exam 1 (review slides) Flashcards
basic characteristics of living things
ordered complexity
body composed of different kinds of cells, each containing complex molecular structures
- well-organized team working together towards a common goal
basic characteristics of living things
sensitivity
respond to stimuli in environment
basic characteristics of living things
growth, development, and reproduction
inherited information carried by genes to offspring
- controls pattern of growth and development
basic characteristics of living things
energy utilization
take in energy and use it to perform work
via metabolism (all chemical reactions that occur within cells of living things)
basic characteristics of living things
homeostasis
maintain relatively constant internal conditions that are different from their environment
reductionism
approach that reduces complex systems to simpler components that are more manageable to study
systems biology
analyzing interactions among the parts of a biological system
- used to study life at all levels
- allows biologists to predict how a change in 1 or more variables will affect other components as well as the whole system
structure & function
- analyzing biological structure gives clues about what it does and how it works
- structure always determines function
2 characteristics of all cells
- enclosed by a membrane that regulates passage of materials between cell and environment
- uses DNA as their genetic information
prokaryotic vs. eukaryotic
prokaryotic: single-celled, lack nucleus or other membrane enclosed organelles
eukaryotic: membrane-enclosed organelles
feedback regulation + 2 types
output, or product of a process, regulates that very process
negative feedback: a loop in which the responses reduces initial stimulus (ex. insulin and glucose levels)
positive feedback: end product speeds up its own production (ex. clotting of blood in response to injury)
evolution
living organisms are modified descendants of common ancestors
process of biological change in which species accumulate differences from their ancestors as they adapt to different environments over time
taxonomy
branch of biology that names and classifies species into groups of increasing breadth
Charles Darwin’s main 2 points
- species showed evidence of “descent with modification” from common ancestors
- “natural selection” is the mechanism behind descent with modification
qualitative vs. quantitative data
qualitative: recorded descriptions rather than measurements
quantitative: recorded numerical measurements, which are sometimes organized into tables and graphs
hypothesis
an explanation, based on observations and assumptions, that leads to a testable prediction
- must lead to predictions that can be tested by making additional observations or by performing experiments
controlled experiment
an experiment designed to compare an experimental group with a control group
- the 2 groups differ only in the factor being tested
independent vs dependent variable
independent variable: factor being manipulated by researchers
dependent variable: factor being measured that is predicted to be affected by independent variable
compound
substance containing of 2 or more different elements in a fixed ratio
- has characteristics (emergent properties) different from those of its elements
element’s atomic number
of protons in its nucleus
element’s mass number
sum of protons + neutrons in nucleus
atomic mass
number of protons, can be approximated by mass number
isotopes
different atomic forms of the same element
- same # of protons, different # of neutrons, thus differing in atomic mass
how valence electrons impact atom interactions
atoms interact in a way that completes their valence shells
reactivity of an atom arises from the presence of unpaired electrons
90% of the time, electrons are found in ________
orbitals
covalent bond
sharing of a pair of valence electrons by 2 atoms
- strongest chemical bonds (individually)
single vs double covalent bond
single covalent bond: sharing of 1 pair of valence electrons
double covalent bond: sharing of 2 pairs of valence electrons
electronegativity
atom’s attraction for electrons in a covalent bond
- the more electronegative an atom is, the more strongly it pulls shared electrons toward itself
nonpolar covalent bond & polar covalent bond
nonpolar: atoms share electrons equally b/c 2 atoms have the same electronegativity
polar: 1 atom is more electronegative, and electrons are not shared equally
- unequal sharing of electrons causes a partial positive or negative charge for each atom or molecule
ionic bonds
more electronegative atoms sometimes strip electrons complete away from their bonding partners
- resulting oppositely charged atoms or molecules are called ions (anions and cations attract each other, this attraction is called an ionic bond)
THEY SELFISH
hydrogen bonds
hydrogen bond covalently bonded to 1 electronegative atom
- hydrogen atoms have partial positive charge that attracts a diff electronegative atom with a partial negative charge nearby
in living cells, electronegative partners are usually oxygen or nitrogen atoms
Van Der Waals interactions
very weak bonds that exists between all molecules
(electrons are not always evenly distributed and may accumulate by chance in one part of a molecule resulting in regions of positive and negative charge that enable all atoms and molecules to stick to one another)
individually weak but can be collectively strong
interactions are very weak, aka reversible
- van der Waals exist in tertiary protein structures –> create functional proteins
the effects of molecular shape
molecular shape determines how biological molecules recognize and respond to one another with specificity
ex. morphine and endorphins have similar effects b/c their shapes are similar and bind to the same receptors in the brain
effect of concentration on rate of reaction
greater concentration = faster the reaction
- more concentration = more collisions b/w molecules and more products
chemical equilibrium & dynamic equilibrium
chemical equilibrium: point where rate of forward reaction equals rate of reverse reaction, so relative concentrations of products & reactants do not change with time
dynamic: reactions are still going on in both directions but with no effect on the concentration of the reactants and products
why does water molecule have a bent shape? what does the bent shape contribute to?
