GREGOR MENDEL AND ELEMENTARY GENETICS Genetics - gen means to become or to grow into something - William Bateson in 1906 - Branch of biology that deals with the principle =s of heredity and variation in all living things Heredity - is our genetic heritage - Passing of traits from the parents to their offspring - Can be physical, a disease, or behavioural Variation - the differences in the genetic makeup or physical appearance of different organisms - Seeks to understand the molecular and physical bases of biological diversity and the principles that govern their heredity from one generation to another Branches of Genetics Molecular Genetics Studies the structure and function of genes at a molecular level Developmental Genetics Studies the process by which organisms grow and develop Cytogenesis Studies the structure and function of the cell (chromosomes) Evolutionary Genetics Studies how genetic variation leads to evolutionary changes Biochemical Genetics Studies the relationship between genes, protein, and metabolism Behavioural Genetics Study that examines the role of genetics in animal (including human) behaviour Population Genetics Studies the allele frequency distribution and change under the influence of their four main evolutionary processes: natural selection, genetic drift, mutation, and gene flow Quantitative Genetics Studies the continuously measured traits (such as height and weight) an their mechanisms BIOL5 (Lecture) Application of Genetics 1. Plant, Animal and Microbial Improvement - includes selective breeding, producing high yielding crops, advancement in meat production through breeding that supplied the protein needs, and the use of selecte microbial strains that improved the fermentation of foods and foo products - GMO, low and high quality 2. Medicine - genetic diseases and abnormalities have been identified - appropriate preventives measures are prescribed 3. Genetic Counselling - knowledge of the inheritance of certain desirable or undesirable characteristics will help individuals, prospective parents, and families to to understand their genetic history and adapt to the most effective way of treatment, if necessary - traits na pedeng maipasa sa mga anak 4. Legal Applications - Genetics helped solve problems of disputed parentage in settling child support, estate claims or even baby mix-up in hospitals. DNA profiles or fingerprints of suspects have been found to be an accurate tool in identifying criminals. 5. Recombinant DNA Technology - This involves joining of DNA segments from different biological sources producing genetically modified organism (GMO) or transgenic plants, animals, or microorganisms. - Therapeutic proteins, hormones and vaccines are also produced using this technology Beginning of Genetics Theory of Pangenesis - Charles Darwin in 1869 - gemmules, small particles in the body, were formed everywhere in the man’s body and such gemmule reflected the characteristics of the body part from where it was formed - Travelled through blood vessels into the male reproductive organ then transmitted to the next generation and are responsible for the transmission of traits from parents to offspring example: blood transfusion experiment Theory of Inheritance of Acquired Characteristics - Jean Baptise de Lamarck - Based on the Pangesesis theory - Body modifications acquired by use or disuse could be transmitted to the offspring because the gemmules formed reflected such modifications - Unused - weaker & disappear - Used- stronger & developed - change is made by what organisms want or need - Focused in two ideas: 1. nature produced successively all the different forms of life on earth 2. environmentally induced behavioural changes lead the way in species change Germplasm Theory - August Weismann in 1883 (disproved the Theory of Pangenesis) - germplasm (genes) or sex cells perpetuated themselves in reproduction generation after generation - somatoplasm or body cells were produced by germplasm to protect and reproduce itself - the germplasm is a continuous stream from generation to generation, while the BIOL5 (Lecture) somatoplasm is formed anew at every generation - Panganay gets the full trait from the parent unlike sa mga sumunod na maunti na daw yung makukuha ex: somatic cell nuclear transfer Gregor Mendel / Johann Gregor Mendel - first to follow a single trait - he discovered that hereditary characteristics were determined by elementary factors that are transmitted between generations. - he believe that gene is inherited from generation to generation that each descendant has a physical copy of this material, and gene provides information regarding the structure, function, and other biological properties of the characteristic it controls. Mendelian Observation - he worked with traits that show discontinuous variation that show one of two, or very few, easily distinguishable traits - A quantitative approach Why does he choose peas: 1. Garden peas are self-pollinating 2. Garden peas mature within one season, giving Mendel several generations within a short period of time 3. Large quantities of garden peas could be cultivated simultaneously, Mendel observed seven characteristics from his garden peas, each with two contrasting traits Law of Independent Assortment (Dihybrid Cross) - lets us predict how a single feature associated with a single gene is inherited - states that the alleles of two (or more) different genes get