Download Introduction to Biology 101

Lecture 1 Biol-101 Chapter 1
Introduction
1. Organisms are adapted to the environments they live in.
2. These adaptations are the result of evolution, the fundamental organizing principle of biology.
3. Biologists ask questions about the living world and seeking science-based answers. Biology is the
scientific study of life.
4. What is life? The phenomenon of life defies a simple, one-sentence definition. We recognize life by
what living things do.
The study of life reveals 5 common unifying themes.
1. Organization
2. Information
3. Energy and Matter
4. Interactions
5. Evolution
Biological Organization
1. Smaller entities interact with one another and form bigger entities that can perform additional
functions.
2. Biological organization is based on a hierarchy of structural levels, each building on the levels below.
a. Atoms Molecules  Cells  Tissues  Organs  Organ-systems  Individual 
Population  Community  Ecosystem  Biosphere
b. Hydrogen, Oxygen, and Carbon are atoms. Atoms combine to make complex biological
molecules like proteins and DNA.
c. Complex molecules arrange into membranes and organelles like mitochondria and
chloroplasts inside cells. The membranes and organelles are main building blocks of cells.
d. A living thing may be made of one cell or an aggregate of cells organized into tissues, organs
and organ-systems.
e. Whether multicellular or unicellular, all organisms must accomplish the same functions:
uptake and processing of nutrients, excretion of wastes, response to environmental stimuli,
and reproduction.
f. Organisms make up populations, localized groups of organisms belonging to the same
species.
g. Populations of several species in the same area combine to form a biological community.
h. Populations interact with their physical environment to form an ecosystem.
i. The biosphere consists of all the environments on Earth that are inhabited by life.
j. Emergent properties are created by new arrangements and interactions of parts as
complexity increases.
3. Reductionism is the approach of reducing complex systems to simpler components that are more
manageable to study.
k. Biologists must balance the reductionist strategy with the larger-scale, holistic objective of
understanding the emergent properties of life—how all the parts of biological systems are
functionally integrated.
l.
m.
n.
o.
p.
Biologists are beginning to complement reductionism with new strategies for studying whole
systems.
The ultimate goal of systems biology is to model the dynamic behavior of whole biological
systems based on a study of the interactions among the system’s parts.
The ultimate aim of systems biology is to answer large-scale questions. For example, how
might a gradual increase in atmospheric carbon dioxide alter ecosystems and the entire
biosphere?
Structure and function are correlated at all levels of biological organization.
Form fits function; how a device works is correlated with its structure. Wings and flight
q. The match between form and function in the structure of life is explained by natural selection.
4. Cells are an organism’s basic units of structure and function.
a. The cell is the lowest level of structure that can perform all the activities of life.
b. The activities of organisms are all based on cell activities.
c. Understanding how cells work is a major research focus of modern biology.
1. All cells share certain characteristics.
○ Every cell is enclosed by a membrane that regulates the passage of materials between the cell
and its surroundings.
○ Every cell uses DNA as its genetic information.
2. There are two basic types of cells: prokaryotic cells and eukaryotic cells.
○ The cells of the two groups of microorganisms called bacteria and archaea are prokaryotic.
○ All other forms of life have more complex eukaryotic cells.
3. A eukaryotic cell is subdivided by internal membranes into various membrane-enclosed
organelles.
○ In most eukaryotic cells, the largest organelle is the nucleus, which contains the cell’s DNA
as chromosomes.
○ The other organelles are located in the cytoplasm, the entire region between the nucleus and
the outer membrane of the cell.
4. Prokaryotic cells are much simpler and smaller than eukaryotic cells.
○ In a prokaryotic cell, DNA is not separated from the cytoplasm in a nucleus.
○ There are no membrane-enclosed organelles in the cytoplasm.
Information
5. Life’s processes involve the expression and transmission of genetic information.
6. DNA provides the blueprints for making proteins, and proteins serve as the tools that actually build
and maintain the cell and carry out its activities.
7. Genes are fragments of DNA. Each gene has information for one polypeptide. A protein is formed of
one or more polypeptides. Cells function by making proteins from genes.
8. Transcription is formation of m-RNA from DNA. Translation is synthesis of a chain of amino acids
from m-RNA. Chain of amino acids undergoes folding to form a protein.
9. Gene Expression: DNA  m-RNA  chain of amino acids  protein (m-RNA is messenger RNA).
10. Cells reproduce by replicating DNA, the process to make 2 DNA from 1 DNA.
11. Nucleotides are building blocks for making DNA or RNA. RNA has pentose (5C) sugar Ribose
(C5H10O5). DNA has Deoxyribose pentose sugar with one less oxygen. (C5H10O4). 4 nucleotides of DNA
are thymine, cytosine, adenine and guanine (TCAG).
