Unit 4: Genetics and Biotechnology

1. Unit 4: Genetics and Biotechnology Miss Hawkins Biology 30

2. Introduction to Genetics What is inheritance? Why do we only get some traits from our parents? How does genetic information get passed from parents to offspring? How does this connect to evolution?

3. Introduction to Genetics What is inheritance? Transfer of genetic information Why do we only get some traits from our parents? Mutation, dominant/recessive traits How does genetic information get passed from parents to offspring? Combination of gametes in sexual reproduction How does this connect to evolution? Those most able to survive, reproduce and pass on their genetics

4. Inheritance Why is it important to know about inheritance? To get an understanding of potential health problems - some are inherited Why might knowing about dominant and recessive genes be important when considering offspring? Knowing about your partner’s genetic makeup could help you avoid the occurrence of genetic conditions that may be recessive or problematic

5. Vocabulary Allele - a copy of coding for a particular trait at a specific gene loci (one letter) A = capital letter means dominant a = lower case letter means recessive Homozygous - pair of identical alleles Heterozygous - has 2 different alleles Gene - basic unit of heredity Genotype- combination of alleles an individual possesses (the letters) Phenotype- the visible expression of the genotype (what we can see) Gene loci - location of coding for an organism’s genetics (DNA), typically for a specific characteristic - however, some phenotypes are coded by multiple loci

6. Gregor Mendel = “Father of Genetics” Austrian Monk He discovered the basic principles of heredity by breeding gardening peas Defined different types of hybridization: • P generation - parental; true breeding parents • F1 generation - 1st generation of offspring • F2 generation - 2nd generation of offspring

7. Mendel’s Process Probability is the fundamental idea behind this. However it might not always be accurate - genetics isn’t just “one gene codes for one trait”, multiple genes can code for one trait

8. Mendel’s Discoveries • If 2 genes differ, one is dominant and one is recessive. • A dominant allele is fully expressed in an organism’s appearance. A recessive allele has no noticeable effect • Alternative versions of genes (alleles) account for variations in inherited characteristics • An organism inherits 2 genes, one from each parent, for every character • A sperm of egg only carries one allele for each inherited trait

9. Mendel’s Laws Mendel’s Law of Dominance: One gene is dominant over another gene Mendel’s Law of Segregation: The pair of alleles from each parents separate during gamete formation (meiosis) & only one allele passes from each parent to the offspring Mendel’s Law of Independent Assortment: Different pairs of alleles are passed to offspring independently of each other.

10. Pedigrees Determining Parental Genotypes Pedigree - help us establish family trees and determine potential phenotypes/genotypes of offspring They are useful in identifying characteristics (good or bad) that children hold and whether or not they may genetically linked. Functions as a record of descent. Can be animal-breed specific, or characteristic specific

11. How to read Pedigrees

12. Practice Pedigree The pedigree shows the presence of dimples through a family’s generation. Having dimples is a dominant trait If individuals II-1 and II-2 have a fourth child, what is the probability that the child will have dimples?

13. Punnett Squares Punnett Square - a square used to show all of the possible combinations of gametes Monohybrid Crosses - mating between two individuals with different alleles are one genetic locus of interest. AA x aa Dihybrid Crosses- mating between two individuals with different alleles at two genetic loci of interest. AaBB x aaBB

14. Punnett Squares Monohybrid Example Example: A blue-eyed mother mates with a homozygous, brown-eye father. What ratio of brown-eyed to blue-eyed children will they have? Brown eyes is the dominant trait, therefore B - Brown b - blue F1: B B F2: B b b B b b Genotype: 100% Bb Genotype: 25% BB, 50% Bb, 25% bb Phenotype: 100% Brown Phenotype: 75% Brown, 25% Blue Bb Bb Bb Bb BB Bb Bb bb

15. Punnett Square Monohybrid Example In sheep, belly fur is dominant to no belly fur. A mother is heterozygous belly fur mates with a homozygous no belly fur. What is the genotype and phenotype for their offspring (F1)

16. Punnett Square Dihybrid Example Example: In rabbits white fur (W) is dominant to black (w) and long ears (E) are dominant to short ears (e). A breeder mates two rabbits that are heterozygous (WwEe) for both traits. What is the phenotype and genotype of their offspring? F1: WE We wE we WE We wE we Genotype: 1 WWEE, 2 WWEe, 2 WwEE, 4 WwEe, 1 WWee, 2 Wwee, 2 wwEe,1 wwee 1 wwEE Phenotype: 9 white fur and long ears 3 white fur and short ears 3 black fur and long ears 1 black fur and short ears WWEE WWEe WwEE WwEe WWEe WWee WwEe Wwee WwEE WwEe wwEE wwEe WwEe Wwee wwEe wwee

17. Punnett Square Dihybrid Example In peas, round (R) is dominant to wrinkled (r). Yellow (Y) is dominant to green (y). Consider a cross between a heterozygous for both traits and a homozygous recessive for both traits. What is the phenotype and genotype of the next generation?

