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BIOLOGY 985 Lecture 1: Properties of Life, Biological Classification & Homeostasis Chapter 1  Read the COURSE OUTLINE course outline course outline course outline course outline...

BIOLOGY 985 Lecture 1: Properties of Life, Biological Classification & Homeostasis Chapter 1  Read the COURSE OUTLINE course outline course outline course outline course outline COURSE OUTLINE  Biology from the Greek word “bio” meaning “life” and the suffix “ology” meaning “study of” A job of biologists is to classify all these different organisms. For example: o There are many different types of animals in the world, and these species can be divided into categories of mammals, reptiles, amphibians, fish, invertebrates, and birds. 86% of all the land species & 91% of all sea species have not been discovered yet! (Mora et al 2011; https://doi.org/10.1371/journal.pbio.1001127) Biological Classification o There are millions of different species on the planet. o Biologists group organisms based in characteristics they share o Biologists classify living things into 3 large groups called DOMAINS: (1) Bacteria, (2) Archaea (3) Eukarya 3 Domain System - Bacteria & Archaea contain organisms with prokaryotic cells (nucleus absent) - Domain Eukarya contain organisms with eukaryotic cells (have a nucleus) 3 Domains of Life: 2 Prokaryotic & 1 Eukaryotic Domain No nucleus a  Binomial System Every living organism has a unique genus & species name The binomial naming system is the system used to name species. Each species is given a name that consists of two parts. The first part is the Genus to which the species belongs, and the second part is the species name. Example: Kingdom Animalia – contains all of the animals – many different kinds of animals – some similar to each other most are not Domain? Choice of 3 Kingdom?  Taxonomic Classification; examples: Kingdom Animalia: jaguar & human Domain Eukarya Each kind of organism has a unique name In this system, each organism gets two Latin names, a genus and a species name. No other organism has it Domain Genus species: Escherichia coli Human: Homo sapiens  Biology is the study of life What is Considered to be ”Alive”? LIVING NON-LIVING LIVING  Properties of Life Have you ever tried to define ‘life’? …or thought about what makes something alive? When asked this question for the first time, many people will say that living things need to ‘breathe’. While this is true for humans and many animals, the act of ‘breathing’ is not performed by the majority living organisms on the planet (e.g. plants, bacteria, fungi)… at least, not in the sense that we think of “breathing” as humans. The characteristics that currently define all living things (i.e. the ‘properties of life’) are summarized by the list below. All Organisms: 1. are composed of cells 2. require energy & process it (Metabolism) 3. grow & develop 4. Respond to environment 5. Reproduce 6. Evolve & Adapt 7. perform homeostasis  1) Organisms are composed of Cells Whether an organism consists of a single cell (unicellular) or many cells (multicellular), all living organisms are composed of at least one cell. The structural components that make up a cell (molecules/organelles) cannot survive outside the context of a cell. Therefore, the cell is the smallest unit capable of sustaining life. Multicellular organisms Single-celled organisms Most organisms that we are most familiar Bacteria are the most with are multicellular ones. The number numerous unicellular of cells of an organism can range from a organisms on the planet. few thousand to trillions of cells! (an average human adult contains ~37.2 trillion cells)  2) Metabolism: Ability to process energy Cells require a constant input of energy in order to carry out the chemical reactions they require to stay alive. Humans, as with many other animals, extract chemical energy from the food molecules that we eat. Metabolism is the term we use to refer to all chemical reactions occurring in the body’s cells to process energy (change food into energy that the cell can use) For example, when a cell breaks down a molecule Cell/Body Maintenance of glucose (from the food that you ate), it can & Work transfer the energy in the chemical bonds of the glucose molecule to create another molecule called Adenosine Triphosphate (“ATP”, for short). The body’s cells then directly use the ATP to build other molecules (e.g. a protein) and to perform specific tasks (e.g. muscle fiber contraction).  3) Organisms Grow & Develop Growth All organisms grow, particularly in the early stages of life. Growth simply means that an organism increases in size. Growth can result from an increase in the number of cells (multicellular organisms) and/or an increase in cell size. Development Changes that take place Start as a fertilized egg that must grow and develop to form specialized structures  4) Response to the Environment Organisms respond to physical and/or chemical changes to their external or internal environment examples: organisms respond to: - odor - temperature - light  5) Organisms Reproduce organisms come from previously existing organisms All organisms reproduce sexually and/or asexually. Ex: Bacterial cell Asexual reproduction involves the creation of another organism from the genetic information of a single parent. o This type of reproduction is typical of unicellular organisms (e.g. bacteria) By contrast, sexual reproduction involves the creation of another organism from the genetic information of two parents. o Humans and many other types of organisms use sexual reproduction to propagate the species.  6) Evolutionary Adaptation camouflage The ability to change in response to the environment Evolution Living species are descendants of ancestral species that were different from the present-day ones. From generation-to-generation species change (sometimes a little, sometimes a lot). Mimicry More details on this in a later lecture….  