BIOL231 Ch 1 FA2024 PDF

What is Cell Biology? Cell biology (also called cytology, from the Greek κυτος, kytos, "vessel") is a branch of biology that studies the structure, function and behavior of the cell, which is the basic unit of life. Cell biology is concerned with the physiological properties, metabolic processes, si...

What is Cell Biology? Cell biology (also called cytology, from the Greek κυτος, kytos, "vessel") is a branch of biology that studies the structure, function and behavior of the cell, which is the basic unit of life. Cell biology is concerned with the physiological properties, metabolic processes, signaling pathways, life cycle, chemical composition and interactions of the cell with their environment. This is done both on a microscopic and molecular level as it encompasses both prokaryotic and eukaryotic cells. Robert Hooke is known as a "Renaissance Man" of 17th century England for his work in the sciences, which covered areas such as astronomy, physics and biology. Hooke’s most important publication was Micrographia, a 1665 volume documenting experiments he had made with a microscope. In this groundbreaking study, he coined the term "cell" while discussing the structure of cork. He also described flies, feathers and snowflakes, and correctly identified fossils as remnants of once-living things.  In 1648, Antonie van Leeuwenhoek was apprenticed to a textile merchant, which is where he probably first encountered magnifying glasses, which were used in the textile trade to count thread densities for quality control purposes. In 1668, van Leeuwenhoek paid his first and only visit to London, where he probably saw a copy of Robert Hooke's 'Micrographia' (1665) which included pictures of textiles that would have been of interest to him. In 1673, van Leeuwenhoek reported his first scientific observations (bee mouthparts and stings, a human louse and a fungus) to the Royal Society. In 1676, van Leeuwenhoek observed water closely and was surprised to see tiny organisms - the first bacteria observed by man. As well as being the father of microbiology, van Leeuwenhoek laid the foundations of plant anatomy and became an expert on animal reproduction. He discovered blood cells and microscopic nematodes and studied the structure of wood and crystals. He also made over 500 microscopes to view specific objects. He also discovered sperm, which he considered one of the most important discoveries of his career, and described the spermatozoa from molluscs, fish, amphibians, birds and mammals, coming to the novel conclusion that fertilization occurred when the spermatozoa penetrated the egg. BBC - History - Historic Figures: Antonie van Leeuwenhoek (1632 - 1723)  Fast-forward 200 years… Matthias Schleiden was the first scientist to appreciate the importance of cells. All living organisms either consist of a single cell or are made up of cells, and organisms grow and reproduce by the division of cells. This fundamental tenet of biology is called the cell theory. It was first stated in 1838 in a book by Schleiden entitled Beiträge zur Phytogenesis (Contributions of phytogenesis). Schleiden based his conclusion on observations of plant tissues. Hooke had examined the dead tissues he found in cork, but Schleiden studied living cells and he saw that their contents moved within. In preparing his theory, Schleiden had consulted his friend the German physiologist Theodor Schwann and the following year, 1839, Schwann extended the cell theory to animals, in Mikroskopische Untersuchungen über die Übereinstimmung in der Struktur und dem Wachstum der Tiere und Pflanzen (Microscopical researches into the agreement between the structure and growth of animals and plants). Schleiden and Schwann are jointly credited with having originated the cell theory. Rudolf Virchow- Schwann had pushed biological science forward dramatically when he established that all animal tissues are made of cells. However, he made a major error when he said new cells are created from a fluid called blastema. Although incorrect, this was the accepted explanation for cell reproduction in the early 1850s. Scientists believed imbalances in the body created blastema in which disease cells start to grow. This belief began changing in 1855 when Virchow, aged 34, published an essay in which famously he declared his now famous aphorism: “omnis cellula e cellula” “Every cell arises from another cell.”  The three tenets to the cell theory are: 1.All living organisms are composed of one or more cells. 2.The cell is the basic unit of structure and organization in organisms. 3.Cells arise from pre-existing cells.  Original Classification of All Cells Prokaryotes - lacks a nucleus; most diverse and most numerous on earth Bacteria Archaea Eukaryotes - contains a nucleus Now use Three Domains 1. Bacteria 2. Archaea 3. Eukaryotes  Modern Classification Separates all Organisms into three Domains Fig 1-10 Typical Prokaryotic Cell Plasma membrane Cell Wall DNA – nucleoid Ribosomes Various shapes and sizes Flagella (sometimes) Fimbriae/pili  Domain: Bacteria most of the commonly encountered single-celled, non-nucleated organisms Examples include: Escherichia coli Streptococcus sp. Salmonella sp. Bacillus sp.  Domain: Archaea Often live in extreme habitats and have diverse metabolic strategies/still non-nucleated Examples: –methanogens - obtain energy from hydrogen and convert CO2 into methane –halophiles - occupy extremely salty environments –thermacidophiles – live in acidic hot springs  Domain: Eukarya Animals Plants Fungi Protozoa Algae Mostly larger than Can be prokaryotes, but still unicellular or small to maximize multicellular SA:VOL  Typical Eukaryotic Cell HW reminder (due on 30 August at 11:00pm): posted in Moodle, you should be able to: Identify the major membrane-bound organelles/cell structures and their functions Compare and contrast a plant and animal cell Compare and contrast a eukaryotic and prokaryotic cell Be able to relate the role of an organelle/cellular structure to the function of a cell  Chalk Talk!!! Let’s draw a generic eukaryotic cell, knowing that our drawing does not represent the variety of shapes and sizes throughout the Domain Eukarya