Introduction: Themes in the Study of Life

Chapter 1

definitions

Evolution process of change transformed life over 3.5

billion years Biology study of living things evidence based answers

Characteristics of life

1. Regulation

Homeostasis = internal conditions relatively constant under changing environmental conditions

Ex. body temperature

2. Energy processing • Capture, Use, Store

Heart rate max 1200 b/m

3. Growth and Development

4. Reproduction Produce next generation

FYI • Female birds, rabbits, reptiles can

store sperm for months • Tilapia (fish) brood eggs in the mouth • Reef fish can switch sex in minutes • Kangaroo raise young in a ventral

pouch

5. Response to environment stimulus response

6. Evolutionary adaptation • Evolve over many generations • Hereditable traits lungfish

7. Order Arrangement of structures

Function Find 5 of the 7 Find the properties of

life in video on frogs

The biosphere

Communities

Populations

Organisms

Ecosystems

Organs and organ systems

Cells

Cell

Organelles

Atoms

Molecules Tissues

Life studied at different organizational levels

power of ten Enhanced scale of universe

The biosphere

Biosphere - all environments on Earth that support life What are these environments?

Ecosystem - living things in an area + nonliving List 2 ecosystems: _______

Communities - all living species in an ecosystem

Population - all individuals of a species in a specific area

Organisms

Organism - individual

Amoeba has properties of life Elephant has properties of life

Organ system - organs work together for specific function

• Organ – has multiple tissue types which function together

Tissues – group of like cells that work together

Dermal tissue

Myocardial tissue

• Cell –basic unit of life – Organisms unicellular or

multicellular

• Organelles – functional components of a cell

Molecules – consist of two or more atoms H2O NaCl C6H12O6 Atom– smallest unit of matter that retains the properties of an element

Chlorophyll C55H72O5N4Mg

Theme: Emergent properties

• Arrangement and interaction of parts in complex organisms lead to complex properties

FYI: Emergent properties of snowflakes (physics)

Reductionism • Study parts of system

Systems Biology study of system

ex. a leaf, a brain

FYI: Example of systems biology

Nucleus Interaction of proteins in a eukaryotic cell

Themes: Organisms interact with environments, exchanging matter, energy 1. Cycling of nutrients Carbon cycle

2. Flow of energy sunlight producers consumers decomposers

www.bcgrasslands.org

Sunlight

Ecosystem

Heat

Heat

Cycling of

chemical nutrients

Producers (plants and other photosynthetic

organisms)

Chemical energy

Consumers (such as animals)

ECOSYSTEM DYNAMICS Cycling of nutrients and Energy flow

heat

Heat is a waste product

Energy has different forms – light, chemical, kinetic, thermal

Light chemical ATP motion heat

• Theme: Structure and function correlated – bird bones have spaces = light weight

Theme: Cells are basic unit of life • Cells:

– Cell membrane – DNA – Replicate

Yeast Bacteria Animal Plant

Two types of cells Eukaryotic cell

– Membrane-enclosed organelles, and nucleus – Plantae, Animalia, Fungi, Protista

Prokaryotic cell – Simpler, smaller – No nucleus or organelles – Bacteria, Archaea

FYI: Who knew? • 500 to 1000 species of bacteria live in the human

large intestine, skin, mouth, and other locations

• Most bacteria in the gut are anaerobes (do not use oxygen)

• 2 species of Archaea are present in the human gut, they are methanogens.

