How do eukaryotic and prokaryotic flagella differ in their protein composition?
Key Terms
What term refers to the tubular structure used for locomotion in some bacteria?
flagellum
How do eukaryotic and prokaryotic organisms differ in the composition of their ribosomes?
Eukaryotic ribosomes are slightly larger, with a 40S and a 60S subunit combining to yield 80S. Prokaryotic ribosomes have a 30S and a 50S subunit, ...
In animal cells, where is most cholesterol found?
plasma membrane Specifically, cholesterol (shown here) is a lipid that confers rigidity to the membrane. Cholesterol can either be acquired through...
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| Term | Definition |
|---|---|
How do eukaryotic and prokaryotic flagella differ in their protein composition? | Eukaryotic flagella are composed of tubulin. Prokaryotic flagella are made up of flagellin. Tubulin is the protein subunit of microtubules. Specifically, each eukaryotic flagellum consists of nine pairs of microtubules surrounding two individual ones. |
What term refers to the tubular structure used for locomotion in some bacteria? | flagellum |
How do eukaryotic and prokaryotic organisms differ in the composition of their ribosomes? | Eukaryotic ribosomes are slightly larger, with a 40S and a 60S subunit combining to yield 80S. Prokaryotic ribosomes have a 30S and a 50S subunit, which combine to form 70S. The abbreviation 'S' refers to the rate at which a molecule settles in a centrifuge. |
In animal cells, where is most cholesterol found? | plasma membrane Specifically, cholesterol (shown here) is a lipid that confers rigidity to the membrane. Cholesterol can either be acquired through the diet or synthesized by cells. |
What is the difference between peripheral and integral membrane proteins? | Peripheral proteins are loosely attached to either the inner or outer face of the plasma membrane. These proteins can be easily removed from the lipid bilayer. Integral proteins are firmly attached to the lipid bilayer and are very difficult to remove. These proteins extend at least partially into the hydrophobic interior region of the bilayer. A transmembrane protein is a specific type of integral protein that spans, or extends through, the entire lipid bilayer. |
What are four functions that can be served by plasma membrane proteins? | function in cell-to-cell adhesion function in cell-to-cell communication and recognition serve as receptors for hormones and other ligands assist in transport across the membrane |
Define: solute | In a solution, it is the substance whose phase is lost after solvation (or the substance of which less is present). For example, dissolving a small amount of solid NaCl into liquid water produces a liquid solution. In this case, NaCl is the solute. |
Define: bulk flow | It is the movement of molecules (typically fluid molecules) in one direction in response to pressure. A classic example is the movement of blood through blood vessels. Blood, like typical fluids, tends to travel from areas of high pressure to areas of low pressure. |
What term is given to the separation of molecules based on their differing abilities to diffuse through a semipermeable membrane? | Dialysis In a dialysis procedure, large particles are unable to diffuse through the dialysis membrane, so small particles are left to diffuse in an attempt to reduce the overall concentration gradient between the compartments. This technique is often used to remove toxins from the blood in cases of kidney failure. |
What term describes diffusion between two regions in which fluids are flowing in opposite directions? | Countercurrent exchange This form of transport allows for a fairly consistent difference in concentration gradient between the two regions, maximizing diffusion. A classic example of this mechanism occurs in the loop of Henle, a region of the nephron (the structural unit of the kidney). |
Name the four phases of the cell cycle. | G1 S (synthesis) G2 M (mitosis) An additional phase is G0, in which the cell is not immediately preparing for cell division. G0 can be either temporary or permanent. |
What is the difference between germ cells and somatic cells? | Germ cells, including sperm and ova, are haploid and participate in reproduction. They are formed via meiosis. Somatic cells are diploid and include the rest of the cells in the body. Somatic cells only undergo mitosis. |
Name the two types of eukaryotic cell division. | mitosis meiosis Mitosis produces somatic cells that are identical to the parent, while meiosis produces germ cells with only half of the parental genetic material. |
Explain the difference between a haploid and a diploid cell. | Haploid cells have only one full set of chromosomes. In humans, the only haploid cells are germ cells (sperm and eggs) produced by meiosis. Diploid cells have two distinct sets of chromosomes. In humans, all somatic cells are diploid and are produced by mitosis. |
What is the significance of the G0 phase? | It is a stage of prolonged inactivity. In this phase, the cell is not preparing for mitosis. Mature neurons and cardiac muscle are in a permanent G0 phase, since they do not undergo mitosis. |
During which phase of the cell cycle would DNA helicase be especially active? | DNA helicase, as well as the other enzymes involved in DNA replication, would be most active during the S phase. In the S (synthesis) phase, DNA is replicated to prepare for cell division. |
List the four phases of mitosis in the order that they occur in a dividing cell. | prophase metaphase anaphase telophase and cytokinesis |
What features distinguish homologous chromosomes from sister chromatids? | Homologous chromosomes can be genetically different; each homologous chromosome has the same loci, but can have different genes than its partner. Homologous chromosomes separate during meiosis I. Sister chromatids are genetically identical, as they result from the replication of a single chromosome. Sister chromatids separate during meiosis II and mitosis. |
What cellular events characterize metaphase? | At this point, spindle fibers are bound to the kinetochore of each chromosome. The chromosomes line up along the center of the cell, a region called the metaphase plate. |
Define: cytokinesis | It is the actual formation of two distinct cells, characterized by the distribution of cytosol and organelles and the pinching of the cell membrane between the two nuclei. Cytokinesis happens simultaneously with the later phases of mitosis and meiosis, but is often grouped with telophase. |