Exam #1 Flashcards
Characteristics of life
Composed of cells and unique molecular structure
Are viruses alive?
Very small- 1/100th size of a of a bacterial cell, not a cell though. “Protein coat” takes from membrane host cell. Contains some genetic material but not enough to replicate by itself. Must infect other organisms and the use their cells and DNA to replicate.
NO THEY ARE NOT ALIVE BECAUSE THEY CAN’T REPRODUCE ON THEIR OWN!
Linnaean taxonomy- categorizing life by genetic relatedness
Do Kings Play Chess On Fine Grain Sand
Domain Kingdom Phylum Class Order Family Genus Species
Three domains of life
Bacteria
Eukarya
Archaea
Taxonomy of a black bear
Eukarya Anamalia Chordata Mammalia Carnivora Ursidae Arctos
Human taxonomy
Eukarya Anamalia Chordata Mammalia Primates Hominidae Homo Sapiens
Members of the hominidae
Mountain gorilla Lowland gorilla Chimpanzees Sumatran orangutan Bonobo Bornean orangutan
What is biology?
Bio=life Logia= study of
Study of life
Life is defined by?
The characteristics of life
Life can be organized
In many ways
Ex:
Increasing complexity- biological levels of organization
Genetic relatedness- Linnaean taxonomy
What is science ?
An objective method of understanding the natural world and Abbie of knowledge
What is a theory ?
Collections of unifying insights (explanations) and supporting facts.
Theories have explanatory power
Facts support theories
Theory is a collection of principals, supported by evidence (facts) that explains some aspect or phenomenon of nature.
What is the scientific method?
Based on observations and measurements or (experiments)
From observations come questions
From questions, formulate hypothesis
Test validity of hypothesis through further observation of experimentation.
Hypothesis ?
Plausible explanation for a natural phenomenon
Science is a process
Observation ➡️ hypothesis ➡️ prediction ➡️ experiment/further observation ➡️ results ➡️ conclusion
If the the results support the conclusion make a new prediction!
If the results don’t support the conclusion revise hypothesis!
Louis pastuers
Test of the spontaneous generation of life!
People in the early 1800 believed life regularly arose from the coming together of chemicals.
Pastuers hypothesis - cases of spontaneous generation of life could be explain by microscopic airborne organisms.
Scientific method
A statement is “scientific” if an objective method can be stated by which it can be disproven
Testable
Refutable
Repeatable
Other ways of perceiving the world
Religious, aesthetic, ethical
Not scientific -often useful perspectives
Assertions are not disproven in the scientific sense
And are based ultimately on- faith, beliefs, cultural, or personal values
Science does not address questions that are
Metaphysical (outside the physical world) or involve value judgements, such as issues of beauty or good and evil
Pseudoscience ?
Pseudo = false
Often referred to as “junk science”
Presented as scientifically valid but in fact not scientific.
Untestable
Lack empirical support
Based on faulty reasoning
Poor methodology
When does chemistry merge with life?
At cellular level
What is matter?
Anything that takes up space and mass.
Liquids
Solids
Gases
What is an element?
Pure form of matter containing only one kind of atom
What is an atom?
Smallest particle of an element. It cannot be broken down by ordinary chemical process.
Earth is made up of <100 elements + some others
Subatomic particles ?
Protons
Neutrons
Elections
Protons
Positive charge, have mass, used to determine identity.
Different # of protons = different element
Neutrons
No charge, have mass, # can change
Electrons
Negative charge, mass is almost not there but still there, # can change
Orbit around nucleus shell “energy levels” of electrons
Inner shell may hold 2 electrons and it has to fill first
Outer shell holds up to 8
How big are atoms
Extremely small
How much of the mass of an atom does the nucleus contain?
99.9%
Elemental composition of organisms
Organism (sea lion) ⬇️ Organ (brain) ⬇️ Cell (neuron) ⬇️ Molecule (water) ⬇️ Atom (hydrogen)
Number of elements important to life?