12. Information in DNA is in the specific sequence of 4 nucleotides.
13. DNA is spooled around small basic protein Histones to form Chromatin. Thin fibers of chromatin fold
and pack into thick strands, Chromosomes. Human cells have 46 chromosomes and egg and sperm
has 23 chromosomes.
14. DNA replicates and cells divide to form trillions of cells in each human body.
15. Genome is the total number of genes present in all individuals of a species. The large scale study of
genomes is Genomics. (another example of systems biology)
Energy and Matter
16. Life requires the transfer and transformation of energy and matter.
17. Living things constantly transform one form of energy to another. Chloroplasts of Producers (plants,
algae) transform sunlight into chemical energy of glucose from CO2 and H2O. Animals feed on plants
and get glucose. Muscles of animals use O2 to break glucose back into CO2 and water. Plants get
water and minerals from soil and CO2 from air. Plants release O2 into air. Animals feed on plants and
use O2 from air and release CO2 into it. Therefore, chemicals cycle in the ecosystem.
18. Energy flows from Sun  producers  consumers  decomposers and get lost in unusable form of
heat from ecosystem and ultimately biosphere.
19. Chemicals constantly cycle between biotic and abiotic components of an ecosystem; but energy
must constantly flow from sunlight into ecosystem because it is regularly lost as unusable heat from
the ecosystem.
Interactions
20. From ecosystems to molecules, interactions are important in biological systems.
21. In ecosystems organisms interact with other organisms and physical environment.
22. Photosynthesis and respiration maintain the balance of O2 and CO2 in biosphere. Plants also affect
rain and soil composition. Animals feed on plants and find shelter in them. Animals help in
reproduction of plants.
23. One main interaction in food chains is predation but parasitism and symbiosis are other examples.
24. Interactions between organisms ultimately result in the cycling of nutrients in ecosystems
25. Human interaction with environment has drastic consequences. This global warming, a major aspect
of global climate change, has already had dire effects on life forms and their habitats all over planet
Earth.
26. Molecular interactions are regulated by negative feedback. For example:
27. Increase in blood glucose  stimulates cells in pancreas  insulin  insulin makes muscle and liver
cells to absorb glucose from blood  feedback response is lowered glucose in plasma.
Evolution
28. Evolution, the core theme of biology. “Nothing in biology makes sense except in the light of
evolution”—Theodosius Dobzhansky
29. Evolution means all species of living things developed from 1 simple single celled ancestor due to
changes in DNA and adaptations to changing environment.
30. Evolution explains unity in diversity. Living things share common characters due to common ancestar
but are different due to adaptations to different local environments.
Classification
31. Documented species - 1.8 million species, thousands discovered each year.
32. Estimated total number of species – 10-100 million
33. Taxonomy is the science to classify living things into different groups. Carlous Linneaus introduced
Binomial Nomenclature, the method of giving 2 names to each species.
34. 8 major groups are used to classify species:
35. Species  Genus  family  order  class  phylum  kingdom  domain.
36. Classification is a hierarchal system. The classification for black bear is:
37. americanus  Ursus  ursidae  carnivora  mammalia  chordata  Animalia  Eukarya
38. Black bear is Ursus americanus. Polar bear is Ursus maritimus, brown bear is Ursus arctos.
39. 8 species of bears form family Ursidae and includes bears including giant panda.
40. Carnivora order has cat like (cats, hyenas, civets, mongoose, seals) and dog like (dogs, wolves, bears,
badgers, otters) carnivore animals.
Scientific Method
41. Science develops by
a) Discovering new things, processes, and phenomena by inductive reasoning, involves repeated
specific observations can lead to important generalizations. Like sun rises in the east.
b) Asking right questions: why did apple fall to ground? Newton.
c) Developing tentative explanations = hypotheses and testing them repeatedly until all wrong
ones are eliminated. Making new observations and developing new hypotheses if required.
42. Deductive reasoning: Main steps include Observation, Question, Hypothesis, Predictions, and
Testing. Conclusions result from supported or rejected hypotheses. A well-supported hypothesis
becomes a Law or Principle.
43. Control – (similar to experiment but lacks variables; helps to eliminate other hypotheses),
44. Scientist need to go back and forth in these steps especially observation, hypothesis and testing. The
text book sequence of steps of scientific method is seldom followed.
45. A scientific Theory includes 2 or more laws and is supported by testing from diverse approaches by
many scientists. For example theory of evolution, inheritance, gas theory etc.
46. A Case Study in Scientific Inquiry: Investigating Coat Coloration in Mouse Populations
47. Color patterns of animals vary widely in nature, sometimes even between members of the same
species
48. Two populations of mice belonging to the same species (Peromyscus polionotus) but with different
color patterns are found in different environments
49. The beach mouse lives on white sand dunes with sparse vegetation; the inland mouse lives on
darker soil