Bio-31-Lecture-2.-Part-1 PDF

(Take 2) Grounding Together https://www.cmu.edu.ph/home/the-university/mission-vision/ 1 Branches of Genetics 1. Cytogenetics – studies the chromo...

(Take 2) Grounding Together https://www.cmu.edu.ph/home/the-university/mission-vision/ 1 Branches of Genetics 1. Cytogenetics – studies the chromosomes which are the carriers of DNA/genes 2. Molecular Genetics – studies the structure & function of genes at the molecular level 3. Developmental Genetics – studies how genes control growth & development of an organism throughout its life cycle 4. Quantitative Genetics – studies the role of genetics & environmental factors on the inheritance of traits that are controlled by many genes & highly affected by the environment (e.g. grain yield) 2 5. Population Genetics – studies the fate of genes in a population & the factors that would change the frequencies of genes & alleles in populations over space & time 6. Biochemical Genetics – studies the relationship of genes & their control over the function of an enzyme in a metabolic pathway 7. Evolutionary Genetics – studies how genetic variation leads to speciation & adaptation, & genetic change in response to selection within populations 8. Human Genetics – studies traits, diseases & abnormalities in humans that are inherited 9. Behavioral Genetics – studies how genetic & environmental influences would affect behavior 3 Some Applications of Genetics ∞ Food production ∞ Plant breeding/crop improvement ∞ Animal breeding/animal improvement ∞ Genetic counselling (human concerns such as diseases) ∞ Forensics & legal matters ∞ Genetic resources conservation & management (plants, animals, microbes) ∞ Medicine: gene therapies, diagnosis of genetic diseases, vaccine development, personalization of medical treatments, etc. ∞ Others 4 Methods Used in Genetic Studies 1. Hybridization or crosses: monohybrid, dihybrid, trihybrid, etc. 2. Phenotyping: qualitative, quantitative & intermediate traits; morphological, agronomic, physiological, biochemical traits 3. Mutation studies/mutagenesis 4. Statistical analyses: ANOVA, Chi-square test, cluster analysis, principal component analysis (PCA), Standardized Shannon-Weaver Diversity Index (SSWDI), etc. 5. Molecular methods: polymerase chain reaction (PCR), gel electrophoresis, DNA sequencing, QTL analysis, association mapping, GWAS (genome-wide association studies), genotyping using molecular markers, etc. 5  BIO 31 Genetics Chapter 1. INTRODUCTION (History, Theories & Important People…) Prepared by: Joy M. Jamago, PhD Department of Agronomy & Plant Breeding College of Agriculture, Central Mindanao University Musuan, Bukidnon, 8710 Philippines 6 https://biology.mit.edu/faculty-and-research/areas-of-research/genetics/  Who am I? What did I do? Next: Historical background Early theories of genetics Pillars of genetics Milestones in genetics https://www.britannica.com/biography/Gregor-Mendel 7 https://www.femtechleaders.com/the-top-8-famous-geneticists-in-the-world/ 8 https://www.femtechleaders.com/the-top-8-famous-geneticists-in-the-world/ Prepared by: JMJamago (August 2024) 9 https://www.facebook.com/photo/?fbid=1822756071093281&set=a.109350895767149 https://www.asianscientist.com/scientist/emil-q-javier/ Prepared by: JMJamago (August 2024) 10  Genetics ▪ derived from the Greek word “gen” – to become or to grow into something ▪ Genetics – coined by William Bateson, 1905 (119 y.a.) ▪ deals with fundamental properties & problems of life & living, hence impinging on all aspects of biology, biochemistry, physiology, development, morphology, anatomy, evolution, ecology & other sciences https://dnalc.cshl.edu/view/16197-Gallery-5-William-Bateson-Portrait.html Prepared by: JMJamago (August 2024) 11 Beginning of Genetics ▪ Science of genetics began with the works of Gregor Mendel (1822-1884); Austrian monk ▪ 1866: discovered that hereditary characteristics were determined by “factors” (now called genes) ▪ factors – transmitted (passed on) between generations in uniform predictable pattern Prepared by: JMJamago (August 2024) 12  ▪ 2 important attributes of the gene (factor): 1. Gene is inherited from generation to generation in such a fashion/pattern that each progeny (offspring, descendants) has a physical copy of the gene; 2. Gene provides information regarding https://www.thespruceeats.com/taste-of-different-color-carrots-2215929 the structure, function, & other E.g. Trait – color of carrot roots biological properties of the characteristic or trait it controls Prepared by: JMJamago (August 2024) 13  Before Mendel:  Heredity was a “blending process”, offspring were thought to be mixtures of characteristics from both parents  True for some cases, not for other cases (i.e. some children would closely resemble 1 parent) → do, other explanation were needed (1) Theory of Pangenesis: by Aristotle (384-322 BC)  Lasted until 19th century, accepted by Charles Darwin (1809-1882)  “semen was formed everywhere in a man’s body & such semen reflected the characteristics of the body part from where it was formed”, semen traveled through blood vessels into male https://investinhistory.ca/2024/02/14/aristotle-athens-greatest-philosopher/ reproductive organs Prepared by: JMJamago (August 2024) 14 (2) Theoryof Inheritance of Acquired