7) Organisms Perform Homeostasis The term homeostasis is a term that means “staying the same”. An organism maintains homeostasis by keeping certain specific internal conditions (e.g., body temperature) within preset limits. For example, the body core temperature of a healthy human adult is between 36-37.5oC despite larger T fluctuations of their surroundings. As soon as body temperature reaches either the upper or lower limit of this range, the body will respond by keeping it within this Thermoregulation is a homeostatic process that maintains a steady internal body narrow range by either shivering or temperature (even if external conditions are sweating. very different)  8 functions that HUMANS must perform to MAINTAIN LIFE Focus on homo sapiens (humans) Responsiveness Movement 8 Processed the body must do to keep you alive: 1) Growth 2) Reproduction 3) Responsiveness: ability to sense changes in the environment Growth 4) Movement 5) Metabolism: all chemical reactions Digestion that occur in body 6) Maintain boundaries 7) Digestion: breakdown ingested food 8) Excretion: removal of wastes Maintain boundaries  To maintain Life Humans have specific Survival Needs o Oxygen: needed to make ATP o Why is ATP essential to stay alive? o Water: provides necessary environment for chemical reactions o Nutrients: chemical substances used for energy and cell budling o Normal Body Temperature: necessary for chemical reactions to occur at life sustaining rates FOOD / + nutrients + Homeostasis To function properly, the cells, organs, organ systems (and therefore, your entire body) need things to be just right! For instance: Temperature O2 or CO2 concentration Homeostasis: The capacity to maintain a stable, relatively constant internal environment no matter external or internal changes. Homeostasis is maintained through dynamic equilibrium. o All systems collaborate to maintain homeostasis; however, the nervous & endocrine systems contribute most through electrical & chemical communication. o Homeostasis = health. Homeostasis ability to maintain internal stability in an organism in response to the environmental changes Variables within the body (e.g., body tº, pH levels, blood pressure) are maintained within a narrow range even if there are large variations in external environment.  The Elements of a Homeostatic Mechanism Maintaining homeostasis requires continuously assessing the status of variables & reacting accordingly Every homeostatic mechanism is coordinated by three different structures: A receptor: detects and reports any changes of a condition’s value to the control center A control center receives stimulus information from the receptor and, if necessary, sends out a motor response to the appropriate effector An effector: executes the action that triggers a change of stimulus direction  Homeostatic Mechanisms Negative feedback: any mechanism that causes a reversal in the direction of a stimulus Negative feedback: the result of the action taken is contrary to the original stimulus sensed. Negative feedback reverses the change in the variable back to within its normal range or within its controlled condition; Negative feedback mechaisms are the most prominent feedback mechanism in the human body & regulates conditions that require stability over long periods of time.  Body Temperature Homeostasis  blood sugar negative feedback loop liver and pancreas act both as sensors and messenger organs.  Positive feedback: reinforces or strengthens the change in a controlled condition. An initial stimulus produces a response that reinforces that stimulus! o “Snowball effect” Positive feedback is involved in the regulation of potentially dangerous or stressful process that must be completed quickly! It must be tightly regulated or else it causes an “over-reaction” which can be inappropriate & harmful; Positive feedback is used to reinforce conditions that are exceptional o example, the immediate danger from a cut / hemorrhage.  Blood Clotting: example of Positive Feedback Mechanism The process of blood clot formation (i.e. coagulation) is another common example of positive feedback. The process is initiated when there is damage to a blood vessel wall. The damage causes platelets to activate and attach themselves to edges of the wound. Once activated, platelets release chemicals that serve to activate and attach more platelets to the site of damage. This is a positive feedback mechanism because platelet activation increases exponentially. The process stops when the tear/wound is entirely covered and blood stops leaking out of the blood vessel.  Childbirth: example of Positive Feedback Mechanism Childbirth is initiated when the fetus’ head begins pushing against the cervix of the uterus. This pressure activates stretch receptors that send a signal to the brain. The brain responds by releasing the hormone oxytocin into the blood stream. Once oxytocin eventually reaches the uterus, it stimulates contraction of the Uterus uterus. Contraction of the uterus causes the fetus’ head Head to push even harder onto the Cervix cervix. This added pressure is again detected by stretch receptors which alert the brain. The brain responds by releasing more oxytocin which intensifies uterine contractions. This cycle continues until the baby is born.  Tips on How to Succeed in Biology 985 1. Review Course outline, be aware of test dates & other important course related information. 2. Skim over lectures before coming to class. 3. Attend lectures & pay attention, take brief notes o do not recopy slides in class o Ppt will be posted on LEA before each lecture o Be prepared when attending lectures 4. After each class, review/ rewrite the lecture notes such that the information is clear to you! YOU MUST MAKE YOUR OWN NOTES. o Condense lecture notes, flow charts, etc., Make a vocabulary list after each lecture. You will learn lots of new terms. Must keep track and review regularly o This is a key step in your learning process and should be done within the first 24-48 hours following the lecture. 5. Homework: Go over all Learning objectives in each lecture. Make sure to understand all of these (include them in your notes). 6. After you have read the material, made your own notes, reviewed them & If you are having trouble with a topic, contact me / schedule an appointment (via email) o Do not wait until the night before the exam to ask questions  Learning is NOT a spectator sport Learning is not a spectator sport. We do not learn much just sitting in classes listening to teachers, memorizing pre-packaged assignments, and spitting out answers. We must talk about what we are learning, write about it, relate it to past experiences, and apply it to our daily lives. We must make what we learn part of ourselves. - Chickering and Gamson  Learning Objectives Did you understand all important topics covered in this lecture? You must be able to: 1. List the 7 properties of all living organisms 2. Briefly describe the classification system for living organisms including binomial nomenclature (binomial system; know that every species has a unique genus and species name) 3. State the three (3) taxonomic Domains (Eukarya, Bacteria, and Archaea) and provide an organism for the Domain Eukarya & Bacteria. 4. Explain the necessary life functions 5. Briefly describe the basic human survival needs 6. Define and understand the importance of homeostasis. 7. Know be able to describe the the 3 components of a homeostatic mechanism. 8. Discuss the difference between a negative and positive feedback mechanism and which one is most often used. Give examples of each.  LABS ❑ First lab: o August 29/30 Lab #1: Introduction to Anatomy ❑ Lab document will be posted on LEA ~ prior to lab date ❑ Must have a lab coat to enter the labs BEFORE each lab period: ❑ Read over the lab document ❑ Lab will be submitted via Testmoz