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66 Cards in this Set

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  • Back
What is energy?
Energy is the ability to do work.
What is work?
Work is a measure of the energy exerted on an object.
What is the 1st law of thermodynamics?
Energy can neither be created nor destroyed.
What is the 2nd law of thermodynamics?
The total amount of energy is flowing from high-energy forms to forms lower in energy.
(this means that the entropy, or measure of degree of disorder in a system, is increasing.)
What is an endergonic reaction?
A reaction that requires energy input.
Products have more energy than starting substances
What is an exergonic reaction?
A reaction that releases energy.
Products have less energy than starting substances
What does ATP do in cells?
Cells "earn" ATP in endergonic reactions and "spend" it in exergonic ones. Regenerating ATP through the ADP/ATP cycle helps drive most metabolic reactions. ATP allows cellular work to occur (e.g., breakdown, rearrangement, and synthesis of substances; contractions of muscle cells; active transport across a cell membrane)
What are enzymes?
Enzymes are catalytic molecules. They speed the rate at which reactions approach equilibrium.
What are the four features of enzymes?
1.Enzymes do not make anything happen that could not happen on its own. They just make it happen 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 only to certain substances.
What is activation energy?
The minimum amount of internal energy that reactants must have before a reaction will run to products.
How do enzymes affect activation energy?
Enzymes enhance reaction rates by lowering the required amount of activation energy.
What is allosteric activation?
This is when an allosteric activator alters an enzyme active site so that a substrate can bind to it.
What is allosteric inhibition?
This is when an allosteric inhibitor alters an enzyme active site so that a substrate cannot bind to it.
What is feedback inhibition (negative feedback)?
A cellular change, caused by a specific activity, that shuts down the activity that brought it about.
What things can affect enzyme performance?
1. Temperature
2. pH
3. Salt concentration
4. Allosteric regulators
5. Coenzymes and cofactors
What are cofactors and coenzymes?
Cofactors are enzyme helpers which include metal ions and coenzymes. Coenzymes are a class of organic compounds that are derived from vitamins. They accept electrons & hydrogen ions (protons), and transfer them within a cell.
What are the two main metabolic pathways?
Anabolic (biosynthetic) pathway: requires a net input of energy to produce glucose, starch, and other large molecules from small ones. Ex.- photosynthesis
Catabolic (degradative): exergonic; end with a net release of usable energy. Ex.: Aerobic respiration
What is chemical equilibrium?
This is when the energy in reactants equals that of the products.
At this point, the amount of reactant almost never equals the amount of product.
What are redox reactions?
Oxidation-Reduction reactions are how cells release energy efficiently. One molecule gives up electrons (it is oxidized) and another gains them (it is reduced). These reactions always occur together.
What is the electromagnetic spectrum?
The range of all wavelengths of radiant energy, from shortest (gamma rays) to longest (radio waves).
What is the relationship between wavelength and energy?
The shorter the wavelength, the higher the energy.
What are photons?
A fixed amount of energy. Energetic photons travel in shorter wavelengths, those with less energy travel in longer wavelengths.
What are pigments? How do they work?
Pigments are a class of molecules that absorb photons in particular wavelengths only. Photons that a specific pigment does not absorb are reflected by it or continue traveling right on through it.
What are the pigments found in plants?
In plants, chlorophyll a and accessory pigments absorb specific wavelengths of visible light. They are molecular bridges between the sun's energy and photosynthesis.
What is the structure of a chloroplast? How does this relate to the process of photosynthesis?
The chloroplast has two outer membranes that enclose a semifluid matrix called the stroma. A third membrane-the thylakoid membrane- is folded up inside the stroma. Pigments are packed together as light-harvesting complexes in the thylakoid membrane, along with photosystems which receive energy from these complexes. This allows photosynthesis to begin by absorbing sunlight energy. The second stage proceeds in the stroma, where energy from ATP drives the synthesis of sugars from water and carbon dioxide.
What is the structure of a leaf?
Inside a leaf there is an epidermis, an interior region called the mesophyll, and an arrangement of veins. The epidermis is covered with pores called stomata which regulate the exchange of gases and water vapor between the exterior and interior of the leaf. There are two parts to the mesophyll, upper palisade and lower spongy. The upper palisade layer is tightly packed with chloroplast-containing cells. The lower spongy layer contains large intercellular air spaces, fewer chloroplasts, and veins. The veins are made up of xylem, which transports water, and phloem, which usually moves sap out.
What are the two stages of photosynthesis? Where do they occur and how are they related to each other?
Light dependent reactions and Light independent reactions. They take place in the chloroplasts. Light dependent reactions take place in the thylakoid membrane and light independent reactions take place in the stroma. THe light dependent reactions produce ATP and NADPH, which are used in the light independent reactions to produce sugars.
What is an antenna complex?
A light harvesting complex that intercepts incoming light energy and transfers it to a photosystem.
