AP BIOLOGY UNIT 2 TEST

What is the Endosymbiosis Theory?

- Mitochondria and Chloroplasts share similar origin, they were prokaryotes that began living in smaller cells.

- Prokaryotic cells (w/ mitochondria and chloroplasts) were engulfed by the ancestors of the eukaryotic cell.

- This is evidenced by the double membrane structure, because prokaryotes and eukaryotes have ribosomes and DNA, and reproduce independently in the cell.

What is the Cell Theory?

-All living organisms are composed of cells. They may be unicellular or multicellular.

-The cell is the basic unit of life.

-Cells arise from pre-existing cells.

Why are cells so small?

- To maintain a large surface area to volume ratio.

- Large surface area includes faster rates of chemical exchange between cell and environment

What are three basic features of all cells?

- They are all bounded by a selective barrier (plasma membrane)

- All cells contain chromosomes, which carry genes in the form of DNA

- All cells have ribosomes, tiny complexes that make proteins according to instructions from the genes.

What is the difference between a prokaryote and a eukaryotic cell?

- In a EC, most of the DNA is in the nucleus, which is bounded by a double membrane. In the PC, the DNA is in the nucleoid (not bounded by a double membrane)

- The interior of a PC is called the cytoplasm, which is also the region between the nucleus and the plasma membrane of a EC. The cytoplasm of an EC has a variety of different organelles with specialized structure/function. These membrane-bound structures are absent in PC's, they only have ribosomes.

- EC's are a lot larger than PC's, they are more complex.

What structures are found in a PC?

- Nucleoids, Cytoplasm & Cytosal, Plasma Membrane, Cell Wall

What is the function of the nucleus? What structures are found within the nucleus?

- It contains most of the genes in the eukaryotic cell. It is the most conspicuous organelle in a eukaryotic cells.

- The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm. This is a double membrane, each membrane has a lipid bilayer with associated proteins.

- The envelope is lined by the nuclear lamina, which is a netlike array of protein filaments that maintains the shape of the nucleus by supporting the envelope.

- Within the nucleus, the DNA is organized into chromosomes. Each chromosome is made up of chromatin, a complex of proteins and DNA.

- The nucleolus appears within the nucleus. In it, a type of RNA called rRNA is synthesized from instructions in the DNA. Also, proteins imported from the cytoplasm are assembled with rRNA into ribosomes, with the help of the cytoplasm.

- It is the site of replication, transcription, and posttrasnscriptional modification of RNA.

What is the functional of the endoplasmic reticulum? What is the difference between the smooth and rough ER?

- The ER of networks of membranes. It consists of membranous tubules and sacs called cisternae. The ER membrane separates the internal compartment of the ER from the cytosol. The ER membrane is continuous with the nuclear envelope.

- SMOOTH ER: Synthesizes lipids, metabolizes carbs, and detoxifies drugs and poisons. Enzymes of the smooth ER are important to the synthesis of lipids. There are no ribosomes on the smooth ER. Membrane bound.

- Also stores calcium ions.

- ROUGH ER: Membrane bound organelle has ribosomes on its cytoplasmic surface. The proteins produced by the rough ER are secreted by the cell and carried by vesicles to the Golgi Apparatus. The rough ER also makes replacement membranes by adding membrane proteins and phospholipids to its own membranes.

What is the Golgi apparatus? What does it do? Define cis, trans, and cisternae, and vesicle.

- Golgi Apparatus: Transport vesicles travel here after they leave the ER. It is the center of manufacturing, warehousing, and shipping (small molecules). Products of the ER are modified and stored and sent to other destinations (in vesicles), it also produces lysosomes.

- Cisternae: Stacks that compose the GA. They are flattened membraneous sacs.

- Cis: Is located near the ER. Transport vesicles move material from the ER to the GA through this; it receives the transport vesicles through fusion.

- Trans: Ships the vesicles, it pinches them off and forces them to travel to other sites.

What are ribosomes? What is the structure of a ribosome (large and small)? What message does the ribosome read?

