Cells and Molecules

Biology

Science of life

Charles Darwin

200 years ago set out on 5 year journey on HMS Beagle, theory of evolution via natural selection, core of science of biology

7 Characteristics of Life

Cellular organization, ordered complexity, sensitivity, growth/development/reproduction, energy utilization, homeostasis/regulation, evolutionary adaptation

Cellular Organization

All of life composed of 1 or more membrane bound cells

Ordered Complexity

Molecules + cells make up an organism exhibit hierarchical + ordered complexity

Sensitivity

Respond to stimuli

Growth, Development, + Reproduction

Governed by molecules of heredity

Energy Utilization

Metabolism, take in energy that’s used for work

Homeostasis/Regulation

Maintain relatively stable internal condtions different from external environment

Nature of Science

Develop increasingly accurate understanding of world around us using observation + reasoning, fundamental nature of universe constant

Scientific Method

Observations → Hypothesis → Predictions (If…then…) → Test (observations, experiments) → Supported or Rejected → Further Tests or New/Revised Hypothesis

Objectivity in Science

Not possible individually, science is a collective endeavor, subject to scrutiny with build-in mechanism of self-correction

Descriptive

Accurately + completely, arrive at increasingly accurate description of nature

Deductive Reasoning

Apply general principles to predict specific results, tests validity of ideas in all branches, mathematics + philosophy, ex. infer species of specimen from characteristics

Inductive Reasoning

Specific observations to construct general set of scientific principles, logic flows oppositve direction of deductive reasoning, generalizations to be tested

Hypotheses

Suggested explanations that account for observed phenomena, prepositions that could be true

Variable

Factor that influences a process, outcome, or observation; isolated to test hypotheses

Control Group

Keep variable of interest constant to evaluate alternative hypotheses, altered in experimental treatment

Germ Hypothesis

Preexisting microbes present in air contaminate broth, predicted sterilized broth remains sterile if microbes prevented from entering

Spontaneous Generation Hypotheses

Living organisms spontaneously generate from nonliving organic molecules in broth, predicted microbes will generate from broth after sterilization

Reductionism

Philosophical approach to understand a complex system by reducing to working parts, limited when applied to living systems as complex interworking of many interconnected functions leads to difficult to predict emergent properties

Scientist Theory

Proposed explanation for some natural phenomenon based on genera principle, body of interconnected concepts supported by scientific reasoning + experimental evidence that explains the facts in some area of study

Evolution

Genetic change in population of organisms over time, populations evolve, explains + describes how organisms on earth changed over time + acquired diversity of forms, every organisms transcends from simple cellular organism that arose ~ 3.6 BYA, DNA + reading of its code common among all living things

Artificial Selection

Change in genetic structure of populations due to selective breeding by humans, many domestic animal breads + crop varieties

Natural Selection

Differential reproduction of genotypes, caused by factors in environment, leads to evolutionary change

4 Mechanisms of Evolutionary Change

Mutation, gene flow, genetic drift, natural selection

Mutation

A gene of brown develops, gets passed down to offspring that turns brown instead of green

Gene Flow

Brown beetle moves to green beetle population and mates creating a brown population in green population

Genetic Drift

In case of chance event, person stepping on only all green beetles, eliminating their population

Natural Selection

Selection pressure, brown beetles able to hide better than green, green eaten by predators

Conceptual Framework

Life subject to chemical + physical laws, no new chemical/physical laws to be found in bio, consistent application of familiar

Structure/Function

Structure determines function, proper functioning of molecules, cells, tissues, + organs

Energy/Matter

Living systems transform energy + matter from single cell to highest level of biological organization, biosphere, all living things have constant need for energy; without energy, living systems would tend toward chaos + entropy

Information Transaction

Living systems depend on it both in present + across time, DNA molecule of hereditary that allows information to be passed generationally, living systems respond to environment in real time