introduction: themes in the study of life - mcccnatalep/documents/ch1intro_post.pdf · biology...
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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
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.