sorted into gametes independently of one another. - In other words, the allele a gamete receives for one gene does not influence the allele received for another gene - Thomas Hunt Morgan (confirmed the chromosome Theory of Inheritance through discovering sex chromosomes on his study about fruit flies. Mendel concluded that the characteristics can be classified as dominant and recessive traits. Dominant traits - those that are inherited unchanged in a hybridization Recessive traits - disappear in the offspring of hybridization but reappear in the offspring of the hybrids Chromosome Theory of Inheritance - Walter Sutton and Theodor Boveri: stated that the segregation of pair factors (in Mendel’s observation) is paralleled by the separation of homologous chromosomes during meiosis. - The individual genes are found at specific locations on chromosomes, and the behavior of chromosomes during meiosis can explain why genes are inherited according to Mendel’s observation. Law of Segregation (Test Cross) - only one of the two gene copies present in an organism is distributed to each gamete (egg or sperm cell) that it makes, and the allocation of the gene copies is random. BIOL5 (Lecture) Observations that support Chromosome Theory of Inheritance: 1. That, chromosomes, like Mendel’s genes, come in matched (homologous) pairs in an organism. 2. the member of the homologous pair separates in meiosis, so that each sperm or egg has just one member (A-Law of segregation) 3. the members of different chromosome pairs are sorted into gametes independently of one another in meiosis (B-Law of Independent Assortment) Chromosomes - comes from the Greek words chroma and soma which stands for colour and body - are thread-like structures located inside the nucleus of the cell. It is made up of protein (histone) and DNA - are also used as sex determinants Protein Histone - provides support for the structure of chromosomes by coiling it and keeping it highly condensed Without protein histone, DNA molecules in a single human cell would stretch up to 6 feet. For sure, they wont fit inside the nucleus Humans - 23 pairs of chromosomes Fruit flies - 4 pairs of chromosomes Rice plant - 12 pairs of chromosomes Gods - 39 pairs of chromosomes Cats - 19 pairs of chromosomes Centromere - the constricted region of the chromosome - helps keep chromosomes properly aligned during cell division and the attachment site for the sister chromatids Telomere - located at the ends of the chromosomes - protect the ends of the chromosomes and sustain chromosome stability Chromosome’s arms - regions on either side of the centromere P arm - short arm Q arm - long arm Types of Chromosome According to Position of Centromere 1. Telocentric - when centromere occupies the terminal position, so that the chromosome has just one arm 2. Acrocentric - when the centromere occupies a sub-terminal position, one arm is very long and the other is very short 3. Sub-metacentric - when centromere is positioned slightly away from the mid-point so that the two arms are unequal 4. Metacentric - when centromere lies in the middle of chromosome so that the two arms are almost equal DNA Structure - DNA - deoxyribonucleic acid - provides the information needed to construct the proteins necessary so that the cell can perform all its function - is composed of repeating nucleotides, which are made up of a pentose sugar (ribose or deoxyribose), a nitrogenous base (purines (G, A) and pyrimidines (C, T)), and phosphoric acid - Oswald Avery, Colin MacLeod, and Maclyn McCarty in 1944 (concluded that DNA is the genetic material) - Friedrich Miescher in 1860 (DNA was identified) - Erwin Chargaff (showed that there are four kinds of monomers (nucleotides) present in DNA molecule, where two types were always present in equal amount and the remaining two types were also present in equal amounts) - James Watson and Francis Crick (concluded that DNA is made up of two strands in the form of a double helix) Central Dogma - first used by Francis Crick in 1958 to summarize the series of events from DNA to RNA to protein production - explains the flow of genetic information in making functional proteins - Replication, Transcription, and Translation BIOL5 (Lecture) Replication - first step in Central Dogma - duplication of DNA - each of the two strands that make up the double helix serves as a template from which new strands are copied Semiconservative replication - new strand will be complementary to the parental or “old” strand Steps: 1. The enzyme helicase unwinds the parental double helix Origin of replication - replication process begins Replication fork - a Y-shaped structure after the helicase unwind the parental double helix 2. Single-stranded binding proteins stabilize the unwound parental DNA 3. The leading strand is synthesized continuously in the 5’ to 3’ direction by DNA polymerase (for DNA) 4. The lagging strand is synthesized discontinuously (for RNA) 5. After the RNA primer is replaced by DNA nucleotides, DNA ligase joins the Okazaki fragments to the growing strand BIOL5 (Lecture) Transcription - how DNA is transcribed into RNA - The process requires the DNA double helix to partially unwind in the region of mRNA synthesis Transcription bubble - region of unwinding Template Strand - it proceeds from one of the two DNA strands - RNA polymerase moves along the template strand, which is the 3’ to 5’ strand. The RNA polymerase separates