- Ribosomes: Complexes made of ribosomal RNA and protein, they carry out protein synthesis. They build proteins in two cytoplasmic locations - free ribosomes are suspended in the cytosol, while bound ribosomes are attached to the outside of the rough ER or nuclear envelope. Most of the proteins made on free ribosomes function within the cytosol. Bound ribosomes make proteins that are destined for insertion into membranes.

- Ribosomes are made up of a large and small subunits, it binds to mRNA.

- Ribosomes read the information contained in the nucleotide sequence of the mRNA.

What is the relationship between ribosomes, amino acids, proteins, and vesicles?

- The two subunits combine with mRNA.The ribosomes then stick amino acids together in the right order to make protein. The protein is then sent to the GA to pack it into a transport vesicle, where it is eventually sent to where it is needed to go.

What are the steps of protein synthesis in the cell? What organelles are involved?

- The nucleus directs protein synthesis by synthesizing messenger RNA (mRNA) according to instructions provided by the DNA. The mRNA is then transported to the cytoplasm via the nuclear pores. Once an mRNA reaches the cytoplasm, ribosomes translate the mRNA's genetic message into the primary structure of a specific polypeptide.

What does the mitochondria do? Describe the structure of the mitochondria.

- It is enclosed by two membranes. The outer membrane is smooth, but the inner membrane has cristae.

-The inner membrane divides the mitochondrion into two internal compartments, the first is the inter membrane space, and the second is the mitochondrial matrix, which is enclosed by the inner membrane. The matrix contains many different enzymes as well as the mitochondrial DNA and ribosomes. Enzymes in the matrix catalyze some steps of respiration.

- The cristae give the inner mitochondrial membrane a large surface area, enhancing the productivity of cellular respiration. The cristae also contains enzymes for ATP production.

How do mitochondria and chloroplasts support the endosymbosis theory?

- They inner membranes have enzymes and transport systems

- They reproduce themselves by splitting into two

- They have their own ribosomes

What is the structure of chloroplasts? What do they do?

- Contain chlorophyll

- Double membrane with a a narrow inter membrane space.

- Inside the chloroplast are sacs called thylakoids. Each stack is called a granum, and the fluid outside the thylakoids is the stroma, which contains the the chloroplast DNA and ribosomes as well as many enzymes.

- The membranes of the chloroplast divide the chloroplast space into the intermembrane space, the stroma, and the thylakoid space.

- It is the site of Photosynthesis

What is the cytoskeleton? What functions does it serve?

- It gives support to the cell and helps maintain its shape.

- It is composed of microtubles, microfilaments, and intermediate filaments.

- Microtubles: They are the largest fibers and shape/support the cell. The track for organelle movement and form spindles for mitosis/meiosis. It is a component of cilla/flagella.

- Microfilaments: smallest fibers, they support the cell and aid cell movement, cytoplasmic streaming, and muscle cell contraction.

- Intermediate filaments: Permanent fixtures, they maintain shape of the cell and fix position of organelles.

What is a centriole? What types of cells are they found in?

- Centrosomes is a region often located near the nucleus and considered the microtuble organizing center.

- Within the centrosome are centrioles, which are composed of nine sets of triplet microtubles arranged in a ring. Before an animal cell divides, the centrioles replicate. They may help organize microtuble assembly.

- They are found in animal cells

What are the cilla and flagella? What are they made from?

- Flagella: Long and few; they propel through water.

Cilla: Short and numerous, they move through fluids.

-They both have a 9+2 arrangement of microtubles. There are 9 fused pairs of microtubules on the outside of a cylinder, and the 2 unfused microtubules in the center.

What are vacuoles?

- Storage organelle that acts as a vault. Vacuoles are quite large in plant cells but small. They contain membrane bound vesicles.

What are the differences between plant and animal and bacteria cells? Similarities?

Plant cells: Central Vacuoles, Chloroplasts, Cell Wall, and Plasmodesmata.

Animal cells: Lysosomes, Centrioles, Flagella, cilia, Desmosomes, tight and gap junctions, and an ECM.

