Biology Ch. 17

genotypes and phenotypes

the process by which DNA directs protein synthesis

the synthesis of RNA using information in DNA

messenger RNA(mRNA)

the synthesis of a polypeptide using information in the mRNA

sites of translation

the initial RNA transcript from any gene prior to processing

the concept that cells have a cellular chain of command
DNA-->RNA-->protein

a series of non overlapping, three-nucleotide words

provides a template for ordering the sequence of complementary nucleotides in an RNA transcript

mRNA base triplets
read in 5'-->3' direction

nontemplate strand, nucleotides are identical to codons

the amino acid going to be placed at the corresponding position along a polypeptide

61 code for amino acids
3 are stop signals to end translation

the first stage of gene expression

catalyzes RNA synthesis
pries the DNA strands apart and joins the RNA nucleotides together

the DNA sequence where RNA polymerase attaches

in bacteria, the sequence signaling the end of transcription

initiation
elongation
termination

promoters

help guide the binding of RNA polymerase and the initiation of transcription

the completed assembly of transcription factors and RNA polymerase II bound to a promoter

a promoter that helps forms the initiation complex in eukaryotes

3' end

the polymerase stops transcription at the end of the terminator and the mRNA can be translated

RNA polymerase II transcribes the polyadenylation signal sequence
the RNA transcript is released 10-35 nucleotides past this polydenylation sequence

the 5' end

the 3' end

the noncoding segments in a gene

other regions of the gene they are eventually expressed

consist of a variety of proteins and several smal RNAs that recognize the splice sites
help remove introns

catalytic RNA molecules that function as enzymes and can splice RNA

it can form a 3D structure because it can base-pair with itself
some bases have functional groups that participate in catalysis
may hydrogen-bond with other nucleic acid molecules

some genes can encode more than one kind of polypeptide depending on which segments are treated as exons during splicing

modular architecture of proteins consisting of discrete regions

genetic information flows from mRNA to protein

helps a cell translate mRNA message into protein
transfer amino acids to the growing polypeptide in a ribosome

carries a specific amino acid on one end
has an anticodon on the other end and it base pairs with a complementary codon on mRNA

a single RNA strand-80 nucleotides long
looks like a cloverleaf when flat

3
P site, A site, E site

holds the tRNA that carries the growing polypeptide chain

holds the tRNA that carries the next amino acid to be added to the chain

the exit site where discharged tRNAs leave the ribosome

when the small ribosomal subunit binds with mRNA and a special initiator tRNA

proteins that bring in the large subunit that completes the translation initiation complex

amino acids are added one by one to the C-terminus of the growing chain
each addition involves elongation factors

codon recognition
peptide bond formation
translocation

5'--> 3' direction along the mRNA

return to the cytoplasm where they will be reloaded with the appropriate amino acid

when a stop codon in the mRNA reaches the A site

a protein the causes the addition of a water molecule instead of an amino acid
the reaction releases the polypeptide

synthesize proteins that function in the cytosol

make proteins of the endomembrane system and proteins that are secreted from the cell

in the cytosol

a sequence of 20 amino acids at or near the leading end of the polypeptide

binds to the signal peptide
escorts the ribosome to a receptor protein built into the ER membrane

formed by multiple ribosomes translating a single mRNA simultaneously
enable a cell to make many copies of a polypeptide very quickly

changes in the genetic information of a cell

changes in just one nucleotide pair of a gene

replaces one nucleotide and its partner with another pair of nucleotides

have no effect on the amino acid produced by a codon because of redundancy in the genetic code

still code for an amino acid but not the correct amino acid

change an amino acid codon into a stop codon

additions or losses of nucleotide pairs in a gene

physical or chemical agents that cause mutations

altering genes in a specific way

a region of DNA that can be expressed to produce a final functional product that is either a polypeptide or an RNA molecule