Exam 1 Study Guide Flashcards
What is Biology?
Biology is the scientific study of life
List and describe the characteristics of life.
1) Presence of cells
2) Order: biological hierarchy
3) Response to the physical environment
4) Energy processing
5) Evolution
Describe how energy flows through an ecosystem. Where does the energy come from, how is it processed, and how in what form does it leave?
Energy flows through an ecosystem, usually entering as light and exiting as heat
- The “light” mentioned here is sunlight
- When you move, some of that energy is released as heat, thats how we regulate our body temperature
What characteristics do eukaryotic and prokaryotic cells have in common? How do they differ?
All cells have a plasma membrane, ribosomes, cytoplasm, and DNA. The primary distinction between these two types of organisms is that eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do not.
What are the taxonomic groups that we use to classify living organisms? Which group is more general? Which is least general?
(most general to more specific): Domain, Kingdom, Phylum, Class, Order, Family, Genus, species
For help: Dumb Kings Play Chess On Fine Glass Squares
How is taxonomy used in the study of evolution?
It helps identify biological specimens
State the three domains of life.
1) Bacteria
2) Archaea
3) Eukarya
Describe the role that DNA plays in the growth, development, and reproduction.
DNA contains the instructions needed for an organism to develop, survive and reproduce.
Compare positive and negative feedback.
Negative feedback: as more of a product accumulates, the process that creates it slows, and less of the product is produced
Positive feedback: as more of a product accumulates, the process that creates it speeds up and more of the product is produced
State and describe the steps of the scientific method.
The scientific process includes:
- Making observations
- Forming logical hypotheses
- Testing hypotheses through experimentation
What does it mean that a hypothesis must be testable and falsifiable?
A hypothesis is called falsifiable if it is possible to conceive of an experimental observation that disproves the idea in question.
Describe what Darwin meant by “descent with modification” and “natural selection.”
Descent with modification: Organisms are modified descendants of common ancestors
Natural selection:
- Individuals in a population vary in their traits, many of which are heritable
- More offspring are produced than survive, and competition is inevitable
- Species generally suit their environment
Can traits acquired over the course of an organism’s life be passed on to its offspring?
Acquired traits are not coded in the DNA of an individual and therefore most scientists believe they cannot be passed down to offspring during reproduction.
How are evolutionary trees used to describe the evolutionary history of organisms?
The branches themselves connect up in a way that represents the evolutionary history of the species—that is, how we think they evolved from a common ancestor through a series of divergence (splitting-in-two) events.
Nutrient cycling
a cyclic process that encompasses the movement of nutrients from the physical environment to living organisms and back to the environment.
chromosome
A carrier of genetic information that is found inside the nucleus of a cell
gene
the basic physical and functional unit of heredity.
theory
- Broader and more general in scope than a hypothesis
- Supported by a large body of evidence in comparison to a hypothesis and can lead to new testable hypotheses
hypothesis
A hypothesis is a tentative answer to a well-framed question
- A scientific hypothesis leads to predictions that can be tested by observation or experimentation
What is matter?
anything that takes up space and has mass
What is an atom?
the smallest unit of matter that still has chemical characteristics
What is an element?
a pure substance that cannot be broken down to other substances by chemical reactions
Which four elements make up 96% of human body mass?
carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)
What is a compound?
A material made up of two or more parts or elements
What is a molecule?
a group of atoms that form the smallest identifiable unit into which a pure substance can be divided and still retain the composition and chemical properties of that substance.
Describe these subatomic particles of the atom: proton; neutron, electron.
Proton: a positively charged particle that resides in the nucleus of an atom
Neutron: an uncharged elementary particle that has a mass nearly equal to that of the proton
Electron: a stable atomic particle that has a negative charge
If a normal atom of an element has 6 protons: a) which element is it? b) how many electrons will it usually have? c) how many neutrons will it usually have?
a) carbon
b) 6 electrons
c) 6 electrons
What is a Dalton?
unit used to express molecular mass
- Neutron mass and proton mass are measured in daltons
How are an element’s atomic number and atomic mass determined?
An element’s atomic number = # of protons in its nucleus
An element’s mass number = protons + neutrons in the nucleus
If Cl has 17 electrons, 17 protons, and 18 neutrons, what is its mass number?
mass number = 35
What are valence electrons? How do they affect the bonding potential of an element?
Valence electrons are those in the outermost shell, or valence shell.
Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms
Calculate the valence of the following elements: C, O, H, N.
carbon: 4
oxygen: 6
hydrogen: 1
nitrogen: 5
What are isotopes? Describe how scientists can use radioactive isotopes.
Isotopes are two atoms of an element that differ in the number of neutrons.
Radioactive isotopes decay spontaneously, giving off particles and energy; have applications in biological research
- Dating fossils
- Diagnosing medical disorders
Describe covalent bonds. What do you call compounds that form from covalent bonds?
