3.4.2 DNA and protein synthesis Flashcards
what is a genome?
the complete set of genes in a cel
what is a proteome?
the full range of proteins that a cell is able to produce
what is the key difference between a genome and a proteome (besides the obvious)?
- the genome should never change (unless a mutation occurs)
- whereas the proteome of the cell is constantly changing depending on which proteins are currently needed
what is the function of RNA?
- to copy and transfer the genetic code from DNA in the nucleus to the ribosomes
- some RNA is combined with proteins to create ribosomes
what is mRNA?
a copy of a gene from DNA
where is mRNA found?
created in the nucleus and then leaves to carry the copy of the genetic code of one gene to a ribosome in the cytoplasm
why do we require mRNA?
- DNA is too large to leave the nucleus and would be at risk of being damaged by enzymes, this could destroy the genetic code
- mRNA is much shorter, as it is only the length of one gene, and can therefore leave the nucleus
what is the structure of mRNA?
- single-stranded
- every 3 bases in the sequence codes for a specific amino acid
- these three bases are called codons
why is mRNA short-lived?
- only needed to temporarily create a protein
- by the time any enzymes break it down, it would have already carried out its function
where is tRNA found?
only in the cytoplasm
what is the structure of tRNA?
- single-stranded
- folded to create a shape that looks like a clover leaf
- clover leaf shape is held in place by hydrogen bonds
what is the function of tRNA?
to attach to one of the 20 amino acids and transfer this amino acid to the ribosome to create a polypeptide chain
how do specific amino acids attach to specific tRNA molecules?
- 3 bases found on the tRNA are complementary to the 3 bases on mRNA
- these are called anticodon because they are complementary to the codon on mRNA
what is rRNA?
- ribosomal RNA
- combines with proteins to make ribosomes
- makes up the bulk of ribosomes
