Introduction To Biology - PDF

Science of Life: Introduction to Biology Cell: The Basic Unit of Life What is Biology? The word biology is derived from the greek words /bios/ meaning /life/ and /logos/ meaning /study/ and is defined as the science of life and living organisms and their interactions with one anot...

Science of Life: Introduction to Biology Cell: The Basic Unit of Life What is Biology? The word biology is derived from the greek words /bios/ meaning /life/ and /logos/ meaning /study/ and is defined as the science of life and living organisms and their interactions with one another and their environment.  Biology is a natural science discipline that studies living things. Life refers to the properties and conditions which distinguish a plant and animal from inorganic matter or dead organism. Life is what animals and plants have. A scientific process- is a process which deals to solve problems and create accurate data through experiments and investigation. Scientific inquiry- involves a set of intellectual skills that are associated with acquiring reliable information. Branches of Biology and its Meaning: The following are the various branches of biology: Botany is the study of plants. Zoology is the study of animals. Anatomy is the study of internal structures of living things. Biochemistry is the use of chemistry in the study of living things. Biological Earth Science is the use of earth sciences, such as geography in the study of living things.  Cell: The Basic Unit of Life The cell is the basic unit of life. All living things are made of one or more cells. Living things that are made up of one cell only, such as bacteria and protozoa, are called unicellular organisms, whereas those are made up of many cells, such ass plants and animals are called multicellular organisms. The Invention of the Microscope and Discovery of the Cell DISCOVERY OF THE CELL Organisms which are visibly seen can be seen only in microscopic techniques are made of cells. A cell is the smallest and basic unit that can carry out all activities needed for life. The Invention of the Microscope Around 1595, the first compound microscope was invented by Zacharias Janssen (1580- 1638). It is believed that Zacharias probably had help from his father, Hans, because he was still young that time. They made these microscopes by placing several lenses together, and discovered that objects were further enlarged upon viewing. The Invention of the Microscope Every major field of science has benefited from the use of some form of microscope, an invention that dates back to the late 16th century and a modest Dutch eyeglass maker named Zacharias Janssen. The Invention of the Microscope and Interested in learning more about the microscopic world, scientist Robert Hooke improved the design of the existing compound microscope in 1665. His microscope used three lenses and a stage light, which illuminated and enlarged the specimens. The Invention of the Microscope The invention of the microscope led to the discovery of the cell by Hooke. While looking at cork, Hooke observed box-shaped structures, which he called “cells” as they reminded him of the cells, or rooms, in monasteries. The Invention of the Microscope Anton van Leeuwenhoek (1632-1723) created a microscope with a much higher magnification than the microscope that Hooke used. Leeuwenhoek used his microscope to observe specimens such as bacteria, blood cells and protists. Antonie van Leeuwenhoek used single-lens microscopes, which he made, to make the first observations of bacteria and protozoa. The Invention of the Microscope and Discovery of the Cell Leeuwenhoek is universally acknowledged as the father of microbiology. He discovered both protists and bacteria. More than being the first to see this unimagined world of 'animalcules', he was the first even to think of looking—certainly, the first with the power to see. The Invention of the Microscope and Discovery of the Cell He is commonly known as "the Father of Microbiology", and one of the first microscopists and microbiologists.Van Leeuwenhoek is best known for his pioneering work in microscopy and for his contributions toward the establishment of microbiology as a scientific discipline.  FAMOUS BIOLOGISTS AND THEIR CONTRIBUTIONS The Invention of the Microscope and Discovery of the Cell BIOLOGIST YEAR STUDY Robert Hooke- 1635- First to use a microscope to English 1703 observe cork and coined what he observed as cells. Was responsible for the beginnings of cytology as a subdivision of Biology Anton van 1632- Discovered bacteria and other Leeuwenhoek – 1723 microscopic organisms in Dutch rainwater and studied the structure of plant and animal cells. FAMOUS BIOLOGISTS AND THEIR CONTRIBUTIONS The Invention of the Microscope and Discovery of the Cell Jean-Baptiste-Pierre-Antoine 1744-1829 Proposed that cells are de Monet French filled with fluids Francesco Redi and Lazzaro 1627-1697 Disproved the Spallanzani 1729-1799 Spontaneous Italian Generation Theory Henri Dutrochet- French 1776-1847 Proposed that cell is the fundamental unit of living organisms Proposed that all living things are made up of cells  The Invention of the Microscope and Discovery of the Cell Felix Dujardin 180-1860 Noted that all living things French contain a thick jelly fluid which he called sarcode (substance inside the cell0 at that time Recognized that one celled organisms are in existence. Matthias Jakob Schleiden and 1804-1881 Introduced the concept that Theodor Schwann 1810-1882 all plants and animals are German botanist and zoologists made up of cells.  