Chapter 1 Cell Theory Updated PDF

BIOFS 01 BIOLOGY CELL THEORY 1 2 3  What Is Life? Life is a complex phenomenon that can be challenging to define precisely Movement- movement from one place to another in itself is not diagnostic of life. Most plants and even some animals do not m...

BIOFS 01 BIOLOGY CELL THEORY 1 2 3  What Is Life? Life is a complex phenomenon that can be challenging to define precisely Movement- movement from one place to another in itself is not diagnostic of life. Most plants and even some animals do not move about, while numerous non-living objects, such as clouds, do move. Sensitivity-Not all stimuli produce responses, however. Imagine kicking a redwood tree or singing to a hibernating bear. This criterion, although superior to the first, is still inadequate to define life 4 Death- A car that breaks down has not died because it was never alive. Death is simply the loss of life, so this is a circular definition at best. Unless one can detect life, death is a meaningless concept, and hence a very inadequate criterion for defining life. Complexity- Even the simplest bacteria organized into many complex structures. A computer is also complex, but not alive. Complexity is a necessary criterion of life, but it is not sufficient in itself to identify living things because many complex things are not alive. 5  Fundamental Properties of Life Life is a complex phenomenon that encompasses various characteristics and processes. While movement ,death ,sensitivity and complexity is one aspect of life, it alone does not define life. Instead, life is often characterized by several key features, including: Cellular organization-Living organisms exhibit a high level of structural organization, with cells as the basic unit of life. Sensitivity. Living organisms respond to external stimuli, such as light, temperature, and touch, through various mechanisms, including movement, chemical reactions, and behavior. Cellular organization (150). These Paramecia, which are6 This father lion is responding to a stimulus: he has just been complex, single-celled organisms called protists, have just bitten on the rump by his cub. ingested several yeast cells.  Growth. : Living Organisms Engage In Metabolic Processes, Such As The Conversion Of Energy From One Form To Another And The Utilization Of Nutrients For Growth, Maintenance, And Reproduction. Development: Living Organisms Grow And Develop Over Time, Typically Increasing In Size And Complexity. Multicellular Organisms Undergo Systematic, Gene-directed Changes As They Grow And Mature, Involving Processes Such As Cell Division, Differentiation, And Tissue Specialization. 7  Reproduction: Living organisms can produce offspring, either sexually or asexually, ensuring the continuation of their species. DNA containing genes is passed along to an organism’s offspring. These genes are the reason that the offspring will belong to the same species and will have characteristics like the parent, such as fur color and blood type.  Regulation : Even the tiniest organisms need various regulatory mechanisms to manage internal functions, like nutrient transport, stimulus response, and dealing with environmental challenges. Organ systems such as the digestive or circulatory systems are examples; they perform tasks like distributing oxygen, eliminating waste, delivering nutrients, and regulating body temperature.  Homeostasis: Living organisms maintain internal stability despite changes in their external environment through processes like temperature regulation, pH balance, and nutrient balance. This is achieved through various regulatory mechanisms.  Primordial soup The primordial soup theory posits that the Earth's early atmosphere, rich in gases like methane, ammonia, hydrogen, and water vapor, combined with lightning strikes and ultraviolet radiation, led to the synthesis of organic molecules. These molecules, including amino acids and nucleotides, accumulated in the oceans, forming a "soup" from which life could have emerged. 11  Over time, these simple organic compounds underwent further chemical reactions, eventually giving rise to more complex molecules such as proteins, nucleic acids, and lipids, laying the groundwork for the development of early life forms. This theory suggests that the primordial soup provided the necessary chemical environment for the origin of life on Earth billions of years ago. Electric Spark and bubble hypothesis 13  Panspermia Panspermia is a hypothesis that suggests life exists throughout the universe and can be spread from one celestial body to another, including planets and moons, by natural means. It proposes that microbial life, or the building blocks of life, could travel through space within meteoroids, comets, or other interstellar debris, and eventually seed new environments with life upon impact. 