Topic 2: Protein synthesis (translation) Flashcards
Key Summary: Translation overview
- {What happens in/what is the point of} translation?
- {What is made?/product?}
- Main things needed?
- Where in the cell does it take place?
- The copy of the genetic code (mRNA) is used to make a polypeptide chain, which can fold to form a protein
- Polypeptide (protein)
- Amino acids, ribosome, tRNA molecules, mRNA
- On a ribosome
A __________ attaches to the start codon on mRNA.
A __________ is a very small cell organelle made of __ _________.
It is found floating free in the cytoplasm or attached to the _______ ___________ ____________ membranes.
ribosome
ribosome
2 subunits
rough endoplasmic reticulum (rough ER)
Key Summary: Explain the role of ribosomes in translation
3 points
- SITE OF TRANSLATION (where polypeptide chain is made)
- ribosome ATTACHES to mRNA and moves along mRNA TRANSLATING CODONS
- tRNA’s bring amino acids to be joined by PEPTIDE BONDS on the ribosome
Key Summary: Explain the role of mRNA in translation
6 points
- mRNA is a copy of the DNA genetic code
- mRNA carries genetic information to ribosomes
- contains the sequence of bases which is translated
4 (this point is important). each mRNA codon determines one amino acid, so mRNA code determine the amino acid sequence (primary structure)
- mRNA codons bind to complementary tRNA anticodons
- mRNA contains start and stop codons.
Key Summary: Explain the role of start codons in translation
3 points
- They are recognised by the ribosome
2 (this point is important). The ribosome attaches to mRNA at the start codon
3 (this point is important). Start codon occurs at the start of a gene and is transcribed into mRNA making the site at which translation begins – start of the polypeptide chain
The ribosomes _______ along the mRNA reading ______ bases at a time.
Every ______ bases on mRNA is called a _______.
______ in the DNA is called a _______.
Each codon on mRNA codes for a ________ amino acid.
moves
three
three
codon
three
triplet
specific
Each tRNA molecule attaches to and carries one _________ ______ _____ to the ribosome.
specific amino acid
Key Summary: Explain the role of tRNA in translation
4 steps
1 (this point is important). each tRNA attaches to and carries a specific amino acid to the ribosome
2 (this point is important). tRNA anticodon binds to a codon on mRNA
- two tRNA bring amino acids together for peptide bonds to be formed between them
- tRNA is continually reused
tRNA is a single-stranded _____________ ______.
It has a ________ _____ where an amino acid attaches.
____________ _____ help to hold tRNA in the correct ________.
On the tRNA, the anticodon is a _________ ___________ of _______ bases which ______________ _____ ______ with a ______ on mRNA.
polynucleotide chain
binding site
hydrogen bonds
shape
specific sequence
three
complementary base pairs
codon
Key Summary: Explain the role of anticodons in translation
5 points
- Found on tRNA
- Made up of 3 bases
- Specific for one amino acid
- Anticodon on tRNA binds to codon on mRNA
- Allows amino acids to be placed in the correct sequence in polypeptide chain (primary structure)
Key Summary: Explain the role of codons in translation
4 points
- Found on mRNA
- Made up of 3 bases
- Each codon codes for a specific amino acid
- Sequence of codons on mRNA determines sequence of amino acids in polypeptide chain (primary structure)
_________ bonds form between amino acids in _____________ __________.
peptide
condensation reactions
Ribosome moves along mRNA and detaches from mRNA at a ______ _______. The polypeptide is ___________.
stop codon
released
Key Summary: Explain the role of stop codons in translation
3 points
- They are recognised by the ribosome
2 (this point is important). The ribosome detaches from mRNA at the stop codon
3 (this point is important). Stop codon occurs at the end of a gene and is transcribed into mRNA, marking the site at which translation ends – signals the end of the polypeptide chain
Key Summary: Explain the process of translation
7 points
- mRNA leaves the nucleus and a ribosome attaches to it at a start codon
- each tRNA ATTACHES TO a SPECIFIC amino acid and carries it to the {ribosome/mRNA}
- two tRNA molecules on ribosome
- COMPLEMENTARY BASE PAIRING between ANTICODON ON tRNA and CODON ON mRNA
- PEPTIDE BONSD FORM BETWEEN AMINO ACIDS in condensation reactions
- tRNAs released from {mRNA / ribosome}
- ribosome moves along mRNA and DETACHES FROM mRNA at a stop codon
