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248 Cards in this Set
- Front
- Back
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All matter is composed of...
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atoms
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What are the three parts of an atom?
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protons (positive), neutrons (neutral), electrons (negative)
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Where are the three parts of an atom found?
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protons and neutrons make up the nucleus and electrons circle around them
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The number of protons an element has determines what element it is the same as its...
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atomic number
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How do you find atomic mass?
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add the number of protons and neutrons together
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What are isotopes?
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atoms of the same element with different numbers of neutrons
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What type of isotopes spontaneously decay into elements of lower atomic number?
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radioactive isotopes
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What are ions?
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atoms that have gained a charge
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What is the difference between cations and anions?
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cations have a positive charge, anions have a negative charge
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How are electrons distributed in energy levels?
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2 electrons in the first level, up to eight in other levels
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What are valence electrons?
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electrons in the outermost energy level
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What is a molecule?
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a group of atoms linked by chemical bonds
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What is the difference between ionic bonds and covalent bonds?
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in an ionic bond, electrons are transferred; in a covalent bond, electrons are shared
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Are ionic bonds or covalent bonds stronger?
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ionic
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When do chemical reactions occur?
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during the formation or destruction of chemical bonds
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In a chemical reaction, the _______ result in the ________
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reactants, products
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What three factors affect the rate of chemical reactions?
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temperature, concentration of reactants and products, and catalysts (enzymes)
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What are the five characteristics of life?
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have cells
use energy for metabolism maintain homeostasis reproduce with inheritance evolve as populations |
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what are some common incorrect definitions of life?
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movement, sensitivity, complexity, order, ability to die (circular logic)
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Why is life difficult to define?
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Because there is an extraordinary amount of variation in living things (diversity). Viruses are a particular group that is difficult to classify as living or nonliving.
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8 important concepts about the Nature of Science
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tentativeness
empirical evidence observation and inference hypotheses, laws and theories scientific methods creativity objectivity and subjectivity a way of knowing |
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hypothesis
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an unproven but testable explanation of a scientific phenomenon
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law
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a description of scientific phenomenon that has been backed up by substantial experimental evidence
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theory
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an explanation of a scientific phenomenon that has been backed up by substantial experimental evidence
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What cell structures are present in prokaryotes?
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cell membrane, cell wall, cytoplasm, ribosomes, flagella, pili, cytoskeleton, free DNA
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cell membrane (prokaryote)
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controls what enters and leaves
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cell wall (prokaryote)
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support and protection
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cytoplasm
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site of chemical reations
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ribosomes
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site of protein synthesis
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flagella
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movement
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pili
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DNA exchange
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cytoskeleton
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provides cell shape
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free DNA
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carries genetic information
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What major structure is not present in a prokaryote?
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nucleus
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What organelles are present in eukaryotes? (both)
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nucleus, cell membrane, cytoplasm, ribosomes, cytoskeleton, mitochondrion, endoplasmic reticulum, golgi, peroxisome, vesicles
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nucleus
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contains DNA, site of RNA synthesis
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mitochondrion
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site of cell respiration
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endoplasmic reticulum
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transports material (rough =ribosomes, smooth=none)
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golgi
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packages prodcts for export from cell
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peroxisome
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for digesting substances dangerous to the cell
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vesicles
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transport materials to/from membrane
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what specialized organelles are found in animal cells?
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lysosomes, centrioles
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lysosomes
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digest material with enzymes
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centrioles
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arrange spindle fibers for cell division
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what specialized organelles are found in plant cells?
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cell wall, large central vacuole, chloroplasts
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cell wall
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support and protection and sturdiness
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large central vacuole
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storage and support
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chloroplasts
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site of photosynthesis
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five steps of the experimental method
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observe, identify question, develop hypothesis, devise a test of the hypothesis, carry out test and analyze results
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a water molecule has oppositely charged ends, meaning it is ____
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polar
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the oxygen end is slightly _______, while the hydrogen end is slightly ______
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negative, positive
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what type of bond do water molecules form?
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hydrogen bonds
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8 properties of water
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cohesion
adhesion capillarity high specific heat high heat of vaporization solid is less dense than liquid universal solvent transparency |
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what three things do living things use water as?
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a coolant, a transport medium, and a habitat
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water cohesion
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water molecules stick to themselves
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what does cohesion create on the surface of water?