14  This concept encompasses various scenarios, such as lithopanspermia (life transfer via rocks or meteoroids) and directed panspermia (deliberate seeding of life by advanced civilizations). Ongoing research in astrobiology and space exploration aims to investigate the plausibility of panspermia and its implications for the search for extraterrestrial life.  ASTEROID SAMPLES CONTAIN 'CLUES TO ORIGIN OF LIFE': JAPAN SCIENTISTS In one paper published Friday, a group of researchers led by Okayama University in western Japan said they had discovered "amino acids and other organic matter that could give clues to the origin of life on Earth".  RNA World Proposes RNA (ribonucleic acid) played a crucial role in the early evolution of life on Earth. RNA molecules served as both genetic material and catalysts for biochemical reactions. Unlike DNA, which is known for storing genetic information, RNA possesses both information- carrying capabilities and catalytic properties. Self-replicating RNA molecules could have arisen spontaneously in the primordial soup of early Earth, potentially facilitated by conditions such as ultraviolet radiation, lightning, and volcanic activity. These early RNA molecules could have replicated themselves and evolved over time, leading to the emergence of more complex RNA-based systems. 17  One of the key pieces of evidence supporting the RNA world hypothesis is that RNA molecules are capable of both storing genetic information (like DNA) and catalyzing chemical reactions (like proteins). This dual functionality suggests that RNA could have served as a transitional stage between simpler prebiotic chemistry and the more complex biochemistry found in modern organisms.  Community Clay It is theorized that in the early Earth's environment, clay minerals could have acted as templates or catalysts for the assembly of organic molecules, such as amino acids and nucleotides, which are the building blocks of proteins and nucleic acids, respectively. These organic molecules could have become concentrated and organized on the surfaces of clay minerals, potentially leading to the formation of more complex molecules and, eventually, the emergence of early life forms. 19  The fundamental Unit of life All organisms are made of cells The cell is the simplest collection of matter that can be alive. The average human being is composed of around 100 Trillion individual cells!!! It would take as many as 50 cells to cover the area of a dot on the letter “i” 20 ROBERT HOOKE BORN: JULY 18, 1635 DIED: MARCH 3, 1703 WROTE AND PUBLISHED “MICROGRAPHIA” KNOWN AS THE “ENGLISH FATHER OF MICROSCOPY” 21  DISCOVERY OF CELLS 1665- English Scientist, Robert Hooke, Discovered Cells While Looking At A Thin Slice Of Cork. He Described The Cells As Tiny Boxes Or A Honeycomb He Thought That Cells Only Existed In Plants And Fungi  ROBERT HOOKE - His Observations Led Him To Coin The Word “Cell.” - “Cell”- Means Little Rooms In Latin - He Compared The Small Boxes To The Small Rooms That Monks Lived In. 23 The story about Robert Hooke calling the structures he observed in cork "cells" because they reminded him of the cells that monks lived in is indeed a popular anecdote. However, there is some debate among historians about the accuracy of this account. While it is not possible to definitively confirm or refute the story, what is known is that Hooke's observations of cork cells were documented in his 1665 book "Micrographia," which played a significant role in the early understanding of cells and microscopy  ANTON VAN LEUWENHOEK 1673- Used A Handmade Microscope To Observe Pond Scum & Discovered Single-celled Organisms He Called Them “Animalcules” He Also Observed Blood Cells From Fish, Birds, Frogs, Dogs, And Humans Therefore, It Was Known That Cells Are Found In Animals As Well As Plants  ANTON VAN LEEUWENHOEK DISCOVERIES: - 1673: He Looked At Pond Scum Under The Microscope And Discovered Small Organisms He Called Animalcules Or Little Animals (Protists) http://www.kent.k12.wa.us/staff/TimLynch/sci_cla ss/chap09/lesson_protista/Protista_Lesson.html# Algae  DEVELOPMENT OF CELL THEORY 1838- German Botanist, Matthias Schleiden, Concluded That All Plant Parts Are Made Of Cells 1839- German Physiologist, Theodor Schwann, Who Was A Close Friend Of Schleiden, Stated That All Animal Tissues Are Composed Of Cells.  DEVELOPMENT OF CELL THEORY 1858- Rudolf Virchow, German Physician, After Extensive Study Of Cellular Pathology, Concluded That Cells Must Arise From Preexisting Cells.  « OMNIS CELLULA E CELLULA » REMAK & VIRCHOW (1858) NOTED THAT: “ALL CELLS COME FROM PRE-EXISTING CELLS” 30 Cell division  THE CELL THEORY MAJOR CONTRIBUTORS: MATTHIAS SCHLEIDEN THEODOR SCHWANN RUDOLPH VIRCHOW 31  THE CELL THEORY The 3 Basic Components Of The Cell Theory Were Now Complete: 1. All Organisms Are Composed Of One Or More Cells. (Schleiden & Schwann)(1838-39) 2. The Cell Is The Basic Unit Of Life In All Living Things. (Schleiden & Schwann)(1838-39) 3. All Cells Are Produced By The Division Of Preexisting Cells. (Virchow)(1858)  EXPLAIN: CELL DIVERSITY Cells Within The Same Organism Show Enormous Diversity In: Size Shape Internal Organization  1. CELL SIZE Female Egg - Largest Cell In The Human Body; Seen Without The Aid Of A Microscope Most Cells Are Visible Only With A Microscope.  CELLS ARE SMALL FOR 2 REASONS Reason 1: Limited In Size By The RATIO Between Their Outer Surface Area And Their Volume. A Small Cell Has More Surface Area Than A Large Cell For A Given Volume Of Cytoplasm. 36 ❖When The Size Of Cell Doubles: ❖Suraface Area INCREASES ❖Volume INCREASES ❖ SA:V DECREASED By Half ❖Cells Need To Be Small Because They Rely On Diffusion For Getting Substances In And Out Of Their Cells. ❖When A Cell Grows, There Is Comparatively Less Membrane (Due To Decreased Sa:v) ❖Diffusion Is Not Highly Rapid ❖Diffusion Is Not Efficient In Distributing Materials Over Long Distances  CELLS MAY INCREASE SA:V RATIO BY ❑ DIVIDE ❑ GET LONG AND THIN RATHER THAN ROUND AND FLAT (EX: NERVE CELLS) ❑ FOLDS IN CELL MEMBRANE (EX: MICROVILLI OF INTESTINAL EPITHELIAL CELLS)  CELLS ARE SMALL Reason 2: The Cell's Nucleus (The Brain) Can Only Control A Certain Amount Of Living, Active Cytoplasm.  2. CELL SHAPE DIVERSITY OF FORM REFLECTS A DIVERSITY OF FUNCTION. THE SHAPE OF A CELL DEPENDS ON ITS FUNCTION. 3. Internal Organization Cell membrane Cytoplasm Prokaryotic Cell Cell membrane Cytoplasm Eukaryotic Cell Nucleus Organelles  MICROSCOPY MICROSCOPES ARE USED TO SEE CELLS BECAUSE THEY ARE VERY SMALL. THERE ARE TWO TYPES OF MICROSCOPES. SIMPLE MICROSCOPE--ONE LENS LIKE A MAGNIFIER. COMPOUND MICROSCOPE/LIGHT MICROSCOPE--TWO LENSES WORKING IN SERIES TO MAKE A MAGNIFIED IMAGE OF THE SPECIMEN.  IMAGING TECHNIQUES Lowest Resolvable Approx Lower Technique Image Formed By Unit Limit 1 μm Optical Microscopy Light Rays Microns (μm) (monochromatic light) Coherent Light Source.1 μm Confocal Microscopy Microns (μm) (Laser) (X-Y Direction) Transmission Electron Microscopy 2Ǻ Electrons Angstroms (Ǻ) (TEM) (high resolution TEM) Scanning Electron Nanometers (nm) to 10 nm Electrons (100 Ǻ) Microscopy (SEM) Angstroms (Ǻ) Atomic Force & Scanning Tunneling Molecular Mechanical 40 Ǻ Microscopies Angstroms (Ǻ) (AFM/STM) Probes (theoretical) THE LIGHT MICROSCOPE AND THE Compound light microscope Transmission electron microscope  THE LIGHT MICROSCOP WHEN VIEWED WITH THE LIGHT MICROSCOPE, ONLY THE NUCLEUS AND CYTOPLASM ARE VISIBLE DYES AND SIMPLE STAINING MAKE INTERNAL AND EXTERNAL STRUCTURES OF CELL MORE VISIBLE BY INCREASING CONTRAST WITH BACKGROUND. THE LIMIT OF RESOLUTION FOR A LIGHT MICROSCOPE IS 200 NM. TOTAL MAGNIFICATION IS PRODUCT OF THE MAGNIFICATION OF ITS OCULAR AND ITS OBJECTIVE LENSES.  OPTICAL MICROSCOPE 1. OCULAR LENS 2. OBJECTIVE TURRET 3. OBJECTIVE LENS 4. COARSE ADJUSTMENT 5. FINE ADJUSTMENT 6. STAGE 7. LIGHT SOURCE 8. CONDENSER 9. X-Y CONTROL COMPOUND LIGHT PHASE CONTRAST LIVE DEAD ASSAY CONFOCAL IMAGE OF SCHWANN CELLS GUESS WHO  ELECTRON MICROSCOPE ELECTRON MICROSCOPES HAVE FAR GREATER RESOLVING POWER THAN LIGHT MICROSCOPES, WITH LIMITS OF RESOLUTION OF ABOUT 0.2 NM TWO MAJOR TYPES OF ELECTRON MICROSCOPES: SCANNING ELECTRON MICROSCOPY (SEM) FOR 3-D IMAGING AND EXAMINING SURFACES TRANSMISSION ELECTRON MICROSCOPY (TEM) FOR OBSERVING INTERNAL CELL STRUCTURE DOWN TO THE MOLECULAR LEVEL WITH THE ELECTRON MICROSCOPE, MANY MORE FINE DETAILS ARE VISIBLE. THESE ARE REFERRED TO AS ULTRASTRUCTURE. Guess Who? 53 54 Guess Who? 55 56 Guess Who? 57 58 59  TRANSMISSION LIGHT MICROSCOPE ELECTRON MICROSCOPE Small and potable Very large and must be operated in special rooms Living and dead material can be Only dead material can be observed observed Preparation of material is simple, Preparation of material is requires only little expertise lengthy and requires considerable expertise Cheap Expensive Magnifies objects up to 1500x Magnifies objects more than 500 only 000x Low resolution High resolution  SEM TEM Studying surface structures of Studying internal structures of cells cells & its components Specimen can be thicker Specimen must be very thin 3-D image 2-D image Resolution : 5-20 nm Resolution : 0.2 nm *(some models 0.5 nm)