AP Biology Chapter 4

Describe the three benefits of compartmentalization found in cells.

1. creates appropriate microenvironment for diverse processes 2. Allows protection from injury 3. Increases cellular efficiency

Evaluate why a cell and a whole organism are both examples of biological systems.

A cell reproduces and comes from a preexisting cell, just like an organism. Both the cell and the organism require nutrients to function.

Explain why a large surface area to volume ratio is needed for the proper functioning of cells.

A large surface-area-to-volume ratio is more advantageous because it can more easily exchange the materials the cell requires for the cellular waste.

Infer how the proportion of organelles might differ between a muscle cell and a nerve cell.

A muscle cell may have more organelles than a nerve cell because the muscles must store energy for movement, while the nerve cells do not contract and expand to function.

Compare surface area to volume ratios for large and small cells.

A smaller (1 cm for a cube) cell has a surface-area-to-volume ratio (6:1) that allows sufficient transport in and out of the cell to support life. A larger (4 cm for a cube) cell has a surface-area-to-volume ratio (1.5:1) that does not support life.

Describe how motor molecules interact with cytoskeletal elements to produce movements.

Actin filaments interact with motor molecules when the molecule myosin uses ATP to pull actin filaments along. Myosin has both a head and a tail. In muscle cells, the tails of several form a thick filament. In nonmuscle, cytoplasmic myosin tails are bound to membranes, but the heads still interact with actin.

Describe the fundamental components of a bacterial cell.

Bacteria are a well known type of prokaryotes. They can be rod-shaped (bacillus), spherical (coccus), stiff spirals (spirilla), or flexible spirals (spirochetes). In bacteria, the cell envelope includes the plasma membrane, the cell wall, and the glycocalyx. -the plasma membrane regulates the entrance and exit of substances into and out of the cytoplasm. can form internal pouches called mesosomes. -the cell wall maintains the shape of the cell, even if the cytoplasm should happen to take up an abundance of water *the cell wall of a bacteria contains peptidoglycan, plants have cellulose -glycocalyx is a layer of polysaccharides that lies outside the cell wall in some bacteria. When hard to wash off and well organized is a capsule.

Compare the energy management of cellular respiration and photosynthesis.

Both chloroplasts and mitochondria are eukaryotic membranous organelles that specialize in converting energy to a form that is usable by the cell. Chloroplasts are used in photosynthesis to synthesize carbohydrates from solar energy. Mitochondria break down carbohydrates to produce ATP. Photosynthesis: solar energy + CO2 + water = carbohydrate + oxygen Cellular Respiration: carbohydrate + oxygen = CO2 + water + energy

Explain why cells are the basic units of life.

Cells bring together all the biomolecules necessary to support life. Only when these components are brought together and organized can life be supported.

Describe Chloroplasts.

Chloroplasts have a three-membrane system. The double membrane encloses the semifluid stroma, which contains enzymes and thylakoids. A stack of thylakoids is a granum. The lumens of the thylakoids are believed to form a large internal compartment called the thylakoid space. Chlorophyll is located in the thylakoid membrane and the enzymes that synthesize carbohydrates are in the fluid of the stroma outside the thylakoids. (chloroplasts are a plastid or plant organelle surrounded by a double membrane. Others are Chromoplasts and leucoplasts)

Genes

Composed of DNA, located on the chromosomes, units of heredity.

What happens during animal cell division?

During animal cell division, two new cells form when actin filaments, in conjunction with myosin, pinch off the cells from one another.

How many chromosomes do gametes have?

Gametes have half the number of chromosomes that somatic cells have. (half of 46 is 23)

How is the Golgi apparatus positioned within the cell?

In animal cells, the inner face (or cis face) of the Golgi apparatus saccules is directed toward the ER and the outer side (the trans face) is directed toward the plasma membrane.

Distinguish the flow of information from DNA to a protein.

In the nucleus, a gene is copied into mRNA, which is exported through a nuclear pore complex into the cytoplasm. Ribosomes receive the RNA, which carries coded instructions from DNA indicating the correct sequence of amino acids in a particular protein.

