Kaylee
Protein Synthesis
What are proteins and why are they important? Proteins are made up of amino acids that are joined together in polypeptide chains. These are folded to give the protein a specific structure that allows it to carry out its function. Proteins are an important component of our cells and bodies. They have roles in cell transport, the immune system, movement, hormonal responses and more!
In prokaryotic cells, transcription and translation both happen in the cytoplasm.
In eukaryotic cells, transcription happens in the nucleus and translation happens in the ribosomes.
DNA is the genetic code that determines the genetic characteristics of organisms, e.g. eye color and blood type. Sections of DNA that code for proteins are called genes. DNA cannot create proteins on its own - it requires the help of mRNA. This is a single strand in a process called transcription mRNA is then used to build a protein in a process called translation.
Transcription
How is RNA different to DNA?
How does transcription work? DNA is unzipped so its bases are exposed. RNA polymerase attaches to a promoter sequence of DNA and begins to add complementary RNA nucleotides one at a time. It builds up a strand of messenger RNA, also called "mRNA". In Eukaryotic, the mRNA has non-coding regions called introns- these must be removed in a process called splicing. The mRNA then leaves the nucleus through nuclear pores.
RNA has uracil bases instead of thymine
Uracil
RNA has ribose sugar- in DNA it is deoxyribose
RNA is usually single stranded, while DNA is usually double stranded.
Translation
How does transcription work? mRNA attaches to a ribosome in the cytoplasm. The ribosome lines up complementary tRNA molecules. Their anti-codon must match the codons on the mRNA strand. Each tRNA carries an amino acid. As they line up, the amino acids form peptide bonds between them, building a polypeptide strand which will become a protein. The tRNA molecules detach from their amnio acids and leave to pick up new amino acids.
<<< codon charts >>>
mRNA
Amino
acids
Reminder- RNA has uracil- not Thymine
UCA - ACC - GUC
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TYR - THR - VAL
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DNA
triplets
mRNA
codons
Amino
acids
GCA - AAT - ACC
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CGU - UUA - UGG
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ARG - LEU - TRP
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