Lecture 14 Flashcards
The process
Describe the structure of a ribosome and explain how its structure is related to its function
Ribosomes provide another good example of structure determining function. These small cellular components are made of protein and ribosomal RNA (rRNA). Their main function is to translate messenger RNA, or mRNA, into strings of amino acids called proteins
Compare and contrast the structural feature of mRNA that are important for translation initiation in prokaryotic and eukaryotic cells
Prokaryotic cells
Amino acid chain contains formylmethonine (acts as an alarm system against infectious bacteria - immune response triggered)
Shine Dalgrano sequence (ribosomes binding site)
Transcription and translation occurs in the same step process and at the same time in the cytosol
Eukaryotic cells
5’ prime cap (ribosome binding site)
poly-A-tail (contains 100-250 adenine nucleotides)
Both required to prevent ribosome degrading by enzymes.
Transcription (nucleus) - Translation (cytoplasma) - ribosome. During this process leaving ribosome exposed it will degrade it
Describe the process of translation and explain what components are used at each stage
Initiation (“beginning”): in this stage, the ribosome gets together with the mRNA and the first tRNA so translation can begin.
Elongation (“middle”): in this stage, amino acids are brought to the ribosome by tRNAs and linked together to form a chain.
Termination (“end”): in the last stage, the finished polypeptide is released to go and do its job in the cell.
Describe what is meant by coupled transcription and translation and explain why it can occur in prokaryotic cells but not in eukaryotic
In prokaryotic cells, translation and transcription occur at the same time in the cytosol. However for eukaryotic cells transcription occurs in the nucleus and translation occur in the cytoplasm and the ribosome is then released in the cell to make proteins
Construct a sentence to clearly explain the relationship between chromosomes, genes and DNA
A chromosome contains many genes, genes are segments of DNA that provides codes to construct protein therefore DNA is the cells genetic material.
