TAKS review

1. DNA, mRNA, and Protein Synthesis TAKS Review

2. DNA stands for Deoxyribonucleic acid Functions: Store and transmit genetic info Contains the blueprint for making proteins What is DNA?

3. Location and Structure of DNA Location: Nucleus Structure: Double stranded, often called double helix Composed of three part nucleotides: Deoxyribose (sugar) Phosphate (PO4) Nitrogen base (1 of 4): Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

4. Base Pairing Rule

5. During cell reproduction an exact copy of the parent cell is made DNA unzips to make two new strands of DNA Location: Nucleus DNA Replication

6. DNA Replication

7. DNA contains the instructions for building proteins Proteins are made at the ribosomes DNA cannot leave the nucleus How does DNA’s information get to the ribosome? Making Proteins

8. Messenger RNA (mRNA) What is mRNA? Ribonucleic acid: Single stranded Nucleotides composed of: Ribose (sugar) Phosphate Nitrogen bases: Adenine (A) Guanine (G) Cytosine (C) Uracil (U)

9. Transcription: RNA is made from a strand of DNA Location: nucleus mRNA leaves the nucleus and takes the information to the RIBOSOME where a protein will be made How does mRNA take DNA’s information to the ribosome?

10. Transcription

11. What happens to mRNA at the ribosome? mRNA will bind to the ribosome tRNA will read mRNA in three part sections (codon) tRNA carries amino acids to the ribosome Amino acids will bond to form a protein

12. Translation

13. Translation

14. Translation (continued)

15. Remember: mRNA is read in 3 part sequences called a codon(there are 64 total) Every 3 part sequence codes for an amino acid Proteins are determined by the order in which amino acids are joined together There are 20 different amino acids which can combine to form many different proteins Genetic Code-language of mRNA

16. Mutations – are changes in the genetic material. 2 Kinds: Gene mutations Chromosomal mutations Mutations

17. Produce changes in a single cell. Types: Point mutations– involves changes in one or a few nucleotides and occur at a single point in the DNA sequence. Substitutions – one base is changed to another; only affects a single amino acid. Insertions & Deletions– a base is inserted or removed from the DNA sequence; much more dramatic because the genetic code is read in 3-base codons. Frameshift mutations– the shifting of codons & the “reading frame” which may change every amino acid that follows the point of the mutation. It can alter a protein so much that it is unable to perform its normal functions. Gene MutationsSee pg. 307, Fig. 12-20

18. Gene Mutations: Substitution, Insertion, and Deletion Deletion Insertion Substitution