Explain why increased membrane surface area is necessary for chloroplast and mitochondrial function.

Increased folding of the membrane increases energy production within chloroplasts and mitochondria.

Distinguish between where peroxisome and lysosome proteins are produced.

Lysosomal proteins are synthesized in the Rough ER, while peroxisomal proteins are synthesized by free ribosomes and transported into a peroxisome from the cytoplasm.

Explain how membranes compartmentalize a cell.

Membranes create internal spaces that divide the labor necessary for function. The compartments of a eukaryotic cell are called organelles and carry out functions that together allow the cell to be efficient and successful.

Describe Mitochondria.

Mitochondria are smaller than chloroplasts and can form long, moving chains or remain fixed in one location. The inner membrane of mitochondria is highly convoluted into folds called cristae that project into the matrix, a semifluid containing mitochondrial DNA and ribosomes.

Explain the importance of nuclear pore complexes.

Nuclear pore complexes act as guards to regulate what comes in and goes out of a nucleus.

Examine how organelles divide cellular work. Examine why organelles increase cell efficiency and function.

Organelles each have specific individual functions like controlling metabolizing, regulating, and conducting life processes. Nearly all organelles are surrounded by a membrane embedded with proteins. Many of the proteins are enzymes that make products specific to the organelle, but their action benefits the whole cell.

Describe how endomembrane vesicles are able to fuse with organelles.

Organelles within the endomembrane system can interact because their membranes fuse together easily. (Also Membrane-associated proteins enable communication and specialized function.) The products of the ER are carried in transport vesicles to the Golgi apparatus, modified, packaged into vesicles, and sent to a cellular location using signaling sequences.

Contrast peroxisomes and vacuoles with endomembrane organelles.

Peroxisomes and vacuoles do not communicate with the organelles of the endomembrane system. While the endomembrane system compartmentalizes the cell so particular enzymatic reactions take place only in specific regions, peroxisomes and vacuoles are free in the cytoplasm so they do not receive the instructions of the Golgi apparatus or the Endoplasmic Reticulum. Peroxisomes and vacuoles do not transport material across the cell, but instead digest and store material.

Describe the role of peroxisomes and vacuoles in cell function.

Peroxisomes are membrane bound vesicles that contain enzymes. The enzymes' actions results in the formation of H2O2 (hydrogen peroxide) which is a toxic molecule. (The hydrogen peroxide is immediately broken down into water and oxygen by another peroxisomal enzyme, catalase.) Peroxisomes are metabolic assistants to the other organelles of the cell, especially cells that synthesize and break down lipids. Vacuoles are membranous sacs that are larger than vesicles. They usually store substances. They are essential to plant function because they contain not only water, sugars, and salts but also water soluble pigments and toxic molecules. (The toxic substances help protect a land plant from herbivorous animals.)

Compare the structure and functions of a peroxisome with a lysosome.

Peroxisomes are membrane bound vesicles that contain enzymes. They bud off from the ER, not the Golgi apparatus. They synthesize and break down lipids. Lysosomes are also membrane-bounded vesicles, but they are produced by the Golgi apparatus. Like peroxisomes, lysosomes digest material into simpler subunits that are sent into the cytoplasm and recycled.

Describe the vacuole of a plant cell.

Plant cells typically have a large central vacuole filled with a watery fluid called cell sap that gives added support to the cell. The central vacuole maintains hydrostatic or turgor pressure.

Do plants also have peroxisomes? What are the peroxisomes' functions?

Plants also have peroxisomes. They oxidize fatty acids into molecules that can be converted to sugar for a growing plant. In leaves, peroxisomes carry out a reaction opposite of photosynthesis, taking in oxygen and releasing CO2.

Explain the major differences between a prokaryotic and eukaryotic cell.

Prokaryotes are structurally less complicated than eukaryotes, but their metabolic capabilities far exceed those of eukaryotes.