A covalent bond is the sharing of a pair of valence electrons by two atoms
Molecular compounds form from covalent bonds
What is electronegativity?
a measure of an atom’s ability to attract shared electrons to itself.
Are the shared electrons distributed evenly between the atoms in a covalent bond?
In pure covalent bonds, the electrons are shared equally.
What is a polar versus nonpolar covalent bond? How do the properties of polar and nonpolar molecules differ?
nonpolar: electrons are shared equally. polar: electron sharing is unequal.
Polar molecules have positive and negative ends which nonpolar do not.
What is an ionic compound? How do ionic bonds form?
An ionic bond is formed by the complete transfer of some electrons from one atom to another.
What is an ion? What do you call an ion with a positive charge? What do you call an ion with a negative charge?
A charged atom (or molecule) is called an ion.
Negative ion: anion; positive ion: cation
What is a hydrogen bond? How does it form? Is it weaker or stronger than a covalent bond?
A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.
It is weaker than a covalent bond
What is a chemical reaction? Describe a reversible reaction? What happens when the relative amounts of product and reactants stabilize?
Chemical reactions make or break chemical bonds
- Chemical reactions start with materials called reactants and produce materials called products
All chemical reactions are theoretically reversible
The products of the forward reaction become the reactants for the reverse reaction
trace elements
Trace elements are those required by an organism in minute quantities
orbital
Electron orbitals are three-dimensional representations of the space in which an electron is likely to be found.
single bond
single bond: shares one pair of valence electrons
double bond
Double bond: shares two pairs of valence electrons
Describe the four emergent properties of water that contribute to Earth’s fitness for life.
1) Cohesive behavior
- water sticks to itself
2) ability to moderate temperature
- keeps things from becoming too cold or too hot
3) expansion upon freezing
4) versatility as a solvent
- universal solvent of life
What properties of water do plants use to move water against gravity?
adhesion and cohesion
What type of energy is temperature used to measure? How do fluctuations of temperature affect the movement of molecules?
heat energy
Temperature change in water will first break hydrogen bonds before heat is absorbed by the water molecules, leading to evaporation
What is specific heat? What is the specific heat of water?
Specific heat is the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius.
For water, this amount is one calorie.
What is the heat of vaporization?
the amount of heat needed to turn 1g of a liquid into a vapor.
How do the properties of solid water differ from those of liquid water?
water’s solid form (ice) is less dense than its liquid form.
What are the differences between hydrophobic and hydrophilic molecules?
A hydrophilic substance is one that has an affinity of water
A hydrophobic substance is one that does not have an affinity for water
mole
One mole = number of daltons per molecule.
molarity
the number of moles per liter of solution
Define acids and bases
An acid is any substance that increases the H+ concentration of a solution
A base is any substance that reduces the H+ concentration of a solution
What effect does H+ ion concentration have on the pH of a solution?
High concentrations of hydrogen ions yield a low pH (acidic substances), whereas low levels of hydrogen ions result in a high pH (basic substances).
What is the pH scale? How is it used to determine how acidic or basic a solution is?
Neutral solution = 7
acidic solution = less than 7
basic solution = greater than 7
How does a buffer regulate pH in a living organism?
substances that minimize changes in concentrations of H+ and OH- in a solution
cohesion
the attraction of molecules for other molecules of the same kind
adhesion
an attraction between different substances
aqueous
one in which water is the solvent
hydration shell
The sphere of water molecules around each dissolved Ion.
hydrogen ion
created when a hydrogen atom loses or gains an electron. (Hydrogen ion symbol: H+)
hydroxide ion
a polyatomic ion consisting of oxygen and hydrogen (OH-)
hydronium ion
water molecules that have gained an extra positive hydrogen ion.
What is an organic compound?
carbon-based compounds (covalently bonded to carbon)
What is the valence of carbon? How many single, covalent bonds can carbon form? How does carbon’s valence give it the ability to form large, complex molecules?
the valence of carbon is 4 so it can form 4 covalent bonds.
Carbon has a strong tendency to form covalent bonds with other atoms in order to complete its octet.
What are hydrocarbons? Are they polar or non-polar?
any of a class of organic chemicals made up of only the elements carbon (C) and hydrogen (H). They are non-polar
structural isomer
molecules with the same molecular formula, but their atoms have different arrangements or bonds.
Cis-Trans isomer
Cis-trans isomers have the same covalent bonds but differ in spatial arrangements
Enantiomer
Enantiomers are isomers that are mirror images images of each other
Hydroxyl group
attaches to molecules containing an oxygen and hydrogen atom, bonded together.
carbonyl group
A carbon atom double-bonded to an oxygen
carboxyl group
a carbon atom that’s double-bonded to an oxygen atom and singly bonded to a hydroxyl group
amino group
nitrogen atom connected by single bonds to hydrogen or carbon.
sulfhydryl group
An R group bound to a sulfur atom and a hydrogen atom
phosphate group
phosphorus attached to four oxygen
methyl group
made of one carbon and three hydrogen atoms.