Whats a photosystem? is there more than 1 kind? why?
reaction centers embedded in the thylakoid membrane that absorb photon energy from light harvesting complexes and send electrons to the electron transfer chain.
there are 2 kinds, photosystem I & II, each absorbs light at slightly different wavelengths (II=680nm; I=700nm). photosystem II helps in the steps required to split water molecules, emit oxygen and create ATP. p.I helps create NADPH
What is a noncyclic pathway (in terms of photosynthesis)? How about cyclic?
In a noncyclic pathway, photon energy drives electrons out of P.II, where they hop on to an electron transfer chain, setting up an electric gradient which pulls H+ into the thylakoid compartment to activate ATP synthases. From the chain, electrons go to P.I and end up in NADPH.
In a cyclic pathway, electrons go back to P.II rather than making NADPH from P.I, this causes slightly more ATP to be produced.
How is ATP generated during photosynthesis?
Photons are absorbed by light harvesting complexes and transferred to Photosystem II, which excites one of its electrons to a higher energy level and sends it through an electron transfer chain. The electric gradient set up by the movement electrons through the chain causes H+ to be pulled into the thylakoid compartment. ATP synthase proteins on the thylakoid membrane use H+ to drive their rotations. This movement causes ADP to bind with inorganic phosphate, creating ATP.
How is ATP used during photosynthesis?
ATP energy drives the light independent reactions (the calvin benson cycle), which produce glucose and regenerate RuBP by extracting carbon from carbon dioxide molecules
What is photorespiration? Why is it bad?
On hot, dry days, stomata close to conserve water. This leads to a buildup of oxygen in the leaf and not enough carbon dioxide. Rubisco starts binding oxygen atoms to RuBP rather than carbon, cutting sugar production by as much as 50%. Only 1 PGAL forms instead of 2.
How do C4 plants photosynthesize and reduce photorespiration?
In C4 plants there are 2 types of photosynthetic cells: mesophyll and bundle sheath. Their mesophyll cells use PEP to fix carbon dioxide (in C4 plants, rubisco will not use oxygen for this step no matter how much there is). PEP becomes oxaloacetate, which becomes malate. Malate diffuses into bundle sheath cells, forming pyruvate and releasing CO2. The infusion of CO2 prevents photorespiration and allows the calvin benson cycle to proceed normally.
How do CAM plants photosynthesize and reduce photorespiration?
CAM plants fix carbon dioxide twice in the same cells. They close stomata during the day and fix CO2 at night, when mesophyll cells use a C4 cycle. Each cell stores malate and other organic acids till the next day, when stomata close. Malate releases CO2, which the cell uses in the calvin benson cycle.
(In other words, They collect and store CO2 at night then release it during the day when light energy is available for photosynthesis.)
What is special about the anatomy of C4 plants?
They have bundle sheath cells
How is ATP made during cellular respiration?
ATP is made through glycolysis, the krebs cycle, and electron transport phosphorylation
What are the 3 parts of cellular respiration? What happens in each? Where in the cell do they occur?
Part 1. Glycolysis- enzymes partly break down glucose to pyruvate. Occurs in the cytoplasm.
Part 2. Krebs Cycle. Pyruvate becomes acetate; acetate becomes Acetyl-CoA; Acetyl-CoA interacts with oxaloacetate to make citric acid; citric acid is broken down to release energy, which is stored in FADH2 and NADH. Occurs inside mitochondrial compartment.
Part 3. NADH and FADH2 produced in glycolysis and the krebs cycle power protein pumps in the mitochondrial membrane to move H+ into the intermembrane space, making a concentration gradient. ATP synthases use this gradient to move H+ back into the inner mitochondria and make ATP. Oxygen combines with free electrons and creates water.
At what stage of cellular respiration is most of the ATP generated?
Electron transport phosphorylation (Stage 3)
What is the difference between substrate level phosphorylation and oxidative phosphorylation?
Substrate level phosphorylation involves the transfer of a phosphate group from a substrate of a reaction to another molecule.
Odixative phosphorylation involves the transfer of electrons from NADH or FADH2 to molecular oxygen.
What is fermentation? Why and when does it occur? Is it as efficient as aerobic respiration?
Fermentation is a process of energy production which occurs in an anaerobic environment. It yields enough energy to sustain many single celled anaerobic species. It helps some aerobic cells when O levels are really low. It is not as efficient as aerobic respiration, much lower ATP output
What is mitosis? Where does it occur? When does it occur? What do you start and end with?
a nuclear division mechanism that occurs in somatic cells of multicelled eukaryotes. It is the basis of increases in body size during growth, replacements of dead or worn-out cells, and repair of damaged tissue.
You start with one cell and end up with two identical cells.
What is meiosis? Why and where does it occur? What do you start with and what do you end with?
Meiosis is a nuclear division mechanism that is the basis of sexual reproduction in single-celled and multicelled eukaryotes.
It precedes gamete formation or spore formation.
You start with 1 diploid germ cell and end up with four haploid gametes. Meiosis halves chromosome number.
What are the 4 stages of mitosis?