- bent shape because of the electronegativity difference (oxygen has partial negative charge while hydrogen has partial positive)
- allows water to create hydrogen bonds with other atoms leading to properties like cohesion
cohesion and adhesion in water
cohesion: attraction between like molecules
- collectively, hydrogen bonds hold water molecules together
- ex. helps transport of water against gravity in plants
adhesion: attraction b/w different molecules
- water adheres to surfaces with polar or charged components
- ex. b/w water & plant cell walls, helps counter downward pull of gravity
surface tension in water
surface tension: measure of how hard it is to break or stretch surface of a liquid
- bent shape gives water high surface tension
- b/c of that, light objects do not fall through the water’s surface
water acts like its covered with an invisible film
specific heat
specific heat: amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1C
as molecules increase in polarity and thus ability to form hydrogen bonds, it takes more energy to change their temperature
- because of default answer: hydrogen bonds
evaporative cooling in water
evaporative cooling: as a liquid evaporates, its remaining surface cools
-“hottest” molecules (greatest kinetic energy) leave as gas
- helps stabilize temperature in organisms and bodies of water
heat of vaporization in water
amount of heat a liquid must absorb for 1g to be converted to gas
- water has high heat of vaporization due to hydrogen bonds
why does ice float on water
water is denser as liquid than as a solid
- hydrogen bonds form hexagonal repeating structure = more space between molecules
hydrophilic & hydrophobic substances
hydrophilic = like water
hydrophobic = hate water
acid & bases
acid: substance that increases H+ concentration of a solutions donates H+
base: substance that increases OH- concentration accepts H+
hydrocarbons
organic molecules consisting of only C and H
- undergo reactions that release large amount of heat (think energy storage when you think of them)
- nice little fatty acids
isomers
compounds with the same molecular formula but different structures and properties
- have same # of atoms of the same element
3 types of isomers
structural: diff covalent arrangements of their atoms
cis-trans: same covalent bonds but differ in their spatial arrangements due to inflexibility of double bonds
- cis: atoms attached to C atoms on the same side of the double bond
- trans: atoms attached to C atoms on different sides of the double bond
enantiomers: isomers that are mirror images of each other
- differ in shape due to presence of asymmetric carbon resulting in molecules that are mirror images
importance of C skeleton
- gives molecule its overall shape
- distinctive properties of organic molecules depend on C skeleton & chemical groups attached to it
- chemical functional groups: groups of atoms attached to C skeleton of organic molecules in a specific way
functional group
hydroxyl group
-OH
- act as weak acids
- polar molecules
- form hydrogen bonds
- soluble in water
- helps dissolve organic compoudns such as sugars
functional group
carbonyl
- C double bond O
- found on molecules acetaldehyde and acetone
- site of reactions that link these molecules into larger, more complex organic molecules
functional group
carboxyl
- COOH
- acts as an acid when in solution
- participates in H-bonding
functional group
amino
- NH2
- acts as a base when in solution
- participates in hydrogen bonding
functional group
sulfhydryl
-SH
- consists of sulfur (S) atom bonded to H atom
- link to one another via disulfide (S-S) bonds
- hydrophobic
- present in proteins
functional group
phosphate
-PO4
- bonded together store chemical energy used in chemical reactions
- carry negative charges on 2 of their O atoms
functional group
methyl
-CH3
- not reactive
- serves as recognizable tag on biological molecules
- silences genes that shouldnt be expressed during transcription
which functional group is NOT hydrophilic
sulfhydryl
which type of chemical bond joins a functional group to the carbon skeleton of a large molecule?
