Chapter 6
Describe the structure and function of a eukaryotic ribosome
1. Composed of proteins and ribosomal RNA 2. Two types Free and Membrane Bound. Free- Proteins for cytosol Membrane Bound- Proteins for cell membranes and export.
Explain why there are both upper and lower limits to cell size.
A cell can get too small to contain all the components necessary for life. As a cell gets larger, its surface area to volume ratio gets much smaller, which means that it takes too long for substances diffusing into the cell at the membrane (e.g., nutrients or oxygen) to get to all parts of the cell.
Explain how the ultrastructure of cilia and flagella relates to their functions.
A core of microtubules sheathed by the plasma membrane, a basal body that anchors the cilium or flagellum and a motor protein called dynein, which drives the bending movements of a cilium or flagellum.
Describe the structure of a mitochondrion and explain the importance of compartmentalization in mitochondrial function
Bound by a double membrane (smooth outer, folded inner, space between is called cristae) and proteins made by free ribosome's and ribosome's within it Contains its own unique, maternally inherited DNA that controls the synthesis of the proteins in its membrane Compartmentalization provides a large surface area that enhances the productivity of the mitochondrion, cellular respiration/ ATP/ energy production and provides a unique internal environment for reactions.
Identify the three functional compartments of a chloroplast. Explain the importance of compartmentalization in chloroplast function.
Bound by a double membrane and proteins, made by free ribosome's and ribosome's within it Contains its own unique circularDNA that controls the synthesis of the proteins in the membrane Contains thylakoids (flattened structures of space and membrane), grana (stacks of flattened structures), and stroma (fluid, where DNA is located) Contains green pigment and enzymes that allow for photosynthesis Compartmentalization provides chloroplasts with more surface area for the enzymes to instigate the reactions required for conversion of light energy to chemical energy, photosynthesis
Explain the significance of the cis and trans sides of the Golgi apparatus
Cis and trans help direst the vesicles to the plasma membrane or to other organelles
Describe how the components of the endomembrane system are derived from the ER, and their pathways
Consists the nuclear envelope: a double membrane perforated by pores that regulate the movement of materials between the nucleus and the cytoplasm, endoplasmic reticulum: continuous with the nuclear envelope and encloses a network of interconnected tubules or compartments called cisternae, Golgi apparatus consists of a stack of flattened sacs, lysosome are membrane-enclosed sacs of hydrolytic enzymes used by animal cells to digest macromolecules, vacuoles are formed as a result of phagocytosis, and the plasma membrane surrounding every cell must provide sufficient surface area for exchange of oxygen, nutrients, and wastes relative to the volume of the cell
List the components of the endomembrane system, and describe the structure and functions of each component
Consists the nuclear envelope: a double membrane perforated by pores that regulate the movement of materials between the nucleus and the cytoplasm, endoplasmic reticulum: continuous with the nuclear envelope and encloses a network of interconnected tubules or compartments called cisternae, Golgi apparatus consists of a stack of flattened sacs, lysosome are membrane-enclosed sacs of hydrolytic enzymes used by animal cells to digest macromolecules, vacuoles are formed as a result of phagocytosis, and the plasma membrane surrounding every cell must provide sufficient surface area for exchange of oxygen, nutrients, and wastes relative to the volume of the cell
Explain the advantages of compartmentalization in eukaryotic cells.
Different cell organelles perform different functions, many of which require specialized components for specific targets. Compartmentalization creates appropriate microenvironments for these diverse processes, allows damage limitation, minimizes non-specific interactions and consequently increased cellular efficiency.
Name three different kinds of vacuoles, giving the function of each kind.
Food vacuole -> A membranous sac formed by phagocytosis. Contractile vacuole -> A membranous sac that help move excess water from the cell. Central Vacuole -> A membranous sac in a mature plant with diverse roles in reproduction, growth and development.
Distinguish between free and bound ribosomes in terms of location and function.
Free ribosomes are used within the cytosol. Bound ribosomes, attached to the endoplasmic reticulum or nuclear envelope, usually make proteins that will be included within membranes, packaged into organelles, or exported from the cell.
Distinguish between prokaryotic and eukaryotic cells.
In a prokaryotic cell, the DNA is concentrated in the nucleoid without a membrane separating it from the rest of the cell. In eukaryotic cells, the chromosomes are contained within a membranous nuclear envelope.
Explain how the nucleolus contributes to protein synthesis
It creates ribsomal RNA which creates ribosomes in the cell and ribosomes create proteins.
Describe the principles, advantages, and limitations of the light microscope, transmission electron microscope, and scanning electron microscope.
