14.2 Bio
rRNA (ribosomal RNA)
an organelle that contains most of the RNA in the cell and that is responsible for ribosome function begin the assembling of amino acids in proteins
genetic code
collection of codons of mRNA, each of which directs the incorporation of a particular amino acid into a protein during protein synthesis
Transcription
(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA
After a strand of mRNA has been built, where does it exist?
nucleus
Where does transcription occur?
nucleus
What do the sequence of mRNA molecules provide?
the order at which amino acids should be joined to create a polypeptide
What happens as each tRNA molecule binds to the mRNA?
the ribosome joins the amino acid carried by the tRNA to the growing amino acid chain.
How is the amino acid carried by the tRNA molecules determined?
the tRNA's anticodon, a set of three unpaired bases.
What do ribosomes use the sequence of codons in mRNA for?
to assemble amino acids into polypeptide chains
tRNA (transfer RNA)
type of RNA molecule that transfers amino acids to ribosomes during protein synthesis
Is DNA directly involved in transcription?
yes, DNA is involved
Is DNA directly involved in translation?
no, DNA remains in the nucleus and this process doesn't occur in the nucleus
How does translation start? What happens next?
-when a ribosome attaches to an mRNA molecule -Then, tRNA molecules, carrying amino acids with them, bind to mRNA codons.
How many commonly occurring amino acids are there?
20
How many stop codons are there?
3 (UAA, UAG, UGA)
How many codons code for amino acids?
61
How many possible three-base codons are there?
64
gene
A sequence of DNA that codes for a specific protein genes determine an organism's inherited traits.
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.
Velma is developing a computer model of translation. Her instructor points out that the model does not include ribosomes or ribosomal RNA. If the model is accurate in other ways, how does the absence of ribosomes and ribosomal RNA affect it?
Amino acids would not join together, and no polypeptides would form.
How are proteins made?
By joining amino acids into long chains called polypeptides
What is the end result of transcription?
DNA is converted to a strand of mRNA to be translated in the ribosome.
What does the ribosome do in the process of the polypeptide assembly?
It breaks the bond holding the first tRNA molecule to its amino acid.
mRNA (messenger RNA)
The form of RNA which is created as a blueprint from DNA; carries instructions for making a protein
What does the genetic code allow for?
a specific codon to code for a specific amino acid.
How is the process of translation completed?
The ribosome reaches a stop codon, releasing the newly synthesized polypeptide and the mRNA molecule
What directs the translation process?
Transcribed mRNA
How can genes be "expressed?"
When a gene (segment) of DNA code is used to build a protein
How are amino acids linked in a ribosome?
in a protein molecule
What is the central dogma of molecular biology?
information is transferred from DNA to RNA to protein
translation
is the process that produces proteins by decoding the sequence of mRNA codons.
What happens as the amino acid chain grows? What does this determine?
it folds and coils to form a three-dimensional shape. the properties of the protein
What RNA types are involved in transcription?
mRNA
What serves as the start codon for protein synthesis?
methionine (Met) codon AUG
What does the ribosome help form?
peptide bond
A sequence of amino acids called a _________ is produced during the process of ____________.
polypeptide translation
What is the end result of translation?
protein
Which RNA types are involved in translation?
rRNA, mRNA, tRNA
What binds to stop codons?
release factors
Where does translation take place?
ribosomes in the cytoplasm
