Protein Synthesis Review What is RNA and Why is it Important? Types of RNA Codons & Anticodons Transcription Translation Amino Acids and The Codon Chart

Review DNA RNA Sugar Nitrogen Bases Shape Deoxyribose Ribose Adenine = Thymine Guanine Cytocine Adenine = Uracil Guanine Cytosine Shape Double Stranded Single Stranded

Review T A C G A A T C U A C G A A U C Remember how the bases bond in DNA? DNA: A T G C T T A G RNA is rearranged in a similar complimentary form: RNA: T A C G A A T C U A C G A A U C

Protein Synthesis In the nucleus The Ribosome Protein Synthesis is the process of making proteins from a DNA template But wait a minute- Where is DNA? Where are proteins made? How do we get proteins from DNA if the DNA can’t leave? We make RNA from the DNA template! Why is RNA important? It uses the code from DNA to make amino acids Amino acids combine to make proteins In the nucleus The Ribosome

What is a protein? Polypeptide Made from amino acids linked together The amino acids are held together with covalent peptide bonds The amino acids are linked together in a long chain called a polypeptide. The polypeptide chain twists up into a complex shape called a protein.

Amino Acids There are 20 different amino acids Combining 3 different RNA nitrogen pairs creates 1 amino acid Example: UAC = Tyrosine (1 amino acid) AAU = Asparginine ( 1 amino acid) GUU = Valine (1 amino acid) Combining 3 or more amino acids creates 1 protein Tyrosine + Asparginine + Valine = 1 Protien!

Amino Acids The order of the amino acids determine the protein’s shape The protein’s shape determines its function. If the protein has the wrong shape, it won’t work right!!!!! So it’s really, really important that the amino acids get put in the right order

Protein Synthesis Before we learn the process of protein synthesis, we need to learn the places: Places: Nucleus Has the DNA template Cytoplasm The fluid within the cell Amino acids are floating within Ribosome Organelle where amino acids are put together Putting together amino acids = making a protein

Protein Synthesis Parts: rRNA = ribosomal RNA mRNA = messanger RNA Before we learn the process of protein synthesis, we need to learn the parts: Parts: rRNA = ribosomal RNA Helps make-up the ribosome (rRNA is 80% of the ribosome) aids in bonding mRNA to tRNA mRNA = messanger RNA Created in the nucleus, travels through the cytoplasm to the ribosome Carries “the message” Codon (more on this later) tRNA = transfer RNA Moves amino acids from the cytoplasm to the ribosome Anticodon (more on this later)

The Cell E Nucleus mRNA DNA tRNA Ribosome Cytoplasm Amino Acids New Protein The Cell E

Protein Synthesis Two step process Transcription Translation Happens in the nucleus with mRNA Translation Happens in the cytoplasm and ribosome with the mRNA, tRNA and amino acids

Protein Synthesis Part One: Transcription Segments of DNA are separated by RNA polymerase One of the detached strands is used as the template to make mRNA RNA polymerase adds mRNA nucleotides to the exposed DNA strand This creates mRNA

(3 nucleotides = 1 codon = 1 amino acid) Protein Synthesis Transcription- Let’s Practice! (remember, in RNA T’s become U’s) DNA = A G C T T A mRNA = (codon) *Codon: every combination of three nitrogen bases or the “letters” (3 nucleotides = 1 codon = 1 amino acid) U C G A A U Codon Codon

Codon Question A piece of mRNA is made of 15 nucleotides (bases) How many codons does it have? A piece of mRNA is made of 30 nucleotides (bases) A piece of mRNA is made of 60 nucleotides (bases)

Protein Synthesis Part Two: Translation The newly formed mRNA leaves the nucleus and attaches to a ribosome The mRNA “translates” the DNA code to the tRNA that is waiting in the cytoplasm. Basically, the codon that mRNA has needs to be paired with the tRNA anticodon

Protein Synthesis AntiCodon AntiCodon Part Two: Translation continued… The tRNA has a specific amino acid attached to it The tRNA anticodon carrying the amino acid attaches to the mRNA codon Practice: DNA: A T G C A T mRNA: (codon) tRNA: (anticodon) U A C G U A A U G C A U AntiCodon AntiCodon

Translation Continued Once two amino acids are present at the ribosome, a peptide bond forms that hold the amino acids together Multiple amino acids bonded together = a protein

The process of matching tRNA to mRNA continues until all mRNA codons are matched to their anticodons OR once a “stop” codon is read. - The end result is a polypeptide (a protein)

Amino Acids If I were to give you a strand of DNA, you should be able to tell me: The complimentary mRNA strand (codon) The amino acid the mRNA is coding for The tRNA strand (anticodon) that brings the amino acid to the ribosome To determine the amino acid the mRNA is coding for, you can use an mRNA codon table

- The anticodon AGC brings Serine to the ribosome If mRNA is UCG Find U for the first base C for the second base And G for the third base -UCG codes for Serine - The anticodon AGC brings Serine to the ribosome

C U G A A U DNA: G A C T T A mRNA: (codon) Use the codon chart on the next slide to determine the amino acid it codes for C U G A A U

CUG= AAU =

Leucine Asparagine DNA: G A C T T A mRNA: C U G A A U Amino Acids: (codon) Amino Acids: What must the tRNA be to attach those amino acids? tRNA: (anticodon) What is the mRNA strand? C U G A A U What amino acids does the mRNA code for? Leucine Asparagine G A C U U A

Thinking about the mutations we saw in Chromosomes…. If we were suppose to have the sequence: GGU- CCA-UGA- UUC But a deletion mutation occurred and eliminated all of the GUANINE bases, what would the altered sequence look like? Deletion mutation for CYTOSINE? What would happen to the protein being made? UCC-AUA-UUC GGU-AUG-AUU

Codon Question A piece of mRNA is made of 15 nucleotides (bases) How many codons does it have? How many anticodons does it have? How many amino acids will the protein have? A piece of mRNA is made of 30 nucleotides (bases) A piece of mRNA is made of 60 nucleotides (bases)

Review The DNA code AAA-CTG- CAA is in the nucleus During transcription, the mRNA strand UUU-GAC- GUU is made The mRNA strand leaves the nucleus and attaches to the ribosome During translation, the mRNA codon tells tRNA it needs the amino acids Phenylalanine, Aspartic acid and Valine out in the cytoplasm tRNA finds Phenylalanine, Aspartic acid and Valine in the cytoplasm, and being the anticodon, attaches to mRNA Phenylalanine , Aspartic acid and Valine are held together by peptide bonds and create a polypeptide (or a protein)