BIO 160 Exam 1
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Lectures 1-8: Characteristics of life, basic chemistry, water, carbon, macromolecules, carbohydrates, lipids, proteins, and nucleic acids.
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161 Terms
What is biology?
The scientific study of life
What does it mean that biological systems are self-organizing?
Their molecules, cells, and organelles can assemble without external help
What are the seven major properties of life?
Order, evolutionary adaptation, response to environment, regulation, energy processing, growth/development, and reproduction
How do organisms interact with their environment?
Organisms and their environments affect one another
Why do organisms require energy?
To perform the work necessary for life
What happens to energy as organisms use it?
It is transformed from one form to another
What is a major characteristic of eukaryotic cells?
They contain membrane-enclosed organelles
What is a major characteristic of prokaryotic cells?
They lack membrane-enclosed organelles, including a nucleus
Where is DNA located in a eukaryotic cell?
Primarily in the nucleus
Where is DNA located in a prokaryotic cell?
In the cell without being enclosed in a nucleus
What is reductionism?
Studying complex systems by breaking them into simpler components
Why can reductionism be useful in biology?
Some large-scale processes cannot be understood without knowing their molecular basis
What are the three domains of life?
Bacteria, Archaea, and Eukarya
What are Bacteria?
Diverse and widespread prokaryotes
What are Archaea?
Prokaryotes, many of which live in extreme environments
What organisms belong to Eukarya?
Protists, plants, fungi, and animals
How do plants obtain food?
They perform photosynthesis
How do fungi obtain nutrients?
They absorb nutrients after decomposing organic material
How do animals obtain nutrients?
By ingesting other organisms
What is a compound?
Two or more elements combined in a fixed ratio
How can a compound differ from its elements?
It can have completely different characteristics
Which four elements make up about 96% of living matter?
Carbon, hydrogen, oxygen, and nitrogen
About what percentage of living matter consists of elements other than CHON?
About 4%
What is an atom?
The smallest unit of matter that retains an element’s properties
What are the three relevant subatomic particles?
Protons, neutrons, and electrons
What are the charges of protons, neutrons, and electrons?
Protons = positive
Neutron= neutral
Electron = negative
What is an element’s atomic number?
The number of protons
What is mass number?
Protons + neutrons
What are isotopes?
Forms of the same element with different number of neutrons
What stays the same between isotopes of an element?
Number of protons
What do radioactive isotopes do?
Spontaneously release particles and energy
What is energy?
The capacity to cause change
What is potential energy?
Energy matter possesses because of its location or structure
Which electrons have the greatest potential energy?
Electrons farther from the nucleus
What are valence electrons?
Electrons in the outermost electron shell
Why are valence electrons important?
They determine an atom’s chemical behavior
What is an orbital?
A 3D space where an electron is found about 90% of the time
What causes a polar covalent bond?
Unequal sharing of electrons due to different electronegativities
Why is water polar?
Oxygen attracts the shared electrons more strongly than hydrogen
What partial charges occur in water?
Oxygen = partial negative
Hydrogens = partial positive
Why are weak chemical bonds important in biology?
They reinforce molecular shapes and help molecules adhere
What is a hydrogen bond?
Attraction between a partially positive H and another electronegative atom
Why is water important to life?
It is Earth’s biological medium, and all organisms require it
What makes water unusual regarding physical states?
It naturally occurs as a solid, liquid, and gas
Why can water molecules form hydrogen bonds?
Water molecules are polar
Are hydrogen bonds between liquid water molecules permanent?
No, they constantly break down and reform
What four properties of water contribute to Earth’s fitness for life?
Cohesion, temperature moderation, expansion upon freezing, and solvent versatility
What causes water’s unique properties?
Its polarity and hydrogen bonding
Why does ice float?
Ice is about 10% less dense than liquid water
Why is ice less dense than liquid water?
Hydrogen bonds become more ordered and space molecules farther apart
What would happen if ice were denser than liquid water?
It would sink and bodies of water could eventually freeze
How does water dissolve salts?
Its polar regions interact with charged ions
Which part of water is attracter to Na+?
The partially negative oxygen
Which part of water is attracted to Cl-?
The partially positive hydrogens
What ions form when water dissociates?
Hydronium/hydrogen ions and hydroxide ions
Why can water dissociation matter biologically?
Changes in H+ and OH- concentrations strongly affect organisms
What is the H+ concentration of pure water?
10-7 M
What does an acid do?
Increases H+ concentration
What does a base do?
Reduces H+ concentration
What determines pH?
Relative hydrogen ion concentration
What pH values indicate acids and bases?
Acid < 7
Bases > 7
What is the relationship between H+ and OH-?
Their concentration product is 10-14
What was vitalism?
The idea that organic compounds could arise only within living organisms
How was vitalism disproved?
Organic compounds were synthesized in laboratories
What did the Miller experiment demonstrate?
Organic compounds could form abiotically under simulated early-earth conditions
What energy source did Miller use to trigger reactions?
Electrical discharges simulating lightning
How many valence electrons does carbon have?
Four
How many covalent bonds can carbon typically form?
Four
Why can carbon form so many different molecules?
It can form four covalent bonds with many different atoms
What do carbon chains form?
The skeletons of most organic molecules
How can carbon skeletons vary?
Length, branching, double-bond position, and rings
What is a hydrocarbon?
A molecule containing only carbon and hydrogen
Where are hydrocarbons found biologically?
In many of cell’s organic molecules
What are isomers?
Molecules with the same molecular formula but different structures and properties
What are the three types of isomers?
Structural, geometric, and enantiomers
What are structural isomers?
Same formula but different arrangements of covalent bonds
What are geometric isomers?
Molecules differing in spatial arrangement around structures such as double bonds
What are enantiomers?
Mirror-image forms of a molecule
What are the six important functional groups?
Hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, and phosphate
Why are functional groups important?
They give organic molecules distinctive chemical properties
What is a polymer?
A long molecule made of many similar building blocks called monomers
Which three major organic molecule classes are polymers?
Carbohydrates, proteins, and nucleic acids
What reaction builds polymers?
Dehydration reaction
What happens during dehydration synthesis?
Water is removed and a new bond forms between monomers
What reaction breaks down polymers?
Hydrolysis
What happens during hydrolysis?
Water is added to break a bond
What are the main functions of carbohydrates?
Fuel and building material
What is the general formula given for carbohydrates
CH2O
What two major carbohydrate categories are listed?
Monosaccharides and polysaccharides
How do carbohydrates differ from hydrocarbons?
Carbohydrates contain oxygen; hydrocarbons contain only C and H
How many carbons are common in monosaccharides?
3, 5, or 6
What are examples of 3-, 5-, and 6-carbon sugars?
Triose, pentose, and hexose sugars
What are examples of hexose sugars?
Glucose, galactose, and fructose
What are examples of pentose sugars?
Ribose and ribulose
What shapes can monosaccharides have?
Linear or ring-shaped
What form do monosaccharides favor in solution?
Rings
What is cellulose?
An unbranched β-glucose polymer
What is cellulose’s major biological function?
It forms a major structural component of plant cell walls
What holds parallel cellulose molecules together?
Hydrogen bonds
What is a cellulose microfibril?
An association of about 80 cellulose molecules forming a major plant cell-wall unit