covalent bond
ATP
adenosine triphosphate
stores the potential to react with water or other molecules, releasing energy that can be used by cell
dehydration synthesis & hydrolysis
dehydration: 2 monomers bond together through a loss of water molecule
hydrolysis: polymers disassembled to monomers through addition of a water molecule (H from water attaching to one monomer and hydroxyl group attaching to other)
3 different types of lipids
- triglycerides
- phospholipids
- steroids
carbohydrates function & classes
- major source of cellular fuel
- raw material for building blocks (e.g. ribose sugar in RNA)
monosaccharides
simple sugars
ex. glucose, fructose, galactose
disaccharide
consists of 2 monosaccharides joined by glycosidic linkage (covalent bond formed b/w 2 monosaccharides by a dehydration reaction)
- broken down into simple sugars to provide useful energy
polysaccharides + 3 examples
- polymers of many sugars joined by glycosidic linkages via dehydration synthesis
examples:
- starch (storage form of glucose in plants, digestible)
- glycogen (storage form of glucose in animals)
- cellulose (structural component of plants, not digested, contribute fiber)
lipids
- only class of large biological molecules that does not include true polymers
- linked by nonpolar covalent bonds (hydrophobic)
- important in physiology (valuable source of energy)
fats composition
- constructed from 3 glycerols and 1 fatty acid
- fatty acids joined to glycerol through dehydration synthesis
- form ester linkages (bond b/w hydroxyl & carboxyl group)
saturated fatty acids vs. unsaturated fatty acids
saturated fatty acids: no double bond b/w C atoms of chain, which allows fat molecules to pack together tightly (butter- solid at room temp)
unsaturated fatty acid: 1 or more double bonds b/w C atoms (double bond forms a lil kink that precent molecules from packing closely together, olive oil- liquid at room temp)
- monounsaturated: 1 double bond is present
polyunsaturated: more than 1 double bond present
hydrogenation of fats
process of converting unsaturated fats to saturated fats by adding hydrogen (allows them to solidify)
ex. peanut butter, margarine
meaning of amphipathic
has both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts or regions within its structure
ex. phospholipids
phospholipids
- amphipathic
- 2 long hydrocarbon tails (hydrophobic)
- 1 glycerol molecule attached to phosphate group (hydrophilic)
- in water, self assemble into a bilayer or micelle with hydrophilic heads on outside and hydrophobic tails inside
what is the bond b/w amino acids
peptide bond
polypeptide & peptide bonds
polymer of many amino acids linked by peptide bonds
- amino acids join by dehydration synthesis
peptide bonds: covalent bond b/w carboxyl group of 1 amino acid & amino group of another
- side chain determines how polypeptide folds and thus its final shape and chemical characteristics
4 parts of the structure of an amino acid
- central carbon atom (alpha carbon)
- h atom
- carboxyl group (COOH)
- R group (variable side chain of 1 or more atoms that identifies a specific amino acid, contribute to overall shape and function of protein)
what determines a protein’s 3D structure?
sequence of amino acids
what are the 4 levels of protein structure?
- primary
- secondary
- tertiary
- quaternary
primary protein structure
- like the order of letters in a long word
- determined by inherited genetic information and:
1. number of amino acids in chain
2. specific sequence of amino acids
secondary protein structure + 2 types of common secondary protein structures
- consists of coils & folds in polypeptide chain resulting from H bonds b/w atoms within polypeptide chain
- alpha helix (simple spiral/coil)
- beta sheet (flat pleated sheet/parallel)
tertiary protein structure
overall folding of a polypeptide, driven by interactions b/w R groups (side chains)
- H bonds (b/w polar side chains)
- Ionic bonds (b/w charged side chains)
- hydrophobic interactions (nonpolar side chains end up in clusters at core of protein, out of contact w water)
- van der waals: helps hold nonpolar side chains together
- disulfide bridges: reinforce protein structure
denaturation of protein
loss of protein’s native structure/shape
- protein becomes biologically inactive
- extremely high fevers can be fatal
nucleic acids vs. nucleosides
nucleic acids: large, complex molecules made up of long chains of nucleotides (pentose- 5C sugar, phosphate group, and nitrogenous base)
nucleosides: simpler molecules composed of a nitrogenous base and a sugar, without the phosphate group
purine and pyrimidines
purine: adenine and guanine
(pure as gold)
pyrimidine: cytosine, thymine, and uracil (cut the py)
phosphodiester linkage
phosphate group that links sugars of 2 nucleotides
- create backbone of sugar-phosphate units w/ nitrogenous bases
nucleotides are linked together by phosphodiester linkages to build a nucleotide
DNA
2 chains held together by H bonds b/w a purine base on 1 chain and pyrimidine base on opposite chain
