Unit 2 - Biochem and Cells Flashcards
What is the plasma membrane? How does it function?
The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition. It is semipermeable, allowing only certain items to pass into the cell.
What is plasmolysis? Does it take place in plant cells or animal cells? When does it usually occur?
A process in plant cells in which the cytoplasm shrivels and the plasma membrane detaches from the cell wall; this occurs when the cell loses water to a hypertonic environment and the vacuole becomes very small.
What does it mean when a cell is prokaryotic?
A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Prokaryotic cells include bacteria and archaea.
What is a ribosome? What are its components?
A complex of rRNA and protein molecules that functions as the site of protein synthesis in the cytoplasm; it consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus.
What is the rough ER? What is its function?
The endoplasmic reticulum with ribosomes attached that makes proteins that will go into the cell membrane, called glycoprotein, which is then transported to the Golgi Apparatus and out of the cell.
What are sister chromatids? Are they involved in mitosis or meiosis, or both?
Two copies of a duplicated chromosome attached to each other by proteins at the centromere. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II.
What is the smooth ER? What is its function?
The endoplasmic reticulum without ribosomes that makes lipids and works with detoxifying.
What is a somatic cell? Are all cells somatic cells?
Any cell in a multicellular organism except a sperm or egg cell. It is not involved in reproduction.
What are glycolipids and why are they important?
A lipid that has one or more covalently attatched carbohydrate chians; assembled in the Golgi. They are found in the membranes of eukaryotic cells and extend into the extracellular fluid. They store energy, and serve as cellular markers for cellular recognition. They also help maintain membrane stability and attact cells to eachother to form tissues.
What are glycolipids and why are they important?
A protein with short saccharide polymers attached to its side-chains; assembled in the rough ER. Their functions include: cell receptors, cellular markers, biological lubricants, and sometimes intracellular enzymes. For example they are the markers for blood type.
What happened in the fig jam warmup activity?
Figs were placed in a bowl with lemon and oranges, and water was drawn out of the figs and the mixture became more liquid. The figs shriveled up as water left the figs. This is an example of a hypertonic solution, since water was moving out of the cell.
What is the difference between bound ribosomes and free ribosomes?
Bound ribosomes make proteins in the rough ER and smooth ER that are destined for insertion into membranes, for packaging within certain organelles, or for secretion from the cell. Free ribosomes make proteins used throughout the cytoplasm for use throughout the cell, such as enzymes that catalyze the first steps of sugar breakdown.
What are the differences between channel proteins and carrier proteins? Name an example of each.
Channel proteins allow certain molecules to pass through without changing the shape of the protein. An example is an ion channel, which transports ions. Carrier proteins interact with the molecules and change shape to allow the proteins to pass through. An example is a sodium-potassium pump.
What is cotransport?
Cotransport is the coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient. For example, a plant cell uses the H+ gradient generated by its proton pumps to drive the active transport of amino acids, sugars, and other nutrients into the cell.
What is the difference between an electrogenic pump and a proton pump?
An electrogenic pump is a transport protein that generates voltage across a membrane. One major electrogenic pump is the sodium-potassium pump. A proton pump is the main electrogenic pump of plants, fungi, and bacteria, which actively transports protons out of the cell. The pumping of H+ transfers positive charge from the cytoplasm to the extracellular solution.
What is the endomembrane system? What are its functions?
The endomembrane system includes the nuclear envelope the endoplasmic reticulum, the Golgi apparatus, lysosomes, various kinds of vesicles and vacuoles, and the plasma membrane. It carries out taste including synthesis of proteins, transport of proteins into membranes and organelles or out of the cell, metabolism and movement of lipids, and detoxification of poisons.
How does mitosis differ from interphase?
Mitosis is the process in which a cell divides into two identical daughter cells for growth and repair; it is also used in asexual reproduction. The two daughter cells are identical to its parent cell and contain the exact number of chromosomes (diploid). Interphase is the period in the cell cycle when the cell is not dividing in which cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase.
What occurs during mitosis? Name the five phases.
- Prophase: Nucleolus disappears, kinetochores develop for future chromosome orientation (attach to centromere), spindle begins to assemble.
- Prometaphase: Attachment of chromosomes to spindle and move towards metaphase plate.
- Metaphase: Chromosomes are attached to kinetochore fibers and aligned at the metaphase plate.
- Anaphase: 2 sister chromatids of each duplicated chromosome separate at centromere, moving to opposite poles.
- Telophase: Spindle disappears, chromosomes decondense and return to chromatin, nuclear envelope reforms, and nucleoli appear, cytokinesis occurs.
What is the structure and function of the nucleolus?
Located in the nucleus, they are made of RNA and proteins, and make ribosomes.
What is a nucleoid? Which cells is it specific too?
Region of prokaryotic cells where the genetic material is located.
What does the nucleus contain?
Membrane enclosed organelle in eukaryotic cells that contains all of the cell’s DNA.
What is the purpose of the nuclear envelope?
Encloses the nucleus, has pores that regulates what molecules enter and exit the nucleus.
How does osmosis work?
Diffusion of a solvent, usually water, through a semipermeable membrane to a region with more solute.
How is passive transport different than active transport?
Transport of molecules across the plasma membrane that does not need ATP.
What happens in phagocytosis?
Process where a cell engulfs and ingests outside material.
What is the purpose of the phloem?
Plant vascular tissue that transports sugars and synthesized food down from the leaves.
What is a ligand? In what processes does it play a key role in?
A molecule that binds specifically to another molecule, usually a larger one. For example, in the specific signal transduction pattern that creates glucose from glycogen, ligand binds to the G-protein - which is embedded in the cell membrane - since it is too big to enter the cell itself. The binding of the ligand causes it to release a subunit, ultimately starting the entire pathway.
What is a lysosome? How is it created inside the cell? What are a lysosome’s key functions as an organelle?
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists. The function of lysosomes is to digest molecules and break down the cell once it dies. A lysosome is basically a specialized vesicle that holds a variety of enzymes. The enzyme proteins are first created in the rough ER. Those proteins are packaged in a vesicle and sent to the Golgi apparatus. The Golgi then does its final work to create the digestive enzymes and pinches off a small, very specific vesicle, which is a lysosome.
