BIO 101 General Biology I Lecture Brief PDF

Adeyemi A., Olaomi Department of Biology, FULokoja LECTURE BRIEF ON BIO101: GENERAL BIOLOGY I (2CUs)...

Adeyemi A., Olaomi Department of Biology, FULokoja LECTURE BRIEF ON BIO101: GENERAL BIOLOGY I (2CUs) DEPARTMENT OF BIOLOGY FACULTY OF SCIENCE FEDERAL UNIVERSITY LOKOJA BIO 101: General Biology (I) Lecture Brief pg. i Adeyemi A., Olaomi Department of Biology, FULokoja Course Aspect  General Reproduction  Hereditary and Evolution  Mendelian Laws  Darwinism  Lamarck’s Theory  Key Genetic Terms GENERAL REPRODUCTION Reproduction is the process by which living organisms give rise to offspring, ensuring the continuation of their species. I. Reproduction in Plants Reproduction in plant is the process by which the plant gives rise to new members of their species. This process ensures the continuity of life. Reproduction in plants occurs either by sexual or asexual forms. A. Sexual Reproduction in Plants In sexual reproduction, progeny or offspring are produced as a result of the fusion of two haploid cells called gametes produced from two organisms (male and female). Gametes are produced by meiosis and when they fuse, they produce a diploid zygote. The union of gametes is generally referred to as Syngamy and the process is called Fertilization. Considering sexual reproduction in flowering plants, the reproductive organs are situated in the flowers. The flower is a specialized shoot of limited growth. A typical flower develops on a receptacle which is the flattened top of the flower stalk or pedicel. The floral parts of the flower are arranged in whorls. The floral parts of the flower are arranged in whorls. These are: a. Calyx (sepals): it covers and protects inner whorls during bud stage. b. Corolla (petals): It is the brightly coloured parts for the attraction of pollinators. c. Adroecium (stamen): male organ of flower consisting of stalk (filament) and a head (anther), pollen grains. d. Gynoecium (pistil): female organ which consists of style, stigma, ovary and ovule. *N.B: Inside the ovary are the ovules. Each ovule contains an egg cell. B. Asexual Reproduction in Plants Asexual reproduction does not involve gametes, nor the participation of two organisms. One parent gives rise to the progeny or offspring. This is common in plants. It is accomplished in various ways such as fission, fragmentation, spore formation, and vegetative propagation. 1. Spore formation: Spores are unicellular bodies formed by cell division in a parent organism. When dispersed, they germinate either directly or indirectly under favourable conditions into new individuals. Spores have thick resistant walls which enable them to survive unfavourable conditions. Fungi are well noted for the production of a vast number of air borne spores and this explains why they spread very rapidly on substrates. BIO 101: General Biology (I) Lecture Brief pg. 2 Adeyemi A., Olaomi Department of Biology, FULokoja 2. Fission: In this process the organism divides into two (binary fission) or more (multiple fission) equal sized parts. Binary fission is the characteristics of bacteria. 3. Vegetative propagation: This is when parts of the body of plants become detached and develop into new self-supporting individual. Detached stems and even leaves produce roots and grow into new individuals. For example, the use of Rhizomes (horizontal underground stems) in propagating plants such as spear grass, ginger, carpet grass etc,detached leaves of Begonia sp and Bryophilum sp can also produce roots that grows into new plants and cassava stem cutting are all examples of vegetative reproduction. 4. Fragmentation:Sometimes an organism may be broken into two or more pieces and each fragment regenerates into new individual. Fragmentation is common in filamentous algae. Fungi also reproduced by fragmentation of the hyphae. II. Reproduction in Animals Some animals produce offspring through asexual reproduction while other animals produce offspring through sexual reproduction. Both methods have advantages and disadvantages. A. Asexual Reproduction in Animals This occurs in many eukaryotic, single-celled and multi-celled organisms. The advantages of asexual reproduction are that it produces offspring that are genetically identical to the parent and a single individual can produce offspring asexually and large numbers of offspring can be produced quickly. This method of reproduction includes; i. Fission/Binary Fission:This occurs in some invertebrate, multi- cellular organisms. It refers to the process where an organism reproduce by splitting itself into two parts and regenerate the missing parts of each new organism. These are found in some species of flatworms commonly called the Planarians (Flatworms). They are able to separate their bodies into head and tail regions and then regenerate the missing half in each of the two new organisms. Figure 1: A Representation of Fission/Binary Fission ii. Budding: This is a form of asexual reproduction that results from the outgrowth of a part of the body leading to a separation of the “bud” from the original organism and the formation of two individuals, one smaller than the other. Budding occurs commonly in some invertebrate animals such as Hydras and Corals. In Hydra, the bud develops into an adult and breaks away from the main body. BIO 101: General Biology (I) Lecture Brief pg. 3 Adeyemi A., Olaomi Department of Biology, FULokoja Figure 2: A Representation of Budding in Hydra iii. Fragmentation: This is the breaking of an organism into parts followed by regeneration. If the animal is capable of fragmentation, and the parts are big enough, a separate individual will regrow from each part. Fragmentation may occur through accidental damage, damage from predators, or as a natural form of reproduction. Reproduction