Introduction to Genetics 3U 2 PDF

Introduction of Genetics The Nature of Heredity GENETICS The study of heredity and the variation of inherited characteristics HEREDITY: the passing of traits from parents to offspring DNA Genetic information is contained in a molecule of DNA The modern DNA model has 3 parts: Composed of pentose...

Introduction of Genetics The Nature of Heredity GENETICS The study of heredity and the variation of inherited characteristics HEREDITY: the passing of traits from parents to offspring DNA Genetic information is contained in a molecule of DNA The modern DNA model has 3 parts: Composed of pentose sugar, a phosphate group and one of four nitrogenous bases (Levene, 1920) 2. The proportion of nitrogenous bases are equal. (Chargaff, 1940) 3. DNA has a helix shape (Franklin, 1951) 1. The backbone of DNA is composed of phosphate group and pentose sugar. The nitrogenous bases pair up: ◦ Thymine-Adenine ◦ Cytosine-Guanine DNA DNA COMPLEMENTARY BASE PAIRING: pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand You only need to know the nucleotide sequence for one strand GENETIC MATERIAL GENE: a segment of a DNA molecule that codes for a particular trait ●Found at a specific location on a chromosome LOCUS: the location of a gene on a chromosome CHROMOSOME: carries information for hundreds or thousands of different genes Chromosomes and Chromatin A chromosome is the condensed form of genetic material. It’s DNA wrapped tightly around small proteins Chromatin is the non-condensed or relaxed form of genetic material. REPRODUCTION The production of offspring from a single parent The genetic makeup of the offspring is identical to that of the parent ASEXUAL The production of offspring from the fusion of two sex cells The genetic makeup of the offspring is different from that of either parent SEXUAL CELL CYCLE There are 3 stages to the cell cycle: ◦INTERPHASE ◦MITOSIS ◦CYTOKINESIS INTERPHASE The period between cell divisions, where the cell grows, DNA replicates and the cell prepares for mitosis. INTERPHASE There are three parts to interphase: ◦ G1 (First Gap) Phase: the cell is growing and preparing for replication. Cell contents duplicated. ◦ S (Synthesis) Phase: duplication of genetic material ◦ G2 (Second Gap) Phase: cell begins final prep for cell division INTERPHASE The chromosomes in the nucleus are formed by a mass of thread like structures called CHROMATIN The replication of chromosomes results in a pair of SISTER CHROMATIDS MITOSIS The process by which a cell divides the genetic material in its nucleus into two identical nuclei Used for: ●Growth ●Reproduction ●Repair PHASES OF MITOSIS There are four phases of mitosis: ●PROPHASE ●METAPHASE ●ANAPHASE ●TELOPHASE PROPHASE Chromosomes shorten and thicken Centrioles move to opposite poles of the cell Spindle fibres form Nuclear membrane starts to dissolve METAPHASE Spindle fibres move to align the chromosomes Chromosomes are lined up at the equator of the cell ANAPHASE The chromosomes move to opposite poles of the cell The chromosomes are pulled by their centromeres TELOPHASE Chromosomes are at opposite poles and start to unwind Spindle fibres start to dissolve Nuclear membranes reform CYTOKINESIS The process in which a cell divides its cytoplasm in to two new INDENTICAL daughter cells The same number and type of chromosomes in each cell CLONING The process of producing one individual that is genetically identical to another using a single cell or tissue EXAMPLES: ●“Dolly” the sheep ●Genetically Modified Organisms (Expensive to create so cloning is a good economic option) ●Pharmaceutical products (Like Insulin) Plant Cloning In 1958 Frederick Stewart cloned a plant from a single carrot cell. He grew specialized cells from another carrot in a nutrient rich medium with plant hormones and was able to get the cells to return to an undifferentiated state. The cells then restarted the process of growth, specialization, and development into new plants. Cloning Animals Cloning animals presented an issue that was not present in plant cells. Animal cells could not be stimulated into restarting the process of growth and differentiation like plants Dr. Ian Wilmut (Roslin Institute in Scotland) used a clever technique to get around this obstacle Making Dolly Dr. Wilmut obtained a body cell from the sheep he wanted to clone and an unfertilized egg from a second donor. Using microsurgery techniques he was able to enucelate (remove the nucleus from) the egg. He then used an electrical shock to fuse the adult body cell from one donor to the enucleated egg of the other Wilmut then triggered the cell to begin dividing and growing. He then implanted the embryo into the uterus of a third sheep. Dolly Dolly was born on July 5th 1996 Dolly was the only successful clone out of 277 attempts Resemblance? I don’t see it... Applications of Cloning Mass production of livestock and plants. This can be used to increase the quality of animals and crop plants. Downsides - Cloned plants and animals may be expensive. People may be hesitant to purchase a food from a GMO. Potentially lowers genetic diversity in the gene pool of the organism. Genetically Modified Organisms GMO’s often carry a gene that was present in another species. Ex. Virtually all commercially available insulin is from GMO Bacteria and yeast. For a time the human insulin gene was also placed into safflower plants. Goats and Spiders A gene from the golden orb spider can be used to produce silk proteins in the milk of goats. GMO’s GMO Salmon GMO Pigs (For Medicine) Will GMO’s hurt my body? CANCER Cancer is occurs when cells divide uncontrollably There are two kinds of cancer tumors: ●BENIGN: the cancer cells are not capable of spreading ●MALIGNANT: the cancer cells are capable of spreading Gene Therapy Experimental treatment that aims to cure genetic disorders by inserting a normal healthy form of a gene into the cells affected by the disorder Usually uses modified viruses as a vector or delivery system