Transcription & Translation Flashcards
Protien synthesis
The process of making proteins in the cells.
The genome
The complete set of genes in an individual’s DNA.
What do the genes in the genome encode?
The different proteins a cell needs.
Proteome
The full range of proteins an individual can produce.
What do the order of the bases on the DNA tell us
The order for combining amino acids to create particular proteins.
What are the two processes involved in synthesising proteins from a base sequence?
Transcription.
Translation.
What do three bases encode
Amino acids
RNA
A single-stranded nucleic acid molecule that is made from the same bases as DNA except for uracil (U) which is used instead of thymine (T)
mRNA
A type of RNA that carries genetic information from the nucleus to the ribosomes for protein synthesis.
a single helix consisting of thousands of mononucleotides.
Ribosomes
proteins that translate mRNA into amino acids and synthesise the polypeptide.
If the original DNA sequence has the codon GCC, the codon in each step is:
DNA codon:
mRNA complementary codon:
tRNA anticodon:
Amino acid:
DNA codon: GCC.
mRNA complementary codon: CGG.
tRNA anticodon: GCC.
Amino acid: Arginine.
If the DNA codon is CAG, what will the mRNA complementary codon be?
GUC
What is the first step of protein synthesis?
Transcription
RNA polymerase
the enzyme that allows transcription to take place and binds to the locus of the gene to be transcribed (the target gene).
What enzyme is used to bind RNA nucleotides to the template strand?
RNA polymerase
Translation
The second phase of protein synthesis that takes place in the ribosomes. mRNA is used as a template for the attachment of tRNA molecules with complementary anticodons. The amino acids carried on adjacent tRNA molecules are joined to form a polypeptide chain.
How many codons can fit inside the ribosome at one time?
2
Steps Involved in Translation
- mRNA binds to the ribosome
- One molecule of tRNA binds to the first codon in the ribs one
- The first molecule of tRNA brings in the corresponding amino acid
- The second molecule of tRNA binds to the second codon in the ribsome
- The second molecule of tRNA brings in the corresponding amino acid
- A peptide bond forms between the 1st two amino acids
- The ribsome moves along the mRNA and new codon enters the ribsome
- New amino acids are continuously brought in and added to the chain until the ribsome reaches STOP codon
- The polypeptide chain is released from the ribsome
What is the mRNA in eukaryotes called?
pre-mRNA.
Splicing
a process that removes sections of non-coding DNA called introns from the mRNA molecule.
Does splicing take place in prokaryotes
no
Does splicing take place in prokaryotes
no. mRNA is completed
What is the role of splicing in eukaryotes?
Removes introns
Transcription
Where one gene on the DNA is copied into mRNA
Translation
Where the mRNA joins with a ribsome, and corresponding tRNA molecules bring specific amino acid the codon codes for
What protein is used to removed introns in splicing
slicesome
Exons
Coding regions of DNA
Step involved in Transcription
- DNA helix unwinds to expose the bases that act as a template.
- Only one chain of the DNA acts as a template
- Like with DNA replication, this unwinding and unzipping is catalysed DNA helicase.
- DNA helicase breaks the H bonds between bases
- Free mRNA nucleotides in the nucleus align opposite exposed complementary DNA bases
- The enzyme RNA polymerase bonds together the RNA nucleotides to create a new RNA polymer chain. One entire gene is copied
What happens when the gene is copied in Transcription.
mRNA is modified and then leaves the nucleust through the nuclear envelope pores
