How Dna and Rna Collaborate to Make Proteins

1. Pages 65-68 How Dna and Rna Collaborate to Make Proteins By- Jahin Akhand

2. Functions Of Proteins • In Addition to its role in cellular reproduction and replication, it also serves as workers in many jobs of a cell. • Antibodies (Recognizes/attacks invaders) • Hormones (Messenger) • Signal Reception (Cell to Cell Communication) • Cell Movement (Cell shape changes) • Transporter • Cell Structure • Enzyme (Ex. DNA/RNA Polymerase)

3. Transcription and Post-Transcriptional Modification • Gene expression- The process by which the information is encoded in a gene is converted first into messenger RNA then into a protein. • In order for the genes to be expressed so proteins can be created on the ribosomes, a molecule must copy the code stored in DNA and take the message to the ribosomes (Like a instruction manual) and this process is called Transcription.

4. Transcription • More Detailed Version: The process starts in the Nucleus where a double-stranded nucleotide reveals it’s single stranded DNA sequence to be transcribed. Using DNA-RNA complementary base pairing rule and RNA polymerase as a builder, the A in a DNA strand places a U on the new and growing RNA strand and a T in a DNA strand places an A on the RNA strand. C in DNA places a G on RNA and G on DNA places C in RNA. DNA Strand New mRNA

5. After Transcription and Translation • Once the entire DNA sequence has been transcribed, RNA polymerase encounters the terminal sequence of the gene and dissociates. • Once the newly created mature mRNA reaches a ribosome, a translator translates DNA/RNA language to protein language. The process is called Translation and this carried out by Transfer RNA (tRNA). There are also 3 important stages in the translatingphase. • 1. Initiation- Begins when mRNA , the first tRNA carrying the first amino acid , and the small/large subunits of a ribosome come together to form a complex. Then a large ribosomal subunit binds to the smaller subunit and forms a docking site for the first tRNA.

6. Translation (Cont.) • 2. Elongation- On the large ribosomal subunit, another docking site is available for binding the next tRNA with a anticodon which matches the next codon on the mRNA molecule. The process continues and a growing peptide chain starts to form. • 3. Termination- The elongation step continues until stop codon is encountered which causes the translation to be terminated. The completed chain then dissociates after the whole complex dissembles. • Proteins made this was may not be ready to perform their job right away.

7. RNA: A Nucleotide • Messenger RNA, tRNA , and rRNA are three important players in protein synthesis • These are not discarded by the cell - Ribozyme and RNAse- in their studies of genetic code and transcription , Thomas Cech and Sidney Altman noticed that RNA not only serves as a genetic code, it also had catalytic activity (means it can also speed up a reaction) - Used as an energy source during protein synthesis , ATP, from protein synthesis.