Molecular Genetics Thursday, March 16-12, 2010

1. Molecular Genetics Thursday, March 16-12, 2010 • Objectives • State that genes are codes for proteins. • Identify the parts of a nucleotide. • Catalyst • Widows peak is dominant to straight hairlines. Show the cross between two heterozygous widow’s peak parents. • Find the genotype and phenotype ratios.

2. Agenda • The Big Picture • Quiz-Quiz-Trade • Punnett Review • Transcription/Translation • Independent Work • Exit Question

3. In The Beginning… • Human beings have 23 pairs of chromosomes (one from mommy, one from daddy). • DNA is made up of two strands of nucleotides in a double helix. • Nucleotide: backbone (sugar and phosphate) plus a base. • Genetic information is stored in the nitrogenous bases. • A  T • G  C • Each chromosome is made up of coiled DNA. • A specific area of chromosome that codes for one trait is called a gene. • Chromosomes  genes  DNA

4. Controls a Trait? How? • Different alleles (versions) of genes code for different traits. • We can predict what traits children will have if we know their parents’ alleles. • A heterozygous free earlobe parent mates with a heterozygous free earlobe parent.

5. How? Where? • OK, so genes code for traits—but how do we get from a gene to a trait? • Proteins! Proteins are the stuff that actually causes our hair to be blonde, eyes to be brown, skin to be dark, etc. • Problem • Chromosomes (genes) are in the nucleus. • Proteins are made in the ribosome. • OH NOES!!!

6. The Solution X X X X X X X X X X X X X X X X X X X X X X X

7. The Solution TRANSLATION: • Information in mRNA is read one codon (three nucleotides) at a time. • tRNA brings the correct amino acid, based on the codon sequence. • Many amino acids = protein. TRANSCRIPTION: • Information in DNA is copied into mRNA • mRNA is formed by complementary base pairs • A  U, T  A • G  C, C  G / / / CGATTA GCUAAU GCU = Alanine AAU = Asparagine

8. The Central Dogma of Biology DNA Transcription RNA Translation Protein

9. Quiz-Quiz-Trade • Find a partner. Quizthem with your question on your notecard. If they can’t get it right, coach them (coaching is not telling them the answer!) • Then your partner quizzesyou. • Once you have each successfully answered your question, trade your notecards. Then raise your hand. • High-five someone with a raised hand. BAM! You’re now partners.

10. Punnett Square Practice • In lions, the allele for yellow eyes is dominant to the gene for brown eyes. • Show a cross between a lion who is heterozygous and one who is homozygous recessive. What are the genotypic and phenotypic ratios?

11. Punnett Square Practice (whiteboard) • In lions, the allele for yellow eyes is dominant to the gene for brown eyes. • Show a cross between a lion who is heterozygous and one who is homozygous recessive. What are the genotypic and phenotypic ratios?

12. Punnett Square Practice (whiteboard) • In lions, the allele for yellow eyes is dominant to the gene for brown eyes. • Nala has yellow eyes and Simba has brown eyes. Nala is heterozygous. What are the chances that they will have children who are homozygous dominant? Who have brown eyes?

13. Punnnett Square Practice (Whiteboard) • In lions, the allele for yellow eyes is dominant to the gene for brown eyes. • Simba got his beautiful brown eyes from his parents Mufasa and Sarabi. However, both his parents had yellow eyes. Show that this is possible since both his parents are heterozygous. What were the chances that this was going to happen?

14. TRANSCRIPTION and TRANSLATION SHOWDOWN In each of these, you have to take a segment of DNA and turn it into mRNA

15. Showdown… AAGTACGTCATTCCGTAT

16. Showdown… TACCATATTGGACAGAAA

17. Showdown… TACGTTAATCAGAAATGT

18. Go over blood typing problem on review sheet • Questions 40,41,42.

19. Independent Work Time

20. Exit Questions • What is ONE question you have about this unit? • I will review the most common questions tomorrow before the unit test.