Introduction to Genetics Chapter 1 PDF

Introduction to Genetics Chapter 1 Rashid Abu-Ghazalah, Ph.D. [email protected] ETB 204 1 Lectures and Office Hours • TA: Ms. Zahara Quadry: [email protected] • Lectures (links are on Avenue): – Mondays 12:30-13:20 – Wednesdays 15:30-17:20 – Office Hours: • By appointment • Suggestions to do...

Introduction to Genetics Chapter 1 Rashid Abu-Ghazalah, Ph.D. [email protected] ETB 204 1 Lectures and Office Hours • TA: Ms. Zahara Quadry: [email protected] • Lectures (links are on Avenue): – Mondays 12:30-13:20 – Wednesdays 15:30-17:20 – Office Hours: • By appointment • Suggestions to do well: – – – – Take notes during class. Not everything I say is on your slides! Take a few minutes of your day to review the lectures of the day Ask yourself questions Be organized 2 Emails • Use McMaster Email only. – Do not send me Avenue mail. • Have a subject line. • Expect a response by two days. 3 Evaluation • • • • • Quizzes: 10 % Mid-terms: (2 x 17.5%) = 35 % Assignments: 15 % Final: 40 % Total = 100% 4 Missed Work and Late Submissions • Late report and assignment submissions: 10 % per day and up to 2 days. After 2 days no submission will be accepted. • Once you submit an MSAF, you will need to contact me ASAP – I will let you know how you will be accommodated – Failure to do so in a timely fashion will result in a zero 5 Plagiarism • You will be reported. • A record will be kept and a second incident will be evident on your transcripts for good. • If you have questions regarding this, feel free to reach out to me. 6 Genetics The science that explores the organization, transmission, expression, variation, and evolution of hereditary characteristics of organisms 7 History of Genetics • Humans have manipulated the genetic composition of species for thousands of years – Domestication of rice in Asia, maize in Central America, wheat in the Middle East • Hippocrates (~500 B.C.) was the first to try to explain the inheritance of traits in humans – “Humors” • Black bile, yellow bile, blood, phlegm • Aristotle (~ 400 B.C.) was critical of this and described mutilations are not passed down. And what about gray hair? 8 History of Genetics • The theory of preformation – The fertilized egg contains a complete miniature “homunculus” • 1600s – William Harvey proposed the theory of epigenesis – An organism develops from the fertilized egg into an adult in several stages 9 History of Genetics • 1830 – Schleiden and Schwann proposed cell theory – All organisms are composed of basic units called cells • Louis Pasteur disproved spontaneous generation, the creation of living organisms from nonliving components • These studies set the stage for Darwin and Mendel in the mid-1800s 10 History of Genetics • 1859 – Charles Darwin publishes The Origin of Species – Natural selection as an explanation of the mechanism of evolutionary change – However, lack of understanding of the genetic basis of variation and inheritance were a significant gap in his theory • 1866 – Gregor Johann Mendel published his findings on the inheritance of traits – Provide the basis for modern genetics 11 From Mendel to DNA • All Mendel’s work was done without any knowledge of DNA • Several years later, with optical advances, chromosomes were identified • This is when the chromosome theory of inheritance was established by Sutton (sea urchins) and Boveri (grasshoppers). – All chromosomes had to be present for proper embryonic development to take place (Sutton). – Chromosomes occur in matched pairs of maternal and paternal chromosomes which separate during meiosis (Boveri). • That’s the physical basis of Medelian law of heredity 12 Chromosomes • It was established that in most eukaryotes, species have a characteristic number of chromosomes: – Diploid (2n) • Humans have 46 chromosomes – Homologous chromosomes • In the last 10 years of the 19th century, researchers observed the behavior of these chromosomes during cell division: mitosis and meiosis 13 Diploid Chromosomes http://4.bp.blogspot.com/0hW1wgwKhc8/UyPxA8LmQPI/AAAAAAAACvM/9gO6EBexEJQ/s1600/HumanChromosomes.jpg 14 Chromosomes: DNA or Proteins? • Work on the Drosophila (fruit fly) showed that certain genes were responsible for eye colour and mutations of these genes are responsible for “differing” traits – Alleles are variants of a gene controlling a trait – Different alleles produce different phenotypes – Set of alleles for a given trait carried by an organism is called the genotype • We know that genes are carried on chromosomes, which are composed of proteins and DNA – But which of the two was responsible for genetic information? • By 1944 it was determined that DNA was responsible and the race for DNA structural elucidation began 15 The Double-Helix • 1953-Watson and Crick used X-ray diffraction to determine DNA structure • Subunits: nucleotides – Adenine-Thymine – Guanine-Cytosine • RNA: – Single-stranded – Sugar is different – Uracil replaces thymine 16 Base-Pairing http://blog.drwile.com/wpcontent/uploads/2011/02/pairing.jpg http://nar.oxfordjournals.org/content/32/1/354/F1.large.jpg 17 DNA Structures http://www.cella.cn/book/12/images/image011.jpg 18 Central Dogma http://www.ncbi.nlm.nih.gov/Class/MLACourse/Modules/MolBioReview/images/central_dogma.gif 19 Proteins • End products of gene expression • Constructs of a combination of 20 amino acids (a.a.) • Imagine a protein made of 10 amino acids and can have any one of 20 a.a. 2010!!!!!!!! • Enzymes, hemoglobin, insulin, etc. etc. • Shape and chemical nature of proteins are determined by their linear sequence of a.a. that make it up 20 Sickle Cell Anemia • Mutation in the amino acid sequence for hemoglobin • A single nucleotide in a gene changes one of 146 amino acids that encode for a molecule in hemoglobin! 21 Biotechnology • The knowledge of molecular biology and genetics formed the basis of biotechnology – Recombinant DNA technology • Agriculture – Include traits such as resistance to herbicides • Medicine: – Anticlotting protein derived from the milk of goats 22