DNA 2 Flashcards
How do ribosomes help make protein (translation)
Ribosomes read RNA code, 1 codon at a time, suck amino acids from cytoplasm and stick them into chain. As the chain grows, it bends and sticks to itself to form a perfectly formed protein. Every 3 letters of RNA code tell ribosome which amino acid to be added next.
Describe transcription
Transcription is process of creating an equivalent strand of mRNA from bases of DNA.
Sectrion of DNA is unzipped and unwound by DNA helicase as H bonds between bases break.
Only one DNA strand (anti sense strand) serves as a template for synthesis of RNA.
Free RNA nucleotides in nucleus line up alongside template strand. Once bases have paired with complementary DNA bases they are joined by RNA polymerase. Complementary bases match (Cytosine and Guanine,Adenine and Thymine) however, in RNA uracil is paired to Adenine instead of thymine being paired with Adenine .
Strand that is formed is RNA.
H bonds of untwisted RNA and DNA ladder break and mRNA leaves the nucleus via small pores. It then goes to cytoplasm to attach to ribosomes.
Describe translation
In translation, sequence of bases on mRNA strand is turned into amino acids making up a protein.
Once in cytoplasm, mRNA lines up at ribosome
All 20amino acids necessary to make human proteins are in cytoplasm.
tRNA picks up specific amino acids. Codon-anticodon bonding occurs at ribosome. Peptide bonds form between adjacent amino acids. Ribosome moves along mRNA strand until STOP codon is reached. Then polypeptide chain is released and folds in tertiary structure.
If DNA was ATCGTACT what would mRNA be
mRNA would be UAGCAUGU
Function of mRNA
Function of mRNA is
mRNA is copy of antisense DNA strand and codes for amino acid sequence. It leaves nucleus and binds to ribosome so it can be used in translation.
Function of tRNA
Function of tRNA is to transport specific amino acid to ribosome, codon-anticodon binding occurs, tRNA carries a particular amino acid and multiple tRNA molecules bring multiple amino acids to together so they can be joined by peptide bonds.
What is a frame shift and why is it bad
Frame shift is insertion or deletion of nucleotides which causes a shift in reading frame of codons in mRNA. This could lead to an alteration of amino acid built
What could happen if there was a mistake in transcription
A mistake in transcription can produce mRNA with 1 or more incorrect codons. This could result in a faulty protein or mo protein at all. However, since fault is in mRNA this would only affect 1 protein on one occasion
What is responsible for inherited genetic conditions
Errors in DNA are responsible for inherited genetic conditions as it would produce problems in every epithelial cell as when cells are made during growth/repair, DNA is copied.
What is shape of tRNA
Shape of tRNA is shaped like a clover leaf, has anticodon complementary to mRNA codon, amino acid binding site (to bind specific amino acid coded for by mRNA codon)
