Protein Synthesis The making of proteins

Why Do We Need Proteins?

Cell structure – Cellular material is 80% composed of proteins Cell structure – Cellular material is 80% composed of proteins Cellular processes – hormones and enzymes Cellular processes – hormones and enzymes Membrane channel proteins for transport of materials in and out of the cells Membrane channel proteins for transport of materials in and out of the cells Cell identification Cell identification To initiate responses. To initiate responses. Neurotransmitters Antibodies Clotting blood Pigments etc...

What is a protein What is a protein ? One of the bodies most abundant organic molecules One of the bodies most abundant organic molecules Made up of 20 kinds of amino acids Made up of 20 kinds of amino acids 100`s of these amino acids are linked together in chains to make one protein molecule (polypeptide). 100`s of these amino acids are linked together in chains to make one protein molecule (polypeptide). The sequence of the particular amino acids determines its shape. The sequence of the particular amino acids determines its shape. The shape of the protein determines The shape of the protein determines its particular function. its particular function.

What do we need for protein synthesis? 1. DNA – the template for making mRNA through transcription. 2. RNA – there are three kinds a) mRNA – messenger RNA. Makes and takes a copy of the DNA to the cytoplasm where protein is constructed. a) mRNA – messenger RNA. Makes and takes a copy of the DNA to the cytoplasm where protein is constructed. b) tRNA – transfer RNA. The compliment to mRNA. Collects the amino acids and brings them to the ribosomes where polypeptide chains are assembled according to the sequence on the mRNA b) tRNA – transfer RNA. The compliment to mRNA. Collects the amino acids and brings them to the ribosomes where polypeptide chains are assembled according to the sequence on the mRNA c) rRNA – ribosomal RNA. Part of the ribosome, reads the mRNA and directs the tRNA c) rRNA – ribosomal RNA. Part of the ribosome, reads the mRNA and directs the tRNA

What do we need for protein synthesis? 3. Amino Acids – building blocks of protein 4. Ribosomes - reads the mRNA, directs the tRNA and creates protiens by binding the amino acids together through translation.

Each in more detail - DNA Contains the information to make all the proteins in our body. Problem: Protein is not made in the nucleus. DNA is too big to leave the nucleus. How do we get the information from the DNA out of the nucleus to where the protein is made?

Each in more detail - RNA RNA: ribonucleic acid.   Smaller than DNA   Function: Helps us get DNA information out of the nucleus. Made in the nucleus but found mostly in the cytoplasm. RNA is used to directly make protein.   Consists of a) single strand of nucleotides b) ribose as the sugar chain c) a phosphate group d) four base pairs (one different from DNA.) Adenine, guanine, cytocine and Uracil   Uracil is a pyrimidine base that replaces thymine and bonds with adenine |C-G and A-U

RNA Differs from DNA 1.RNA is smaller 2. RNA has a sugar ribose DNA has a sugar deoxyribose 3.RNA contains the base uracil (U) DNA has thymine (T) 4.RNA molecule is single-stranded DNA is double-stranded

Structure of RNA

Each in more detail - Amino Acids Long chains of amino acids link together to make a polypeptide chain (protein) Every amino acid has 5 parts 1. Central carbon 2. Amino group 3. Carboxyl Acid group 4. A single hydrogen 5. The ``R`` group – a chain that varies making each of the 20 amino acids unique It is the sequence of nucleic acids on the mRNA strand that determines which amino acids go together.

Let’s Review the Steps we Know so Far… 1. DNA makes a message (DNA makes mRNA) 2. Message is sent out into the cytoplasm (mRNA leaves the nucleus) 3. Message arrives at destination (mRNA goes to ribosome). 4. Message is read and directions followed (tRNA reads the mRNA, a small piece at a time, and gets whatever amino acid that small piece of mRNA says to get). 5. A protein is assembled

Steps of Protein Synthesis Transcription (writing the “message”) Using DNA to make mRNA which is the messenger that carries code to cytoplasm Translation (reading the “message”) mRNA and tRNA assemble the amino acid chain. In other words the message is translated into a protein.

Transcription Transcription is the process of copying a sequence of DNA to produce a complementary strand of RNA. Occurs in the nucleus. Only one gene is transferred into a message, not the entire chromosome.

Transcription – The making of RNA RNA polymerase and other proteins form a transcription complex. The transcription complex recognizes the start of a gene and unwinds a segment of it. start site nucleotides transcription complex

Transcription – The making of RNA Nucleotides pair with one strand of the DNA. RNA polymerase bonds the nucleotides together. The DNA helix winds again as the gene is transcribed. DNA

Transcription – The making of RNA The RNA strand detaches from the DNA once the gene is transcribed. The DNA zips back up and the single strand of RNA is released. RNA

Transcription is similar to Replication Transcription and replication both involve complex enzymes and complementary base pairing. The two processes have different end results. Replication copies all the DNA; Transcription copies a segment of the DNA – one gene. Replication copies all the DNA; Transcription copies a segment of the DNA – one gene. Replication makes one copy; Transcription can make many copies. Replication makes one copy; Transcription can make many copies. In replication the pairs stay together In replication the pairs stay together In transcription the copied RNA strand breaks away and the two strands of DNA rebind and recoil.

Transcription

Summing Transcription up in simple terms 1. DNA unzips. 2. RNA bases attach to make strand of mRNA COMPLEMENTARY to DNA (just like when we copied DNA) 3. Only one strand is made (like open-faced sandwich). 4. Use URACIL instead of thymine. 5. mRNA leaves nucleus 6. DNA zips back up.

