GENBIO

• Every task of the body requires the use of energy
• Bioenergetics


  Subfield of biochemistry that studies the concept of energy flow within living systems
• No cell in the body can make energy, but instead it must get energy from outside sources in the environment
• If only a fraction of the energy that a herbivore gets from plant food becomes part of the herbivore's body (its biomass), what happens to the rest of it?
• A plant cell, an animal cell, and microbial cell all run on the chemical energy found in food in the form of carbohydrate molecules, which can be traced from photosynthesis
• Mitochondria


  Small, specialized cellular organelles that produce energy from food by breaking down carbon-containing molecules and releasing energy packets in the form of ATP
• Autotrophs


  Organisms that can produce their own food from inorganic substances
• Heterotrophs


  Organisms that cannot produce their own food and must obtain organic compounds from other sources
• Cellular Respiration


  1. Glycolysis

  2. Krebs cycle

  3. Electron transport chain
• Glycolysis


  Process that occurs inside the cytoplasm, does not require oxygen, and produces 2 NADH, 2 ATP, and 2 pyruvate
• Krebs Cycle


  Citric acid cycle that starts with the end-product of glycolysis, pyruvate, and involves a series of enzyme-controlled processes that occur inside the mitochondrial matrix, producing 4 CO2, 6 NADH, 2 FADH2, and 2 ATP
• Electron Transport Chain


  Involves a series of enzyme-controlled reactions that transfers the chemical energy present in hydrogen electrons to ATP
• Products of cellular respiration are carbon dioxide produced from the breakdown of pyruvate from Krebs cycle and water from the electron transport chain, with a net gain of 38 ATP for every glucose molecule
• Phases of Cellular Respiration and ATP Yield

  • Glycolysis: 2 NADH, 2 ATP
  • Krebs cycle: 6 NADH, 2 FADH2, 2 ATP
  • Electron transport chain: 10 NADH, 30 ATP
  • Total: 38 maximum ATP
• Anaerobic pathway supplies immediate energy source for the cells, as cells in the body cannot store large amounts of oxygen for cellular respiration
• Fermentation


  Energy extraction pathway that is only glycolysis, with one or two extra reactions tacked on the end
• In muscle cells, if oxygen is unavailable, a molecule of glucose can be split by glycolysis and lactic acid fermentation can occur, causing muscles to feel "burn" or hurt during extreme exercise
• The role of fermentation provides glycolysis with a steady supply of NAD+, but does not produce ATP
• Without the presence of anaerobic microorganisms, Earth will become oxygen poor
• Evolution


  Descent with modification - descent implies inheritance, modification refers to changing of traits from generation to generation
• Evolution


  Cumulative genetic change in a population of organisms over time
• Many people think of evolution as something that takes a long time or something that might require millions of years
• Today, our experience with antibiotic and pest resistance has revealed that bacteria and insects can ride an evolutionary fast track
• The present and extensive knowledge of evolution is a contribution by many scientists who were bold enough to understand how life arose on the planet
• Pre-Darwinian theories


  • Most naturalists believed in the idea that species have been created separately and remained unchanged from the time of their creation until the present time
  • In the 1600s, with the idea of creationism predominating the common thinking at that time, other scientific exploration began to unfold new facts that contradicted the present-day thinking that all organisms were products of a single creation with unchanging species
  • If all types of organisms were created in one place and at one point in time, how come do we have different groups of unique organisms in different parts of Earth?
• George-Louis Leclerc, Comte de Buffon

  A mathematician and naturalist who openly suggested that closely related species may have arisen from a common ancestor
• Erasmus Darwin


  An English physician, poet, and amateur scientist who believed that evolution could occur in living organisms as well as in humans
• Jean Baptiste Lamarck


  Proposed the idea that species, including humans, descended from other species and attributed the change to natural laws and proposed a mechanism of how it can all happen
• Lamarck's mechanisms


  • The physical desire of an animal determines how the body will develop into something
  • The changes in organ size caused by its use and disuse can be inherited by offspring
• Theory of Acquired Characteristics


  Lamarck's theory that changes in an organism during its lifetime can be passed on to its offspring
• How did Lamarck pave the way for the work of later biologists?
• Charles Darwin and Alfred Russel Wallace


  • They were able to make detailed observations in various parts of the world because of their work as naturalists
  • Darwin pursued his own interests by joining geological field trips and meeting renowned geology professors
  • He was appointed as the ship's naturalist for the five-year journey of the HMS Beagle (1831-1836) to map the coastline of South America
• Survival of the fittest

  Darwin's theory that individuals best adapted to their environment are more likely to survive and reproduce
• Darwin's observations


  • He studied the beaks of finches that varied from island to island and discovered that the finches adapted to the agriculture differently thus changing a key physical feature: their beaks
• In 1858, Wallace published several researches on the theory of evolution, which included natural selection as a mechanism for the changes over time among organisms from a common ancestor, as well as the idea of survival of the fittest
• Darwin attracted more attention when he published his monumental and well-documented manuscript, titled "On the Origin of Species by Means of Natural Selection"
• Darwin and Wallace's essential concepts

  • Descent with modification - the idea that organisms descended from common ancestors
  • Natural selection - the mechanism that ensures survival and reproductive success of individuals who better adapted to their environment
• Darwin's conclusion


  • Individual members within a population of species are varied and some of these variations could be inherited by future generations
  • Members of the population have the capacity to produce more offspring than the environment could provide, such as food, shelter, or space
• Natural selection


  The process whereby organisms better adapted to their environment tend to survive and produce more offspring
• It is nature that selects the traits that could favor one organism that can be passed on to the next generation