5 Written questions
5 Matching questions
- Adherens Junctions
- Tertiary Structure
- Nuclear Lamina
Internal compartments formed by the inner membrane of a mitochondrion. They are studded with proteins, including ATP synthase and a variety of cytochromes. The maximum surface for chemical reactions to occur is within the mitochondria. This allows cellular respiration (aerobic respiration since the mitochondrion requires oxygen) to occur.
A waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes and is required to establish proper membrane permeability and fluidity.It causes areas of rigidity in the membrane due to the interaction of its four fused ring sections with the hydrophobic tails of surrounding lipids.In addition, cholesterol is an important component for the manufacture of bile acids, steroid hormones, and vitamin D. Cholesterol is the principal sterol synthesized by animals; however, small quantities can be synthesized in other eukaryotes such as plants and fungi. It is almost completely absent among prokaryotes including bacteria. Although cholesterol is important and necessary for mammals, high levels of cholesterol in the blood can damage arteries and are potentially linked to diseases such as those associated with the cardiovascular system (heart disease).
- c The network of intermediate nuclear filament proteins (Lamins) which is located just below the nuclear membrane and is linked to the membrane and chromatin.
- d These junctions function in the same way as anchoring junctions, linking intercellular cytoskeletons using cadherin. Unlike the anchoring junctions these junctions use the actin filaments not the intermediate filaments to secure the cells.
In biochemistry and molecular biology, this structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates. Proteins and nucleic acids are capable of diverse functions ranging from molecular recognition to catalysis. Such functions require a precise three-dimensional tertiary structure. While such structures are diverse and seemingly complex, they are composed of recurring, easily recognizable tertiary structure motifs that serve as molecular building blocks. Tertiary structure is considered to be largely determined by the biomolecule's primary structure, or the sequence of amino acids or nucleotides of which it is composed. Efforts to predict tertiary structure from the primary structure are known generally as structure prediction.
5 Multiple choice questions
- The name by which the -NH₂ free end of a peptide is known.
An flexible protein found in the extra cellular matrix of blood vessels.
- A technique used to measure the rate of activity of an enzyme by measuring the products expected of the enzyme activity, for example CO₂.
This matrix is secreted by cells and laid down externally and it's properties vary enormously depending on it's chemical composition and which tissue is being examined. In some cells it acts as cement or scaffolding. In plants it can be associated with individual cells.
This stage of endosome matures in several ways to form late endosomes.They consist of a dynamic tubular-vesicular network (vesicles up to 1 µm in diameter with connected tubules of approx. 50 nm diameter). Markers include RAB5 and RAB4, Transferrin and its receptor and EEA1. They become increasingly acidic mainly through the activity of the V-ATPase. Many molecules that are recycled are removed by concentration in the tubular regions of early endosomes. Loss of these tubules to recycling pathways means that late endosomes mostly lack tubules. They also increase in size due to the homotypic fusion of early endosomes into larger vesicles.
5 True/False questions
SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis, is a technique widely used in biochemistry, forensics, genetics and molecular biology to separate proteins according to their electrophoretic mobility (a function of length of polypeptide chain or molecular weight). SDS gel electrophoresis of samples that have identical charge per unit mass due to binding of SDS results in fractionation by size. This method can be used to separate all types, even those that are not water soluble.
The point on a rectangular hyperbola which is half the value of the Vmax. It indicates the affinity of an enzyme and substrate a high value means low affinity and a low value means high affinity (the enzyme substrate locks more securely and takes longer to seperate and release products).
Active transport →
This form of transport is the movement of a substance against its concentration gradient (from low to high concentration). In all cells, this is usually concerned with accumulating high concentrations of molecules that the cell needs, such as ions, glucose, and amino acids. If the process uses chemical energy, such as from adenosine triphosphate (ATP), it is termed primary active transport. Secondary active transport involves the use of an electrochemical gradient. Active transport uses energy, unlike passive transport, which does not use any type of energy. Active transport is a good example of a process for which cells require energy. Examples of active transport include the uptake of glucose in the intestines in humans and the uptake of mineral ions into root hair cells of plants.
FRAP (Fluorescence recovery after photobleaching) →
An optical technique capable of quantifying the two dimensional lateral diffusion of a molecularly thin film containing fluorescently labeled probes, or to examine single cells. This technique is very useful in biological studies of cell membrane diffusion and protein binding. In addition, surface deposition of a fluorescing phospholipid bilayer (or monolayer) allows the characterization of hydrophilic (or hydrophobic) surfaces in terms of surface structure and free energy. Similar, though less well known, techniques have been developed to investigate the 3-dimensional diffusion and binding of molecules inside the cell; they are also referred to as FRAP.
Cadherins (named for "calcium-dependent adhesion") are a class of type-1 transmembrane proteins. They play important roles in cell adhesion, ensuring that cells within tissues are bound together. They are dependent on calcium (Ca2+) ions to function, hence their name. The extra cellular domains on cadherins interact with their counterparts in other cell membranes and their intracellular domains interact intracellular proteins. The intracellular proteins are then bound to cytoskeleton intermediate filaments known as keratin.