2. Protein synthesis Notice that scientists can’t spell “e” before “i”

3. Proteins Recall they are more than just muscle, most of the substances we think of in our bodies are a type of protein. – Color pigment, hormones and other enzymes, and much of the cellular structures are made of proteins. The sub-units are called amino acids. There are only 20 different amino acids, various numbers and arrangements make millions of proteins (think words)

4. Proteins Protiens are made up of Amino acids.

5. So how are they made The DNA in the nucleus are the blueprint for making proteins Another structure called the ribosome, outside the nucleus builds or assembles the proteins from amino acids. RNA is used to both copy the “blue print” and bring amino acids to the ribosomes

6. It’s a two step process The answer lies in an intermediate substance known as mRNA. Information is copied from DNA onto mRNA, this is transcription mRNA leaves the nucleus and enters the cytoplasm of the cell Ribosomes use the mRNA as a blueprint and utilize tRNA to synthesize proteins from amino acids, this is translation.

7. DNA vs. RNA DNA deoxyribose sugar nitrogen bases – G, C, A, T – T : A – C : G double stranded RNA ribose sugar nitrogen bases – G, C, A, U – U : A – C : G single stranded

9. 8 Structure of RNA

10. 9. Three Types of RNA Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized

11. Transcription: in the nucleus an enzyme called RNA polymerase binds to a segment of DNA and opens up the double helix RNA polymerase, helped by other enzymes, recognizes the promoter region which is a sequence of DNA rich in A and T bases (TATA box) found only on one strand of the DNA.

12. RNA binds mRNA (messanger) nucleotides now bond to the exposed DNA nucleotides (remember H- bonding) The mRNA strand formed now has a mirror image of the DNA nucleotides (with U instead of T) 11

13. 12 RNA Polymerase

14. Transcription http://sepuplhs.org/hig h/sgi/teachers/genetics _act16_sim.html http://sepuplhs.org/hig h/sgi/teachers/genetics _act16_sim.html To end of transcription https://www.youtube.c om/watch?v=D3fOXt4M rOM https://www.youtube.c om/watch?v=D3fOXt4M rOM Start to 2:00

15. Codons We’ll see shortly that it takes a set of 3 nucleotide bases to code for one amino acid. Therefore each set of 3 bases in called a codon. Ex; AUG, CGA The section which codes for a whole protein is called a gene. 14

16. Start n Stop Every gene starts with the mRNA sequence (codon) AUG and ends with one of UAA, UAG or UGA. (the stop codons do not code for any amino acid) This means every protein of every organism every studied for proteins starts with the same amino acid, Methionine. 15

17. Codon wheel read from center out

18. copyright cmassengale17

19. 18 Name the Amino Acids GGG? UCA? CAU? GCA? AAA?

20. 19 The mRNA mRNA leaves the nucleus through pores and carries the “message” to the ribosomes to be translated copyright cmassengale

21. Translation 20

22. 21 Ribosomal RNA (rRNA) rRNA is a globular complex of RNA and proteins found both free in the cytoplasm and on many folds of the ER (making “rough ER”) rRNA is a globular complex of RNA and proteins found both free in the cytoplasm and on many folds of the ER (making “rough ER”) rRNA binds to a mRNA to translate it into proteins rRNA binds to a mRNA to translate it into proteins

23. 22 Transfer RNA (tRNA) Clover-leaf or globular triangle shaped Single stranded, but folded in and H-bonded to it’s own nucleotides, one end has an exposed active site that binds to a specific amino acid. Opposite end has three nucleotide bases exposed due to folding, called the anticodon

24. 23 Transfer RNA

25. tRNA

26. 25 Codons and Anticodons the ribosome helps bind the tRNA anti-codon to the appropriate codon Example: Codon ACU Anticodon UGA UGA ACU

27. The polypeptide is built Each time an anticodon attaches to the active site of the mRNA an enzyme helps its amino acid bond to the previous one releasing it from the tRNA. The tRNA is then released to bind to another amino acid, and the mRNA is shifted up to expose the next codon. 26

28. Transcription http://sepuplhs.org/hig h/sgi/teachers/genetics _act16_sim.html http://sepuplhs.org/hig h/sgi/teachers/genetics _act16_sim.html. https://www.youtube.c om/watch?v=D3fOXt4M rOM https://www.youtube.c om/watch?v=D3fOXt4M rOM 2:24-

29. Protein Synthesis Eukaryotes: transcription occurs in the nucleus and translation occurs in the cytoplasm Prokaryotes: Transcription and translation occur simultaneously in the cytoplasm

30. Compound protein Some large proteins can be built from two or more smaller proteins. Transcribed exons on the mRNA can be rearranged and linked by enzymes in the nucleus to produce different compound proteins. The human DNA contains some 32 000 genes but can produce over a 100 000 proteins 29

31. Interons and Exons 30 Many sections of an animal DNA strand (especially at the ends) do not seem to code for proteins. These are called interons. Coding sections are called Exons.

32. Assignment Peruse pages 233-243 #3,4 page 237 Complete and hand in the protein synthesis worksheet attached #2-6,14,20 page 244/45 31