Explain the role of ribosomes in protein synthesis.

Ribosomes are particle where protein synthesis occurs. A large and small ribosomal subunit (made of proteins and rRNA) are necessary components of a functional ribosome. Some ribosomes occur freely within the cytoplasm (singly or in a group {polyribosome}). Others attach to the endoplasmic reticulum (a membrane of flat saccules and tubules). They are bound the the ER only if the protein being synthesized by a ribosome begins with a sequence of amino acids called a signal peptide.

Contrast the structure and function of rough and smooth endoplasmic reticulum.

Rough ER is studded with ribosomes on the side facing the cytoplasm, so it produces proteins. In its lumen (center) it allows proteins to fold and take on their final 3D shape. It contains enzymes that can add carbohydrate (sugar) chains to proteins to form glycoproteins which are important in many cell functions. Smooth ER is continuous with the nuclear envelope and the rough ER. It does not have attached ribosomes, which produces more lipids. It helps detoxify the body.

Where is the DNA of a prokaryote found?

The DNA of a prokaryote is found in a single chromosome located in the nucleoid. Many bacterias also have extrachromosomal pieces of circular DNA called plasmids. (plasmids used as a molecular vehicle- or vector- to transport DNA from different organisms into a bacterium) The proteins encoded by bacterial DNA are synthesized on ribosomes.

Describe the relationship between the components of the endomembrane system.

The ER forms vesicles that transport molecules to the Golgi apparatus. The Golgi apparatus produces lysosomes, which aid in digestion within the cell.

Describe the function of the bacterial cell envelope, cytoplasm, and appendages.

The cell envelope aids against dehydration and boosts immunity. The cytoplasm cushions the organelles, contains a variety of enzymes that speed metabolism, and holds water. Appendages of a bacterium like flagella, fimbriae, and conjugation pili are made of protein. -flagella: consists of a filament, a hook, a basal body (a series of rings anchored in the cell wall and membrane.) the rotation of the hook propels bacteria. -fimbriae: small, bristle-like fibers that sprout from the cell surface. not involved in locomotion, attach bacteria to the surface. -conjugation pili: rigid tubular structures used to pass DNA from cell to cell. a way for bacteria to exchange DNA since the reproduce asexually by binary fission.

List the tenets of cell theory.

The cell theory states that: All organisms are composed of cells Cells are the basic units of structure and function in organisms. Cells come only from preexisting cells because cells are self-reproducing.

Examine how cellular function would be affected if the Golgi apparatus ceased to function.

The cell would cease digesting nutrients and die. Without the lysosomes created by the Golgi apparatus, the cell would not be able to easily transform subunits into a useable form for energy.

Compare the structure and function of actin filaments, intermediate filaments, and microtubules. Differentiate between the components of the cytoskeleton and how they provide support to the cell.

The cytoskeleton contains actin filaments, intermediate filaments, and microtubules. Actin filaments provide structural support just under the plasma membrane as long, thin, flexible fibers that occur in bundles or mesh-like networks. (They are anchored by special proteins.) Intermediate filaments come between actin filaments and microtubules. They form a ropelike assembly of polypeptides. Some support the nuclear envelope, and others support the plasma membrane. Other still take part in the formation of cell-to-cell junctions. Microtubules are small, hollow cylinders made of a globular protein called tubulin, which is of two types called alpha and beta. Microtubule assembly is regulated by a microtubule organizing center (MTOC) in the centrosome which lies near the nucleus. They help maintain the shape of the cell and act as tracks along which organelles can be moved. (The motor molecules kinesin and dynein are associated with microtubules.)

Explain the importance of the endomembrane system in cellular function.

The endomembrane system consists of the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, and several types of vesicles. It compartmentalizes the cell so particular enzymatic reactions take place only in specific regions. It increases overall cell efficiency and transports material across the cell.

Examine how the endoplasmic reticulum, the Golgi apparatus, and the lysosome membranes differ from one another.

