7.2 Protein Synthesis. From DNA to Protein Animation

Transcription

1 7.2 Protein Synthesis From DNA to Protein Animation

2 Proteins Why are proteins so important? They break down your food They build up muscles They send signals through your brain that control your body They transport nutrients throughout your body They help your immune system

3 Protein Synthesis Since proteins are so important, we re going to learn how proteins are made: *Remember the central dogma: DNA RNA Proteins This means DNA is converted into RNA, and RNA is used to make proteins.

4 What is RNA? Ribonucleic acid Carries instructions from DNA to ribosomes There are 3 different types of RNA: Messenger RNA (mrna) Carries info from DNA to the cytoplasm Ribosomal RNA (rrna) Helps make ribosomes Transfer RNA (trna) Used to make proteins

5 Protein Synthesis: DNA TRANSCRIPTION mrna TRANSLATION Protein

6 Transcription 1. Initiation- DNA is unwound (unzipped), and mrna starts to be made 2. Elongation- nucleotides (A, U, C, G) are added to create mrna 3. Termination- the mrna strand is complete

7 Transcription

8 mrna is a copy of DNA Polymerase is the protein that copies DNA and makes mrna. For every G, it puts a C. For every C, it puts a G. For every T, it puts an A. For every A, it puts a U (because RNA uses U instead of T). RNA

9 Transcription DNA G C T A G C T A G C T A mrna C G A U C G A U C G A U

10 Processing mrna Once mrna has been made, it s not ready to leave the nucleus yet: Splicing removes introns from the mrna strand, and puts the exons together Introns are sections of mrna that do not code for proteins A tail is added to the mrna strand to protect the mrna when it leaves the nucleus

11 The Genetic Code Now that information to make proteins is coded in the mrna strand, we need to figure out how to translate that information into proteins. This is done through the genetic code The A, U, C and G letters are grouped into threes, called codons Each codon codes for one amino acid Amino acids are linked together to make proteins

12 Translation After detaching from DNA, mrna leaves the nucleus and travels to a ribosome. A ribosome is a protein factory. A ribosome is made out of rrna. The process of reading mrna and creating proteins is called Translation.

13 Reading the Genetic Code 1. AUG = start Once those letters are read, translation starts 2. The next three letters are read, which code for an amino acid 3. The next three letters are read, which code for an amino acid 4. This continues until the stop codon is reached UAG, UGA, UAA All of these amino acids are put together to make a specific protein

14 Reading the Genetic Code- Charts There are two different charts you can use to decode codons CUU would be Leu, or Leucine. UAC would be Tyrosine.

15 trna A ribosome will read a codon in mrna and tell trna what amino acids to bring to make a protein. trna will deliver the needed amino acid to the ribosome based on the codon being read. trna is the molecule that delivers amino acids.

16 How trna knows trna knows what amino acid to bring because it has the complementary RNA sequence. For example, if the codon is GCG, the trna carrying the correct amino acid will have the CGC codon. The trna will bond to the mrna and then release its amino acid The ribosome will add this amino acid to the chain that forms the protein as the trna leaves. The process will be repeated for the next codon.

17 The steps in translation

18 Label the image...

19 amino acids DNA trna protein anticodon mrna codon ribosome

20 Protein Synthesis Review 1. A mrna copy of DNA must be made in a process called transcription. A copy of DNA will be made using complementary bases to make mrna (e.g. T A; G C; A U). 2. The mrna copy travels out of the nucleus to the ribosomes to undergo translation. The ribosome reads the mrna copy in groups of three bases (or codons). For each codon, trna delivers the appropriate amino acid. 3. Each amino acid that is delivered by trna is assembled in a long chain. That chain of amino acids is what becomes the protein

21 Transcription occurs in the nucleus. Translation occurs in the ribosomes. Transcription involves making the mrna copy of DNA. Translation involves using the mrna copy to make a functional protein out of amino acids in the ribosome. DNA and mrna are a part of transcription. mrna, rrna, and trna are a part of translation.