18. Exceptions to Mendel While many genes follow the patterns outlined by Mendel’s Laws, many do not. These include incomplete dominance, codominance and multiple alleles

19. Incomplete Dominance = Partial expression Both alleles partially contribute to the phenotype of a heterozygous individual producing a trait that is not exactly like either parent Example: Japanese four-o’clock plant. A cross between a homozygous red- flowered plant (CRCR) and a homozygous white-flowered plant (CWCW) produces offspring with pink flowers (CRCW) * They are written with the same capital letter and different superscript letters to indicates the different colours on the same allele F1: CR CR F2: CR CW CWPhenotype: 100% Pink CR CWGenotype: 100% CRCW CW Phenotype: 25% red, 50% pink, 25% white Genotype: 25% CRCR, 50% CRCW, 25% CWCW CRCR CRCW CRCW CWCW CRCW CRCW CRCW CRCW

20. Codominance = Full expression Both alleles FULLY contribute to the phenotype of a heterozygous individual combining both traits identical to the parents. Example: A homozygous red bull breeds with a homozygous white cow HR HR HW HW

21. Multiple Alleles = 2+ alleles for the species Although a single individual cannot have more than two alleles for each trait, different individuals can have different pairs of alleles when multiple alleles exist. Example: Human blood type In the early 20th century, Karl Landsteiner classified blood according to these differences. He observed 2 distinct chemical molecules present on the surface of red blood cells. He labeled one “A” and the other “B” antigens. If the red blood cell only has “A” antigens, it is Type A If the red blood cell only has “B” antigens, it is Type B If it has a mixture of both antigens, it is Type AB If it have neither “A” or “B” antigens, it is Type O

22. Blood Types If two blood types are mixed together, the blood cells may begin to clump together. Therefore it is important that blood types be matched before blood transfusions occur. Type O is known as the Universal Donor Type AB is known as the Universal Acceptor

23. Blood type problem 1 A women with type A blood (IAi) is married to a type B person (IBi). What blood types will their children have? Genotype: Phenotype:

24. Blood type problem 2 A women with blood type A is claiming that a man with type AB blood is the father of her child, who also has type AB blood. Could he be the father? Show all the possible situations

25. Sex Traits Sex Determination - x and y chromosomes are sex chromosomes; other chromosomes are known as autosomes XX = girl XY = boy Sex-Influenced - when genes on autosomal chromosomes ( not on the x and y chromosomes) show up differently in the present of different hormones Ex: Baldness allele is dominant, but testosterone is needed for it to show up which results in more men being bald and females being carriers Sex-Linked - a trait that is controlled by a gene found directly on the X and Y chromosomes. Ex: Hemophilia, Muscular Dystrophy, Colour Blindness

26. Sex-linked problem Webbed fingers is inherited as an X-linked disease. An unaffected male marries an affected female. What is the likelihood their children having webbed fingers? XfXf x XFY F1: Xf Xf XFGenotype: Female 100% XFXf , Male 100% XfY Phenotype: Female 100% carriers for webbed fingers Y Male 100% webbed fingers

27. Sex linked problem Color Blindness is inherited as a sex-linked recessive disease. An affected male marries a heterozygous female. Draw a punnett square and list the possible phenotypes Normal vision: XN Colour Blind: Xn

28. Cell Cycle Vocabulary Mitosis- somatic/autosomal cell division Meiosis- sex/gamete/germ cell division Diploid- 2 sets of chromosomes (2n) Haploid- 1 set of chromosomes (n) Interphase - The in between stages of cell division, broken down into: G1 + S + G2

29. Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide During the cell cycle, a cell grows, prepares for division and divides to form two daughter cells, each of which begins the cycle again Interphase is the period of growth that occurs between cell division Interphase is divided into three phases: G1, S & G2

30. Cell Cycle G1 Phase The G1 phase is a period of activity in which cells do most of their growing. Cells will increase in size and synthesize new proteins and organelles. *Checkpoint that checks size and condition of cell before it moves on. S Phase The S phase replicates chromosomes and synthesizes DNA molecules. When DNA replication is completed, the cell enters the G2 phase G2 Phase During the G2 phase, many of the organelles and molecules required for cell division are produced (Preparation for cell division). When G2 is completed, the cell is ready to enter the M phase (mitosis). *Checkpoint - checks to see if chromosome is copied correctly

31. Mitosis and Meiosis Vocabulary Centromere - the region of a chromosome to which the spindle fibres attach Centrioles - help the formation of spindle fibres Chromatin - DNA complex - when condensed turns into chromosomes Spindle fibres - microtubules that help pull apart chromosomes Sister chromatids - identical copies of chromosomes connected by the centromere

