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Biology in the 21st Century

Ch. 1

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1.1 The Study of Life

Incredible diversity on earth

Bottoms of oceans

Ice shelves

Tropical rain forests

Deserts

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Diversity

Small like bacteria

Huge like blue

whale!

Single celled

Multi-celled

Heterotrophic

Autotrophic

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Biosphere

All living organisms and all the places they

are found on earth

Land environments:

Deserts

Grasslands

Forests

Water environments:

Fresh

Salt

Atmosphere

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Biosphere

Includes even strange

places!!!

Ex:

Inside of your nose

Fungi and bacteria love to

live here!

Between your toes

On your cell phone key

pads . . .

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Biodiversity

The variety of life across a biosphere

Generally:

Increases as latitude decreases (closer to equator)

Warmer temperatures

Less variation in temperatures

Organisms grow larger – More food

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Where are the tropics?

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Species

Several definitions . . .

:: A particular type of living thing that can reproduce by interbreeding among themselves

~ 2 million identified

> ½ are insects

Millions to be discovered!

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Every year . . .

~10,000 new species discovered

~ 50,000 species become extinct

Sometimes, the “extinct” species is discovered again:

Ivory-billed woodpecker

– “extinct” in 1944

– Discovered again in Arkansas in 2004

International video of biodiversity 8:27

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Biology

Study of all life forms (organisms)

Organism – any individual living thing

Life is not simple to define

Ex: viruses show some characteristics

of life but not all . . .

Classify as alive or dead?

Still controversy

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Cell

Basic unit of life All organisms = 1 or more

Unicellular (one celled) = most common!

Multicellular = cells with specialized functions

Ex: Muscle cells contract

Nerve cells send impulses

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Energy

Ability to cause change or do work

Chemical energy – used by all living things

Autotrophs – make own energy

Heterotrophs – eat organisms to obtain energy

Metabolism – sum of all chemical

processes that build up or break down

materials

Must have energy!

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Response to Environment

All organisms react to stimuli

Light, touch, sound

Survival tactic

Ex: Eyes when exposed to bright light

Plant grows toward light

Fly scoots away before capture

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Reproduction and Development

Organisms must be able

to make more of their

kind

DNA is passed on

Deoxyribonucleic acid

Genetic material

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Reproduction and Development

Unicellular organisms

Cell divides into two

Exact same DNA

Multicellular

organisms

Often DNA comes

from two parents

½ from each

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Development

Allows organisms

to:

Mature

Reproduce

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What characteristics are shared by

ALL living things???

1) one or more cells

2) need energy

3) respond to environment

4) ability to reproduce

The Biology Song.mp4

3 min

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1.2 Unifying Themes

Theme – a concept that comes up over and over again

Connect different areas of biology

Topics may SEEM unrelated

But there is always a common thread

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All levels have systems w related

parts

System organized group of

related parts that interact to form

a whole

Must be arranged correctly to work

Characteristics of organism

determined

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Systems

Exist at all levels:

Molecule Ex: chemical

Cell heart cell

Tissue cardiac muscle

Organ heart

Organ systems cardiovascular system

Organism YOU!

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Ecosystem

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Ecosystem

Different species

interact w each

other and physical

environment

Can be large or

small area

Ex:

Coral reef

Rotting log

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Structure and Function

Shape directly relates to

what it does

Ex:

Teeth = sharp = chewing

Heart = muscular =

constant work

Hands = mobile = grasping

Form fits function!

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Explain How: Form = Function

Red Blood Cells

Nerve Cells

Foot

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Homeostasis

Maintaining constant internal

conditions despite what is

happening outside

Temperature

Blood sugar

Acidity (Ph)

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Homeostasis

Can = loss of life if not

maintained

Cells function best in limited

conditions

Ex:

Maintaining body temperature

What happens when you get cold?

– Hot?

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Evolution

Change of living things over

time

Theory of Evolution

idea that complicated species

evolved from less

complicated species

Not proven

Not agreed upon by all

scientists

Charles Darwin

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Natural Selection

A trait may allow some

individuals to survive

more easily

Survivors reproduce

more

Adaptation - A trait

that is passed on to

offspring because it

gives an advantage

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Adaptation

Different populations

of same species

might have different

adaptations in

different

environments

Eventually may not

be able to interbreed

Leads to new species

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Adaptation

Occur over many generations

Caused by environmental pressures

Not due to choices made by organisms

Long term response to environment

Does not necessarily lead to higher complexity

No special endpoint

Continual

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Unity and Diversity

Similarities of life

Diverse organisms, but

common characteristics

What is responsible for such a

complex network of life?

Science gives us insight and

continually raises questions

Evolution. . . 1:46 clip

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1.3 Scientific Process

Biology requires inquiry

Based on curiosity and skepticism

Skepticism – use of critical and

logical thinking to evaluate results and

conclusion

Requires evidence

Exchange of data

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Observations

Careful

Systematic

Use senses

Use other tools

Computers

Microscopes

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Data

Observations can be recorded as such

Two types of data

Qualitative – sights, sounds, smells

Report WHAT happened but not HOW

Quantitative – can be measured or counted

Mass, volume, temp, etc

Can be expressed as a number

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Hypothesis

Proposed answer for scientific

question

Must be specific and testable

Use scientific literature, observations,

and data

Poison dart frog clip 8:00

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Testing Hypotheses

One test is not usually enough

Biological systems are

variable

Testing many times takes these

variances into account

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Hypotheses Outcomes

2 Possible:

Nonsignificant – data show no effect

OR could have happened by chance

Rejected

Still useful

– Develop new hypotheses!