through fragmentation is observed in Sponges and Echinoderms. In some sea stars, a new individual can be regenerated from a broken arm and a piece of the central disc. iv. Parthenogenesis:This is a form of asexual reproduction in which an egg develops into an individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process in the species. Parthenogenesis occurs in invertebrates such as water fleas, aphids, stick insects, ants, wasps, and bees. Ants, bees, and wasps use parthenogenesis to produce haploid males (drones).Some vertebrate animals such as certain reptiles, amphibians, and fish also reproduce through parthenogenesis. B. Sexual Reproduction in Animals This is a biological process that creates a new organism by combining the genetic materials of two organisms in a process that starts with meiosis, a specialized type of cell division. Each of two parent organisms contributes half of the offspring's genetic makeup by creating haploid gametes. Sexual reproduction involves a complex life cycle in which diploid mother cells divide to produce haploid cells known as gametes in a process called meiosis. Sexual reproduction usually involves the fusion of a sperm and an egg is a process called Fertilization. This fertilization can occur either inside (internal fertilization) or outside (external fertilization). i. External fertilization mostly occurs in aquatic environments where both eggs and sperm are released into the water. After the sperm reaches the egg, fertilization takes place. ii. Internal fertilization occurs most often in terrestrial animals, although some aquatic animals also use this method. Internal fertilization may occur by the male directly depositing sperm in the female during mating. It may also occur by the male depositing sperm in the environment, usually in a protective structure, which a female picks up to deposit the sperm in her reproductive tract. Following internal fertilization, There are three ways offspring are produced BIO 101: General Biology (I) Lecture Brief pg. 4 Adeyemi A., Olaomi Department of Biology, FULokoja i. Oviparous: this occurs were the fertilized egg is laid outside the female body,usually enclosed in a hard shell.This type of reproduction is seen in all birds, some bony fishes, reptiles, amphibians and and few mammals (platypus and echidna). ii. Ovoviparous: here, the fertilized eggs are retained in the female’s body until they hatch inside of her, or she lays the eggs right before they hatch. This process helps protect the eggs until hatching. This occurs in sharks, lizards, snakes and some invertebrate animals (Madagascar hissing cockroach) iii. Viviparous: in viviparity,the young are usually born alive. They obtain their nourishment from the female mammary gland and are born in varying states of maturity. This occurs in most mammals, some cartilaginous fish, and a few reptiles. HEREDITARY AND EVOLUTION A. HEREDITARY This is the study of mechanisms of transmission of characters from parents to offspring i.e., how characteristics are passed from generations to generations. Hereditary is defined as the transmission and expression of characteristics or traits in an organism from parents to offspring. The basic of hereditary is referred to as Chromosome It is only those traits that constitute the genetic makeup of the parents that can be transmitted and expressed in the offspring. These traits include colour of the skin, colour of eyes, colour of the hairs and hair texture, size of body stature, shape of the head , shape of the ears, shape of the month, lips, shape of the nose, length of the hands and legs, length of neck , Blood grouping, baldness, tongue rolling, while transmissible in plants include; colour and shape of the leaves, shoot , seed size and shape, colour of the flowers, size of the fruit and pigmentation. Mendelian Laws of Genetics Gregor Mendel (1822 - 1884), a Monk in Austria who is referred to as Father of Genetics because of his work which formed the foundation for scientific study of heredity and variation. Mendel carried out several experiment on how hereditary characters were being transmitted from generation to generation. He worked with Garden Pea (Pisum sativum). Reasons for using the pea are follows; i. Peas are usually self-pollinating and he could pollinate them by himself ii. They have a very short life span than animals and some other plants In Mendel’s early experiments, he crossed pure bred short plant with a pure bred tall plant. All the seeds resulting from this cross produced tall plants when sown. This implied that the short character have been overshadowed or suppressed by the tall character of the tall plants. The overriding character (tall character) is said to be Dominant over the short character whose influence has been suppressed and which is said to be Recessive. Mendel called these plants resulting from a cross between pure bred tall and short plants first Filial Generation (F1). BIO 101: General Biology (I) Lecture Brief pg. 5 Adeyemi A., Olaomi Department of Biology, FULokoja Tall short To get 2nd filial generation (F2) TT x tt parent plant Tt x tt parent plant T T t t gametes T T t t Tt Tt Tt Tt F1 TT Tt Tt tt (All tall plants) (3 tall : 1 short ) To get 3rd filial generation (F3) 1. TT x tt = all tall plants (bred true 2. Tt x tt = all short plants (bred true) 3. Tt x Tt = this will produce the same as indicated in the cross to get F2 generation The discoveries of Mendel provided two fundamental laws (the law of segregation of genes and the law of independent assortment of genes) on which the modern theory of heredity is based. 1. First law Law of segregation states that “genes are responsible for the development of individual and that they are independently transmitted from one generation to another without undergoing any alteration”. 