two strands of DNA apart and hooks together the RNA nucleotides as they base-pair along the DNA template; can add nucleotides only to the 3' end of the growing polymer - 5' - 3' direction
RNA polymerase
DNA sequence where RNA polymerase attatches and initiates transcription
Sequence that signals the end of transcription
Stretch of DNA that is transcribed into an RNA molecule
Transcription unit
Eukaryotes only; collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription
Transcription factors
Completed assembly of transcription factors and RNA polymerase bound to the promoter
Initiation (transcription) complex
Helps form the initiation complex
Helps protect the mRNA from degradation by hydrolytic enzymes; after mRNA reaches the cytoplasm, it's an "attatch here" sign for ribosomes - guanacine triphosphate (modified guanine)
5' Cap
3' end - 50 - 250 Adenine nucleotides; inhibits degradatoin; also facilitates of mRNA from the nucleus; also shares the nontranslated leader and trailer segments of RNA to which they are attatched
Poly (A) tail
Removal of a large portion of the RNA molecule that is initially synthesized
RNA splicing
Noncoding segments of nucleic acid that lie between coding segments
Translated into amino acid sequences, exiting the nucleus
Recognize splicing sites; composed of RNA (snRNA) and protein molecules - binds at beginning of intron
Interacts with the splice sites at the ends of an intron, cuts at specific points to release the intron, then joins togteher the two exons that flanked the intron
RNA molecules that function as enzymes; helps the idea of a catalytic role for snRNA
Discrete functional and structural regions
Interpretator of the message of series of codons; transfer amino acids from the cytoplasm's amino acid pool to a ribosome; folds with hydrogen bonds
Transfer RNA (tRNA)
Holds tRNA with polypeptide chain
P Site
Holds tRNA with amino acid to be added
A site
Exit site for empty tRNA
E site
Marks the protein to the ER or for secretion - about 20 amino acids at or near the leading (amino) acid of the polypeptide recognized as it emerges from the ribosome by signal-recognition partical (SRP)(protein-RNA complex)
Signal peptides
Changes in the genetic material of a cell (or virus)
Chemical changes in just one base pair of a gene
Point mutation
Replacement of one nucleotide and its partner in the complementary DNA strand with another pair of nucleotides
Base-pair substitution
No effect on the encoded protein
Silent mutation
The attended codon still codes for an amino acid
Misssense mutation
Alterations that change an amio acid codon to a stop signal - nonfunctional proteins
Nonsense mutation
Alteratoin of the reading frame - occurs whenever the number of nucleotides inserted or deleted is not a multiple of three
Frameshift mutation
Physical and chemical agents that interact with DNA to cause mutations
64 possible codons but only 20 amino acids, most amino acids are encoded for by more than one codon, difference occurs in the 3rd base, may help to prevent mutations from altering protein structure
Redundency in Genetic Code