Bacteria: Mesosome, Capsule, Bacterial Flagellum, Fimbriae, Plasmid DNA.

All: Ribosomes, Plasma membrane, Peroxisome (P&A)

Describe the cell membrane.

- Selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to service the entire cell.

- It is composed of a mix of proteins and lipids, they give the membrane its flexibility and proteins monitor and maintain the cell's chemical climate and assist in the transfer of molecules across the membrane.

What are other names for the cell membrane?

Plasma membrane.

Describe the hydrophobic and hydrophilic interactions of the phospholipid bilayer.

- It has a hydrophobic barrier that keeps hydrophilic molecules out.

- In low temperatures, phospholipids form kinks, which prevent close packing, these kinks are caused by unsaturated tails.

- Cholesterol resists changes by limiting fluidity at high temperatures, and hindering close packing at low temperatures.

- Small molecules cross easily.

- Hydrophobic core prevents passage of ions, and large polar molecules.

What are the proteins embedded in the cell membrane and what is their function?

- Integral proteins: They are embedded in the membrane. Many are transmembrane proteins, which span the membrane; other integral proteins extend only partway into the hydrophobic core.

- Peripheral Proteins: Not embedded in the lipid bilayer, but are loosely bound to the surface of the membrane. They are held in place by the cytoskeleton or ECM. They provide a stronger framework.

- Proteins may transport substances, enable enzymatic activity, signal transduction, recognize other cells, and preform intercellular joining.

What are the types of passive transport? Active transport?

- No energy is needed for PT. Diffusion down the concentration gradient.

- Osmosis is a form of PT that diffuses H20.

- Hypotonic: Water entering an area of high concentration of solute, the cell would get bigger.

- Hypertonic: The cell will lose water to its environment and shrivel up.

- Isotonic: equal amounts of water on both sides, nothing will happen.

- Facilitated diffusion: Transport proteins help get a hydrophilic substance across. They provide a hydrophilic channel or loosely bind/carry the molecule across.

- Active transport: The movement of a particle across a selectively permeable membrane against its concentration gradient. This uses energy.

- Sodium-Potassium Pump: It is a electromagnetic pump, which generates voltage across the membrane. It moves potassium into the cell and sodium out of the cell against the concentration gradient; it is used for nerve transmission.

- Proton Pump: Also a electromagnetic pump that pushes protons (H+) across the membrane.

- Exocytosis: Substances are exported out of the cell, this is achieved through the fusion of vesicles with the plasma membrane.

- Endocytosis: The cell takes in biological membranes by forming new vesicles from the plasma membrane.

Define diffusion and osmosis.

- Diffusion: The movement of molecules across their concentration gradient without the use of energy.

- Osmosis: The passive diffusion of water down its concentration gradient across selectively permeable membranes. Water moves from a region of high water concentration to a region of low water concentration.

How does osmosis affect the turgor pressure of plants?

- Turgor pressure is the pressure exerted by water inside the cell against the cell wall. Depending on how much water is inside the cell, osmosis may break the cell, force it to shrivel, or do nothing.

Describe the reaction of a cell when placed in hypertonic, hypotonic, and isotonic solutions.

- Hypotonic: Water entering an area of high concentration of solute, the cell would get bigger.

- Hypertonic: The cell will lose water to its environment and shrivel up.

- Isotonic: equal amounts of water on both sides, nothing will happen.

What is a contractile vacuole? What organisms have them?

- Freshwater protists have these.

- They pump excess water out of the cell, maintaining a suitable concentration of ions and molecules inside the cell.

Compare endocytosis to exocytosis.

- Exocytosis: Substances are exported out of the cell, this is achieved through the fusion of vesicles with the plasma membrane.

- Endocytosis: The cell takes in biological membranes by forming new vesicles from the plasma membrane.

-- Phagocytosis: solids

--Pinocytosis: fluids

Describe how the Na-K pump works.

-It is a electromagnetic pump, which generates voltage across the membrane. It moves potassium into the cell and sodium out of the cell against the concentration gradient; it is used for nerve transmission.