2. Second Law Law of independence assortment states that “when more than one factor are considered, each character behaves as a separate unit and is inherited independently of any other character”. B. EVOLUTION This refers to the series of gradual changes which living organisms had undergone in response to changes in the environment since the beginning of life. The theory of evolution gradually came to be accepted in the decades following the publications of Charles Darwin on “The Origin of Species” in 1858 where he assembled a great mass of evidence in support of the theory and also suggested the mechanism by which evolution might occur. Lamarck’s Theory of Evolution Jean Baptist Lamarck, a French biologist was the first to put forward the theory of evolution in 1801. His idea of evolution was based on the following theories; BIO 101: General Biology (I) Lecture Brief pg. 6 Adeyemi A., Olaomi Department of Biology, FULokoja 1. The Theory of Need This theory states that “the development of a new part or organ by an organism (plant or animal) result from the need of part or organ to the organism”. For instance, the early ancestors of snake had short bodies and legs. As the land was changing during its formation, many narrow places and dense vegetation, were formed, and for snakes to walk through narrow places and dense vegetation, they started stretching their bodies to become elongated so that they could easily crawl through the vegetation instead of walking. The theory emphasized that organs become well developed and achieve, become functionless or disappeared with disuse. For instance, each generation of snakes continue to stretch their bodies resulting in the strengthening of their bodies. Their legs then became useless and finally disappeared since they would hinder crawling through narrow places and dense vegetation. 2. Theory of Acquired Characterizes of Inheritance The theory states that “Structures or variation acquired by organism during their life time are transmitted to the next generation by inheritance”. For instance, the modern giraffe believed to have evolved from a giraffe with short neck and short legs. When competition for low grasses among herbivorous animal happened, the short neck and short legged giraffe started to starch their neck and legs so as to reach the leave of the trees. The duck originally had no webs between their toes, but as they continue frequently visiting water for food therefore the need to develop webs for swimming become a necessity and thus pass it on to their offspring. Darwin’s Theory of Evolution (Theory of Natural Selection) Charlie‟s Darwin, a British biologist in 1859 propounded a theory of organic devolution by natural selection leading to the origin of species. His theory of natural selection is as follows: a. All living organisms should be allowed to produce more offspring than can survive b. Struggle for existence: Due to overpopulation of offspring, there is a constant competition for existence among offspring c. Offspring shows variation: No two individual are exactly the same d. Adaptive characteristics: Some of the offspring‟s are well adapted or fitted to survive the competition than others e. Inheritance of adaptive characteristics: The well adapted ones or the fittest will transmit such variation to their offspring‟s. Those with poor adaptation will die off (extinct) f. Development of new species: An accumulation of favourable variation will in a long time head a divergence (spread) from the original stock resulting in the formation of new species BIO 101: General Biology (I) Lecture Brief pg. 7 Adeyemi A., Olaomi Department of Biology, FULokoja KEY GENETIC TERMINOLOGIES 1. Gene This is defined as the physical unit of inheritance transmitted from generation to another and responsible for controlling the development of characters in the new organisms. 2. Chromosomes These are strands of genetic materials which are recognizable during cell division. They are found in the nucleus where they carry the genes. They contain of DNA (deoxyribonucleic acid) and protein. 3. Character or Trait These are inheritable attributes or features possessed by an organism‟s height or size. 4. Phenotype Is the sum total of all observable features of an organisms that is the physical, physiological and behavioral traits e.g., height, weight, skin colour 5. Genotype The term in used to describe those traits or sum total of the genes inherited from both parent or in order word, it is the genetic makeup or constitution of an individual. Genotype includes both the dominant and the recessive traits that form the genetic makeup of an individual. 6. Dominant Charater This is a trait that is expressed in an offspring when two individual with contrasting characters are crossed. 7. Recessive Character This is the trait from one parent which is masked or does not produce its effect in the presence of dominant gene or character. 8. Homozygous This is an individual with identical alleles in respect of a particular trait or character (TT or tt). 9. Heterozygous This is an individual with two different alleles in respect of a particular trait or character (Tt or Rr). 10. Hybrid This is an offspring from a cross between parents that are generically different parents but of the same species. 11. Locus This is the site for location of gene in a chromosome. 12. Haplold This is when an organism has one set of chromosomes in the reproductive cell, it is represented by (n). 13. Diploid This is when an organism has two sets of chromosomes in the body cell. The bodies of animals and plants are diploid. Diploid number is represented by (2n). 14. Mutation This is a change in the genetic makeup of an organism that resulting in a new characteristic that is inheritable. BIO 101: General Biology (I) Lecture Brief pg. 8