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surface tension, a measure of the force necessary to stretch or break the surface of a liquid
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water adhesion
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water is attracted to other substances with which it can form hydrogen bonds
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capillarity
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due to a combination of cohesion and adhesion, water is pulled up little tubes, such as the ones that bring water to treetops
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specific heat
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the amount of heat that must be absorbed or released to change the temperature of 1g of a substance 1 degrees Celsius
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what does it mean to say that water has a high specific heat?
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large amounts of energy are needed to break its hydrogen bonds and raise its temperature, but the energy is released again when the water is cooled
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what does it mean to say that water has a high heat of vaporization?
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a large amount of energy is required to change 1g of liquid water into a gas, breaking hydrogen bonds
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evaporative cooling
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as a liquid evaporates, the surface of the liquid that remains behind cools
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Why is water the universal solvent?
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it can form hydrogen bonds; water clings to polar molecules causing them to be soluble in water but repels nonpolar molecules
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hydrophilic
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attracted to water
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hydrophobic
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repelled by water
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why is it important that ice is less dense than liquid water?
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oceans and lakes don't freeze solid because ice floats on the surface and insulates the water underneath, meaning living organisms can survive there
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why is it important that water is transparent?
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it allows light to pass through it so that aquatic plants can receive sunlight
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what does pH stand for?
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parts of hydrogen
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On the pH scale (0-14), a substance below 7 is________ and a substance above 7 is _________. 7 is ________
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acidic, basic/alkaline, neutral
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acids have many _______ ions
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H+
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bases have many ______ ions
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OH-
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what happens when acids dissolve in water?
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they dissociate to increase the concentration of H+
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what happens when bases dissolve in water?
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they combine with H+ ions, thus decreasing H+ concentration
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buffers
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offer protection from extreme pH levels by donating or removing H+ ions as necessary
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Macromolecules
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the molecules that make up living cells and the cells of living things
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4 types of macromolecules
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carbohydrates, lipids, proteins, nucleic acids
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What 6 elements are found in macromolecules?
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CHONPS
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All macromolecules contain carbon. This means they are...
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organic
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Why is carbon found in all living things?
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It is a versatile atom; has 4 valence electrons and a variety of bonding patterns; easily forms isomers
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What are isomers?
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molecules with same chemical formula but different structure
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What are functional groups and what do they do?
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atoms or clusters of atoms that are covalently bonded to a carbon backbone; give organic compounds their different properties
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What are polymers and how are they formed?
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groups of monomers linked together through dehydration synthesis to form a single unit of a macromolecule
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How are polymers separated?
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hydrolysis
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What is formed as a byproduct of dehydration synthesis?
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water
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What elements are in carbohydrates?
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carbon, hydrogen, and oxygen in about a 1:2:1 ratio
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What are the three classes of carbohydrates?
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monosaccharides, disaccharides, and polysaccharides
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What are monosaccharides?
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the simplest carbohydrates, monomers
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Describe the structure of a monosaccharide
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ring structure with a 5 or 6 carbon backbone
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Give 5 examples of monosaccharides
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fructose, glucose, galactose, ribose, deoxyribose
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What are disaccharides?
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two monosaccharides joined by a covalent bond
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Give 3 examples of disaccharides
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sucrose, maltose, lactose
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What are polysaccharides?
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more than 2 monosaccharide monomers joined together
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Give 4 examples of polysaccharides
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starch, glycogen, cellulose, chitin
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Name and give examples of 2 polysaccharide functions
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energy storage (plants - starch, animals - glycogen), structural support (plant cell walls - cellulose, insect, shellfish shells, cell walls of fungi - chitin)
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What is a characteristic of lipids?
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tend to be insoluble in water
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What are the four major types of lipids?
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fats, phospholipids, steroids, waxes
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Which type does not have fatty acids?
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steroids
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What do all fatty acids have at one end?
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a carboxyl group
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All fatty acids are built on what?
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a carbon backbone
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What does it mean if a fatty acid is saturated?
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every C atom is bonded to at least two H atoms, max number of H
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Give an example of a saturated fatty acid
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butter, lard, peanut butter
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What does it mean if a fatty acid is unsaturated?
