Unit 1 Ch 4 - Molecular Information Flow and Protein Processing Flashcards
from Unit 1 -The Foundations of Microbiology
Amino acid
one of the 22 different monomers that make up proteins; chemically, a two-carbon carboxylic acid containing an amino group and a characteristic substituent on the alpha carbon
Aminoacyl-tRNA synthetase
an enzyme that catalyzes attachment of an amino acid to its cognate tRNA
Anticodon
a sequence of three bases in a tRNA molecule that base-pairs with a codon during protein synthesis
Antiparallel
in reference to double stranded DNA, the two strands run in opposite direction (one runs 5’ to 3’ and the complementary strand 3’ to 5’)
Bacteriocin
a toxic protein secreted by bacteria that inhibits or kills other, related bacteria
Chaperone
a protein that helps other proteins fold or refold from a partly denatured state
Chromosome
a genetic element, usually circular in prokaryotes, carrying genes essential to cellular function
Codon
a sequence of three bases in mRNA that encodes an amino acid
Codon bias
nonrandom usage of multiple codons encoding the same amino acid
Complementary
nucleic acid sequences that can base-pair with each other
Denaturation
loss of the correct folding of a protein, leading (usually) to protein aggregation and loss of biological activity
DNA (deoxyribonucleic acid)
a polymer of deoxyribonucleotides linked by phosphodiester bonds that carries genetic information
DNA gyrase
an enzyme found in most prokaryotes that introduces negative supercoils in DNA
DNA helicase
an enzyme that uses ATP to unwind the double helix of DNA
DNA ligase
an enzyme that seals nicks in the backbone of DNA
DNA polymerase
an enzyme that synthesizes a new strand of DNA in the 5’ to 3’ direction, using an antiparallel DNA strand as a template
Exons
the coding DNA sequences in a split gene (contrast with intron)
Gene
a segment of DNA specifying a protein (via mRNA), a tRNA, an rRNA, or any other noncoding RNA
Genetic code
the correspondence between nucleic acid sequence and amino acid sequence of proteins
Genetic element
a structure that carries genetic information, such as a chromosome, as plasmid, or a virus genome
Genome
the total complement of genes contained in a cell or virus
Informational macromolecule
any large polymeric molecule that carries genetic information, including DNA, RNA and protein
Introns
the intervening noncoding DNA sequences in a split gene (contrast with exon)
Lagging strand
the new strand of DNA that is synthesized in short pieces and then joined together
Leading strand
the new strand of DNA that is synthesized continuously during DNA replication
Messenger RNA (mRNA)
an RNA molecule that contains the genetic information to encode one or more polypeptides
Nonsense codon
another name for stop codon
Nucleoside
a nitrogenous base (adenine, guanine, cytosine, thymine or uracil) plus a sugar (either ribose or deoxyribose) but lacking phosphate
Nucleotide
a monomer of a nucleic acid containing a nitrogenous base (adenine, guanine, cytoside, thymine or uracil), one or more molecules of phosphate and a sugar, either ribose (in RNA) or deoxyribose (in DNA)
Open reading frame (ORF)
a sequence of DNA or RNA that could be translated to give a polypeptide
Operon
a cluster of genes that are cotranscribed as a single messenger RNA
Peptide bond
a type of covalent bond linking amino acids in a polypeptide
Phosphodiester bond
a type of covalent bond linking nucleotides together in a polynucleotide
Plasmid
an extrachromosomal genetic element that is usually not essential to the cell
Polynucleotide
a polymer of nucleotides bonded to one another by covalent bonds called phosphodiester bonds
Polypeptide
a polymer of amino acids bonded to one another by peptide bonds
Primary structure
the precise sequence of monomers in a macromolecule such as a polypeptide or a nucleic acid
Primary transcript
an unprocessed RNA molecule that is the direct product of transcription
Primase
the enzyme that synthesizes the RNA primer used in DNA replication
Primer
an oligonucleotide to which DNA polymerase attaches the first deoxyribonucleotide during DNA synthesis
Promoter
a site on DNA to which RNA polymerase binds to commence transcription
Protein
a polypeptide or group of polypeptides forming a molecule of specific biological function
Purine
one of the nitrogenous bases of nucleic acids that contain two fused rings; adenine and guanine
Pyrimidine
one of the nitrogenous bases of nucleic acids that contain a single ring; cytosine, thymine and uracil
Quaternary structure
in proteins, the number and types of individual polypeptides in the final molecule
Replication
synthesis of DNA using DNA as a template
Replication fork
the site on the chromosome where DNA replication occurs and where the enzymes replicating the DNA are bound to untwisted, single stranded DNA
Replisome
a DNA replication complex that consists of two copies of DNA polymerase III, DNA gyrase, helicase, primase and copies of single strand binding protein
Ribosomal RNA (rRNA)
types of RNA found in the ribosome; some participate actively in protein synthesis
Ribosome
a cytoplasmic particle composed of ribosomal RNA and protein, whose function is to synthesize proteins
RNA (ribonucleic acid)
a polymer of ribonucleotides linked by phosphodiester bonds that plays many roles in cells, in particular, during protein synthesis
RNA polymerase
an enzyme that synthesizes RNA in the 5’ to3’ direction using a complementary and antiparallel DNA strand as a template
RNA processing
the conversion of a primary transcript RNA to its mature form
Secondary structure
the initial pattern of folding of a polypeptide or a polynucleotide, usually dictated by opportunities for hydrogen bonding
Semiconservative replication
DNA synthesis yielding two new double helices, each consisting of one parallel and one progeny strand
Signal sequence
a special N-terminal sequence of approximately 20 amino acids that signals that a protein should be incorporated into or exported across the cytoplasmic membrane
Spliceosome
a complex of ribonucleoproteins that catalyze the removal of introns from primary RNA transcripts
Start codon
a special codon, usually AUG, that signals the start of a protein
Stop codon
a codon that signals the end of a protein
Termination
stopping the elongation of an RNA molecule at a specific site
Tertiary structure
the final folded structure of a polypeptide that has previously attained secondary structure
Transcription
the synthesis of RNA using a DNA template
Transfer RNA (tRNA)
a small RNA molecule used in translation that possesses an anticodon at one end and has the corresponding amino acid attached to the other end
Translation
the synthesis of protein using the genetic information in RNA as a template
Transposable element
a piece of DNA able to move (transpose) from one site to another on host DNA molecules
Wobble
a less rigid form of base pairing allowed only in codon-anticodon paring