Intro to Biology

Bio 9CCSF

Lecture Outline• Welcome & syllabus• Intro to Biology• The scientific method

Biology is the study of life

Biology has many subdisciplines• Biochemistry• Cell biology• Ecology• Physiology• Microbiology• Genetics• Molecular biology• Population genetics• Botany• Agriculture

• Bioinformatics• Systems biology• Health• Medicine• Pharmacology• Evolution• Anatomy• Taxonomy• Paleobiology• Etc., etc., etc.

Biology from a human perspective

• Focuses on human body• Biological principles and

their relevance to human health, human physiology, and the human experience

• Environment, evolution, and other biology topics are also of significant human interest

Biology is transforming our lives

• As available biological information increases, our knowledge of biology advances

Biology is transforming our lives

• Antibiotics have saved countless lives

• Antibiotics are part of a constant war against microbes

• The war isn’t over yet

Biology is transforming our lives

• Oscar Pistorius, South Africa, 400m

• Fastest time: 46.25 sec• World record: 43.18sec• Cleared to compete in

the Olympics• Didn’t compete (3rd at

S.A. Oly trials; but Oly standard = 45.55)

Knowing Biology is a good way to get a job

• Developments in biological knowledge have led to discovery of new drugs

• Many drugs require special manufacturing procedures

• The bay area is a pretty good place to get such a job

Knowing biology is a good way to get a job

• America has a rapidly aging population

• Jobs in healthcare are rapidly increasing

Knowing Biology is a good way to help out

• Biology addresses many needs and dangers the earth and its inhabitants currently face

Knowing biology is a good way to stay healthy through a long life

Knowing Biology can help you make decisions about right and wrong

Knowing Biology can help you avoid being deceived

Knowing Biology can stop crime

On a piece of paper

• Write the following– Your name– Where you’re from– Guilty pleasure music– The goals you have for CCSF– How Bio 9 fits into those goals

• Share with your tablemates when you are done

Biology and other sciences owe their progress to the Scientific Method

Hypothesis testingExperimental design

Clinical trials

• Jane Goodall did not conduct “experiments”

• Neither did Charles Darwin

• Experiments are still very important

• Two basic forms of the scientific method:

• Discovery Science• Hypothesis testing

There is no set “Scientific Method”

The scientific methodObservations of interesting phenomena lead to a hypothesis (educated guess) as to their causes

Predictions based on the hypothesis lead to experimental tests

The scientific methodWhen results are obtained according to predictions, the hypothesis is supported, and further predictions about the hypothesis can be made

When results contradict hypothesis, the hypothesis is rejected, and the hypothesis must either be revised or discarded for a new one

LE 1-8a-1

Observations

Question

Hypothesis testing an important

means by which science

advances

LE 1-8a-1

Observations

Question

Hypothesis #1:Dead batteries

Hypothesis #2:Burnt-out bulb

A good hypothesis

must be testable

LE 1-8a-3

Observations

Question

Hypothesis #1:Dead batteries

Prediction:Replacing batterieswill fix problem

Hypothesis #2:Burnt-out bulb

Prediction:Replacing bulbwill fix problem

Test prediction Test prediction

A good hypothesis

must be falsifiable

Observations

Question

Hypothesis #1:Dead batteries

Prediction:Replacing batterieswill fix problem

Hypothesis #2:Burnt-out bulb

Prediction:Replacing bulbwill fix problem

Test prediction Test prediction

Test falsifies hypothesis Test does not falsify hypothesis

While good hypotheses are always falsifiable,

proving them "true” can be very

difficult

Scientists record data using SI (metric) units of measurement

In what way(s) is the science of biology influencing and changing

our culture? A) by providing new tools that can be used in

forensics B) by revolutionizing medicine and agriculture C) by helping us evaluate environmental issues and the impacts of human actions D) all of the above E) none of the above

Does excess iron decrease growth?• How can we test this?

Does excess iron decrease growth?• How can we test this?• How many groups should we

use?• What size are the groups?• How shall we create the groups?• What is the

dependent/independent variable?

Does excess iron decrease growth?• How can we test this?• How many groups should we

use?• What size are the groups?• How shall we create the groups?• What is the

dependent/independent variable?

• How would this experiment be different if it were conducted with people?

Good experiments are controlled• Controls are references

which can be used for comparison

• Experimental group- receives treatment (independent variable)

• Control group- does not receive treatment

• Control variable- something besides the independent variable which affects the outome

Experimental terminology• Experimental group- group

receiving treatment in question

• Control group- group not receiving treatment

• Independent variable- the treatment

• Dependent variable- expected measurable result of treatment with independent variable

• Sample size- number of subjects in study group

• Positive control- a control group created to resemble a positive result

• Negative control- group resembling a negative result

• Placebo- accounts for human mind

• Double-blind- neither patient (subject) nor doctor (test administrator) knows who is getting placebo

• Confirmation bias- The tendency to view results according to predictions

Clinical trials look at results in people

Drugs must be proven safe by the FDA

• The drug approval process is lengthy and costly

• Usually costs $500m- $1bn

• The drug is tested in vitro first

• Then on cell culture flasks• Then on animals• Then clinical trials begin

Clinical trials on humans require multiple phases

• Phase I: a small (20-50) group of healthy volunteers determine pharmacokinetics and pharmacodynamics of drug

Anyone want to volunteer?

