Biology 8.4
How long doe the ribosome continue to translate the MRNA strand
Until it reaches a stop codon. Then it releases the new proteina dn disassembles.
How is RNA base pairing different from DNA base Pairing
Uracil, NOT thyamine, pairs with
What does Transfer RNA (TRNA) do
Brings amino acids fromt eh cytopolasm to the ribosome to help make the growing protein
What is RNA made up of
Like DNA, it is a chain of nucleotides each made of a sugar, a phostphate group and a nitrogen contining base. It's like a termproray copy of DNA that is used and then destroyed
What is the third step of transcription
Once gene has been ranscribed, the RNA strand detaches completely from the DNA
What enzyme catalyzes transcription
RNA polymerases
What is the first step of translation
The exposed codonin the first site attracs a complementary tRNA bearing an amino acid. The tRNA anticodon pairs with the mRNA codon, bringing it close to the other tRNA molecule
3rd process of central dogma
Translation interprets an RNA message into a string of amino acids called a polypeptide
What is a codon
A sequence of three nucleotides that codes for an amino acid It is a "word" in the genetic code
What is mRNA
A short-lived molecule that carries instructions from DNA I the nucleus to the cytoplasm
How many amino acids does the "language" of proteins use
20
How are the end results of transcription different from the end results of replication
A cell may need hundreds or thousands of copies of certain proteins or the rRNA and tRNA molecules needed to make proteins Transcription enables a cell to adjust to changing demands by making a single-stranded complement of only a segment of DNA and only when the particular segment is needed. Many RNA molecules can be transcribed from as single gene at the same time
RNA
A chain of nucleotides
What actually happens during the process of transcription
A gene (not an entire chromosome) is trenaferred into an RNA message.
What does it mean to say that the genetic code is universal
All organisms follow the genetic code. Scietists can insert a gene from one organism into another to make a functional protein
How are RNA transcription and DNA replication similar
Both take place in the nucleus in Eukaryotic cells Both are catalyzed by large complex enzymes Both involve unwinding of the DNA double helix Both involve nucleotide base pairing
What are stop codons
Codons that singnal the end fo the amino acid chain
What does replication do
Copies DNA
Location for replication translation and transcription in a prokaryotic cell
Cytoplasm
What enzyme catalyzes replication
DNA polymerase
What does Ribosomal RNA (rRNA) do
Forms part of ribosomes, a cell's protein factories
How many nucleotides does the "languge of nucleic acids use
Four A, G, C and T in DNA: A, G, C and U in RNA
Where does translation occur in prokaryotic and eukaryotic cells
In the cytoplasm
Where and when do replication, transcription and translation occur in the prokaryotic cell
In the cytoplasm at about the same time.
What is an anticodon
It is a set of three nucleotides that is complementary to an mRNA codon.
Wht does Messenger RNA (MRNA) do
It is an intermediate message that is translated to form a protein
What must happen with the RNA strand before it can exit the nucleus of a eukaryotic cell
It must be processed, which occurs during or just after transcription
What does transcription involve
It produces an RNA molecule form a DNA template
What is a start codon
It signals the start of a translation and the amino acid methionine.
What does translation always begin with
Methionine
Transcription
Process of copying a sequence of dna to produce a complementary strand od rna
What acts as the intermediate link between DNA in the nucleus and protein synthesis in the cytoplasm
RNA
What is the second step of transcription
RNA polymerase strings together a complementary strand of RNA nucleotides. RNA hangs freely and DNA zips back together
What are the first step of transcription
RNA polymerase unwinds a segment of the DNA molecule
How are the end results of replication different from the end results of transcription
Repication ensures that each new cell will have one complete set of genetic instructions Replicaiton occurs only once during each round of the cell cycle because the cell only needs to make one copy of its DNA
Where and when do replication, transcription and translation occur in the eukaryotic cell
Replication and transcription occur in the nucleus Translation occurs in the cytoplasm In addition, the RNA in eukaryotic cells goes through a processing step before it can be transported out of the nucleus.
1st process of central dogma
Replication copies dna
What does a cell use to translate a codon into an amino acid
Ribosomes and tRNA
Central dogma
States that information flows in one direction
What is translation
The orcess that converts ro translates an mRNA message into a polypeptide.
What happens if the reading frame is changed
The resulting protein is changed
What happens in the second step of translation
The ribosome forms a peptide bond between the two amino acids and breaks the bond between the first tRNA and its amino acid
What happens in step three of translation
The ribosome pulls the mRNA strand the lentgth of one codon. The first tRNA is shifted into the eit site where it leqves the ribosome and returns to the cytoplasm to recharge. The first site is again empty, exposing the next mRNA codon
What are three ways that RNA differs from DNA
The sugar in RNA is ribose which has one additional sugar RNA has the base uracil in place of thyamine which forms base paris with adenine RNA is a single strand nucleotide while DNA is double
How many steps are there to translation
Three
How many types of RNA does transcription make
Three Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (TRNA)
2nd process of dna
Transcription converts a DNA message into an intermediate molecule called RNA
What does Translation do
interprets and RNA message into a string of amino acids called polypeptides. Either a single polypeptide or many polypeptides working together make up a protein
What is the reading frame
the order in which the codons are read
Can an amino acid be coded for by more than one codon.
yes