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there is at least one double bond between successive C atoms (liquid at room temp)
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Give an example of an unsaturated fatty acid
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olive oil, vegetable oil, corn oil
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Animal fats are... while most plant fats are....
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saturated, unsaturated
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Describe the structure of a fat molecule
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fatty acids attached to glycerol, triglycerides are most common (3 fatty acids)
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What are the three functions of fats?
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long term energy storage (more than carbs), protection, insulation, membranes
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What are phospholipids?
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main component of biological membranes like cell membrane
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Describe the structure of a phospholipid molecule
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polar hydrophilic head, phosphate group, nonpolar hydrophobic tails, 2 fatty acids, glycerol backbone
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What do phospholipids form?
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membranes
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Describe the backbone of a steroid molecule
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4 fused together C rings, rigid
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What is cholesterol?
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most common steroid in animals
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What are some substances cholesterol forms?
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hormones (estrogen, testosterone, adrenaline, regulate body systems), vitamins (D)
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Describe the structure of a wax molecule
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long chain of fatty acids linked to a long chain of alcohols or C rings
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What are some characteristics of waxes?
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firm consistency, repel water
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Why are waxes important?
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they are waterproof
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Where are waxes used in nature?
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beeswax, bird feathers, coats of water mammals, leaves, fruits
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What are the elements in proteins?
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CHONS
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What is the monomer of a protein?
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amino acids
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Describe the structure of an amino acid
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has an amino group, a carboxyl group, a H atom, and an R group all bonded to a central C atom
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How many types of amino acids are there?
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there are 20 types, which are grouped into 5 classes based on R group
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Describe protein synthesis
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dehydration synthesis links amino group of one amino acid with carboxyl group of the next, forming a peptide bond
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Describe the structure of a protein polymer
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1 or more long chains of amino acids linked by peptide bonds
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What are the 2 classes of protein polymers?
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dipeptides (2 linked amino acids) and polypeptides (3 or more amino acids)
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What is the sequence of elements in the backbone of any polypeptide?
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N C C N C C N C C N
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What are the four structural classes of proteins?
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primary, secondary, tertiary, and quaternary
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Describe the primary structure of a protein
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linear sequence of amino acids linked together by peptide bonds; unique for each protein
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What are the two types of secondary structures formed by hydrogen bonding?
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the alpha helix (coils) and the beta pleated sheet (fold-backs)
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Name two examples of proteins dependent on secondary structures
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spider and worm silk
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Describe a tertiary structure
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final folded shape of 3d protein based on bonding of R groups
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Give an example of a tertiary structure
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enzymes
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What is a quaternary structure?
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two or more polypeptide chains associated to form a functional protein
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What is the process of changing a protein's shape called?
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denaturation
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What effect does denaturation have?
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usually renders proteins biologically inactive
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Name and give examples of the three ways proteins can be denatured
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changing pH (adding lemon juice to fish), changing temperature (cooking eggs), changing ionic concentration (salt-curing and pickling used to preserve food)
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Why are enzymes catalysts?
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they speed up chemical reactions without being altered and lower the energy the energy of activation, or the amount of energy needed to start a reaction
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What is active site?
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the place on an enzyme where the reaction occurs
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What are substrates?
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the molecules that the enzyme changes during a chemical reaction
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Describe the basic process of an enzyme
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1) substrate binds to enzyme's active site, forming enzyme-substrate complex 2) chemical reaction takes place that changes substrate, 3) enzyme and substrate break apart
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What the four features of enzymes?
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1. enzymes do not make anything happen that could not happen on its own. They just make it happen much faster
2. Reactions do not alter or use up enzyme molecules 3. The same enzyme usually works for both the forward and reverse reactions 4. Each type of enzyme recognizes and binds to only certain substrates |
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What is the difference between a lock-and-key model and an induced-fit model?
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in an induced fit model of an enzyme-catalyzed reaction, the enzyme slightly folds around the substrate, whereas in the lock-and-key model the substrate fits without the enzyme folding around it
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What is the difference between competitive and noncompetitive inhibition?
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in competitive inhibition, a molecule other than the substrate bonds directly to the active site, whereas in noncompetitive inhibition the molecule bonds to a different part of the enzyme, permanently changing the shape of the enzyme and rendering it useless.
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What is allosteric activation?
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an allosteric activator must bind to the allosteric binding site for a substrate to be able to bind with the enzyme
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What is allosteric inhibition?