25
Atomic number?
of protons
Atomic mass?
of protons and neutrons
Elements in humans
CHNOPS Carbon 19.37% Hydrogen 9.31% Nitrogen 5.14% Oxygen 62.81% Phosphorus 0.63% Sulfur 0.64%
How many protons in carbon?
6
Isotopes
Atoms of a particular element all have the same number of protons but differ in # of neutrons
Carbon 12, 13, and 14
12 is stable because it has 6 protons, 6 neutrons, and 6 elections
13 is still considered stable
14 is radioactive
Valence electrons?
Electrons in the outer most shell
7 P,N, and E =
Nitrogen
Chemical bonds
Bonds between atoms form chemical energy
Atoms form bonds because it moves them to a more stable state
Atoms have a propensity to attain complete shells thus becoming more stable
Molecular formulas
Water=
Oxygen gas=
Glucose=
Water = H2O
Oxygen gas= O2
Glucose = C6H12O6
Three types of bonds ?
Covalent
Ionic
Hydrogen
Covalent bond
Sharing of electrons between atoms
Ex: an atom of oxygen is almost always bound to some other atom(s), often O2 or H2O
Law of conservation of mass?
Matter can not be neither created more destroyed in chemical reactions.
E=mc^2
Energy is the same law. Cannot be created or destroyed
Molecule?
Group of atoms bonded together it is the smallest fundamental unit of chemical compounds.
Atoms may be the same element or different
Ionic bonds
Transfer of electrons between atoms.
In neutral atoms: electrons = protons
Lose or gain of electrons and an atom takes on an electrical charge either (- or +)
Ion= charged atom
Oppositely charges atoms attract
Ex: sodium chloride sodium gives an electron to make salt
Hydrogen bonds
Bonds between already covalently bonded hydrogen and an electronegative atom.
Polarity
In water, the oxygen atom is much more electronegative than the two hydrogen atoms covalently bonded to it.
Gives water unique properties
Great solvent
Polar vs nonpolar covalent bonds
Nonpolar- where two atoms share a pair of electrons with each other.
Polar- is a type of chemical bond where a pair of electrons is unequally shared between two atoms.
Hydrogen bonding among water molecules
Already covalently bonded hydrogen with an electro negative atom.
Hydrophilic ?
Water loving!
Compounds that readily interact with what like salt
Hydrophobic
Water hating!!
Compounds that water forms around like oil
Is sodium chloride hydrophilic or hydrophobic
Well sodium chloride is salt which dissolves (ionizes) in water and it’s not attracted to negative pole but attracted to oxygen therefore hydrophilic
Is water crucial to life?
Duh, life first evolved in water.
Life first evolved in water then colonized land.
To do so m, terrestrial organisms evolved to carry a water environment with them (inside them).
Vertebrates are 70%-80% water
Terrestrial plants are 90% water
Polarity
When there is an uneven distribution of charges on the two ends of a molecule. Allows water to interact with many substances. Main transport medium for organisms.
Covalent, ionic, and hydrogen bonds type of attraction and bond strength
Covalent- sharing of electrons strongest bond!!
Ionic- transfer of electrons still a strong bond but not the strongest.
Hydrogen bond- slight attraction between already covalently bonded hydrogen and an electronegative atom has a weak bond
Acids and bases
Water molecules can disassociate to produce ions
Acids yield H+ (hydrogen ions)
Bases accept H+
Example of acid ?
Hydrogen chloride (a covalently bonded, polar molecule) when it dissociates in water.
HCL ↔️ H+ + CL-
H+ released increases these ions in the solution.
Example of a base?
NaOH disassociate in water.
NaOH ↔️ Na+ + OH-
Hydroxide ions released react with hydrogen ions in the solution
pH?
Concentration of hydrogen ions (H+) in a solution.
pH levels
0 very acidic
7 neutral
14 basic
Based on log scale, 10 fold differences
(Moles/liter) scientific notation bs decimals
Buffers ?
Substances that keep pH from changing.