Translation – The making of a protein Amino acids are coded by mRNA base sequences. Translation converts mRNA messages into polypeptides. A codon is a sequence of three nucleotides that codes for an amino acid. codon for methionine (Met) codon for leucine (Leu)

Translation – The making of a protein The mRNA joins with the ribosome which begins reading the code of nucleic acids Any portion of the strand NOT responsible for coding a polypeptide is discarded and is called INTRON The nucleotide sequence that encodes the amino acid sequence (called EXON) is identified by the AUG initiator codon and later followed by a terminator.

Translation – The making of a protein Each codon matches a specific amino acid or function. ***Use the codon to read the chart*** Twenty possible amino acids Twenty possible amino acids three stop codons three stop codons one start codon, codes for the amino acid methionine one start codon, codes for the amino acid methionine

Translation – The making of a protein A change in the order in which codons are read changes the resulting protein. Regardless of the organism, codons code for the same amino acid.

Translation – The making of a protein This is a molecule of messenger RNA. It was made in the nucleus by transcription from a DNA molecule. Each set of three nucleotides is a codon. A U G G G C U U A A A G C A G U G C A C G U U another codon mRNA molecule Initiator codon

A U G G G C U U A A A G C A G U G C A C G U U A ribosome either free in the cytoplasm or attached to the rough endoplasmic reticulum connects to the mRNA molecule. ribosome Translation – The making of a protein

A transfer RNA molecule arrives. It brings an amino acid to the first three bases (codon) on the mRNA. The three unpaired bases (anticodon) on the tRNA link up with the codon. A U G G G C U U A A A G C A G U G C A C G U U Amino acid tRNA molecule anticodon U A C Translation – The making of a protein Met

A U G G G C U U A A A G C A G U G C A C G U U Another tRNA molecule comes into place, bringing a second amino acid. Its anticodon links up with the second codon on the mRNA. U A C C C G Translation – The making of a protein Met Gly

A U G G G C U U A A A G C A G U G C A C G U U A peptide bond forms between the two amino acids. Peptide bond C C G U A C Translation – The making of a protein Met Gly

The first tRNA molecule releases its amino acid and moves off into the cytoplasm. Translation – The making of a protein A U G G G C U U A A A G C A G U G C A C G U U C C G U A C Met Gly

A U G G G C U U A A A G C A G U G C A C G U U C C G The ribosome moves along the mRNA to the next codon. Translation – The making of a protein Met Gly

A U G G G C U U A A A G C A G U G C A C G U U Another tRNA molecule brings the next amino acid into place. C C G A A U Translation – The making of a protein Met Gly Leu

A U G G G C U U A A A G C A G U G C A C G U U A peptide bond joins the second and third amino acids to form a polypeptide chain. C C G Translation – The making of a protein Met Gly Leu

A U G G G C U U A A A G C A G U G C A C G U U G U C A C G The process continues. The polypeptide chain gets longer. This continues until a terrmination (stop) codon is reached. The polypeptide is complete. Translation – The making of a protein Met Gly Leu Lys Glu Cys

Summing Translation up in simpler terms 1. mRNA goes to ribosome in cytoplasm (proteins made here!) 2. Exon is identified by the START codon (AUG) 3. Intron is discarded 4. tRNA reads each codon (three nucleotide set code for amino acid) and transfers the correct amino acid accordingly. 5. The amino acids are linked together in the codon order. 6. tRNA will read the mRNA until it reaches a TERMINATOR or STOP codon at which point the polypeptide is released from the ribosome. 7. This string of amino acids takes on it’s unique shape - PROTEIN!

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TAC CCT GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUG CCT GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUAC CCT GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCT GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGA GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCU GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGACCU ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGACCUGGA ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGACCUGGAPRO ACC TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGACCUGGAPRO ACCUGGACCTRP TAT ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGACCUGGAPRO ACCUGGACCTRP TATAUAUAUILE ACT

Synthesis Practice DNA triplet mRNA codon tRNA Anticodon Amino Acid TACAUGUACMET CCTGGACCUGLY GGACCUGGAPRO ACCUGGACCTRP TATAUAUAUILE ACTUGATermination

Over simplified Protein synthesis 1. DNA unzips 2. mRNA made from DNA. 3. mRNA leaves nucleus and enters ribosome. 4. tRNA reads mRNA from “start” to “stop” 5. As tRNA reads mRNA, it brings the correct amino acids. 6. Amino acids are linked together to make a protein DNA makes mRNA (complement) mRNA matches up with tRNA (complement) tRNA brings amino acid

Sources library.thinkquest.org/.../cell_membrane.gif library.thinkquest.org/.../cell_membrane.gif Synthesis%20Lesson.pdf 0Synthesis%20Lesson.pdf 0Synthesis%20Lesson.pdf 0Synthesis%20Lesson.pdf cp.hanna.anderson5.net/modules/groups/integrated_home.phtml?gid=40155 &sessionid=0e0ead763c304672d5ac0ddf7fa2b5c3 cp.hanna.anderson5.net/modules/groups/integrated_home.phtml?gid=40155 &sessionid=0e0ead763c304672d5ac0ddf7fa2b5c3 cp.hanna.anderson5.net/modules/groups/integrated_home.phtml?gid=40155 &sessionid=0e0ead763c304672d5ac0ddf7fa2b5c3 cp.hanna.anderson5.net/modules/groups/integrated_home.phtml?gid=40155 &sessionid=0e0ead763c304672d5ac0ddf7fa2b5c