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BIOLOGY 102BIOLOGY 102

Lecture 1: Introduction to BiologyLecture 1: Introduction to Biology

BiologyBiology

•• Scientific studyScientific study

of lifeof life

•• From GreekFrom Greek

•• BiosBios “life”“life”

•• Logia Logia “study of”“study of”

What Makes Something Alive?What Makes Something Alive?1.1. All All living things are made of one or more living things are made of one or more cellscells

What Makes Something Alive?What Makes Something Alive?2.2. Living things carry out Living things carry out metabolismmetabolism

•• All chemical reactions required to sustain lifeAll chemical reactions required to sustain life

•• Includes respiration, digestion, building Includes respiration, digestion, building

things, breaking them downthings, breaking them down

What Makes Something Alive?What Makes Something Alive?3.3. Living things maintain Living things maintain homeostasishomeostasis

•• Internal balance that keeps things constantInternal balance that keeps things constant

What Makes Something Alive?What Makes Something Alive?4.4. Living things grow and reproduce themselvesLiving things grow and reproduce themselves

•• Living things come from other living thingsLiving things come from other living things

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What Makes Something Alive?What Makes Something Alive?5.5. Living Living things contain genetic information in the things contain genetic information in the

form of DNA and form of DNA and RNARNA

•• Universal genetic codeUniversal genetic code

What Makes Something Alive?What Makes Something Alive?6. Living things pass on 6. Living things pass on heritableheritable information to information to

their offspringtheir offspring

What Makes Something Alive?What Makes Something Alive?7.7. Living things detect and respond to their Living things detect and respond to their

surroundingssurroundings

•• Light, sound, touch, chemicals, heat, etcLight, sound, touch, chemicals, heat, etc

What Makes Something Alive?What Makes Something Alive?8.8. Living things Living things adaptadapt in the short termin the short term

•• Adjust to new conditionsAdjust to new conditions

What Makes Something Alive?What Makes Something Alive?9.9. Living things Living things evolve evolve in the long termin the long term

•• Genetic distribution in a population will Genetic distribution in a population will

change over many generations based on change over many generations based on

natural selectionnatural selection

What Makes Something Alive?What Makes Something Alive?10.10. Living things are highly Living things are highly organizedorganized

•• Some of these topics are covered in BI 102Some of these topics are covered in BI 102

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What Makes Something Alive?What Makes Something Alive?10.10. Living things are highly Living things are highly organizedorganized

•• Some of these topics are covered in BI 102Some of these topics are covered in BI 102

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So… Is A Virus Alive?So… Is A Virus Alive?•• Passes on heritable informationPasses on heritable information

•• Detects and responds to surroundingsDetects and responds to surroundings

•• AdaptsAdapts

•• EvolvesEvolves

BUT…BUT…

So… Is A Virus Alive?So… Is A Virus Alive?•• Is not made of cellsIs not made of cells

•• Does not carry out metabolismDoes not carry out metabolism

•• Does not maintain homeostasisDoes not maintain homeostasis

•• Does not growDoes not grow

•• Cannot reproduce itselfCannot reproduce itself

•• Contains RNA Contains RNA oror DNA, not bothDNA, not both

NOPENOPE

BiomoleculesBiomolecules•• Molecules that make up living thingsMolecules that make up living things

•• All living things are made of the same 4 types of All living things are made of the same 4 types of

biomoleculesbiomolecules

•• CarbohydratesCarbohydrates

•• LipidsLipids

•• ProteinsProteins

•• Nucleic acidsNucleic acids

How Do We “Do” Biology?How Do We “Do” Biology?

Many questionsMany questions

The Scientific MethodThe Scientific Method

Many careersMany careersAll the same approachAll the same approach

The Scientific MethodThe Scientific Method•• Organized method of problem solvingOrganized method of problem solving

•• Always follows the same stepsAlways follows the same steps

•• You do this every day without realizing itYou do this every day without realizing it

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The Scientific MethodThe Scientific Method•• Example: Your car won’t startExample: Your car won’t start

•• How would you use the scientific method to find How would you use the scientific method to find

out why?out why?

The Scientific MethodThe Scientific Method•• Step 1: Make an observationStep 1: Make an observation

•• Notice the problem or phenomenon, and state Notice the problem or phenomenon, and state

it clearlyit clearly

•• What is the observation in our scenario?What is the observation in our scenario?

The Scientific MethodThe Scientific Method•• Step 2: Ask a questionStep 2: Ask a question

•• Gather information about the observation, Gather information about the observation,

and phrase it as a questionand phrase it as a question

•• The most obvious question in our scenario is The most obvious question in our scenario is

“Why won’t the car start?”“Why won’t the car start?”

The Scientific MethodThe Scientific Method•• Step 3: Formulate a hypothesisStep 3: Formulate a hypothesis

•• Proposed explanation or answer to the Proposed explanation or answer to the

questionquestion

•• What would be some hypotheses here?What would be some hypotheses here?