- It occurs in animal cells

Describe cell to cell communication (tight junctions, desmosomes, plasmodesmata, gap junctions)

- Tight junctions: The plasma membranes of neighboring cells are very tightly pressed against each other, bound by specific proteins. They prevent leakage of extracellular fluid across a layer of epithelial cells.

- Desmosomes: They fasten cells together into strong sheets. Intermediate filaments made of keratin anchor them in the cytoplasm.

- Plasmodesmata: Cell walls are perforated with these channels. Cytosol passes through it and connects the chemical environments of adjacent cells. They allow passage of molecules. They are in plant cells.

- Gap Junctions: Channels through which ions, sugars, and small molecules can pass.

What is a redox reaction and why is it important to cells?

- Redox reactions are the transfer of one or more electrons from one reactant to another.

- Loss of electrons: oxidation

- Addition of electrons: reduction

Define cellular respiration.

-Glycolysis: Krebs Cycle: Oxidative Phosphoralaytion.

- C6H12O6 + 602 = 6CO2 + ATP

- Glycolysis: Believed to be ancient, and it occurs in the cytosol. It oxidizes glucose (6 carbons) to 2 Pyruvates. It makes 2 ATP and 2 NADH and 2H2O. No oxygen is required.

-- 2 phases: Energy investment: The cell uses ATP to phosphorylate compounds of glucose. Energy payoff: 2 ATP is produced by substrate-level phosphorylation (ADP + P) and NAD+ is reduced to 2NADH by electrons released. Also, two 3-C compounds are oxidized.

- Citric Acid Cycle/Krebs: Occurs in the matrix of the mitochondria. The pyruvate is converted to acetyl CoA, a process which also produces NADH. The acetyl CoA goes through an 8-step cycle that converts Citrate to Oxaloacetate. The pyruvate is eventually reduced to H2O and CO2. The net gain is 2 ATP, 6 NADH, and 2 FADH2 (the electron carrier). The ATP is produced by substrate level phosphorylation.

- OP: Requires oxygen. The NADH and FADH2 produced are used to create ATP. The ETC is a collection of molecules embedded in inner membrane of the mitochondria. It alternates between a reduced/oxidized state as it accepts and donates electrons. Electrons removed from glucose by NAD+ during glycolysis and the citric acid cycle are transferred from NADH to the first molecule of the electron transport chain. Another source of electrons for the transport chain is FADH2, the other reduced product of the citric acid cycle. FADH2 adds its electrons at a lower energy level than NADH does. Both NADH and FADH2 provide 2 electrons for oxygen reduction, and the ETC eases the fall of electrons from food to oxygen. When oxygen accepts a pair of electrons, it pics up a pair of hydrogen ions to produce water. As electrons move through the ETC, proton pumps move H+ across inner mitochondrial membrane. This creates a proton gradient that drives the production of ATP. The difference in hydrogen concentration on the two sides causes the protons to flow back into the matrix of the mitochondria through ATP synthase channels. ATP synthase is an enzyme that uses the flow of hydrogens to drive the phosphorylation of an ADP molecule to produce ATP. OP produces 36-38 ATP, and regenerates NAD+ so that glycolysis and the Krebs cycle can continue.

Define photosynthesis.

- 6H2O + 6CO2 + light = C6H12O6 + H2O + 602.

- Light-dependent - Calvin Cycle

- The light reactions convert solar energy to chemical energy of ATP and NADPH. They occur in the thylakoid. Chlorophyll absorbs the light, and one of its electrons is elevated to a higher energy level, the excited electron drops back down to the ground state, giving off heat in the process. This energy is passed along to chlorophyll a, which passes its electron to the primary electron acceptor. Photosystem II begins , which absorbs wavelengths at a wavelength of 680 nm. Here, energy is absorbed and passed along until it reaches P680 chlorophyll. When this chlorophyll is excited, it sends its electrons to the primary electron acceptor. Electrons are taken from H2O and passed to P680 to replace the electrons given to the primary acceptor. This forces O2 to form. The electrons are passed to photosystem 1 through the ETC (The light reactions also generate ATP, using chemiosmosis to power the addition of a phosphate group to ADP, which is photophosphorylation.) and the photosystem 1 electrons become excited, P1 passes the energy to its own primary electron acceptor, which are sent through the ETC , which donates the electrons to NADP+ to produce NADPH.