Phase 1: Prophase. Duplicated chromosomes condense. Spindles form and move one of the centriole pairs to the opposite side of the cell. Nuclear envelope begins to break up.
Phase 2: Metaphase. Nuclear envelope breaks up completely and spindle microtubules become attached to the sister chromatids of each chromosome.
Chromosomes are dragged to the cell equator.
Phase 3. Anaphase. Sister chromatids separate and move to opposite poles.
Phase 4. Chromosomes arrive at spindle poles. New nuclear membranes form for the 2 new cells.
(When mitosis is complete, cells enter interphase. This is when chromosomes are duplicated for the next round of mitosis.)
What are the 8 stages of meiosis?
Phase 1: Prophase 1. Duplicated chromosomes condense and pair w/homologues. Nonsister chromatids in homologous pairs exchange segments (Crossing over).
Phase 2: Metaphase I. Homologous pairs are aligned at spindle equator.
Phase 3: Anaphase I. Homologous pairs are separated.
Phase 4: Telophase I. Chromosomes arrive at opposite poles and nuclear envelopes form around each set. Cytoplasmic division follows.
Phase 5: Prophase II. Spindles attach to the duplicated chromosomes.
Phase 6: Metaphase II. Chromosomes align at spindle equator.
Phase 7: Anaphase II. Chromatids separate and are now called chromosomes.
Phase 8: Telophase II. Chromosomes arrive at opposite poles and cytoplasm divides. There are now 4 haploid cells.
What makes Prophase in Mitosis different from Prophase I in Meiosis?
In Mitosis Prophase, homologous pairs dont interact with each other.
In Meiosis Prophase I, homologous pairs become zippered together and crossing over occurs.
What makes Metaphase in Mitosis different from Metaphase I in Meiosis?
In Mitosis metaphase, all chromosomes line up in the equatorial plane.
In Meiosis Metaphase I, chromosomes line up in 2 planes. The lineup is random between paternal and maternal chromosomes.
What makes Anaphase I in Meiosis different from Anaphase in Mitosis AND Anaphase II in Meiosis?
In Anaphase I of Meiosis, homologous chromosomes separate

In Anaphase Mitosis and Anaphase II Meiosis, sister chromatids of a chromosome separate from each other
What is cytokinesis?
Cytokinesis that partitions a cell into two separate daughter cells, each with a nucleus, after division.
How does cytokinesis occur in animals?
A contractile ring partition mechanism partitions a dividing animal cell. A band of actin filaments around the cell midsection contracts and pinches the cytoplasm in two.
How does cytokinesis occur in plants?
Cell plate formation partitions plant cells. Golgi-derived vesicles deposit material at a plane of cytoplasmic division to form a cross-wall, which connects to the parent cell wall.
What are chromosomes?
A double-stranded DNA molecule with a lot of proteins attached to it.
What are chromatids?
Chromatids are copied chromosomes; they stay attached until late in the cell division process.
What are spindle fibers?
Spindle fibers are microtubules that latch onto and move around chromosomes during cell division
What is cancer? Malignant? Benign?
Cancers are the abnormally growing and dividing cells of a malignant neoplasm. They disrupt surrounding tissues, are grossly disfigured, can break loose from home tissues, and are able to slip into and out of blood/lymph vessels, invading other tissues where they do not belong.

Benign tumors are typically slow growing and stay put in their home tissue.
Cells of a malignant tumor migrate abnormally through the body & establish colonies even in distant tissues.
What are genes? Alleles? Whats a locus?
Genes are units of information about heritable traits. Alleles are variations of a specific gene.
Locus is a genes location on a chromosome.
what are homologous chromosomes?
non-identical chromosomes that contain information for the same biological features and contain the same genes at the same loci but possibly different genetic information, called alleles, at those genes
what is heterozygous?
Possessing two different forms of a particular gene, one inherited from each parent.
What is the P generation? How about F1 and F2?
P stands for true breeding parents, F1 for first generation offspring and F2 for the second generation offspring of self fertilized or intercrossed F1 individuals.
Whats codominance?
a pair of nonidentical alleles affecting two phenotypes are both expressed at the same time in heterozygotes.
what is incomplete dominance?
in incomplete dominance, one allele of a pair is not fully dominant over its parter, so the heterozygote's phenotype is somewhere between the two homozygotes
what is pleiotropy?
Pleiotropy occurs when a single gene influences multiple phenotypic traits.
What is epistasis?
interaction between the products of gene pairs. (common among genes for hair color in mammals.)
what is linkage? complete? incomplete?
Complete linkage is defined as the state in which two loci are so close together that alleles of these loci are virtually never separated by crossing over.

In incomplete linkage, gametes cross over genes .
Where do we develop variation during meiosis?
Lineup of chromosomes in meiosis is random; which segments of a chromosome that will be swapped in crossing over is random; which two gametes unite in fertilization is also random
What is continuous variation and how does it occur?
a more or less continuous range of small differences in a given trait among individuals. The greater the number of genes and environmental factors that affect a trait, the more continuous the variation in versions of that trait.