The inner membrane of mitochondria contains many proteins, has no pores and is very selective; It contains many enzyme complexes and transmembrane transport systems, which are involved in translocation of molecules. This membrane forms invaginations or folds called mitochondrial ridges, which considerably enlarge the surface for affixing these enzymes. In most eukaryotes, the folds form flattened partitions perpendicular to the mitochondrial axis, but some protists have a tubular or discoid shape. In the composition of the inner membrane there is a great abundance of proteins (80%), which are, moreover, exclusive of this organ, namely:
1. The electron transport chain, consisting of four fixed enzyme complexes and two mobile electron transporters:
- Complex I or NADH dehydrogenase containing flavon mononucleotide (FMN).
- Complex II or succinate dehydrogenase. Complexes I and II give electrons to coenzyme Q or ubiquinone.
- Complex III or cytochrome bc1 that yields electrons to cytochrome c.
- Complex IV or cytochrome c oxidase that gives off electrons to O2 to produce two water molecules.
2- An enzymatic complex, the H + ATP synthetase channel that catalyzes the synthesis of ATP (oxidative phosphorylation).
3- Carrier proteins that allow ions and other molecules to pass through the membrane, such as fatty acids, pyruvic acid, ADP, ATP, O2 and water. The following mitochondrial transporters may be highlighted:
- Adenine translocase nucleotide. It is responsible for transporting to the mitochondrial matrix the cytosolic ADP formed during the energy consuming reactions and, in parallel, translocates to the cytosol the newly synthesized ATP during oxidative phosphorylation.
- Phosphate translocase. Cytosolic phosphate translocation together with the proton to the matrix; Phosphate is essential for phosphorizing ADP during oxidative phosphorization.
<h2>Down Syndrome</h2>
Explanation:
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
- Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
- Down syndrome is usually caused by an error in cell division called nondisjunction which results in an embryo with three copies of chromosome 21 instead of the usual two
- Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separates
- With development in embryo the extra chromosome is replicated in every cell of the body;this type of Down syndrome which accounts for 95% of cases is called trisomy 21
- Maternal age is the only factor that has been linked to an increased chance of having a baby with Down syndrome resulting from nondisjunction;here environmental agents such as drugs, chemicals, and radiation act as mutagens which induce mutation in the fetus
Answer:
All antigen receptors produced by a single B or T cell are identical and bind to the same epitope.
Explanation:
Epitope or antigen determinant is the specific part of the antigen that is recognized by an antibody or T-cell receptor. During clonal selection, a lymphocyte proliferates and differentiates to form a group of highly specialized cells in response to a specific antigen present in the body.
The result of clonal selection is the formation of a population of identical cells that recognize the same specific epitope of the same antigen. A lymphocyte that undergoes clonal selection gives rise to two major types of cells in the clone: effector cells and memory cells.
For instance, the clonal propagation of B lymphocytes forms plasma cells (the effector cell) and memory cells. The plasma cells synthesize and secrete specific proteins called antibodies. All the antibodies derived from a plasma cell can bind to and inactivate the same specific antigen.
No this is FALSE. It is caused by bacteria infection...normally Staphylococcus aureus (and other Staph) and the toxins they produce.
<span> 2. These genes code for proteins that normally promote cell division. </span>
DNA genetic code is copied in a process called transcription when the cell needs to make some proteins that it needs, that is during the process of protein synthesis.
In the cell nucleus, transcription occurs when coded information is copied (transcribed) from DNA onto messenger RNA (mRNA) with the help of an enzyme called RNA polymerase.