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when an allosteric inhibitor binds to the allosteric binding site, substrates can no longer bind with the enzyme
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Is allosteric activation/inhibition temporary or permanent?
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temporary
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Describe feedback inhibition
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when enough of the final product of a series of enzyme reactions has been produced, one of the final product goes back to the first enzyme and binds with it, stopping the production temporarily
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What factors affect enzyme rates of reaction?
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enzyme concentration, temperature, and pH - NOT substrate concentration
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What is the effect of enzyme concentration?
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higher concentration = more active sites = higher rate of reaction
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What is the effect of temperature?
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small increase in temperature increases molecular collisions and reaction rates, high temps disrupt bonds and destroy shape of active site
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What is the effect of pH?
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every enzyme has a very narrow range of pH within which it works properly, increasing or decreasing pH denatures the protein and slows/stops reaction rate
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What are the elements in nucleotides?
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CHONP
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Describe the structure of a nucleotide
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has a 5-carbon sugar (ribose or deoxyribose), a phosphate group, and a nitrogen-containing base
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What types of nucleotides do not form nucleic acids?
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ATP (biological energy carrier), NAD+, NADP+, and FAD
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What types of nucleotides DO form nucleic acids?
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deoxyribonucleic acid and ribonucleic acid
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What is the main job of DNA?
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encodes information (genes) used to assemble proteins
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What is the main job of RNA
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reads DNA-encoded information to direct protein synthesis
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Describe the structure of DNA
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double-helix with antiparallel strands of a deoxyribose sugar-phosphate backbone (covalent bonds) and hydrogen bonds between bases
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What are the four bases and which bonds with which?
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adenine, thymine, guanine, cytosine (AT, GC)
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Which bases are purines (double-ringed) and which are pyrimidines (single-ringed)?
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purines: A and G, pyrimidines: C T and U
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What is uracil
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used instead of thymine in RNA strands
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What did Chargaff's work show?
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the complementary base pairing of A/T and C/G
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How did Rosalind Franklin examine DNA and what did she conclude?
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she used X-ray crystallography and concluded that DNA was some sort of helix
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What did the Watson-Crick Model look like?
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a double helix with two nucleic strands running in opposite directions held together by hydrogen bonds between bases, A/T and C/G
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How did the discovery of DNA illustrate aspects of the nature of science?
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competition, collaboration (cultural endeavor), international, there is not only one scientific method
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What are the differences between RNA and DNA
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RNA is a single strand, contains uracil instead of thymine, and ribose instead of deoxyribose
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How many types of RNA are key players in protein synthesis?
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3
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Why are cells so small?
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the extra surface area helps them perform functions faster (division, energy production, absorbing and releasing substances)
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What is a group of cells working together called?
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tissue
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What is a group of tissues working together called?
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organ
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What is a group of organs working together called?
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organ system
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What gives the cell membrane its fluid properties?
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the lipid bilayer
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What is the difference between integral and peripheral proteins?
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integral go all the way through the membrane and peripheral are only on the surface and do not go all the way through
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Why is the cell membrane like a mosaic?
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it's made of little pieces of phospholipids, glycolipids, sterols, and proteins
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What are the two main functions of the cell membrane?
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protection and regulation of matter moving into and out of the cell
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What does it mean to say that the cell membrane is semi-permeable?
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O2, CO2, and other small molecules can pass through; glucose and other large, polar molecules cannot
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What is the concentration gradient?
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the difference between the number of molecules in one area and the number of molecules in another area
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In the absence of other forces, how would the cells move?
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from an area of high concentration to an area of lower concentration, or "down" the gradient until equilibrium is reached
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What is the difference between active and passive transport?
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active requires energy (ATP), passive does not
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What are the two types of passive transport?
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diffusion (directly between phospholipids) and facilitated diffusion (through a channel in cell membrane)
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What affects the diffusion rate?
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the steepness of the concentration gradient (steeper = faster), the size of the molecules (smaller = faster), temperature (higher = faster), and electrical or pressure gradients
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What is osmosis?
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diffusion of water
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How do water molecules move in osmosis?
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to areas of lower water concentration (higher solute concentration)
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What is tonicity?