Describe dehydration synthesis and hydrolysis.
A dehydration reaction occurs when two monomers bond together through the loss of a water molecule
Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction
- Lyse: to break apart
Which macromolecules always contains N?
proteins and nucleic acids
Which functional groups are found in all proteins?
amino group
What are carbohydrates used for in the body?
help in producing energy
What is the name of the covalent bond between monosaccharides?
glycosidic linkage
Describe monosaccharides, disaccharides, and polysaccharides.
monosaccharides are monomers of sugars and disaccharides are composed of two monomers whereas polysaccharides are composed of a large number of monomers.
What is glucose? How many carbon atoms are in a molecule of glucose? What is glucose used for in the cell?
Glucose is the main type of sugar in the blood and is the major source of energy for the body’s cells. Glucose has 6 carbon atoms.
What is starch? What do plants use starch for? What monosaccharide do we obtain from hydrolysis of starch?
Starch is found in plants and used to store energy. It serves the plant as a reserve food supply.
Maltose is produced by the enzymatic hydrolysis of starch.
What is cellulose? Which organisms produce cellulose? How is it different from starch? What is its function: a) in plants, b) in animals?
Cellulose is a molecule consisting of carbon, hydrogen, and oxygen atoms.
Cellulose is used for structural support whereas starch is used for energy storage.
Cellulose is the main substance in the walls of plant cells. Humans cannot digest cellulose, but it is important in the diet as a fiber.
What characteristic is used to group lipids?
hydrophobic molecules
Describe the three types of lipids.
1) fats: store energy
2) Phospholipids: cell membranes
3) Steroids: cholesterol, testosterone, estradiol
What is glycerol? What is a fatty acid?
Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon
A fatty acid consists of a carboxyl group attached to a long carbon skeleton
What is the name of the covalent bond is used to attach fatty acids to glycerol in triglycerides? What are fats used for in the body? Compare and contrast saturated and unsaturated fats.
ester linkage
Fat is a source of essential fatty acids, which the body cannot make itself.
Saturated fats are solid at room temperature. Unsaturated fats are liquid at room temperature.
Describe the structure and function of phospholipids. How do phospholipids behave in an aqueous solution? What are phospholipids used for in the body?
The structure results in a bilayer arrangement found in cell membranes.
in an aqueous solution, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior.
Phospholipids are structural components of cell surface membranes
Describe the structure and function of steroids. What are some purposes of cholesterol?
Steroids are lipids characterized by a carbon skeleton consisting of four fused rings
Cholesterol is used to produce estradiol and testosterone
What are some major functions of proteins?
They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs.
Describe the structure of amino acids. What does the ‘R’ group on an amino acid determine?
made up of a basic amino group, an acidic carboxyl group, and an organic R group
The R group determines the characteristics for each type of amino acid.
How do polymers of amino acids form or break apart? What is the name of the covalent bond between amino acids?
Polymers are broken down into monomers in a process known as hydrolysis.
Peptide bonds
Describe the 4 levels of protein organization.
1) primary structure
2) secondary structure
3) tertiary structure
4) quaternary structure
What types of proteins catalyze chemical reactions?
enzymes
State the two types of nucleic acids.
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
How do DNA and RNA interact to produce proteins?
DNA makes RNA and RNA makes Protein.
Describe the 3 components of a nucleotide.
phosphate, sugar molecule, and one of four bases.
What are the 5 nitrogenous bases?
adenine (A), thymine (T), cytosine (C), and guanine (G).
Which bases are complementary between DNA strands, DNA and RNA strands?
bases for RNA — adenine (A), thymine (T) cytosine (C), and guanine (G) — are also found in DNA. In RNA, uracil (U) replaces thymine (T)
Macromolecule
large biological molecules
monomer
small building-block molecules
polymer
a long molecule consisting of many similar building blocks
glycosidic linkage
when a dehydration reaction joins two monosaccharides
fatty acid
the building blocks of the fat in our bodies and in the food we eat.
ester bond
The bond between the glycerol and fatty acids in lipids between an oxygen molecule and a carbon molecule.
phosphate
a salt or ester of phosphoric acid.
triglyceride
consists of a glycerol backbone esterified with three fatty acids.
enzyme
a biological catalyst
catalyst
any substance that increases the rate of a reaction without itself being consumed.
polypeptide
a polymer of amino acids joined together by peptide bonds
polynucleotides
a compound comprised of several nucleotides
purine and pyrimidine
the two chemical compounds that cells use to make the building blocks of DNA and RNA
nucleoside
the structural subunit of nucleic acids such as DNA and RNA.
peptide bond
when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water
denaturation
the breaking of many of the weak linkages, or bonds within a protein molecule
double helix
a description of the molecular shape of a double-stranded DNA molecule
