Biology 330- Genetics

1. Biology 330- Genetics Welcome!!

2. My cell phone policy • Don’t use it • If you do, and I see you using it, • I’ll publicly come up to you and take it from you; you’ll get it back at the end of class. • 

3. Overview • What is Genetics??? • Four areas of Genetics • A bit of history, people to learn • Mitosis and Meiosis, Cell cycle

4. What is Genetics?? • The study of biological information: its form, how it is expressed, stored, repaired, and transmitted. • Includes heredity, but when you think about it, heredity has to do with information. • Think of a CD or DVD or flash drive

5. Four ways to study Genetics • Transmission Genetics: How are traits transmitted from one generation to another? (AKA MENDELIAN Genetics); describing an allele as dominant or recessive, a gene as sex-linked, would be describing how it is transmitted. • Molecular Genetics: What are genes made up of? • How are they duplicated? • How is the information in the genes expressed? • How are genes turned on and off? • Where are genes located?

6. Four ways to study Genetics • Population Genetics: How do genes vary in a population? What causes this variation within populations? How are populations affected by their genes, and vice versa? • Cytogenetics: This area has to do with the relationship between the chromosome and traits that are exhibited. Generally involves changes that can be observed under the microscope to chromosomes. It also is involved in the location of genes.

7. Quick quiz- which is it? • A disease that is the result of one chromosome being improperly attached to another chromosome. • You’ve cloned the gene for Muscular Dystrophy (MD), and located it on a particular part of the X chromosome. • MD is sex-linked. • Cystic fibrosis allele is found in 5% of the Americans of Northern European descent.

8. My approach- DNA first • We’ll review Mendelian genetics in lab. • A little mitosis & meiosis • Then DNA-> RNA-> Protein • While we’re on the subject of spelling… • Separate Complementary

9. Chapter 1- a bit of history • Prehistory- our ancestors weren’t all that stupid; knew that creatures reproduced after their own kind, and did extensive improvement of animals and crops for our benefit. They also had “nature vs nurture” arguments as well. • But- usually thought of traits as “fluids”- for good reason!

10. Mendel: Laws of Segregation and Independent Assortment. • Mendel and those who rediscovered him showed that genes were inherited as if they were "particles" that stayed intact, not "fluids" that blended. • Gregor Mendel (1865): Monk in Czech Republic • Worked with true-breeding peas. • Published his results, but no one paid any attention until others did the same, 35 yrs later. Those three were Carl Correns, Hugo DeVries, and Eric Von Tschermak. We’ll come back to Mendel later.

11. Thomas Hunt Morgan et al (~1910): Genes are on chromosomes; genes near each other on the chromosome are linked. We now take this for granted, but it took some work to establish this as a fact. Morgan and his coworkers were the first to actually establish this fact. • Oswald Avery, et al(~ 1945): DNA is the genetic material. They worked with bacteria to show that the transforming material was DNA. • James Watson, Francis Crick, Rosalind Franklin, Maurice Wilkins ~1953: Structure of DNA. Watson and Crick used other people’s data to figure out a way that DNA could exist in a form that could contain information, and be its own template for replication.

12. Recombinant DNA : allows the manipulation of genes. Since the 1950's, we've discovered a tremendous amount about how genes work, as well as discovering how to manipulate them. Specifically, Herbert Boyer/Stanley Cohen discovered how to manipulate genes in 1973. • More recent: DNA sequencing, especially the ability to sequence entire genomes, has changed much of biology and genetics. Fred Sanger developed the basic method of sequencing DNA that we use today, and J. Craig Venter developed methods for large-scale sequencing.PCR- Kary Mullis

13. What to know from Chapter 1 • All those people, and what they did • Four ways to study genetics Chapter 2 • A bit of cell structure, Eukaryotes and prokaryotes, especially chromosomes in Euk. • Mitosis • Meiosis

14. Chapter 2- Mitosis, Meiosis, Cell Cycle Typical size- 20X 40 um

15. Typical size- 1X3 um

16. Chromosomes- the highly coiled, microscopically visible forms of the genetic material. • Usually uncoiled, not distinguishable as separate chromosomes. • The coiled form only appears during mitosis. Species have a variety of numbers of chromosomes (Table 2.1). • Chromatin: chromosomal material. Chromatin consists of both DNA and protein (mostly a particular type called histones), and we’ll discuss its structure later.

