Diversity in the Living World Biol 1403 What is biology? The science or study of life. What is life? A way of capturing and using energy and raw materials
Characteristics of Life • A way of sensing and responding to the environment • A capacity to reproduce • It’s an evolving process, this means that the traits characterizing individuals in a population can change from one generation to the next
More about Living Organisms There will be many examples that we will come across in this course that will explain how organisms are; • Constructed • Function • Able to live in an environment • Able to do certain tasks
Concepts Throughout these lectures I will provide an overview of basic biological concepts. • Unity underlies the world of life • All organisms are alike in key aspects • Ex: kidneys • Ex: reproduction
Concepts - they all consist of one or more cells made of the same kind of substances and put together involving the same basic principles. - they require energy for their activities which they obtain from their surroundings - all organisms sense and respond to the changing conditions of their environment
Variety - they all have the capacity to grow and reproduce, based on instructions contained in DNA • There is tremendous variety in the life forms that we see around us - millions of different kinds (species) of organisms
Variety DNA Helix
Variety Who knows how many more species of organisms there may have been at the earliest stages of life on earth, each with their own unique characteristics (traits) Charles Darwin, a 19th century naturalist, developed theories of evolution which helped to explain the diversity that exists among organisms, especially his theory of evolution by natural selection
Darwin and Evolution Darwin’s theories attempted to coalesce various disciplines of biology. Like other branches of science, biology depends on observations, hypotheses, predictions, and observational and experimental tests To test these scientific theories, it is necessary to get out among the various organisms and study them carefully
Variety • Scientific Method Flowchart • Define/Identify the Problem • Form a Hypothesis • Make Observations or Test Hypothesis and Perform Experiments • Organize and Analyze Data • Do Experiments and Observations Support Hypothesis? • If No, Perform New Experiments and Repeat Step 4 • Draw Conclusions • Communicate Results
DNA, Energy and Life • A book • A car • A computer • A jellyfish • A dog • A whale What do these items have in common?
Molecular Make-Up They are all made of atoms - atoms have protons, electrons, and neutrons as building blocks. What do living things have (i.e., building blocks) that provide the organism the potential for life?
Variety Sodium atom
Essential Molecules Some building blocks; - nucleic acids - proteins - carbohydrates - lipids In nature, only cells build these molecules
Building Blocks DNA RNA
Building Blocks Proteins Lipids
Building Blocks Carbohydrate
DNA What is the smallest unit that has the capacity for life? - It is the nucleic acid called, DNA, deoxyribonucleic acid DNA has the instructions for assembling a variety of proteins from smaller molecules known as Amino acids.
DNA Helical Structure
Products of DNA A particularly important type of protein made by DNA is the Enzyme. - Enzymes can give energy to a chemical reaction, build, split and rearrange molecules of life. - Some enzymes are involved with nucleic acids such as, RNA (ribonucleic acid) which then take the message they receive from DNA to make proteins
From DNA to Protein The basic pathway would look like this: DNA → RNA → Protein
DNA and Inheritance All cells contain this nucleic acid and as the cell divides, the molecule (DNA) is replicated in the new cells. New cells and multi-celled organisms inherit their defining traits from their parents.
Inheritance This is the acquisition of traits through the transmission of DNA from the parents to the offspring. The term, reproduction, is used for the actual mechanisms of transmitting DNA to offspring.
DNA is the Key DNA also guides development. In a multi-celled organism, tissues and organs are specialized to perform specific functions. Consequently, the DNA contained in these cells is programmed to transcribe a set of instructions to another nucleic acid, mRNA.
DNA is just the start This molecule carries the genetic message from DNA to outside the nucleus. • The mRNA then attaches to a ribosome • It is at the site of the ribosome where proteins are assembled.
Roles for Proteins Proteins are required by an organism for specific functions • Transporting molecules out of the cell • Repairing membranes • Building additional tissues • And much more.
Protein involvement Proteins needed for overall development • Insect development and growth • Moth metamorphosis - Egg, larva, pupa, and adult
Metamorphosis Cicada moulting
Connections Amino acid to Protein
How things get done. Energy - Besides needing DNA, cells need Energy to survive. - This work is seen at the level of the atom - Atoms either give up, share or accept electrons
ATP? This process or activity occurs during the phase of molecular synthesis, catabolism or rearrangement. Energy is needed to make these things happen. In biological systems, energy will be provided in the form of ATP, adenosine triphosphate.
Further Defining Life Metabolism This is another characteristic of whether something can be considered as living. - all the controlled enzyme-mediated chemical reactions by which cells acquire and use energy to synthesize, store, degrade and eliminate substances in ways that contribute to growth, survival and reproduction.
Metabolism Every living cell has the capacity to: • Obtain and convert energy from its surroundings • To use energy to maintain itself, grow and produce more cells
A Metabolic Process An example of metabolism might be: - Photosynthesis - - sunlight is converted into chemical energy, in the form of ATP molecules light 12H2O + 6CO2→ → 6O2 + C6H12O6 + 6H20 energy
Photosynthesis 6 Oxygens 1 Sugar 6 Waters
Plant Metabolism We will discuss later how the plant captures the sunlight energy and converts it into chemical energy in the form of glucose, water and energy.
Metabolism • ATP is involved in helping hundreds of metabolic events proceed by transferring energy to reaction sites where it affects enzymes in a way that enables them to synthesize or breakdown molecules that can be used by the organism.
Aerobic Respiration • This is a process that can release energy that cells stored earlier in the form of starch and other kinds of molecules.
Respiration Krebs Cycle
Characteristics of Life • Living things are made of cells. • Living things obtain and use energy. • Living things grow and develop. • Living things reproduce. • Living things respond to their environment. • Living things adapt to their environment
Characteristics of Life • A Stimulus is a specific form of energy that a receptor can detect. • EX: sunlight energy heat energy binding energy mechanical energy
Characteristics of Life • Cells adjust metabolic activities in response to signals from receptors • EX: glucose and diabetes (receptors) Organisms respond nicely to energy changes so that their internal operating conditions usually remain within tolerable limits
Characteristics of Life • This state in which physical and chemical aspects of the internal environment are being maintained within ranges suitable for a cell’s activities is called, Homeostasis
Biological Organization • A cell is the smallest organizational unit having a capacity to survive and reproduce on its own, given DNA instructions, building blocks, energy inputs and other suitable conditions. • EX: Amoeba
Single Cell Animal Amoeba