the two strands while complementing DNA template nucleotides with RNA nucleotides 1. rRNA (ribosomal RNA) - are complexed with ribosomal proteins to form ribosomes 2. mRNA (messenger RNA) - provides the template that contains the nucleotide code for the amino acid sequence of a protein 3. tRNA (transfer RNA) - transfers amino acids from the cytoplasm to the ribosomes Translation - how RNA is translated into proteins - the process by which the mature mRNA molecule is used as a template for synthesizing protein Codon - a three-nucleotide sequenc Genetic code - relationship between a nucleotide codon and its corresponding amino acid Genes and Gene Interactions Gene - are carried on chromosomes - unit of heredity occupying a particular location on the chromosome and passed on to offspring Alleles - gene variants that exist at the same relative locations on homologous chromosomes Dominant allele - a hereditary factor that expresses itself when present; expressed unit factor; capital leter Recessive allele - a hereditary factor that is hidden and expressed only when two recessive alleles are combined; latent unit factor; small letter - Wilhelm Johannsen pointed out phenotype (appearance of the organism), genotype (organism’s underlying genetic make up) The dominant allele is capitalized, and the recessive allele is lower case BIOL5 (Lecture) Homozygous - organisms has two identical alleles Heterozygous - contrasting trait Law of Dominance This states that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic. Rather than both alleles contributing to a phenotype, the dominant allele will be expressed exclusively. Recessive will remain latent but is transmitted to the offspring in the same manner as the dominant allele. Monohybrid Cross - the fertilization between true breeding parents that differ by only the characteristic being studied Punnett square - a device invented by Reginald Punnett, used for determining probabilities (measures of likelihood) because it is drawn to predict all possible outcomes of all possible random fertilization events and their expected frequencies Test Cross - way to determine if homogenous or heterogenous ang parent - the dominant-expressing organism is crossed with an organism that is homozygous recessive for the same characteristic Dihybrid Cross BIOL5 (Lecture) ANIMAL STRUCTURE AND FUNCTION Common Characteristic of Animals Animal - came form the Latin word animalis, which means having breath - Animals are diverse group of organisms that make up the Kingdom Animalia - first animals are thought to have evolved over 550 million years ago Timbrian Explosion - most of the animals went extinct Characteristics common to all animals 1. Multicellular - animals are composed of many cells that are fused together - multicellular bodies of animals consist of tissues that make up more complex organs and organ system Humans : 30-50 trillion cells Adapted because: • to obtain the necessary nutrients and other resources needed by the cells of the body • to remove the wastes these cells produce • to coordinate the activities of the cells, tissues, and organs throughout the body • to coordinate the many responses of the individual to its environment 2. Heterotrophic - Animals obtain their energy by consuming the bodies of other organisms - Animals get their energy and required nutrients through ingestion followed by digestion and absorption Biological molecules necessary for animal function: Amino acids (proteins) Lipid molecules Nucleotides Simple sugar (carbohydrates) Food consumed consists of: Proteins Fat Complex carbohydrates BIOL5 (Lecture) Animals must convert these macromolecules into the simple molecules required for maintaining cellular function. This conversion is a multistep process involving : Digestion - food particles are broken down to smaller components which are later absorbed by the body 3. Sexual Reproduction - animal reproduction is necessary for the 4. survival of species the genetic material of two individuals combines to produce offspring that are genetically different from their parents Restores the diploid number and increases genetic variation Development - the process in which an organism develops from a single-celled zygote to a multicellular organism is complex and well-regulated Oviparous - na ngingitlog Viviparous - hindi na ngingitlog Zygote undergoes rapid cell division to form blastula in the process termed as cleavage. During cleavage, the cells divide without an increase in mass; that is, one large single-celled zygote divides into multiple smaller cells. The blastula arranges themselves in two layers: the inner mass cells and the outer layer called the trophoblast. The inner mass cells will go on to form the embryo and consists of embryonic stem cells. While the trophoblast will contribute to the placenta and nourish the embryo. Differentiation - the embryonic stem cells express specific sets of genes which will determine their ultimate cell type 5. Movement Motility - the ability of an organism to move of its own accord by expending energy and it can be in the form of walking, slithering, swimming, or flying to propel themselves through world Sessility - the biological property of an organism describing its lack of means of self- locomotion - animals can move via external forces such as water currents to protect themselves and for sexual and asexual reproduction Nerve tissue - nagpapagalaw Muscular