BISC 1111 - lecture 1

biology: science of life

nearly 200 years ago, Charles Darwin set out on 5 year journey on HMS beagle

led to theory of evolution via natural selection, become core of the science of biologu today

seven characteristics of life

cellular organization, ordered complexity, sensitivity

growth, development, & reproduction

energy utilization, hemeostasis, evolutionary adaption

cellular organization

all life is composed of one or more membrane bound cells

ordered complexity

molecules and cells making up an organsim exhibit hierarchical, ordered complexity

sensitivity

respond to stimuli

growth, development, & reproduction

governed by molecules of heredity

energy utilization

metabolism, take in energy that is used for work

homeostasis

maintain relatively stable internal condtions different from external environment

evolutionary adaption

organisms interact with one another and thier environment in ways that infleunce survival, and therefore, populations evolve to adapt to their environments

the nature of science

science is concerned with developing an increasingly accurate understanding of the world around us using observation and reasoning

scientists assume that the fundamental nature of the universe is constant

objectivity in science

scientists attempt to be as objective as possible in data interpretation and observations

NOT completely possible on an individual level, as we are only human

science is a COLLECTIVE endeavor, subject to scrutiny, with a built-in mechanism of self-correction

much of science is descriptive

the first step in understanding anything, is to first be able to describe it accurately and completely

therefore, much of biology is concerned with arriving at an increasingly accurate descriptions of nature

studyof logic informs nature

deductive reasoning

biologist might use deductive reasoning to infer the species of a species of a specimen from its characteristics

inductive reasoning

inductive reasoning leads to generalizations that can then be tested

deductive reasoning

applies general principles to predict specific results, used to test validity of ideas in all branches of science, but especially in mathematics and philosophy

a biologist might use deductive reasoning to infer the species of a specimen from its characteristics

inductive reasoning

uses specifc observations to construct a general set of scientific principles (the logic flows in the opposite direction of deductive reasoning)

inductive reasoning leads to generalizations that can then be tested

hypotheses

suggested explanations that account for observed phenomena

a set of propositions which might be true

establishes a controlled experiment

scientists are interested in learning about processes that are influenced by many factors or variables

variable

to evaluate alternative hypotheses, we keep the variable of interest constant in a control group, and alter it in the experimental treatment.

variable

factor that influences a process, outcome, or observation

in experiments, scientists attempt to isolate variables or test hypotheses

germ hypothesis

preexisting microbes present in the air contaminate broth

predicts that sterilized broth will remain sterile if microbes are prevented from entering flask

spontaneous generation hyp.:

living organisms will spontaneously generate from nonliving organic molecules in broth

predicts microbes will generate from broth even after sterilization

reductionist approach to understanding

reductionism

limited when applied to living systems, as complex interworking of many interconnected functions leads to difficult to predict emergent properties

reductionism

philosophical approach to understand a complex system by reducing it to its working parts

nature of scientific theories: dual meanings

to a scientist - theory is a proposed explanation for some natural phenomenon, often based on some general principle

theory is a body of interconnected concepts, supported by scientific reasoning and experimental evidence, that explains the facts in some area of study

to a lay person - to the public, theory implies opposite of certainly…lack of knowledge or a guess

evolutionary theory - basis of biology

evolution

individuals do not evolve, populations do

Darwin’s theory of evolution via natural selection explains and describes how organims on earth changed over time and acquired a diversity of forms

evolution

genetic change in a population or organisms over time

artificial selection

change in genetic structure of populations due to selective breeding by humans

many domestic animal breeds and crop varieties have been produced through artificial selection

natural selection

the differential reproduction of genotypes; caused by factors in the environment; leads to evolutionary change

4 mechanisms of evolutionary change

mutation

gene flow

genetic drift

natural selection

structure determines function

proper functioning of molecules. cells, tissues, and organs depends on their structure

can thus infer function from structure and vice versa cross contexts

living systems transform energy and matter

from a single cell to the highest level of biological organization, biosphere, all living systems have constant need for energy

without constant energy input, living systems would tend toward chaos and entropy

living systems depend on information transaction

both in present and across time

DNA - molecule of heredity allowing information to be passed generationally

living systems respond to their environment in real time

evolution explains unity and diversity of life

biologist agree that all organisms alive today descend from a simple cellular, organism that arose ~ 3.5 BYA

some characteristics of that organism have been preserved through time, for example, DNA and reading of its code is common among all livings