- The Calvin Cycle uses NADPH (hydrogen and energy) and ATP, and 3CO2 (brought about by carbon fixation when CO2 binds to RuBP, this reaction is assisted by rubisco - this reaction results in a 6 carbon molecule that breaks into 3 carbon molecules known as 3PG, 6ATP and 6NADPH donate a phosphate group to form G3P.) it occurs in the stroma of the chloroplast. Some of the G3P is converted to RuBP (which uses 3 ATP) to fix more carbon, and the rest is converted to glucose used to build carbs for the plant. It produces NADP+, ADP, and glucose.

What is ATP? Describe the ATP molecule.

-Adenosine Triphosphate, it contains the sugar ribose, with the nitrogenous base adenine and a chain of 3 phosphate groups. Their hydrolysis releases lots of energy.

What is the relationship between the LR and the Calvin Cycle?

- LR produces NADPH and ATP used by Calvin Cycle, while the Calvin Cycle produces the NADP+ and ADP used by LR.

What are the products of the light reaction? of the calvin cycle?

LR - ATP, NADPH, and O2.

CC - NADP+, ADP, and glucose.

What is photolysis?

- A chemical process by which molecules are broken down into smaller units through the absorption of light.

- It occurs in the thylakoid space

Describe the flow of protons and electrons in the light depending reactions.

- Protons and electrons flow from H2O and light energy.

Compare and contrast P2 and P1.

Photosystem II begins , which absorbs wavelengths at a wavelength of 680 nm. Here, energy is absorbed and passed along until it reaches P680 chlorophyll. When this chlorophyll is excited, it sends its electrons to the primary electron acceptor. Electrons are taken from H2O and passed to P680 to replace the electrons given to the primary acceptor. This forces O2 to form. The electrons are passed to photosystem 1 through the ETC (The light reactions also generate ATP, using chemiosmosis to power the addition of a phosphate group to ADP, which is photophosphorylation.) and the photosystem 1 electrons become excited, P1 passes the energy to its own primary electron acceptor, which are sent through the ETC , which donates the electrons to NADP+ to produce NADPH.

What is a C4 and a CAM plant?

- C4: They combat photorespiration by changing the first step of the calvin cycle. The carbon fixation produces a 4 carbon molecule, oxalacetate, which is later converted to malate. It is sent from the mesophyll cells to the bundle sheath cells, where the CO2 is used to produce sugar. On hot, dry days, the stomata closes.

- CAM: (water storing plants) Plants close their stomata during the day, and collect CO2 at night which is converted to an organic acid, and stored in the mesophyll cells. During the day, the stomata is closed and light reactions supply ATP, NADPH. The CO2 that was stored is incorporated into the sugar product of of the Calvin Cycle.

What environment factors affect the rate of photosynthesis?

- Distance from the light, Temperature (the higher the temperature the faster the rate, the amount of CO2 available

What is the difference between aerobic and anaerobic respiration?

- Anaerobic: Generates ATP using other electron acceptors besides O2, they can be sulfate, nitrate, sulfur - it is respiration without oxygen,

Aerobic is cellular respiration.

What is fermentation?

- Cytosol. The process that begins with glycolysis and ends when NAD+ is regenerated. A glucose molecule that enters the fermentation pathway produces two ATP. NAD+ is recycled from NADH by the movement of electrons to pyruvate.

- Alcoholic: Pyruvate is converted to Ethanol and CO2. This regenerates 2 NAD+ molecules.

- Lactic: Human and animal muscle cells when oxygen isn't available. The pyruvate is directly reduced to lactate by NADH to regenerate NAD+ needed for the resumption of glycolysis.