Introduction to Biology - Valverdevalverdescience.pbworks.com/w/file/fetch/108826360... · 2020. 9....

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Introduction to Biology

Why is Biology important?

● To study DNA: forensics ● Health, medicine. ● Agriculture ● Animals ● Bacteria/ Viruses !

● BIO=life ● LOGY=study ● Biology : The study of life


Why a Study of Biology is Important?

Personal • To be informed • Support your cause • Make it your life work

http://articles.orlandosentinel.com/2011-04-06/health/os-killer-amoeba-research-20110406_1_killer-amoeba-naegleria-fowleri-primary-amebic-meningoencephalitishttp://peopleofperu.org/https://www.aamc.org/students/medstudents/cim/


[bahy-ol-uh-jee]

● Bio = life !

● ...ology = the study of !

● Biology is the science that studies life


The Scientific Method in Action

● A systematic way of gaining information


The Scientific Method: Observation

● An observation is a thoughtful and careful recognition of an event or a fact. !

● The careful observation of a phenomenon leads to a question. – How does this happen? – What causes it to occur?


The Scientific Method: The Hypothesis

● Hypothesizing – question an observation – propose possible solutions to questions based on what

is already understood about the phenomenon ● Hypotheses must:

– be logical – account for all current information – make the least possible assumptions – be testable


Testing Hypotheses

● Hypotheses need to be tested to see if they are supported or disproved. – Disproved hypotheses are rejected – Hypotheses can be supported but not proven !

● Ways to test a hypothesis: – Gathering relevant historical information

● Retrospective Studies – Make additional observations from the natural world – Experimentation


The Scientific Method: Experimentation

● Experiments – rigorous tests to determine if the solutions are supported !

● Experiments attempt to recreation an occurrence – tests whether or not the hypothesis can be supported or

rejected !

● There are many types of experiments – laboratory, clinical trials, surveys, statistical analyses


Experimental Design

● All experiments have key elements in common: !

– Experiments must be controlled ● this means that all aspects except for one variable must be kept

constant ● usually include any two groups.

– Experimental group: variable is altered, independent variable – Control group: variable is not altered, dependent variable !

– Experiments use models to recreate occurrences, but in a controlled setting ● model organisms, ISS, cohorts

http://news.bbc.co.uk/2/hi/health/1949073.stmhttp://www.nasa.gov/mission_pages/station/main/index.html


Experimental Design

● Experiments must: – use large numbers of subjects and/or must be

repeated several times (replication) – be independently reproducible !

● The validity of experimental results must: – be tested statistically

● chi-squared test for statistical significance – be scrutinized by other scientists

● peer reviewed


Theory

● If the hypothesis is supported by ample experimental data, it leads to a theory.

● A theory may be defined as a widely accepted, plausible general statement about a fundamental concept in science.

– The germ theory states that infectious diseases are caused by microorganisms. ● Many diseases are not caused by microorganisms, so we must be

careful not to generalize theories too broadly. – Theories continue to be tested

● Exceptions identified ● Modifications made


A Scientific Law

● A scientific law is a uniform and constant fact of nature that describes what happens in nature.

– An example: All living things come from pre-existing living things. ● Scientific laws promote the process of generalization.

– Inductive reasoning – Since every bird that has been studied lays eggs, we can generalize

that all birds lay eggs. ● Once a theory becomes established, it can be used to

predict specific facts. – Deductive reasoning – We can predict that a newly discovered bird species will lay eggs.


Scientific Communication

● Data is shared with the scientific community through research articles published in scientific journals.

– peer review !● Scientists present preliminary

data at conferences. !● Scientists collaborate directly by

phone and  e-mail.

http://www.washingtonpost.com/wp-dyn/content/article/2009/11/21/AR2009112102186.html


A Sample Experiment

Scientific American August 2010

http://www.lscc.edu/faculty/christopher_c_leibner/BSC%2525201005/Forms/AllItems.aspx


A Sample Experiment

● Article: Hardt, Marah J. and Safina, Carl. “Threatening Ocean Life from the Inside Out.” Scientific American August 2010: Vol. 303 2. !

● What types of observations were being made? ● State a hypothesis that was tested. ● Describe an experiment that was conducted. ● Discuss a variable that was studied and describe how constants

where maintained in the experiment. ● How was a model system was used to simulate the conditions being

studied. ● How were the complex processes being studied reduced to their

simplest parts? ● What was learned from the experiments?

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The Science of BiologyChapter 1

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1.1 The Science of Life

• Biology unifies much of natural life !

• Biology attempts to define life !

• Biology Living reveals a hierarchical organization of living systems

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How do we know that something is alive?

breathing pale pulse

breathing pulse !

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How do we know that something is alive?

» Leewenhock *all living things are made of cells !*reproduce *create waste *respond to the environment *evolves

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Levels of Organization

CELLTISSUE

ORGAN

ORGAN systemorganism

community

ecosystem BIOSPHERE

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DARWIN AND EVOLUTION

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Natural Selection

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the Galapagos

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Voyage of the Beagle

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Exit Ticket 6/13/16

» What is biology? !

» How do we know when something is alive? !

» Who is Darwin? Why is his name remembered?

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Charles Darwin

• Evolution: Modification of a species over generations

• “descent with modification” !

• Natural Selection: Individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics

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Darwin’s Evidence

• Similarity of related species • Darwin noticed variations in related species living in different locations

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1.4 Unifying Themes in Biology

Cell theory • The cell theory describes the organization of

living systems • All living organisms are made of cells, and all

living cells come from preexisting cells

Fig. 1.11a

Single Celled Organisms

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Fig. 1.11b

Multi-Cellular Organisms

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1.4 Unifying Themes in Biology

Molecular basis of inheritance • The molecular basis of inheritance explains

the continuity of life • DNA encodes genes which control living

organisms and are passed from one generation to the next

• The DNA code is similar for all organisms (The Central Dogma)

Fig. 1.12

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Unifying Themes in BiologyStructure and Function • The proper function of a molecule is

dependent on its structure • The structure of a molecule can often tell

us about its function • Four major classes of Biomolecules

1. Nucleic Acids 2. Amino Acids 3. Lipids 4. Carbohydrates

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Unifying Themes in BiologyEvolutionary Change • The diversity of life arises by evolutionary

change leading to the present biodiversity we see

• Biology attempts to classify life’s great diversity based on these unifying themes

• Currently all living things are classified into 3 Domains subdivided into Kingdoms (more on taxonomy to come)

• This process is always changing

Fig. 1.13

The Diversity of Life

Three Domains: 1. Eukarya 2. Archaea 3. Bacteria

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Fig. 1.13-1

Domain Eukarya is Divided into four Kingdoms: 1. Plantae 2. Fungi 3. Animalia 4. Protista

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Fig. 1.13-2

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Fig. 1.13-3

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Unifying Themes in Biology

Evolutionary Conservation • Evolutionary conservation explains the unity

of living systems • The underlying unity of biochemistry and

genetics argues that all life has evolved from the same origin event

• Critical characteristics of early organisms are conserved and passed on to future generations

Fig. 1.14

Homeodomains

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Cells are information-processing systems • Every cell in an organism carries the same

genetic information • The control of gene expression allows cells

to differentiate into different cell and tissue types

• Cells also process information received from the environment and respond to maintain homeostasis

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Emergent properties • New properties are present at one level of

organization that are not seen in the previous level

• The whole is greater than the sum of its parts

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The Science of BiologyEnd Chapter 1

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