BIOL 150 Chapter Notes - Chapter 1: Cytoplasm, Dna Replication, Cell Membrane
Chapter 1: Chemical, Cellular, and Evolutionary Foundations
1.1 THE SCIENTIFIC METHOD
➔Observation- the act of viewing the world around us.
➔Experimentation- disciplined and controlled way of asking and answering questions
about the world in an unbiased manner.
Observation allows us to draw tentative explanations called hypotheses.
➔Observations allow us to ask focused questions about nature.
◆ie) watching hummingbird hovering near a red flower
●What motivates this behavior?
●Is the bird feeding on some substance within the flower?
●Is it drawn to the vivid color?
●What benefit does the bird receive from the flower?
◆Allow tentative explanations to be proposed- hypotheses.
➔Hypotheses
◆ie) hummingbird is carrying pollen from one flower to the next, facilitating
reproduction in the plant.
◆ie) Birds actions reflect need for food, suggesting that the flower provides
nutrition for the hummingbird.
➔Charles Darwin’s, On the Origin of Species,
1859
◆Illustrates how we can piece together individual observations to construct a
working hypothesis.
◆Discusses wide range of observations.
◆He noted the success of animal breeders in selecting specific individuals for
reproduction, generating new breeds for agriculture or show.
◆Argued that life has evolved over time by means of natural selection.
A hypothesis makes predictions that can be tested by observation and experiments.
➔Two features set hypotheses apart from other ways of going about problems.
◆1.) Good hypothesis makes predictions and observations not yet made or
experiments not yet run.
◆2.) Hypotheses make predictions, we can test them.
●Can devise an experiment to see whether the predictions made by the
hypothesis actually occur, or go into the field to try to make further
observations predicted by the hypothesis.
➔Definition: A statement about nature that can be tested by experiments or by new
observations.
◆Are testable.
➔ie) Can test the hypothesis that the hummingbird is transporting pollen from one flower to
the next, enabling the plant to reproduce.
➔A single observation or experiment can lead to the rejection of a hypothesis, or it can
support, cannot prove the hypothesis to be correct.
➔Experimentation
◆Controlled experiment- researcher sets up several groups to be tested, keeping the
conditions and setup as similar as possible from one group to the next.
●Powerful type
●Researcher deliberately introduces something different, variable, into one
group that they hypothesize might have an effect. (Test group)
●Another group, variable is not introduced. (Control group)
○Provides a baseline that is compared to the results of the test group.
●Expected that no effect will occur in this group.
●By changing one variable at a time, researcher is able to determine if
variable is important.
➔Scientific Method
◆Observations→Hypothesis→Predictions→Experiments→THEORY
General explanations of natural phenomena supported by many experiments and observations are
called theories.
➔Hypothesis will provide only one of several possible ways of explaining existing data.
◆Repeated observation and experimentation strengthens hypothesis.
➔Theory- general explanation of the world supported by a large body of experiments and
observations.
◆When a number of related hypotheses survive repeated testing and are accepted as
good bases for explaining nature, scientists articulate a broader explanation that
accounts for all the hypotheses and the results of their tests.
◆Only a theory if hypotheses have withstood testing to the point where they
provide a general explanation for many observations and experimental results.
◆ie) theory of gravity, theory of evolution.
1.2 CHEMICAL AND PHYSICAL PRINCIPLES
➔Living organisms are clearly different from nonliving things.
◆Easy comparison: A rock is much simpler than any living organism.
◆Hard comparison: Relatively simple bacterium contains hundreds of different
chemical compounds organized in a complex manner.
●Changes continuously, especially in response to the environment.
●Reproduce and evolve.
◆Both are subject to the basic laws of chemistry and physics.
➔Gerald Joyce
◆Defined life as a chemical system capable of undergoing Darwinian evolution.
➔4 key characteristics of living organisms
◆1. Complexity, with precise spatial organization on several scales.
◆2. The ability to change in response to the environment.
◆3. The ability to reproduce.
◆4. The capacity to evolve.
The living and nonliving worlds follow the same chemical rules and obey the same physical
laws.
➔Chemical elements found in rocks and other non living things are no different from those
of living organisms.
➔Universe as a whole..
◆Hydrogen and helium make up more than 99% of known matter.
◆Earth’s crusts contains mostly oxygen and silicon, significant amounts of
aluminum, iron and calcium.
➔In organisms
◆Most abundant elements are oxygen, carbon, and hydrogen.
◆Carbon provides the chemical backbone of life.
➔All living organisms are subject to the physical laws of the universe.
◆Physics helps understand how animals move and why trees don’t fall over.
◆2 laws of thermodynamics, determine how living organisms are able to do work
and maintain their spatial organization.
➔1st law of thermodynamics- states that energy can neither be created nor destroyed; can
only be transformed from one form into another.
◆Total energy in the universe is constant, form of energy can change.
◆Living organisms- acquire energy from the environment and transform it into a
chemical form that cells can use.
◆All organisms obtain energy from the sun or from chemical compounds.
●Some is used to do work (moving, reproducing, building cellular
components), rest is dissipated as heat.
●Total=energy used to do work+heat that is generated
○(input energy)
➔2nd law of thermodynamics- states that the degree of disorder (number of possible
positions and motions of molecules) in the universe tends to increase.
◆ie) full box of marbles disturbed randomly; line up the red ones and blue ones in a
row, work is done (energy is added),
●Addition of energy increases order of the system (decreases disorder).
●Entropy- the amount of disorder (number of possible positions and
motions of molecules) in a system.
➔Living organisms are highly organized.
Document Summary
Observation- the act of viewing the world around us. Experimentation- disciplined and controlled way of asking and answering questions about the world in an unbiased manner. Observation allows us to draw tentative explanations called hypotheses. Observations allow us to ask focused questions about nature. Ie) watching hummingbird hovering near a red flower. Allow tentative explanations to be proposed- hypotheses. Ie) hummingbird is carrying pollen from one flower to the next, facilitating reproduction in the plant. Ie) birds actions reflect need for food, suggesting that the flower provides nutrition for the hummingbird. Charles darwin"s, on the origin of species, 1859. Illustrates how we can piece together individual observations to construct a working hypothesis. He noted the success of animal breeders in selecting specific individuals for reproduction, generating new breeds for agriculture or show. Argued that life has evolved over time by means of natural selection. A hypothesis makes predictions that can be tested by observation and experiments.
