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Protein, Transcription, and Translation
PROTEINS
the most diverse and abundant group of macromolecules
important in the structure of cells and organisms and participate in everything they do.
proteins are made up of varying numbers of amino acids (50300)
a protein's specific shape determines it's function
Remember with DNA:
1 is a monomer or nucleotide.
more than one is a polymer
Now with Proteins:
Why do you think this is called polypeptide?
Protein, Transcription, and Translation
There are 20 amino acids.
9 of them cannot be made by your body so you have to get them from your diet. These are referred to as essential amino acids.
Protein, Transcription, and Translation
Protein Synthesis (Creating Proteins)
DNA sends directions from the nucleus
These DNA directions act as a code that specifies what order to join the amino acids in to form the desired protein
The DNA remains in the nucleus, and the proteins are created in the ribosomes (in the cytoplasm) so there has to be some sort of messenger system between the DNA and the ribosomes.
This messenger is called messenger ribonucleic acid or mRNA
There is a twostep process for all of this to happen.
Step 1: Transcription (DNA to RNA)
Step 2: Translation (RNA to protein)
Protein, Transcription, and Translation
Transcription
DNARNA
Goal: to create a copy of a small piece of DNA
Steps:
1. The double helix unzips.
2. RNA polymerase creates a complementary strand of RNA to the strand of DNA it wants to copy.
3. Transcription of RNA stops at a certain point and leaves the nucleus. The RNA is ready to transport its information for protein synthesis.
What does this RNA strand look like? It's different from DNA because
it's only one strand
instead of thymine, it has uracil as a base.
it still has a sugar but it's sugar is ribose, and in DNA it's deoxyribose.
The nucleotides in RNA are grouped into threes called RNA codons. This is the type of code that can be read and turned into proteins.
Protein, Transcription, and Translation
Translation
RNA codons get translated into proteins.
Steps:
1. The mRNA codons are read by the ribosomes to determine which amino acid is being coded for.
2. Transfer RNA (tRNA) brings specific amino acids from the cytoplasm to the ribosomes. These amino acids are attached to the anti codon (the complementary side of the mRNA).
3. The anticodon in the tRNA molecule binds to the codon on the mRNA molecule.
4. The ribosome adds the amino acid on the tRNA molecule to the peptide chain.
5. The tRNA molecule then leave sthe ribosome to find another amino acid.
6. This process continues until a "stop" codon is reached.
Protein, Transcription, and Translation
1. What are three differences between RNA and DNA?
2. Along one strand of the DNA double helix is GGCATAGGT. What is the complementary sequence for the other strand?
3. What is the function of DNA polymerase in DNA replication?
4. When we go from DNA to protein, what are the functions of transcription and translation?
5. If a particular protein is 100 amino acids long, how many nucleotides are necessary to code for this protein?
6. If the mRNA sequence is CCA UUU ACG, what was the original DNA sequence?
What would the tRNA anti codons be?
7. What is a start codon?
9. What is an anticodon and what is it's function?
Protein, Transcription, and Translation
Try the assignment using a codon wheel!
*Note, you are provided a codon wheel on the departmental so that most likely means you'll have to be comfortable enough to use it!
Protein, Transcription, and Translation