32. Mitosis Mitosis is a form of eukaryotic cell division that produces two daughter cells with the same genetic component as the parent cell Autosomal cells (every type except sex cells) divide using mitosis 1 diploid parent(2n) → 2 diploid daughter cells (2n) 5 stages during mitosis: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis *Checkpoint: checks the alignment of chromosomes in metaphase

33. Phases of Mitosis Prophase: • Chromatin condenses into chromosomes. • Centriolesseparate • Spindle fibres form • Nuclear envelope breaks down Metaphase: • The chromosomes line up across the centre of the cell • Each chromosome is connected to a spindle fibre at its centromere

34. Phases of Mitosis Anaphase: • The sister chromatids separate into individual chromosomes and are moved apart Telophase: • The chromosomes gather at opposite ends of the cells & lose their distinct shapes • Two new nuclear envelopes will form

35. Cytokinesis The cytoplasm pinches in half Each daughter cell has an identical set of duplicate chromosomes

36. Meiosis Meiosis is a form of eukaryotic division that produces 4 daughter cells with half the genetic component as the parent cell Sex cells (sperm and egg) divide using meiosis 1 diploid parent cell (2n) → 4 haploid daughter cells (n) 4 phases repeated twice: Prophase I, Metaphase I, Anaphase I, Telophase I Prophase II, Metaphase II, Anaphase II, Telophase II

37. Phases of Meiosis Prophase I: • Chromosomes begin to condense and pair up • Crossing over occurs Crossing over = the exchange of genetic material between homologous chromosomes

38. Phases of Meiosis Metaphase I: • Spindle fibres attach to chromosomes • Chromosomes line up in the centre of the cell Anaphase I: • Chromosomes start to move to opposite ends

39. Phases of Meiosis Telophase I: • Nuclear membrane reforms Cytokinesis Prophase II: • Chromosomes begin to condense and pair up • Spindle fibres forms

40. Phases of Meiosis Metaphase II: • Spindle fibres attach to chromosomes • Chromosomes line up in centre of cell Anaphase II: • Centromeres divide • Sister chromatids move to opposite ends of cell

41. Phases of Meiosis Telophase II: • Chromosomes reach opposite ends • Nuclear membrane forms Cytokinesis: • In males, 4 sperm cells • In females, 3 polar bodies and 1 mature egg cell

43. Chromosomal Disorders Chromosome mutations- a change in the genetic material that involves either the whole or a piece of a chromosome The most common cause of chromosome mutation is nondisjunction Nondisjunction- the failure of the chromosomes to separate properly during meiosis

44. Chromosomal Disorders Down’s Syndrome (Trisomy 21) - the 21st pair of chromosomes has one extra chromosome, for a total of 3 rather than 2 - this results in 47 chromosomes instead of 46 Turner’s Syndrome(monosomy X) - missing the other sex chromosome. Features include: short, thick necks, lower intelligence. 1/10,000 births - many are miscarried 45 chromosomes in total Klinefelter’s syndrome(trisomy X) - XXY Male at birth, female hormones during maturity. Sterile (not able to reproduce) 1/1000 births 47 chromosomes in total

45. Karyotype Karyotype- a photograph or map showing the homologous pairs of chromosomes

46. DNA Nucleic acids are compounds that contain phosphorus and nitrogen in addition to carbon, hydrogen and oxygen. There are two kinds of nucleic acids: deoxyribonucleic acid(DNA) and ribonucleic acid (RNA) Each living cell has its own DNA and RNA. Information stored in DNA controls all cell activities and determines the genetic/hereditary characteristics of the cell and, as a result, the organism. RNA is required for protein synthesis

47. Discovering DNA Who? Friedrich Miescher, Francis Crik and James Watson When? 1869, 1950’s Where? University of Cambridge How? X-ray image

48. Role of DNA DNA is a long chain of repeating units called nucleotides Nucleotide = 5 carbon sugar bonded to a phosphate group and a nitrogen base • There are 4 nitrogen bases: Adenine - Thymine, Guanine - Cytosine • There are always bonded in their pairs: A-T and G-C These four bases can be attached in any sequence along the length of the molecule. This sequence provides genetic variation

49. Role of DNA The shape of the DNA molecule represents the shape of a ladder - a double helix On each of the side of the chains are deoxyribose sugar and phosphate. The nitrogen base pairs make up the middle of the helix.

50. RNA Ribonucleic Acid is required for protein synthesis, including enzymes There are differences in the chemical composition of RNA and DNA • RNA molecules consist of only one chain/strand of nitrogen bases. • Sugar is ribose in RNA and deoxyribose in DNA • The nitrogen base thymine is replaced by uracil who also pairs up with adenine