LIGHT MICROSCOPE Principals -> Visible light is passed though the specimen and then through glass lenses. The lenses refract the light in such a way that the image of the specimen is magnified as it is projected. Advantages -> Organisms survive. Limitations -> Limited resolving power. SCANNING/TRANSMISSION ELECTRON MICROSCOPE Principals -> Focuses a beam of electron through the specimen or onto its surface. Advantages -> Higher resolving power because electrons have shorter wavelengths than light. Limitations -> All organisms die.
Briefly describe the energy conversions carried out by mitochondria and chloroplasts.
MITOCHONDRIA = CELLULAR RESPIRATION = GENERATE ATP BY EXTRACTING ENERGY FROM SUGARS, FATS, AND OTHER FUELS WITH THE HELP OF OXYGEN. CHLOROPLASTS = PHOTOSYNTHESIS = CONVERT SOLAR ENERGY TO CHEMICAL ENERGY AND SYNTHESIZE NEW ORGANIC COMPOUNDS SUCH AS SUGAR FROM CO2 AND H2O.
Compare the structure, and functions of microtubules, microfilaments and intermediate filaments.
Microtubules have hollow rods constructed of columns of globular proteins called tubulins. Microtubules change length through the addition or subtraction of tubulin dimers. They also provide the supporting framework of the cell, microtubules serve as tracks along which organelles move with the aid or motor molecules. Microfilaments are solid rods consisting of a twisted double chain of molecules of the globular protein actin. Actin filaments are microfilaments function in support forming a network just inside the plasma membrane and the core of small cytoplasmic extensions called microvilli. Intermediate filaments are intermediate in size between microtubules and Microfilaments are more diverse in their composition. Intermediate fibers appear to be important in maintaining cell shape. The nucleus is securely help in a web of intermediate filaments, and the nuclear lamina lining the inside of the nuclear envelope is composed of intermediate filaments.
Describe the evidence that mitochondria and chloroplasts are semiautonomous organelles.
Mitochondria and chloroplasts have little bits of their own DNA. They also grow and reproduce within the cell.
Explain the roles of peroxisomes in eukaryotic cells.
Perixomes are oxidative organelles filled with enzymes that function in a variety of metabolic pathways, such as breaking down fatty acids for energy or detoxifying alcohol and other poisons.
Describe the basic structure and components of a plant cell wall.
Plant cell walls are composed of microfibrils of cellulose embedded in a matrix of polysaccharides and protein.
Describe the 2 main functions of the cytoskeleton.
The cytoskeleton is a network of protein fibers that give mechanical support, function in cell motility (of both internal structures and the cell as a whole), and transmit mechanical signals from the cell's surface to its interior. It also interacts with special proteins called motor proteins to produce cellular movements.
Describe the major steps of cell fractionation and explain why it is a useful technique.
The major steps of cell fractionation are homogenization and differential centrifugation. It is a useful technique because it enables researchers to prepare specific cell components in bulk and identify their functions.
Briefly explain how the nucleus controls protein synthesis in the cytoplasm
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 molecule reaches the cytoplasm, ribosomes translate the mRNA's genetic message into the primary structure of a specific polypeptide.
Compare the structure and functions of smooth and rough ER.
The smooth ER serves diverse functions in different cells: Its enzymes are involved in phospholipids and steroid (including sex hormone) synthesis, carbohydrate metabolism, and detoxification of drugs and poisons. The smooth ER is also in storage and release of calcium ions during muscle contraction. The rough ER manufactures membranes from the cell. Enzymes built into the membrane assemble phospholipids, and membrane proteins formed by bound ribosomes are inserted into the ER membrane.
Distinguish among amyloplasts, chromoplasts, and chloroplasts
colorless plastid that stores starch; a colored plastid other than a chloroplast, typically containing a yellow or orange pigment provide color to flowers and fruit; A plastid that contains chlorophyll and in which photosynthesis takes place
Describe three examples of intracellular digestion by lysosomes.
phagocytosis (ingestion of other dying cells or larger extracellular material, like foreign invading microbes), endocytosis (where receptor proteins are recycled from the cell surface), and autophagy (where in old or unneeded organelles or proteins, or microbes that have invaded the cytoplasm are delivered to the lysosome
Describe the cisternal maturation model of Golgi function.
the cisternae of the Golgi apparatus move by being built at the cis face and destroyed at the trans face. Vesicles from the endoplasmic reticulum fuse with each other to form a cisterna at the cis face, consequently this cisterna would appear to move through the Golgi stack when a new cisterna is formed at the cis face. This model is supported by the fact that structures larger than the transport vesicles, such as collagen rods, were observed microscopically to progress through the Golgi apparatus.