The endoplasmic reticulum consists of a system of membranous channels and saccules. It is physically continuous with the nuclear envelope. Consists of Rough and Smooth ER. The Golgi apparatus consists of a stack of three to twenty slightly curved saccules. Lysosomes are membrane-bounded vesicles produced by the Golgi apparatus.

Describe the evidence that suggests chloroplasts and mitochondria are derived from ancient bacteria and endosymbiosis.

The endosymbiotic theory states that chloroplasts and mitochondria are derived from a prokaryote engulfed by a eukaryotic cell. Chloroplasts are said to be derived from a photosynthetic bacterium. Chloroplasts are bounded by a double membrane, have their own prokaryotic-type chromosome and ribosomes, and produce some of their own enzymes. Mitochondria also have a double membrane and individual genes, which consists with the endosymbiotic theory.

Apply the endosymbiosis theory to eukaryotic cell structure.

The mitochondria and chloroplasts of the eukaryotic cell is thought to have arisen when a large eukaryotic cell engulfed independent prokaryotes. Mitochondria and chloroplasts are bounded by a double membrane and contain their own genetic material separate from the nucleus's.

Describe the role of motor molecules in cilia and flagella.

The motor molecule dynein, found in microtubules, is responsible for the beating of cilia and flagella. Each cilia and flagellum has a basal body lying in the cytoplasm at it's base. Basal bodies have the same circular arrangement of microtubules as centrioles, and may organize the microtubules within cilia and flagella. (This is not supported by the observation that cilia and flagella grow by the addition of tubulin dimers to their tips.)

Describe the structure and function of the nucleus.

The nucleus is an oval like structure found near the center of most cells. It contains chromatin (a network of strands that condense and undergo coiling into chromosomes just before the cell divides) in a semifluid matrix called the nucleoplasm. Chromosomes contain DNA, proteins, and RNA.

Do vacuoles all have the same function? Do animal cells have vacuoles? If so, which type of animal cell?

The vacuoles of some protists are very specialized, including contractile vacuoles for ridding the cell of extra water or digestive vacuoles for breaking down nutrients. Few animal cells have vacuoles, except for fat cells, which contain very large lipid filled vacuoles.

Examine the evolutionary relatedness of prokaryotes, eukaryotes, and archaeans.

There are three different types of cells that exist in nature: prokaryotes, eukaryotes, and archaeans. Prokaryotes lack a membrane-enclosed nucleus. Eukaryotic cells have a nucleus. Archaeans possess qualities of both prokaryotes and eukaryotes, but are genetically and biochemically distinct from them.

The types of RNA

Three types of RNA produced in the nucleus: ribosomal RNA (rRNA), messenger RNA (mRNA), and transfer RNA (tRNA). rRNA is produced in the nucleolus, a dark region of chromatin where rRNA joins with proteins to form the subunits of ribosomes.

Describe the role of ATP in photosynthesis and cellular respiration.

When a cell needs energy, ATP supplies it by driving synthetic reactions, active transportation, and other energy-requiring processes in cells.

What happens when a lysosome fuses with either a vesicle or a vacuole?

When a lysosome fuses with either a vesicle or a vacuole, the lysosomal enzymes are activated and digest the material into simpler subunits that are exported into the cytoplasm and recycled by other cell processes.

Cytoplasm

a semifluid solution composed of water and inorganic and organic molecules encased by the plasma membrane.

Basal Body

an organelle that lies at the base of cilia and flagella and may direct the organization of microtubules within those structures.

cyanobacteria

bacteria capable of photosynthesis, cytoplasm contains thylakoids where chlorophyll and other pigments absorb solar energy for production of carbohydrates.

Mesosomes

increase the internal surface area for the attachment of enzymes that are carrying on metabolic activities.

Motor molecules

proteins that can attach, detach, and reattach farther along an actin filament

Centrioles

short cylinders with nine sets of microtubule triplets arranged in an outer ring but the center does not contain a microtubule. A centrosome contains two centrioles lying at right angles to each other. A centrosome is the major microtubule-organizing center for the cell.