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the relative concentration of solutes in two fluids
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Describe an isotonic situation
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concentration of solutes in cell is equal to concentration of solutes surrounding cell, no net movement
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Describe a hypertonic situation
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concentration of solutes is lower in cell than surrounding it, fluid exits cell and cell shrivels
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Describe a hypotonic situation
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concentration of solutes is higher in cell than surrounding areas, fluid enters and cell swells and may burst
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What is turgor pressure?
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the water pressure in plants that helps support non-woody plants
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What is plasmolysis?
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when plants lose water and the cytoplasm shrinks, wilting occurs
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Why does active transport require ATP?
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to pump solutes against the concentration gradient
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What is endocytosis?
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when the cell membrane encloses particles and pinches them off the cytoplasm in vesicles
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What are the two kinds of endocytosis?
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pinocytosis ("cell drinking") and phagocytosis ("cell eating")
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What is the difference between pinocytosis and phagocytosis?
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in pinocytosis, the cell membrane forms an indent to which small particles flow before the membrane closes around them, in phagocytosis the cell membrane actively engulfs larger molecules
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What is exocytosis?
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vesicles enclosing molecules move in the cytoplasm to the cell membrane; the vesicle fuses to the membrane and releases the molecules outside the cell
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Describe the endomembrane system
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proteins are created by the ribosomes on the rough ER and are sent to the Golgi body; there they are packaged into vesicles which are sent to the cell membrane and released by exocytosis
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What is energy?
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the capacity to do work
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What is the initial source of energy for almost all living communities?
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the sun
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How do organisms acquire energy?
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they consume or produce organic compounds for food (carbs, lipids, or proteins) which have energy stored in the bonds of their molecules
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What is cellular respiration?
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the process of breaking down organic molecules for energy (ATP)
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How do autotrophs (producers) get food?
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they use energy from light (photosynthesis) or heat (chemosynthesis) to create organic molecules "food" from inorganic molecules
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How do heterotrophs (consumers) get food?
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they must consume organic molecules
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What is ATP?
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the chief energy currency of the cell
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Where is energy stored in ATP?
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the triphosphate group
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How is ATP phosphorylated?
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energy is required to link another phosphate group to ADP, endergonic reaction
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How is ATP hydrolyzed?
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third phosphate from ATP is released to form ADP, exergonic reaction
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What is the equation for photosynthesis?
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12H20 + 6CO2 = 6O2 + C6H12O6 + 6H20
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Explain why photosynthesis sustains all consumers
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because original energy from the sun moves through food chains as organisms are eaten
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Describe the interior of a chloroplast
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thylakoids are folded into grana (stacks of disks) and channels surrounded by the stroma
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Describe thylakoids
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they have a phospholipid bilayer embedded with photosystems and a thylakoid space continuously filled with H+ needed for photosynthesis
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Light dependent reactions take place in the...
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thylakoid membrane
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Light INdependent reactions take place in the...
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stroma
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What do pigments do?
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they act as antennae to absorb photons from sunlight
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What pigments make up photosystems?
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200-300 molecules of chlorophyll a, chlorophyll b, carotenoids, and anthocyanins
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What happens when light hits photosystem II?
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the energy jumps from pigment to pigment as they exchange electrons until eventually it is trapped by chlorophylls in the photosystem's reaction center
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What happens when the reaction center receives enough energy?
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it releases two electrons down the electron transport chain
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Why must the energy from sunlight also split a water molecule?
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so that 2 electrons can be taken from the hydrogens to replace the electrons released by the reaction center
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What happens to the H+'s and O?
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the O2 is released and the H+ are pushed into the thylakoid space when the electrons go down the electron transfer chain
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What happens when H+'s accumulate in the thylakoid space?
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the concentration and electric gradients are so steep that when they exit the space through ATP synthase, there is enough energy to join ADP with another phosphate group and make ATP.
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What is it called when ATP is formed this way?
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chemiosmosis
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What happens to the original two electrons?
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they eventually reach Photosystem I, where they are used to replace two electrons sent down another electron transfer chain by that reaction center
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What happens when the electrons reach the end of the second electron transfer chain?
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they encounter NADP+; one electron transfers to it to make it NADP and one transfers to an H+ and joins NADP to make NADPH
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What happens to the ATP and NADPH?
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they are used in the Calvin Cycle
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What are the three steps of the Calvin Cycle?
