Cell BIO unit-2 chapter6
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.
Describe the structure and roles of the extracellular matrix in animal cells
Animals cells secrete ECM which is composed mostly of glycoproteins and other carbohydrate-containing moleculues. It function in animal cells are for support, adhesion, movement and regulation.
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 how the ultrastructure of cilia and flagella relate to their functions
Cilia and flagella are constructed like a wheel spoke with two microtubules at the center like the hub of a wheel, and 9 microtubules making up the wheel, connected by spoke-like "arms" made from dynein, which are a motor protein that slide when they come in contact with ATP, which is how cilia and flagella move.
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 and create protein which functions 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.
Endomembrane system describe the structure and function of each component
Functions of Smooth ER The smooth ER Synthesizes lipids Metabolizes carbohydrates Detoxifies poison Stores calcium;Functions of Rough ER The rough ER Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates) Distributes transport vesicles, proteins surrounded by membranes Is a membrane factory for the cell; lysosomes are digestive vacuoles; Functions of the Golgi apparatus: Modifies products of the ER Manufactures certain macromolecules Sorts and packages materials into transport vesicles The Golgi Apparatus: Shipping and Receiving Center
Explain the role of the nucleolus in protein synthesis
It synthesizes ribosomal RNA (rRNA) and combines it with protein to assemble ribosomal sub-units to pass which then passes through the Nuclear pores to the cytoplasm.
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.
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.
Describe the structure and function of the nuclear envelope, including the role of the pore complex
Nuclear envelope -> Double membrane enclosing the nucleus, perforated by pores. The nuclear envelope is a double membrane. The envelope is perforated by pores that are about 100 nm apart. At the lip of each pore, the inner and outer membrane of the nuclear envelope are fused. The nuclear envelope encloses the nucleus separating its contents from the cytoplasm.
Distinguish between prokaryotic and eukaryotic cells
Prokaryotic cells -> A type of cell lacking a membrane bound nucleus and membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea. Eukaryotic cells -> A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles, present in protists, plants, fungi, and animals <- eukaryotes
Explain the structure and role of centrioles and basal bodies
site at the base of flagella or cilia from which microtubules grow, anchored on the cytosolic side of the plasma membrane; Structure: Small, cylindrical parts of the cytoskeleton.;Function: Aid in cell division
Explain the advantages of compartmentalization in eukaryotic cells
The cell's compartments provide different local environments that facilitate specific metabolic functions, incompatible processes can go on simultaneously inside the same cell. 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.
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 functions of the cytoskeleton
The cytoskeleton helps to maintain cell shape. But the primary importance of the cytoskeleton is in cell motility. The internal movement of cell organelles, as well as cell locomotion and muscle fiber contraction could not take place without the cytoskeleton. The cytoskeleton is an organized network of three primary protein filaments: microtubules, actin filaments, and intermediate fibers.
Explain how the extracellular matrix may act to integrate changes inside and outside the cell
The ecm is made up of a network of proteoglycans; they attach to glycoproteins like fibronectin which attaches to cell proteins called integrins which integrates information from both outside and inside the cell
List the components of the endomembrane system, and describe the structure and function of each component
The endomembrane system regulates protein traffic and performs metabolic functions in the cell Components of the endomembrane system : Nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Plasma membrane These components are either continuous or connected via transfer by vesicles.
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.
Name the intercellular junctions found in plant and animal cells and list the function of each type of junction
Three intercellular junctions between animal cells are tight junctions--where proteins hold adjacent cell membranes tightly together, creating an impermeable seal across a layer of epithelial cells; Demosomes (anchoring junctions)--are reinforced by intermediate filaments and rivet cells into strong sheets, Gap junctions (communicating junctions)--are cytoplasmic connections that allow for the exchange of ions and small molecules between cells through protein-lined pores.
Explain the roles of peroxisomes in eukaryotic cells
breaks down fatty acids for energy or detoxifying alcohol and other poisons; Oxidation Peroxisomes are specialized metabolic compartments bounded by a single membrane Peroxisomes produce hydrogen peroxide and convert it to water Oxygen is used to break down different types of molecules
Cis and Trans of golgi apparatus
cis face ("receiving" side of Golgi apparatus) Cisternae trans face ("shipping" side of Golgi apparatus)
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
Compare the structure, monomers, and functions of microtubules, microfilaments, and intermediate filaments
hollow tubes of protein about 25 nanometers in diameter, support the cell and moves organelles within the cell; Long, thin fibers that function in the movement and support of the cell; range from 7-11nm in diameter, and strengthen the cell and help maintain its shape, stabilize the positions of organelles, and stabilize the position of the cell with respect to surrounding cells through specialized attachment to the cell membrane
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.