Statistically Significant – effect not

likely due to chance

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Evaluation of methods/results

Peer review – other scientists go over

How was:

Experiment done?

Data analyzed?

Did conclusion support data?

Bias?

Results may then be accepted

Lead to new experiments

Continuous cycle

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Experiments

Used to test hypotheses

Find out how something

happens

Use variables to find out

cause-and-effect

relationships

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Variables

Independent – manipulated by scientist

Usually only one in experiment

Dependent observed and measured

The experimental data that we record

Changes in dependent variables “depend upon” the manipulation of independent variables

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Remember:

Independent variable affects

dependent variable

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Constants

Conditions that do not

change during

experiment

Control Group –

conditions in this group

remain constant

Compare other groups to

this group

“baseline” group

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Theory

Proposed explanation for wide range

of observations and experimental

results

Supported by evidence

NOT a speculation

May become widely accepted

NOT proven

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Theory

Not easily accepted

Never “proved”

Always subject to change or

replacement

Ex: Germ theory

Used to think illness was caused by

imbalance in humors

Then realized there were microorganisms

Now studying prions and viruses

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Law

Truth that is valid everywhere in the

universe

Ex: law of conservation of energy

Energy may change form, but cannot be

created nor destroyed

Describes nature of energy, but does not

give explanations

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1.4 Biologists’ Tools & Tech

Cells not

discovered until

late 1600s

Microscope

invented

Allows study of

enlarged images

Changed

biological studies

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Microscopes

Light microscopes (LM)

magnify up to 1500x - 2000x

See living or preserved specimen

Samples often stained

See pg. 21 images

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Microscopes

Electron microscopes

1950s

Up to 500,000x magnification

Study individual proteins

Cannot study living specimens In a vacuum

Black and white images seen on computer

Artificial color added for our viewing pleasure

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Electron Microscopes

Scanning Electron Microscope (SEM)

Uses beam of e- to scan surface of specimen

Usually surface coated w thin layer of metal

– Deflects e-

Computer forms 3D image of deflected e-

Used in forensic science – Fingerprints, gunshot residue,

forged money

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Electron Microscopes

Transmission Electron

Microscope (TEM)

Transmits e- thru thin

slice of specimen

2D image

Mitochondria section image

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Medical Imaging

X-rays

Pass thru soft tissue (skin, muscle)

Absorbed by hard tissue (bone, teeth)

Great for looking at skeleton

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Medical Imaging

MRIs (magnetic resonance imaging)

Magnetic field produces cross-sections

Used to view soft tissues

fMRI – functional MRI

Used to show brain activity

MRI of knee joint

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Computers

Used to model complex

systems

Ex: atoms in a cell

How water flows thru cell

membrane

Ex: how diseases spread

How far?

How fast?

Who will get it?

When?

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Molecular Genetics

Study and manipulation of

DNA on a molecular level

Study:

Evolution

Ecology

Biochemistry

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Molecular Genetics

40 years ago:

Did not know how genetic code

worked

Now:

Manipulate genes

Implant from one species to

another

Replace faulty genes

Gene – segment of DNA that

codes for a trait

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Genomics

Study and comparison of genomes

both within and across species

Combines molecular genetics with

computers

All info is managed by computers

Entire genomes known

Genome – entire DNA sequence of an

organism

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Data Mining

Searching computer data

bases

Find DNA patterns,

similarities, and differences

This is all new within the last

20 years

What will your kids be

learning about in school????

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1.5 Biology and Your Future

Many of your decisions involve

biology

Personal and societal

Medical research

Pollution

Health

Endangered species

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Bio and Your Health

Food and water

contamination

Food poisoning

Vitamin and mineral

deficiencies

Food allergies

Can be life threatening

Ex: peanuts, shellfish

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Bio and Your Health

How much to eat?

What to eat?

~60% of adults in the U.S. are

overweight or obese

Increased risk:

Diabetes

Stroke

Heart disease

Breast cancer

Colon cancer

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Bio and Lifestyle Choices

Sunscreen

Exercise

Tobacco

Illegal drugs

Alcohol

How do these impact my longevity?

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Funky Frogs

1995

Students discovered frogs w

abnormalities in MN

What caused the problem?

Parasitic infection

Is it linked to chemical

produced by factories too?

What action does one take?

Deformed Frogs 4:18

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Understanding Biology Helps!

Ask questions

Make informed decision

Take proper action

Pollution

Biodiversity

Habitat preservation

Natural resource use

You play an important role

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Biotechnology

The use and application of living things and biological processes

Some used for centuries

Ex: making bread and cheese

Some recent

DNA testing

Medicine

Agriculture

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Biotech and Organisms

Domestic animals and

plants

Selective breeding has been

occurring for centuries

Choose organisms to breed

that have desired traits

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Transgenic Organisms

Have genes from more than one

species OR have altered copies

of their own genes

Ex:

Bacteria make insulin

Sheep and cows make antibodies

and proteins

Genetically modified foods

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GM Food

Benefits:

More

Extra nutrition

Resistant to pesticides, drought, etc

Risks:

Gene spread to wild plants

Healthy?

Effects not fully known

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Human Genetic Screening

Analysis of genes to ID variations

Benefits:

Determine disease risk in offspring

Treat illness before it occurs

Risks:

Access

Insurability

Choose child’s characteristics

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Unanswered Questions

1953 – structure of DNA discovered

2003 – entire human genome

known

Cure for cancer? AIDS?

Extreme environments

Bottom of Gulf of Mexico

Frozen methane

– Methane worms!

Life on other planets?