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carbon fixation, reduction, and regeneration
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How do plants capture carbon?
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it diffuses from the air through plant pores, across the cell membrane and into the stroma
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How is carbon 'fixed'?
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the enzyme RuBisCO attaches three carbon molecules to three RuBP, producing six molecules of 3-carbon PGA
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What happens to the PGA?
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ATP loses a P and NADPH loses H to each PGA molecule through redox reactions, forming 6 G3P
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What happens to one molecule of G3P?
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it is used to form glucose - Calvin Cycle must be complete twice for enough G3P for glucose
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What happens to the five remaining G3Ps?
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ATP is used to rearrange them back into three RuBP so that the cycle can start all over again
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What factors affect the rate of photosynthesis?
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availability of CO2, availability of light, and temperature
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Describe the graphs of the three factors that affect the rate of photosynthesis
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both CO2 and light availability go up and eventually plateau, temperature goes up until it reaches a peak and falls down as the temperature reaches a point where it denatures RuBisCO
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What is the equation for aerobic cellular respiration?
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C6H12O6 + 6O2 = 6CO2 + 6H20
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What does cellular respiration accomplish?
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the controlled release of chemical energy from glucose into a usable form (ATP)
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What is glycolysis?
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first step in obtaining energy from glucose. Involves investment of 2 ATP, followed by payoff of 4 ATP. Results in 2 molecules of pyruvate.
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What is anaerobic respiration?
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anaerobic means without oxygen. Anaerobic respiration is done by organisms that either cannot do aerobic respiration, or in cells that are capable of aerobic respiration but do not have enough oxygen at a certain point in time.
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What is alcoholic fermentation?
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done by yeasts and bacteria, a type of anaerobic respiration. Involves removing CO2 from pyruvate, producing ethanol. Allows glycolysis to continue. Involved in production of bread, yogurt, and alcoholic beverages
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What is lactic acid fermentation?
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done by animals when oxygen cannot be pumped to cells fast enough. Pyruvate is converted to lactic acid to allow glycolysis to continue.
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Where does aerobic respiration take place?
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mitochondria
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What is the structure of a mitochondrion?
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double membrane. Inner membrane extremely folded, forming cristae, which provide large surface area for reactions to take place. Interior of inner membrane is called the mitochondrial matrix.
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What are the steps in aerobic respiration after glycolysis?
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link reaction, Krebs Cycle, electron transport chain, chemiosmosis
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What is the link reaction between glycolysis and the Krebs Cycle?
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pyruvate enters the mitochondrion, CO2 is added, NADH is produced, and coenzyme A is added to produce acetyl coA, which enters the Krebs cycle
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What are the products of the link reaction?
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CO2 (released), NADH (goes to electron transport chain), and acetyl-CoA (goes to Krebs cycle)
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What are the reactions of the Krebs cycle?
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acetyl coA (2 carbons) combines with a 4 carbon molecule to form citric acid (6 carbons). Citric acid loses one CO2 and produces NADH. This produces a 5 carbon compound, which again loses a CO2 and produces NADH. This leaves a 4 carbon molecule, which reacts to form ATP, NADH, and FADH2
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What are the products of one turn of the Krebs cycle?
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3 NADH, 1 ATP, 1 FADH2
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Where do these products go to be used?
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electron transport chain (ETC)
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How many times does the Krebs cycle run for 1 glucose molecule?
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2, because glucose splits into 2 pyruvate
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What happens in the electron transport chain?
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oxidative phosphorylation
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Explain oxidative phosphorylation
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NADH and FADH2 releases electrons onto protein complexes and electron carriers on the inner mitochondrial membrane. Energy from these electrons is sued to pump H+ across to the inter-membrane space, producing an electrochemical gradient. The electrons are eventually accepted by oxygen, which then combines with H+ to form water.
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What is chemiosmosis?
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H+ flow back down their concentration gradient, powering the ATP synthase pump, which combines ADP and Pi to form ATP
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How many total ATP can be formed from one glucose molecule during cellular respiration?
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38 = 2 from glycolysis, 2 from Krebs Cycle, 34 from ETC
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What are the prefixes for the metric system and what do they mean?
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k = 1000
base units - meters, liters, grams, seconds c = 0.01 m = 0.001 u = 0.000001 |
