1. Leaving Cert Biology Genetics – section 2.5 Genetics 2.5 2.5.4( RNA), 2.5.5, 2.5.15

2. Leaving Cert Biology Genetics – section 2.5 2.5.4 RNA Structure It is made up of nucleotide units Each nucleotide unit has a backbone one of four nucleotide bases: Adenine A, Guanine G, Cytosine C, and Uracil U (instead of thymine!) U RNA (ribonucleic acid) is another nucleic acid.

3. Leaving Cert Biology Genetics – section 2.5 RNA Structure Unlike DNA, RNA is single stranded!

4. Leaving Cert Biology Genetics – section 2.5 2.5.5 Protein synthesis Every protein has a particular sequence of amino acids that it is made up of. 3-D image of Melanin 1. Our DNA contains the instructions (in the form of a code) to make proteins

5. Leaving Cert Biology Genetics – section 2.5 Protein synthesis 2.The code contained in our DNA is transcribed (copied) to make messenger RNA (mRNA).

6. Leaving Cert Biology Genetics – section 2.5 3. The mRNA carries the code into the ribosome Protein synthesis The mRNA The protein chain

7. Leaving Cert Biology Genetics – section 2.5 The function of mRNA in protein synthesis is to carry a copy of the DNA instructions (codes) from the nucleus to the ribosomes.

8. Leaving Cert Biology Genetics – section 2.5 Protein synthesis 4. In the ribosome the code is translated and the amino acids are assembled into the correct sequence to make the protein.

9. Leaving Cert Biology Genetics – section 2.5 Protein synthesis 5. The protein folds into its functional shape.

10. Leaving Cert Biology Genetics – section 2.5 Protein synthesis – higher level 1. Enzymes unwind the double helix

11. Leaving Cert Biology Genetics – section 2.5 RNA nucleotide bases bond with one strand of exposed DNA. The enzyme RNA polymerase assembles these bases to form mRNA. 2. Transcription mRNA has a series of bases that are complementary to those in DNA !

12. Leaving Cert Biology Genetics – section 2.5 The function of mRNA in protein synthesis is to carry a copy of the DNA instructions (codes) from the nucleus to the ribosomes.

13. Leaving Cert Biology Genetics – section 2.5

14. Leaving Cert Biology Genetics – section 2.5 mRNA moves into the cytoplasm Each three base sequence of mRNA carries a genetic code (codon) that specifies either: a starting codon, a particular amino acid or a stop codon. 3. mRNA sequence

15. Leaving Cert Biology Genetics – section 2.5 Ribosome subunits (rRNAs) attach to the mRNA. These subunits form the ribosome, the site of protein synthesis. 4. The ribosome

16. Leaving Cert Biology Genetics – section 2.5 Free floating tRNAs with their attached amino acids, within the cytoplasm are attracted to the complementary mRNA already attached to the ribosome. This ensures the amino acids are aligned in a sequence determined by the codons of the mRNA 5. tRNA

17. Leaving Cert Biology Genetics – section 2.5 Aligned amino acids bond to form links of the new protein molecule 6. Protein synthesis

18. Leaving Cert Biology Genetics – section 2.5 tRNAs continue to move to the ribosome, until a stop codon on the mRNA code sequence tells the ribosome that the process is complete and the protein is synthesised. 7. End of Translation

19. Leaving Cert Biology Genetics – section 2.5 8. Protein folding 5. The protein folds into its functional shape.

20. Can you.. Tell what RNA stands for Explain how mRNA is made Give the function of mRNA Tell the location of transcription Describe what happens to mRNA after it leaves the nucleus Explain how the code of mRNA is translated Leaving Cert Biology Genetics – section 2.5