Transcription and Translation: Protein synthesis

1. Transcription and Translation: Protein synthesis

2. What we already know… • DNA encodes the information to make proteins • DNA cannot leave the nucleus • Protein synthesis occurs outside of the nucleus, on a ribosome

3. How does it happen? DNA encodes the information to make RNA.........and RNA molecules function together to make protein

5. Structure of RNA • Single stranded • Built of nucleotide • 5-Carbon Sugar = ribose sugar • Phosphate Group • Nitrogenous base: • Adenine, Uracil, Guanine, and Cytosine

6. NO THYMINE IN RNA

8. 3 Types of RNA • Messenger RNA (mRNA) • DNA cannot leave the nucleus so mRNA carries information to ribosomes for protein production • Transfer RNA (tRNA) • brings specified amino acids from the cytoplasm to the ribosomes where the protein chain is made • Ribosomal RNA (rRNA) • the ribosome and protein

9. 3 Types of RNA

11. Transcription DNA  mRNA

12. Transcription • Process by which a molecule of DNA is copied into a complementary strand of mRNA • Occurs in the nucleus

13. How does it happen? • DNA unzips and exposes one gene as a template • A complementary strand of RNA is formed • A – U • G – C • mRNA strand exits the nucleus and moves into the cytoplasm • The two strands of DNA re-attach and recoil

15. Transcription movie • http://learn.genetics.utah.edu/units/basics/transcribe/

16. Try it yourself … • Transcribe Strand 1 of the DNA molecules below • 1 - T T A G G A C T G C A A T T G 2 - A A T C C T G A C G T T A A C • 1 - C A G T C C G A A C G T T T A 2 - G T C A G G C T T G C A A A T

17. Answers • A A U C C U G A C G U U A A C • G U C A G G C U U G C A A A U

19. Translation mRNA  protein

20. Translation • Process by which the mRNA is “read” and a protein is created from amino acids • Occurs at the ribosome

21. Steps of Translation 1. mRNA moves to the ribosomes 2. the rRNA on the ribosome binds to the mRNA and starts “reading” codons. • Codons – 3 letter code that specifies a particular amino acid. • start codon = AUG • stop codon = UAA, UAG, or UGA 3. AUG binds to the first anticodon of tRNA

22. 4. tRNA transfer amino acids until the rRNA reaches a stop codon on the mRNA 5. the ribosome releases the protein and the mRNA • protein to be used by the cell • mRNA to synthesize more protein molecules

23. Movie of Translation • http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#

24. mRNA-amino acid chart

25. Try it yourself! • DNA template strand DNA: TACGATCGAACGTAT • mRNA codon: • tRNA anticodon: • Amino Acids :

26. mRNA Activity • Here is a strand of mRNA. Arrange your tRNA molecules to determine the sequence of Amino Acids that this mRNA codes for. • AUG CUA UCA UCA UAU GGA GUA ACU AGU UUU CGC AUU CCG CAU ACA CGG GUU  CUC CCU CAC AGG UGG GGG UGU CUA ACC  UUA CCC GCA UCG UAA

27. Mutations • Mutations lead to mistakes in the proteins being made. • Mutations can happen during DNA replication and change the “blueprint of the cell” Or During transcription or translation so a wrong protein or no protein is made

28. Types of mutation • Point mutation- one nucleotide changes • Frameshift mutation- an insertion or deletion of a nucleotide that changes all codons after that point • Chromosomal mutation- all of the genes on a certain chromosome can be affected. Or change the location of genes on the chromosome.

29. Transcription • The information in the DNA not only contains amino acid (aa) sequences, it also has “junk” DNA. • Exon: RNA that codes for a.a. • Intron: junk RNA/DNA • Enzymes in the nucleus snip out the exon and the RNA molecule is protected and sent outside of the cell.

30. mRNA splicing http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html