• Phase II: larger groups of actual patients (20-300) and are designed to assess how well the drug works

• Phase III: randomized controlled multicenter trials on large patient groups (300–3,000 or more) in comparison with current 'gold standard' treatment

• Phase IV: After drug is released to public

Sometimes clinical trials are outsourced to foreign countries

Critical thinking about experiments and their results is a vital check to the scientific method

• Drug compaines often suffer from confirmation bias when they fund their own studies

• Clinical trials are extremely costly

• Successful drugs can be extremely profitable

• Vioxx revenues: $2.5bn/yr• Projected additional heart

attacks: 90,000-130,000 (~30-40% fatal)

Vioxx doubles risk of heart attack compared to placebo

The scientific method has advanced society

The scientific method is applicable beyond the hard sciences

• Parents Grossly Underestimate The Influence Their Children Wield Over In-Store Purchases.

• 178 parents shopping with their child in Austrian supermarkets were unobtrusively observed while strolling through the aisles…When asked how many products their children had made them buy, on average parents only reported half the number of purchases that had been secretly observed.

Does excess iron decrease growth?• How can we test this?• How many groups should we

use?• What size are the groups?• How shall we create the groups?• What is the

dependent/independent variable?

• How would this experiment be different if we used people?

"An athlete who uses dietary supplements will perform better than one who doesn't." This

statement would be an example of which of the following?

• A) Theory • B) Hypothesis • C) Skeptic • D) A haphazard statement

Defining life

Characteristics of life vs. nonlife

Biology is the study of life

Charles Darwin, Born Feb 12, 1809HIV, with genes corresponding to proteins

What is life?

• We know it when we see it

• Characteristics not so easy to define

• Some are more basic than others

Life is orderly in a disorderly universe

Seven important characteristics common to living things

1. Macro-molecular composition

2. Cellular structure

3. Growth and reproduction

4. Use of energy and materials

Seven important characteristics common to living things

1. Response to stimuli

2. Maintenance of homeostasis

3. Evolution and adaptation

1. All living things are composed of 4 common macromolecules

• Nucleic Acids• Proteins• Carbohydrates• Lipids

• DNA is a nucleic acid

2. Cellular structureUnicellular- Bacteria, Archaea, some protists

Multicellular- Eukarya: plants, animals, fungi, other protists

3. Living things grow and reproduce

• Bacteria reproduce by binary fission

• Daughter cells of bacteria are nearly identical

• But not quite…• Sexual reproduction

ensures offspring are different from parents

4. All living things utilize energy and raw materials

The ultimate source for energy for all ecosystems is the sun

Humans and other animals get energy & raw materials from food

5. All living things respond to their environment

6. All living things regulate their

internal environment

against external changes

• Homeostasis- “staying the same”

7. All life evolves across generations, thereby adapting to its environment

• Variation in offspring allows natural selection

• Variation in offspring ultimately has its roots in imperfect replication of DNA

• Important note- Individuals do NOT evolve- populations evolve

Natural Selection in the Peppered Moth

• Same species, 2 variants• Which one is better

adapted to its current environment?

• What does the future hold for this population of moths?

Evolutionary history traces back to a single origin for all known life

What is biology?

A) the study of life B) the study of the environment C) the study of genetics D) DNA fingerprinting E) the study of biomes

Major themes of biology

ClassificationEvolution

DNALevels of organization

A primary goal of biology is classification of life

• Living things are primarily organized according to ancestry rather than similarity of appearance

Life is organized into 3 major groups called domains- Bacteria,

Archaea, and Eukarya

Within the Eukaryotes, there are 4 major kingdoms- Protists, Fungi, Plants, and Animals

The unifying theme of biology is evolution

• The evolution of millions of species belies the common ancestry of all life

• Evolution: “change over time”

-Natural Selection is the mechanism by which populations evolve

- “Survival (and reproduction) of the fittest”- those which best fit their environment

Population with varied inherited traits

Elimination of individuals with certain traits

Reproduction of survivors

Figure 1.15b

The increasing prevalence of antibiotic –resistant pathogenic microbes is an example of evolution by natural selection in action

Scientists seek to classify life according to its common ancestry

All living things have DNA

• DNA is an orderly, self-replicating molecule

• DNA stores all genetic information

• It does not reproduce itself perfectly every single time…

• As DNA evolves, living things evolve

Changes in DNA are called mutations, and can be inherited

• When DNA is changed, proteins change

• Ear proteins in cats can cause curled ears

LE 1-1a

Biosphere

EcosystemFlorida coast

CommunityAll organisms onthe Florida coast

PopulationGroup of brown

pelicans

OrganismBrown pelican

Life can be studied at many levels

LE 1-1b

OrganismBrown pelican

Spinal cord

Nerve Brain

Organ systemNervous system

OrganBrain

TissueNervous tissue

CellNerve cell Nucleus

OrganelleNucleus Molecule

DNA

Atom

New properties emerge at each new level of complexity

Which of the following is not a characteristic of all living things?

• A) They are composed of multiple cells. • B) They respond to stimuli. • C) They contain organic molecules such as

carbohydrates, proteins, lipids, and nucleic acids.

• D) They have adaptive traits.