The Scientific MethodThe Scientific Method•• Step 4: Make a predictionStep 4: Make a prediction

•• Decide which hypothesis is most likelyDecide which hypothesis is most likely

•• Assume that the hypothesis is true, and Assume that the hypothesis is true, and

predict what will happen when you test itpredict what will happen when you test it

•• Example: The car battery is probably dead; Example: The car battery is probably dead;

if I jump it, the car will startif I jump it, the car will start

The Scientific MethodThe Scientific Method•• Step 5: Test the hypothesis by experimentStep 5: Test the hypothesis by experiment

•• Manipulate only one variableManipulate only one variable

•• Goal is to support or refute the hypothesisGoal is to support or refute the hypothesis

•• Multiple experiments are requiredMultiple experiments are required

•• Results must be repeatableResults must be repeatable

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IMPORTANT!!IMPORTANT!!•• Key to designing a good experimentKey to designing a good experiment

•• No matter the outcome, you will have new, No matter the outcome, you will have new,

useful informationuseful information

•• What is a good experiment here?What is a good experiment here?

•• A bad one?A bad one?

The Scientific MethodThe Scientific Method•• Step 6: Draw a conclusion about the validity of Step 6: Draw a conclusion about the validity of

the hypothesisthe hypothesis

•• Do the results support the hypothesis?Do the results support the hypothesis?

•• Example: We jump the car and it startsExample: We jump the car and it starts

•• Our hypothesis is supportedOur hypothesis is supported

•• What if it doesn’t start? Now what?What if it doesn’t start? Now what?

oror

The Scientific MethodThe Scientific Method•• Revise the hypothesis and repeatRevise the hypothesis and repeat

•• Example: Maybe it’s out of gasExample: Maybe it’s out of gas

The Scientific MethodThe Scientific Method•• Scientists repeat this process many timesScientists repeat this process many times

•• Gradually accumulate knowledge to understand Gradually accumulate knowledge to understand

some part of naturesome part of nature

6. Conclusion6. Conclusion

1. Observation1. Observation

2. Question2. Question

3. Hypothesis3. Hypothesis

4. Prediction4. Prediction

5. Experiment5. Experiment

Revise and Revise and

repeatrepeat

The Scientific Method at WorkThe Scientific Method at Work•• Classic experiment by Francisco Classic experiment by Francisco RediRedi (1621(1621--1697)1697)

•• Known that maggots appear on spoiled meatKnown that maggots appear on spoiled meat

•• Thought to be proof of spontaneous generationThought to be proof of spontaneous generation

The Scientific Method at WorkThe Scientific Method at Work1.1. ObservationObservation

•• Flies swarm around meat; maggots appear on meatFlies swarm around meat; maggots appear on meat

2.2. QuestionQuestion

•• Where do the maggots come from?Where do the maggots come from?

3.3. HypothesisHypothesis

•• Maggots come from fliesMaggots come from flies

4.4. PredictionPrediction

•• Keeping flies away from meat will prevent the Keeping flies away from meat will prevent the maggots from appearingmaggots from appearing

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The Scientific Method at WorkThe Scientific Method at Work5. Experiment5. Experiment

Obtain two identical Obtain two identical

jars and two pieces of jars and two pieces of

meatmeat

Leave the jar Leave the jar

uncovereduncovered

Seal the jarSeal the jar

Maggots appear on Maggots appear on

meatmeat

No maggots appearNo maggots appear

Control situationControl situation Experimental situationExperimental situation

Place meat in each jarPlace meat in each jar

The Scientific Method at WorkThe Scientific Method at Work6.6. ConclusionConclusion

•• Maggots do not generate spontaneouslyMaggots do not generate spontaneously

•• But does this really prove that the maggots come But does this really prove that the maggots come from flies?from flies?

7.7. Revise and repeatRevise and repeat

The Scientific Method at WorkThe Scientific Method at Work5. Experiment5. Experiment

Obtain two identical Obtain two identical

jars and two pieces of jars and two pieces of

meatmeat

Leave the jar Leave the jar

uncovereduncovered

Place gauze on the jarPlace gauze on the jar

Maggots appear on Maggots appear on

meatmeat

Maggots appear on Maggots appear on

gauze, not on meatgauze, not on meat

Control situationControl situation Experimental situationExperimental situation

Place meat in each jarPlace meat in each jar

The Scientific Method at WorkThe Scientific Method at Work6.6. ConclusionConclusion

•• Maggots come from fliesMaggots come from flies

More Science TermsMore Science Terms•• HypothesisHypothesis

•• Educated guess based on prior observationsEducated guess based on prior observations

•• TheoryTheory

•• A generalization based on many observations A generalization based on many observations

and experimentsand experiments

•• Scientific theoryScientific theory

•• A wellA well--tested, verified set of hypotheses that tested, verified set of hypotheses that

fit together and have yet to be disprovedfit together and have yet to be disproved

•• LawLaw

•• An observation with no known exceptionsAn observation with no known exceptions

More Science TermsMore Science Terms•• Scientific theoriesScientific theories

•• Cell theoryCell theory

•• Germ theoryGerm theory

•• Theory of evolutionTheory of evolution

•• Atomic theoryAtomic theory

•• LawsLaws

•• GravityGravity

•• Conservation of massConservation of mass