Genetics And Protein Synthesis Flashcards
Why is the DNA copied into RNA?
The DNA is too large to move out of the nucleus, so it is copied into RNA.
What is the organelle for protein synthesis and where is it found?
The ribosomes are found in the cytoplasm.
What is transcription?
A section of DNA is copied into RNA
RNA is a single $$$ strand?
RNA is a single POLYNUCLEOTIDE strand.
What does RNA contain?
The sugar ribose
Uracil replaces which base in protein synthesis?
THYMINE!
When the RNA leaves the nucleus it joins with what in the cytoplasm?
A RIBOSOME!
Once the RNA has joined with a ribosome, it can be used to synthesise a ¥¥¥ in the cytoplasm?
Protein!
In simple, brief terms what is translation?
The RNA joining with a ribosome and synthesising a protein.
mRNA?
- carries the genetic code from the DNA in the nucleus to the cytoplasm,where it’s used to make a protein during translation.
- three adjacent bases are called a codon.
tRNA?
- it carries the amino acids that are used to make proteins to the ribosomes
- it has an amino acid binding site at one end and a sequence of 3 bases at the other end called a codon.
Which comes first, transcription or translation?
Transcription then translation
TRANSCRIPTION: step 1
Transcription starts when RNA polymerase attaches to ¥¥¥ &&&& at the beginning of a gene
DNA double-helix
TRANSCRIPTION: step 2
the
HYDROGEN!
TRANSCRIPTION: step 3
What is used as a template to make an mRNA copy.
One of the uncoiled DNA strands
TRANSCRIPTION: step 3
What is the antisense strand?
The DNA template strand
TRANSCRIPTION: (step 4)
The RNA polymerase lines up
Free RNA nucleotides
TRANSCRIPTION: (step 4)
What is complimentary base pairing?
It means that the mRNA strand ends up being a reverse copy of the DNA template strand (except the base T is replaced by U in RNA)
TRANSCRIPTION: (step 5)
What molecule is formed when the RNA nucleotides have paired up with their complementary bases on the DNA strand and been joined together?
An mRNA molecule
TRANSCRIPTION:(step 6)
What does RNA polymerase do once the first mRNA molecule has been formed?
The RNA polymerase moves along the DNA, separating the strands and assembling the mRNA strand.
TRANSCRIPTION (step 7)
What happens to the uncoiled strands of DNA now the RNA polymerase has passed by?
The hydrogen bonds between the uncoiled strands of DNA reform and the strands coil back into a double helix.
TRANSCRIPTION (step 8)
What stops RNA polymerase making mRNA
A stop codon, and then the RNA polymerase detaches from the DNA.
TRANSCRIPTION (step 9)
Through what does the mRNA move out of the nucleus
Nuclear pore
TRANSCRIPTION (step 9)
Once the mRNA has left the nucleus, what does it do?
The mRNA attaches to a ribosome in the cytoplasm, where translation takes place.
What are introns?
Sections of DNA that don’t code for amino acids.
What are exons?
Bits of DNA that do code for amino acids
During transcription, the introns and exons are both copied onto what?
mRNA
After transcription where both the introns and exons are copied into mRNA, what happens to the introns and what is the process called?
The introns are removed by a process called ‘splicing’ where introns are removed and exons are joined forming mRNA strands.
Where does splicing take place?
The nucleus
The exons can be joined together in different orders to form different mRNA strands. Why?
This means that more than one amino acid sequence and so more than one protein can be produced from one gene.
TRANSLATION (step 1)
The mRNA attaches itself to a ribosome and which molecules carry amino acids to the ribosome?
tRNA molecules.
TRANSLATION (step 2)
How does the tRNA molecule attach itself to the mRNA molecule?
Complementary base pairing.
TRANSCRIPTION (step 3)
What happens after the first tRNA molecule attaches itself to the mRNA?
A second tRNA molecule attaches itself to the next codon on the mRNA in the same way.
TRANSLATION (step 4)
What kind of bond joins the two amino acids attached to the tRNA molecules?
a peptide bond
TRANSLATION (step 4)
The first tRNA molecule moves away once the two amino acids have been joined by peptide bonds, and the first tRNA’s what is left behind?
Amino acid!
TRANSLATION (step 5)
A third tRNA molecule binds to the next codon on the mRNA. It’s
Amino acid!
TRANSLATION (step 6)
The process of tRNA molecules moving away from the mRNA once the amino acids have joined continues, what does it produce and when does it stop?
A polypeptide chain, and it stops when there’s a stop codon on the mRNA molecule.
TRANSLATION (step 7)
What is the final step?
The polypeptide chain (protein) moves away from the ribosome and translation is complete.
