CH. 2 - Cell Physiology Flashcards
- State the principles of the cell theory.
■ The cell is the smallest structural and functional unit capable of carrying out life processes.
■The functional activities of each cell depend on the specific structural properties of the cell.
■Cells are the living building blocks of all multicellular organisms.
■An organism’s structure and function ultimately depend on the collective structural characteristics and functional capabilities of its cells.
■All new cells and new life arise only from preexisting cells.
■Because of this continuity of life, the cells of all organisms are fundamentally similar in structure and function.
- Compare the average size of cells in your body with those in a mouse and in an elephant.
They are about the same size
- State the functions of DNA and the different types of RNA.
- DNA provides the genetic code for protein synthesis and serves as a genetic blueprint during cell replication. The DNA code is transcribed into messenger RNA (mRNA), which is translated into the specified protein by ribosomes that contain ribonucleic RNA (rRNA). Transfer RNA (tRNA) delivers the appropriate amino acids to their designated site in the protein under construction.
- Define genome, proteome, and epigenetics.
- The genome is all of the genetic information coded in a complete single set of DNA in a typical body cell. The proteome is the complete set of proteins coded for by the genome. Epigenetics refers to the environmentally induced modifications that influence gene activity without altering the gene’s DNA code.
- Distinguish among cytoplasm, organelles, cytosol, and cytoskeleton.
- Cytoplasm is the portion of the cell interior not occupied by the nucleus. It consists of organelles, cytosol, and cytoskeleton. Organelles are distinct, highly organized structures that perform specialized functions within the cell.
- The cytosol is the gel-like portion of cytoplasm that surrounds the organelles.
- The cytoskeleton is a scaffolding of proteins within the cytoplasm that serves as the cell’s “bone” and “muscle”
- Cytoplasm is the portion of the cell interior not occupied by the nucleus. It consists of organelles, cytosol, and cytoskeleton. Organelles are distinct, highly organized structures that perform specialized functions within the cell.
Compare the contents of a transport vesicle and a secretory vesicle.
A transport vesicle contains a mixture of proteins that have been newly synthesized by the rough ER. A secretory vesicle contains a specific finished protein product that has been modified and sorted by the Golgi complex.
- Distinguish between the rough ER and smooth ER structurally and functionally.
- The endoplasmic reticulum (ER) is one continuous, extensive organelle. The rough ER consists of stacks of relatively flattened interconnected sacs studded with ribosomes that synthesize proteins. The smooth ER is a meshwork of tiny interconnected tubules that in most cells serves as a central packaging and discharge site for products synthesized by the ER.
- Discuss the structure and function of a ribosome.
- A ribosome is a nonmembranous organelle consisting of a large and a small subunit that are brought together to serve as the “workbench” for protein synthesis. When messenger RNA moves through a groove formed between the two subunits, the ribosome translates the mRNA into chains of amino acids in the ordered sequence dictated by the DNA code.
- State the destination of proteins synthesized by the rough ER.
- secreted out of the cell or used for construction of new membrane
- Describe the function of the ubiquitin–proteasome pathway.
- Misfolded, damaged, or unneeded intracellular proteins are tagged with ubiquitin. Proteasomes break down ubiquinated proteins into recyclable building blocks.
What happens to the surface area of the plasma membrane as a result of exocytosis and of endocytosis?
The surface membrane increases during exocytosis and decreases during endocytosis.
- Describe the structure and functions of a Golgi complex.
- The Golgi complex consists of a stack of flattened, slightly curved, membrane-enclosed sacs. It
(1) processes raw materials synthesized by the ER into their final form and
(2) sorts and directs the finished products to their final destinations.
- Define secretion.
- Secretion is release to the cell’s exterior by exocytosis of a specific product synthesized by the cell for a particular function.
- Explain how secretory vesicles can dock only with the plasma membrane to release their contents to the cell’s exterior.
- The v-SNARE docking marker of a secretory vesicle can bind lock-and-key fashion only with the t-SNARE docking-marker acceptor on the targeted plasma membrane, thus ensuring that secretory vesicles can dock only with the plasma membrane to release their contents to the cell’s exterior.
- State the function of hydrolytic enzymes.
- Hydrolytic enzymes catalyze hydrolysis, the breakdown of organic molecules by the addition of water at a bond site.
- Illustrate the three types of endocytosis.
- See Figure 2-9, p. 32. Forms of endocytosis:
(a) pinocytosis. The surface membrane dips inward to form a pouch, then seals the surface, forming an intracellular endocytic vesicle that nonselectively internalizes a bit of ECF.
(b) receptor-mediated endocytosis. When a large molecule such as a protein attaches to a specific surface receptor, the membrane pockets inward with the aid of a coat protein, forming a coated pit, then pinches off to selectively internalize the molecule in an endocytic vesicle.
(c) phagocytosis. White blood cells internalize multimolecular particles such as bacteria or old red blood cells by extending pseudopods that wrap around and seal in the targeted material. A lysosome fuses with and degrades the vesicle contents.
- Define autophagy.
- Autophagy is selective self-digestion of dysfunctional organelles
How many each of NADH and FADH2 molecules are generated for each “turn” of the citric acid cycle? How many of each are produced for every glucose molecule processed?
3 NADH and 1 FADH2 are generated for each “turn” of the citric acid cycle. Because glycolysis splits glucose into two pyruvate molecules, each of which enters one “turn” of the citric acid cycle, 6 NADH and 2 FADH2 are produced by this cycle for every glucose molecule processed.
Where does the O2 that serves as the final electron acceptor at Step 4 come from?
From air breathed in
If no O2 is available, pyruvate is converted to lactate instead of an acetyl group. Compare the energy yield of glucose degradation with O2 and without O2.
32 ATPs with O2 , 2 ATPs without O2
- Draw and label a mitochondrion.
- See Figure 2-10a, p. 34.
The outer membrane is smooth, whereas the inner membrane forms folds known as cristae that extend into the matrix. An intermembrane space separates the outer and inner membranes. The electron transport proteins embedded in the cristae are ultimately responsible for converting much of the energy of food into a usable form.
- List the stages of cellular respiration, and state where each is accomplished.
- The stages of cellular respiration:
(1) glycolysis in the cytosol,
(2) the citric acid cycle in the mitochondrial matrix, and
(3) oxidative phosphorylation (consisting of the electron transport system and chemiosmosis) at the mitochondrial inner membrane.
- Compare the amount of ATP produced from one glucose molecule in anaerobic and aerobic conditions.
- In anaerobic conditions 2 molecules of ATP are produced (by glycolysis) and in aerobic conditions 32 molecules of ATP are produced (2 by glycolysis, 2 by the citric acid cycle, and 28 by oxidative phosphorylation) from one glucose molecule.
- Contrast apoptosis and necrosis.
- Apoptosis is intentional suicide of a cell that is no longer useful. Necrosis is uncontrolled, accidental death of useful, injured cells.