17. Gross structure: Chromosomes can be examined by karyotyping- picture of all the chromosomes arranged by number. Typically, they have two chromatids when visible, because the chromosome has already replicated. You’ll get a chance to produce metaphase chromosome preparations in cell biology.

18. A karyotype P ,q arms Meta, submeta,acro, telocentric (no human chr.) Number-large -small

19. Diploid and haploid organisms, haploid cells, and homologous chromosomes: We are diploid- we have two sets of chromosomes, one from Mom, one from Dad. • This works because our chromosomes come in pairs; they are called homologous chromosomes- similar, but not identical. One of each pair came from mom, one from dad. We arise from a fusion of two haploid gametes-sex cells- that result in a new person, with a full set of chromosomes.

20. Some organisms are haploid: fungi, bacteria, the vegetative forms of some lower plants, etc.

21. Genes and Alleles • Genes: Usually(but not always) a piece of DNA that codes for a protein- so it is transcribed and translated. Some more recent findings have complicated this definition, but it’ll work for the most part. • Alleles- varieties of the same gene.

22. a a A A • Quick quiz: • Distinguish between chromosomes, chromatin, and chromatids • What type of chromosome is this and which is the q arm? Why are there two? • If gene A is on chr. 14, and an organism is heterozygous for A and a alleles, how might you show that on the chromosome? • Name a haploid prokaryote and eukaryote

23. Mitosis • Cell cycle: G1, S, G2, M, Go; run by signals!!!

24. Already duplicated You can’t see the chromosomes in interphase disjunction kinetochore

25. What to know about mitosis : Match an event or description to the stage.

26. MEIOSIS: “purpose”: to produce sex cells, with half the chromosome number, and exactly one of each pair of homologous chromosomes. This is where segregation and independent assortment actually occur. • Overall Flow: Chromosome # and DNA content: the chromosome # is halved, while the amount of DNA is ¼ of that of a cell prior to meiosis. • Stages:- prior to meiosis, the cell has undergone S phase, so the chromosomes have doubled, and are consist of two chromatids. This is key in understanding the fact that we produce FOUR cells

27. Stages:- prior to meiosis, the cell has undergone S phase, so the chromosomes have doubled, and are consist of two chromatids. This is key in understanding the fact that we produce FOUR cells

28. Tetrads, bivalents Thin threads Continue-terminalization Pairing up Thicken; recombination occurs Begin to pull apart; chiasmata

30. Meiosis II- Prophase, metaphase, anaphase, telophase II: By the end of telophase I we have two haploid cells, but each chromosome still consists of two chromatids. Meiosis II essentially takes the two cells with chromosomes consisting of sister chromatids and produces FOUR cells with single chromosomes.

31. Male & female differences • Males: 4 sperm produced/meiotic event • Females: 1 egg produced- difference between the roles of the egg and sperm; thus females produce polar bodies. • The other difference is that there can be enormous time gaps between prophase I and ovum formation. In women, their eggs hang around in prophase I. Ovulation stimulates completion of Meiosis I, and what is fertilized is actually an egg that hasn’t completed Meiosis; Meiosis II is completed after fertilization.

32. From Stem cells

33. Correlation between meiosis and Mendel’s laws of segregation and independent assortment So what happens during Anaphase I??

34. Both Segregation AND Independent Assortment are happening here! (G and g segregate, G sorts with either W or w, g sorts with either W or w)

36. Alternation of Generations

37. So these are actually like a small organism! In some cases, they are!

38. What to know • Obviously, the terms. • How meiosis relates to segregation and independent assortment.

39. Quick quiz • What did DeVries do? Sanger? Mullis? • When chromosomes are moving towards the equator of the cell, they are in what phase? • What happens in pachytene? • A diploid cell with 16 chromosomes would produce how many gametes, with how many chromosomes?