Characteristics: by Jean Baptiste de Lamarck (1744-1829) https://byjus.com/question-answer/theory-of-inheritance-of-acquired-characters-was-given-bydarwinde-vrieswallacelamarck/  based on the Pangenesis Theory  proposed as the fundamental mechanism of evolutionary change Prepared by: JMJamago (August 2024) 15 (3) Germplasm Theory by August Weismann (1834-1914) o Challenged Aristotle’s & de Lamarck’s theories o Experiments: cut off tails of for many generations but offspring always had normal tail length o Conclusion: inheritance of tail length did not depend on particles produced in the tails of parent mice, but on the germplasm cell(s) which were not affected when tails were cut o Germplasm Theory: germplasm or sex cells perpetuated themselves in reproduction generation after generation, whereas, the somatoplasm or other body parts were produced only to protect & reproduce itself Prepared by: JMJamago (August 2024) 16 August Weismann 1st to distinguish heritable changes & non-heritable changes Other books call his theory: the Weismann Barrier “Germline (sex cells) contain information that is passed on to the next generation unaffected https://www.britannica.com/biography/August-Weismann by experience & independent of somatic cells (from other parts of the body)” Prepared by: JMJamago (August 2024) 17 Joseph Kolreuter (1733-1806): o Crossed red carnations x white carnations = produced pink carnations o Crossed pink x pink = red, white & pink carnations o Conclusion: hybrids between species might show uniform appearance but their fertile offspring would usually produce diverse outputs Gartner (1772-1850) Naudin (1815-1899) similar observations Darwin (1809-1882) Dzierzon (bee-hybridizer) – reported similar observations & considered the numerical ratios of the diverse offspring Prepared by: JMJamago (August 2024) 18  Most likely due to his brilliant insights & methodologies* Mendel – not first to study biological inheritance but still was named the “Father of Genetics” Prepared by: JMJamago (August 2024) 19 1. Choice of garden peas (Pisum sativum L.) as experimental crop was advantageous Peas: self-pollinating, starting materials were relatively the same (or homozygous) Peas produce many seeds so ratios or proportions of characteristics being studied could be monitored/accounted easily 2. Mendel concentrated on 1 single trait at a time (whereas, other scientists observed whole plants or more complex traits) Selected plant traits with clear-cut differences or the alternative types contrasted sharply; e.g. round vs. wrinkled seeds 3. Made sure that pea strains or varieties used in hybridization were “true breeding” by growing them for 2 years; selected parent materials only those that produced progenies or offspring that resembled the parents Prepared by: JMJamago (August 2024) 20  4. Mendel introduced quantitative approach in his experiments: classified hybrid progenies (based on type) & determined their respective frequencies 5. He formulated theories that explained his experimental results 6. He formulated appropriate https://www.istockphoto.com/photos/mendel experimental tests to validate his theories Prepared by: JMJamago (August 2024) 21  Reflection: Mendel’s important contribution to science of genetics: demonstrated that appearance of different characters in heredity followed specific laws & can be determined by counting the diverse kinds of offspring produced from any sets of crosses Published his work in 1866 but was ignored for almost 40 years  He had wrong timing : during his time, most biologists had Hawkweed little interest in mathematics & vice versa, & Mendel tried to bridge the gap  But, he wasn’t able to show similar results in other plants or animals  Studied hawkweed (Hieracium sp.) – which unfortunately was an apomictic species Prepared by: JMJamago (August 2024) 22 https://en.wikipedia.org/wiki/Hieracium_lachenalii  https://species.wikimedia.org/wiki/Hugo_de_Vries https://dnalc.cshl.edu/view/16216-Gallery-6-Carl-Correns-signed-portrait.html https://dnalc.cshl.edu/view/16218-Gallery-6-Erich-von-Tschermak-Seysenegg-1941-signed.html Carl Correns (German) Erick Von Tschermak (Austrian) Hugo de Vries (Dutch) Prepared by: JMJamago (August 2024) 23 The “Rediscoverers of Mendel” In 1990, independently duplicated Mendel’s experiments on garden peas, corn, primroses, poppies & other flowering plants. https://species.wikimedia.org/wiki/Hugo_de_Vries https://dnalc.cshl.edu/view/16216-Gallery-6-Carl-Correns-signed-portrait.html https://dnalc.cshl.edu/view/16218-Gallery-6-Erich-von-Tschermak-Seysenegg-1941-signed.html Obtained same ratios as Mendel German Austrian Dutch Provided the follow-up work that Mendel was unable to do Prepared by: JMJamago (August 2024) 24  William Bateson Edith Rebecca Saunders Lucien Cuenot (British/English) (British) (French) https://en.wikipedia.org/wiki/William_Bateson https://www.lib.cam.ac.uk/women-of-cambridge/edith-rebecca-saunders Prepared by: JMJamago (August 2024) 25  William Bateson Edith Rebecca Saunders Lucien Cuenot (British/English) (British) (French) https://en.wikipedia.org/wiki/William_Bateson https://www.lib.cam.ac.uk/women-of-cambridge/edith-rebecca-saunders 1902: showed that Mendelian principles also applied to animals Prepared by: JMJamago (August 2024) 26