Chapter 1 - The Cell Flashcards
What are obligate intracellular parasites? What are some examples?
Obligate intracellular parasites are organisms that require a host cell to express their genes and reproduce.
Viruses are a classic example, but bacteria such as Yersinia (black plague) and eukaria such as Leishmania are also examples of obligate intracellular parasites.
What are bacteriophages and what makes them unique?
Viruses that can only infect bacteria. Unlike most viruses bacteriophages do not actually enter bacteria; rather, they simply inject their genetic material, leaving the remaining structures outside the cell.
What is the function and structure of the chloroplast?
The site of photosynthesis in plants and other photosynthetic organisms. The chloroplast contains chlorophyll, is semiautonomous, and has two cell membranes. They are responsible for the generation of energy using water, carbon dioxide, and sunlight.
What is the function of the cytoskeleton?
The cytoskeleton gives the the cell mechanical support, maintains shape, and functions in motility. It is comprised of microtubules, intermediate filaments, and microfilaments.
What are the three components of the cytoskeleton and what are their functions?
Microfilaments: comprised of solid polymerized rods of actin, these are the smallest of the cytoskeletal components. They are important in muscular contraction and movement of materials within the cellular membrane, and are responsible for amoeboid movement.
Intermediate filaments: a collection of fibers that help maintain the overall integrity of the cytoskeleton.
Microtubules: comprised of hollow polymers of tubulin, microtubules are the largest of the cytoskeletal components and provide both structural support and transport. They are the structural basis for cilia and flagella and are involved in chromosomal separation during mitosis and meiosis.
What is the primary function of mitochondria?
The mitochondria is the site of Aerobic respiration that provides the cell with a majority of its energy in the form of ATP.
Define the structure and function lysosome
The lysosome is a membrane bound vesicle that contains hydrolytic enzymes used for intracellular digestion. It is responsible for the breakdown of materials ingested (endocytosed) by the cell, as well as the removal of old cellular components. The pH of the lysosome is approximately 5.
Describe the structure of the mitochondrion
The mitochondrion is a semiautonomous organelle enclosed by two membranes (inner and outer mitochondrial membrane) separated by an intermembrane space. The inner membrane surrounds the mitochondrial matrix.
What are the four forms of movement across the cell membrane?
The four forms of movement across a cellular membrane are:
1) Simple Diffusion
2) Facilitated Diffusion
3) Active transport
4) Endocytosis and exocytosis
Note: All movement across membranes is based on concentration gradients. The gradient will define whether the process will be passive or active.
Define Facilitated Diffusion
Facilitated Diffusion is the passive movement of membrane impermeable particles from a region of higher concentration to one of lower concentration. These are large polar molecules (e.g. glucose), or ions (Na+, Cl–) where the energy barrier is too high to cross the membrane. In all cases, facilitated diffusion moves these molecules down the gradient using integral membrane proteins such as transmembrane channels or carrier proteins. This process does not require energy.
Define Simple Diffusion and provide some examples of molecules that move across membranes by simple diffusion.
Simple diffusion is the passive movement of particles from a region of higher concentration to one of lower concentration, down the concentration gradient, without the use of energy. Small, nonpolar molecules such as molecular oxygen and carbon dioxide utilize simple diffusion. Generally the more nonpolar a molecule is, the easier time it will have to traverse the hydrophobic core of the cell membrane.
Define Active Transport
Movement of particles from a region of lower concentration to a region of higher concentration. Active transport utilizes energy (often in the form of ATP) to move substrates against the concentration gradient.
Osmosis
A specific form of passive diffusion referring to the movement of water from a region of higher water concentration to one of lower water concentration. Alternately, this can be thought of as the movement of water from a region of lower solute concentration to one of higher solute concentration. Does not require energy.
What are the three types of tonicity (relating to osmotic pressure)
The three types of tonicity are:
Hypotonic – the concentration of solutes inside the cell is higher than the surrounding solution. Such a solution will cause the cell to swell, often to the point of lysis (bursting).
Isotonic – the concentration of solutes inside and outside the cell are equimolar, i.e. they are in equilibrium.
Hypertonic – the concentration of solutes outside the cell is lower than the surrounding solution. Such a solution will cause water to leave the cell, leading it to contract.
Mnemonic: The O in hyp-O-tonic looks like a swollen cell.
What are the functions of Epithelial Tissues?
These tissues cover the body and line its cavities; they provide a means for protection against invasion and dessication. The epithelium is also involved in absorption, secretion, and sensation.