• No known Archaea cause disease

• Theme: The continuity of life is based on heritable information (DNA)

• Chromosomes – Strands of DNA

• Genes – DNA that encodes proteins – Proteins determine traits

Genome = all the DNA in a cell (has all instructions)

DNA

Cell

Nuclei containing DNA

Sperm cell

Egg cell

Fertilized egg with DNA from both parents

Embryo’s cells with copies of inherited DNA

Offspring with traits inherited from both parents

DNA is inherited Before a cell divides, DNA is copied

The human genome and others have been sequenced

http://imgs.sfgate.com/c/pictures/2004/08/30/mn_genome30gr.jpg

Theme: Feedback mechanisms • Allow body to self-regulate • Negative feedback

– as more of product accumulates, the process that creates it slows and less product produced

Negative feedback: insulin action

Describe how the sweating response is negative feedback

D

D D

D

C

B

A

Enzyme 1

Enzyme 2

Enzyme 3

–

• Positive feedback – As more of product accumulates, the process that

creates it speeds up and more product produced

Positive feedback: uterine contractions

Z

Enzyme 4

Enzyme 5

Enzyme 6 Z

Z

Z

Y

X

W

+

Core Theme: Evolution “Nothing in biology makes sense except in the light of evolution”—

Theodosius Dobzhansky

All organisms living on Earth are descendants of common ancestors – Shared (homologous) features

• Ex. Backbone in vertebrates

Use shared features to group organisms by evolutionary relatedness

– Divergent features • Ex. Number of toes in foot

Evolutionary biology is supported by:

• Embryology • Paleontology • Biogeography • Anatomy • Physics • Botany • Biochemistry • Molecular biology

Crash course evolution

Grouping Species

• Taxonomy – name and classify species into groups

Species Genus Family Order Class Phylum Kingdom Domain

Ursus americanus (American black bear)

Ursus

Ursidae

Carnivora

Mammalia

Chordata

Animalia

Eukarya

Ursus americana Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya

September 15, 2009 Niger --Scientists excavate the 43-foot-long (13-meter-long) skeleton of a new species of sauropod--or four-legged plant-eater. Spinophorosaurus nigerensis, had a tail studded with bony spikes that the animal likely swung at predators

FYI

• Fossil whales (palenotology)

Homologous structures Ex. Mammalian limb

• Charles Darwin On the Origin of Species by Means of Natural Selection in 1859

• 2 main points: 1. Descent with modification

• Species share a common ancestor

100 mya Mesozoic ancestor to mammals

FYI: horse evolution

FYI: Extant (living) horses

FYI: Evolutionary tree

COMMON ANCESTOR

Warbler

finches

Insect-eaters Seed-eater

Bud-eater

Insect-eaters

Tree finches

Green warbler finch Certhidea olivacea

Gray warbler finch Certhidea fusca

Sharp-beaked ground finch Geospiza difficilis Vegetarian finch Platyspiza crassirostris

Mangrove finch Cactospiza heliobates

Woodpecker finch Cactospiza pallida

Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus Large cactus ground finch Geospiza conirostris Cactus ground finch Geospiza scandens

Small ground finch Geospiza fulig inosa

Medium ground finch Geospiza fortis

Large ground finch Geospiza magnirostris

Ground

finches

Seed-eaters

Cactus-

flower-eaters

Evolutionary tree shows ancestral relationships Galapagos (Darwin’s) finches

• natural selection – ancestral species descendent species – Ex. finch species of Galápagos Islands

2. Natural selection mechanism of evolution

Natural Selection a. Traits vary randomly

b. More offspring produced than can survive

Elephants start to breed at around age 30. They breed to 90 years old. In that time, one elephant has 6 offspring. Darwin calculated that after 750 years, there would be 19 million desendants from the original breeding pair IF all survived.

"In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long- continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work".

c. Competition for:

Mates Food Habitat Water

d. Reproductive fitness is: e. Traits are heritable

Number of offspring Ability to attract mate Health Offspring survival Avoiding predators Avoiding parasites

• Because of natural selection, in time, more individuals in a population will have advantageous traits

• No acquired traits inherited!