FAMOUS BIOLOGISTS AND THEIR CONTRIBUTIONS The Invention of the Microscope and Discovery of the Cell Henri Dutrochet 1776-1847 In 1832, Dutrochet showed that gas French exchange in plants was via minute openings (stomata) on the surface of leaves and the deep cavities with which they communicate. He further demonstrated that only cells containing chlorophyll can fix carbon and thus transform light energy into chemical energy. Robert Brown- 1773-1858 Discovered the presence of nuclei within Scottish cells Describe nucleus as small dense, round body inside the cells  The Invention of the Microscope and Discovery of the Cell Max Schultze 1825- Use the term protoplasm to show that this German 1847 material Is found in all types of organisms, making the protoplasm as the physical basis of life. Rudolf Virchow 1821- Found that cells divide to form new cells and German 1902 concluded that cells come from pre-existing cells Formulated the cell theory Louis Pasteur 1882- Supplied the proof for Virchow’s theory of French Chemist 1895 biogenesis James Watson and 1928- Built model for the structure of DNA Francis Crick 1916- American British 2004 Cell Theory cell theory, fundamental scientific theory of biology according to which cells are held to be the basic units of all living tissues. First proposed by German scientists Theodor Schwann and Matthias Jakob Schleiden in 1838, the theory that all plants and animals are made up of cells marked a great conceptual advance in biology and resulted in renewed attention to the living processes that go on in cells. The Cell Theory The idea that we are all made up of cells is called “The Cell Theory“ How did the Cell Theory form? In 1665, English scientist Robert Hooke was the first of mankind to discover cells. 1830, two botanists named Theodor Schwann and Matthias Schleiden were the first scientists to propose the Cell Theory-based off on Hooke’s essential discovery Rudolf Virchow expanded on the idea of the Cell Theory and contributed to the fundamental concepts we have today. Assumptions of the cell theory: Cell is the fundamental unit of life in all living things. All living things are composed of one or more cells. Cells arise from pre-existing cells The idea of the cell theory are still accepted up today and viewed as very important discoveries in the study of biology. Prokaryotic and Eukaryotic Cells Prokaryotic and Eukaryotic Cells Cell types. Cells are of two types: eukaryotic, which contain a nucleus, and prokaryotic cells, which do not have a nucleus, but a nucleoid region is still present. Prokaryotes are single- celled organisms, while eukaryotes may be either single-celled or multicellular.  CHARACTERISTICS PROKARYOTES EUKARYOTES 1. Organisms Bacteria and cyanobacteria Protist(algae, amoeba) fungi (yeast, molds), plants and animals 2. Nuclear Membrane absent present 3. DNA Loop of DNA in the cytoplasm Thin, very long DNA organized into chromosomes in the nucleus 4. RNA and protein Both synthesized in the same RNA is synthesized in the compartment nucleus while protein is synthesized in the cytoplasm 5. Cytoplasm No cytoskeleton, very few Cytoskeleton present, may organelles present organelle present 6. Cellular organization Mainly unicellular multicellular  Types of Cells Plant cell are eukaryotic cells. The DNA in a plant cell is enclosed within the nucleus. The most important distinctive structure of plant cell is the presence of the cell wall outside the cell membrane. Animal Cell Structure In general, animal cells are smaller than plant cells. Its uneven form is another distinguishing feature. This results from the lack of a cell wall. However, because both plant and animal cells descended from eukaryotic cells, they share some cellular organelles.  Distinctive Features of Plant Cell The features that are distinctive in plant cells are as follows: Cell wall provide plant cells rigidity and structural support and cell to cell interaction. The outermost rigid covering of the plant cell. It is a salient feature of plant cell. Cell membrane or the plasma membrane is the outer lining of the cell inside the cell wall.  The features that are distinctive in plant cells are as follows: Plastids help in storage of plant products. - Chloroplasts aid in carrying out the process of photosynthesis to produce food for the plants. -Vacuoles are water-filled, membrane bound organelles which stores useful materials.  Cytosol or cytoplasm is the gel-like matrix inside the cell membrane which constitutes all other cell organelles. Nucleus is the control center of the cell. It is a membrane bound structure which contains the hereditary material of the cell - the DNA Chloroplast is a plastid with green pigment chlorophyll. It traps light energy and converts it to chemical energy by the process of photosynthesis.  Mitochondria carries out cellular respiration and provides energy to the cells. Golgi body is the unit where proteins are sorted and packed. Ribosome's are structures that assemble proteins. Endoplasmic reticulum are membrane covered organelles that transport materials  Parts of Animal Cell Animal cell contains membrane bound nucleus, it also contains other membrane bound cellular organelles. These cellular organelles carry out specific functions that are necessary for the normal functioning of the cell. Animal cells lack cell wall, a large vacuole and plastids. Due to the lack of the cell wall, the shape and size of the animal cells are mostly irregular. The constituents of animal cells are structures like centrioles, cilia and flagella and lysosomes. Parts of Animal Cell Cell membrane - forms the outer covering of the cell, and is semi- permeable. Cytoplasm - is a gel-like matrix where all the other cell organelles are suspended inside the cell. Nucleus - contains the hereditary material DNA and directs the activities of the cell. Centrioles - organize the microtubules assembly during cell division. Endoplasmic Reticulum - are a network of membranes composed of rough and smooth endoplasmic reticulum. Golgi complex - is responsible for storing, packaging of cellular products. Lysosomes - are enzyme sacs, that digest cellular wastes. Parts of Animal Cell Microtubules - are hollow rods, function primarily as support and shape to the cell. Mitochondria - is the site for cellular respiration and producers of energy. Ribosomes - are made of RNA and proteins, and are sites for protein synthesis. Nucleolus - is the structure within the nucleus and helps in synthesis of ribosomes. Nucleopore - is the tiny hole in the nuclear membrane, allows the movement of nucleic acids and proteins in/out of the cell.