tissue - gumagalaw 6. Main Animal Division A. Symmetry 3. Asymmetrical - animals have no pattern or symmetry; example is a sponge 4. Radial Symmetry - when any plane cut along the longitudinal axis through the organism produces equal halves, but not a definite left or right side; mostly found in aquatic animals 5. Bilateral Symmetry - when an animal can be divided into roughly mirrorimage halves only along one particular plane through the central axis Homeostasis - the constancy of the body’s internal environment Feedback Systems - these equilibrium conditions are maintained by mechanisms collectively Negative Feedback - reverses or negates the initial change; pinapababa yung input stimulus Positive Feedback - maintains the direction of the stimulus; pinapataas yung input stimulus Animals can be divided into two groups: 1. those that maintain a constant body temperature in the face of differing environmental temperatures 2. those that have a body temperature that is the same as their environment and thus varies with the environment temperature. These animals use their circulatory systems to help maintain body temperature. Thermoregulation - maintaining temperature Endotherm - warm-blooded animals Ectotherm - cold-blooded animals Osmoregulation - maintaining water BIOL5 (Lecture) Cephalization - the concentration of sensory and brain structure in the anterior - produces an anterior (head) end, where sensory cells, sensory organs, cluster of nerve cells, and organs for ingesting food are concentrated. The other end of a cephalized animal is designated posterior and may feature a tail. We also have the dorsal side that contains the cranial and spinal cord and the ventral side that contains the thoracic activity – one that surrounds the lungs and heart. Dorsal - back Ventral - front Anterior - head Posterior - tail B. Germ Layers 1. Ectoderm - gives rise to the nervous system and the epidermis, which is located in the outer layer of body wall 2. Mesoderm - gives rise to the muscle cells and connective tissues in the body 3. Endoderm - gives rise to columnar cells found in the digestive system and many internal organs, gastrodermis, which is located in the lining of the guts? cavity C. Body Cavities Coelom - most widespread type of body cavity - a fluid-filled cavity that is completely lined with a thin layer of tissue that develops from mesoderm - Outer wall of the body during development Coelomates - animals that have coelom - These are the annelids, arthropods, mollusks, echinoderms, and chordates Pseudocoelomates - animals have a body cavity that is not completely surrounded by a mesodermderived tissue - roundworms Acoelomates - animals that do not have body cavity at all - flatworms and sponges Profostomes - mouth (invertebrates) Deuterostomes - anus (vertebrate) humans Types of Animal Tissue - named according to cell layer and shape of cells • Epithelial Tissues - the body’s gatekeepers, protecting regulating the movement of substances in and out of the body - bind with connective tissues to form membranes which cover the body and line body cavities such as the mouth, the stomach, and the bladder Types: Number of layers: 1. Cuboidal 1. simple 2. Columnar 2. stratifies 3. Squamous 3. pseudostratified BIOL5 (Lecture) • Connective Tissues - serve mainly to support and bind other tissues 3 Categories: 1. Loose connective tissues - also called the areolar connective tissue; this combines with the epithelial tissues to form the membranes; contain a diffuse network of protein fibers, surrounds, cushions and supports most organs of the body. 2. Fibrous connective tissues - contains collagen fibers, which are densely packed in an orderly parallel arrangement – a design that contributes to the flexibility and tremendous strength of tendons and ligaments tendons connect bones to muscles ligaments connect bones to bones. 3. Specialized connective tissues - this includes the cartilage, bone, fat, and blood. Cartilage - covers the ends of bones at joints, provides the supporting framework for the respiratory passages, support the ears and the nose, and forms shock-absorbing pads between the vertebrae Bone or osseous tissue - has large amount of two types of matrix material – organic and inorganic matrix Fat cells collectively known as adipose tissue are modified for long-term energy storage and serve as insulations to help maintain body temperature, and function in cushioning against damage to body organs Blood is considered a connective tissue because it has a matrix • Muscle Tissues - the long, thin cells of muscle tissue contract (shorten) when stimulated, then relax passively 3 types that differ by the presence or absence of striations or bands, the number and location of nuclei, whether they are voluntary or involuntary, and their location within the body: 1. Skeletal muscle - under voluntary, or conscious control; main function is to move the skeleton, as occurs when you walk or turn the pages of a book 2. Cardiac muscle is located only in the heart; is spontaneously active and involuntary 3. Smooth muscle lacks the orderly arrangement of thick and thin filaments; is embedded in the walls of digestive tract, the uterus, the bladder, and large blood vessels; produces slow, sustained contractions that are mostly involuntary BIOL5 (Lecture) Tissues are the building blocks of organs – discrete structures that perform complex functions. BIOL5 (Lecture)