• Natural selection results in adaptations Ex. Bat wings

Examples of adaptations

Diversity of Life

• Evolution unifies biology ~1.8 million extant species have been identified (could be >10 million) FYI 6,300 bacteria 10,000 fungi 290,000 plants 52,000 vertebrates 1 million insects New species 2012

Three Domains of Life

• Domain Bacteria and Domain Archaea - Prokaryotic cells

• Domain Eukarya – Eukaryotic cells

Anthrax T. aquaticus Paramecium

Methanosarcinia rumen is anaerobic, produces methane, is found in rumen of cows

Staphylothermus is found in 98oC hot spring, thrives on sulfur

Halococcus salfodinae lives in high salt

http://www.microbiologyonline.org.uk

Methanobrevibacter smithii lives in the human gut digests polysaccharides

Amoeba in motion yeast

(a) DOMAIN BACTERIA

(b) DOMAIN ARCHAEA

(c) DOMAIN EUKARYA

Kingdom Protista

Kingdom Fungi Kingdom Plantae

Kingdom Animalia

Kingdom Plantae

Eukarya includes kingdoms:

Plantae Fungi Animalia Protista

THE SCIENTIFIC METHOD

• Inquiry – search for information and explanation

• 2 types of scientific inquiry: – discovery

• Describe nature

– hypothesis-based • Test hypothesis

Hypothesis - tentative answer to well-framed question, an educated guess

• leads to predictions that can be tested

Hypotheses

• must be testable • test one hypothesis at a time • Must be falsifiable • does not need to be correct

More in lab

• Independent (experimental) variable • the one aspect that varies among test groups

• Control group – baseline group for comparison

• Controlled variables – Held constant, do not vary among groups

• Dependent variable – What is measured

EXAMPLE • 2005, NJEM published results of study of Echinacea for

prevention and treatment of the common cold.

• The research team tested 3 preparations of the roots of a Echinacea angustifolia. They extracted the root using procedures that represent some of the different ways that Echinacea is used to treat colds.

• Hypothesis: • Independent variable: • Control group: • What is a placebo? • What is a double blind study?

437 healthy adult volunteers were assigned at random to receive one of the three root preparations or a placebo. The volunteers received Echinacea or a placebo in two phases: a preventive phase and a treatment phase. The preventive phase lasted 7 days. On the 7th day, the volunteers were exposed to a nasal spray with a virus that induces a cold in ~ 2 days. Then, volunteers were isolated for 5 days while the research team observed and tested them as to the appearance and severity of cold signs and symptoms. Controlled variables: Dependent variable(s):

100 nm = 0.0000001 meters Scientific notation?

The researchers found that none of the 3 preparations of Echinacea at the 900 mg per day dose had effects on whether volunteers became infected with the cold virus The 3 preparations did not affect the severity or duration of symptoms among those who developed colds. Critics of this study believe the dose of E. angustifolia used was too low.

• Hypothesis – Zinc helps people

recover from colds Y axis??

Data • Qualitative = descriptions • Quantitative = measurements-organized into

tables and graphs

http://thesituationist.files.wordpress.com/2008/02/jane-goodall.jpg

Quantitative: Qualitative:

Limitations of Science

• Results must be repeatable • Science investigates natural world • Use natural processes in the explanation • Evidence based

Which hypothesis are testable/have evidence to support? Some plants eat meat. Extraterrestrial beings have visited Earth. Without light green plants will die. Humanoid giants once lived on earth Euthanasia is the right thing to do for terminally ill patients Meditation can extend the length of life Sunscreen prevents skin burning Mermaids swim in the ocean The flu virus mutates every year

Theories in Science

• Theory – Broader in scope than hypothesis – Can lead to new testable hypotheses – Supported by large body of evidence

Theory of gravity Theory of evolution Theory of round earth

FYI: Summary of evidence supporting theory of round earth

• When at sea it is possible to see mountains in the distance • The sun is lower in the sky as you travel away from the tropics. • The earth throws a circular shadow on the moon during a lunar

eclipse. • It is possible to circumnavigate the world. • An artifical satellite can circle the earth continuously • The earth appears as a disc on photographs taken from space,

regardless of the vantage point.