3.4.2 DNA and protein synthesis Flashcards
What is the genome
The complete set of genetic information contained in the cells of an organism
What is the proteome
The complete set of proteins that can be produced by a cell
Describe the structure of mRNA
Long single strand
Its base sequence is complementary to the DNA it was transcribed from
Advantages of using mRNA rather than DNA for translation
Shorter and contains uracil - breaks down quickly, no excess polypeptides form
Single stranded and linear - ribosome moves along strand and tRNA binds to exposed bases
No introns
Describe the structure of tRNA
Single strand, folded into clover leaf
One end is an anticodon and the opposite side is an amino acid binding site
What is produced by transcription
mRNA
Where does transcription take place
Nucleus
Outline transcription
Hydrogen bonds are broken between base pairings by DNA helicase, uncoiling DNA. One is used as a template strand
Free RNA nucleotides join to complimentary base pairings, AU, CG, by RNA polymerase
Forming phosphodiester bonds
Forming pre-mRNA
Outline transcription
DNA uncoils into two strand with exposed bases. One is used as a template strand
Free nucleotides line up next to complementary bases and are joined together by RNA polymerase
What happens to mRNA after transcription
It is spliced to remove introns
Moves out the nucleus and attaches to a ribosome
What is produced by translation
Proteins
Where does translation take place
Cytoplasm on ribosomes
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Describe translation
- mRNA attaches to a ribosome
- tRNA brings a specific amino acid
- Anticodons on tRNA bind to codons on mRNA
- The ribosomes moves along to next codon
- Amino acids join by peptide bonds
