Chapter 17: Gene Expression - From Gene To Protein Flashcards
Gene expression
The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNA that are not translated into proteins and instead function as RNAs
Transcription
The synthesis of RNA using a DNA template
Messenger RNA
A type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein
Translation
the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of language from nucleotides to amino acids
Transfer RNA
An RNA molecule that functions as a translator between nucleic acid and protein languages by picking up a specific amino acid and carrying it to the ribosome, where the rRNA recognized the appropriate codon in mRNA.
Anticodon
A nucleotide triplet at one end of a tRNA molecule that base pairs with a particular complementary codon on an mRNA molecule
Aminoactyl tRNA synthase
An enzyme that joins each amino acid to the appropriate tRNA
Wobble
Flexibility in the base-pair rule in which the nucleotide at the 5 end of a tRNA codon can form hydrogen pairs with more than one kind of base in the third position of a codon
ribosomal RNA
RNA molecules that, together with proteins, make up ribosomes; the most abundant type of RNA
P site
One of a ribosome’s three binding sites for tRNA during translation. The P site holds the tRNA carrying the growth polypeptide chain
A site
One of a ribosomes three binding sites for tRNA during translation. The A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain
E site
One of a ribosomes three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome
Primary Transcript
An initial RNA transcript from any gene; also called pre-mRNA when transcribed from a protein-coding gene
Triplet Code
A genetic information system in which a series of three-nucleotide-long words specifies a sequence of amino acids for a polypeptide chain
Template strand
The DNA strand that provides the pattern or template, for ordering, by complementary base pairing, the sequence of nucleotides in an RNA transcript
Codons
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code
Coding strand
Nontemplate strand of DNA, which has the same sequence as the mRNA except it has thymine instead of uracil
Reading Frame
On an mRNA, the triplet grouping of ribonucleotides used by the translation machinery during polypeptide synthesis
RNA polymerase
An enzyme that links ribonucleotides into a growing RNA chain during transcription based on complementary binding of nucleotides on a DNA template strand
Promoter
A specific nucleotide sequence in the DNA of a gene that bind RNA polymerase positioning it to start transcribing RNA at the appropriate place
terminator
In bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecules and detach from DNA
Transcription Unit
A region of DNA that is transcribed into an RNA molecule
Start Point
In transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA
Transcription factors
A regulatory protein that binds to DNA and affects transcription of specific genes
TATA box
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
RNA processing
Modification of RNA primary transcripts, including the splicing out of introns, joining together of exons, and alteration of the 5 and 3 ends
5’ Cap
A modified form of guanine nucleotides added onto the 5’end of a pre-mRNA molecule
Poly-A tail
A sequence of 50-250 adenine added onto the 3’ end of a pre-mRNA molecule
RNA splicing
After synthesis of eukaryotic primary RNA transcript, the removal of portions of transcript, introns, that will not be included in the mRNA and the joining together of the remaining portions, exons.
Introns
A non coding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; also refers to the region of DNA from which this sequence was transcribed
Exons
A sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from this sequence was transcribed
Spliceosome
A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons
Ribozyme
An RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing
Alternative RNA splicing
A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
Domains
A discrete structural and functional region of a protein
Mutations
A change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus
Point Mutation
A change in a single nucleotide pair of a gene
Nucleotide-pair substitution
A type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides
Silent mutation
A nucleotide pair substitution that has no observable effect on the phenotype
For example, Within a gene a mutation that results in a codon that codes for the same amino acid
Missense mutation
A nucleotide pair substitution that results in a codon that codes for a different amino acid
Nonsense mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein
Insertions
A mutation involving the addition of one or more nucleotide pairs to a gene
Deletion
A mutational loss of one or more nucleotide pairs from a gene
Frame shift mutation
A mutation occurring when nucleotides are inserted in or deleted from a gene and the number inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.
Mutagens
A chemical or physical agent that interacts with DNA and can cause a mutation
Polyribosome
A group of several ribosomes attached to, and translating the same messenger RNA molecule.
