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tatuchka [14]
3 years ago
9

Which of the following statements is FALSE? A. Class 1 MHC molecules are built into the plasma membranes of all body cells. B. C

lass II MHC molecules appear only on the surface of antigen-presenting cells and T cells that have been activated by exposure to antigens. C. MHC proteins are the cell's identity markers. D. It is common for unrelated individuals to have the same MHC molecules.
Biology
1 answer:
Sonbull [250]3 years ago
4 0

Answer:

The correct answer is option B.

Explanation:

MHC or The major histocompatibility complex is a series of genes that have information and rise to cell surface proteins required for the adaptive immune system to recognize the pathogen or the foreign molecules, There are three classes of MHC - MHC1, MHC2, and MHC3.

MHC class II generally present only on antigen-presenting cells such as single nuclear phagocytes, dendritic cells, thymic and B cells.

Thus, the correct answer is option B.

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What consequence does higher altitude have on people?
Marta_Voda [28]

Depending on baseline oxygen saturation and the pathological condition of the lungs, risks associated with altitude exposure include profound hypoxemia, pulmonary hypertension, disordered ventilatory control, impaired respiratory muscle function, and sleep‐disordered breathing.

4 0
2 years ago
1. Suppose the synthesis of an amino acid was accomplished by four enzymes encoded by four genes that formed an operon. Draw a m
vivado [14]

I have attached lac operon model having 4 genes. See attachment for better understanding.

Answer:

The Lac operon is controlled  by two signals.

Initiation

Glucose and lactose  concentrations control the initiation of  transcription of the Lac operon through  their effects on the Lac repressor protein  and Cap.

Lactose absent (Repression)

When lactose is absent, the Lac  repressor binds the Lac operator and shuts  off expression of the operon.

Lactose present (Transcription)

Addition  of lactose increases the intracellular  concentration of a related compound,  allolactose. allolactose binds to the  Lac repressor, causing it to undergo a  conformational change that releases its grip  on the operator DNa.

Glucose absent (Repression)

When  glucose is absent, cyclic aMp (red triangle)  is produced by the cell and Cap binds to  DNA.

Glucose present (Transcription)

LacZ, the first gene of the operon,  encodes the enzyme b-galactosidase, which  breaks down lactose to galactose and  glucose.

7 0
3 years ago
After allowing his F1 crosses to self-pollinate, Mendel observed that
frutty [35]

Answer:

Explanation:

First-generation (F1) progeny only showed the dominant traits, but recessive traits reappeared in the self-pollinated second-generation (F2) plants in a 3:1 ratio of dominant to recessive traits. Mendel then crossed these pure-breeding lines of plants and recorded the traits of the hybrid progeny

4 0
3 years ago
Growth factors and cytokines both lead to tyrosine phosphorylation through receptors, but they do so through different mechanism
gladu [14]

Answer:

The growth factor receptors have a kinase domain while the Cytokines receptors do not contain a kinase domain as part of their structure.

Explanation:

The two are signaling molecules that control cell activities in some manners, such paracrine, endocrine and autocrine manners.

The receptor kinase domain can be specific for substrate sites in which phosphorylation occurs.

3 0
3 years ago
Color in poison dart frogs is controlled by a single gene with multiple alleles. A blue poison dart frog that is heterozygous fo
8_murik_8 [283]

Answer:

Cb>Cy>Co>Cr

Explanation:

First of al we need to do the Punnett square. As a result we get the genotypes:

CyCb

CyCr

CoCb

CoCr

Because there are no red frogs, red is the least dominant as it isn't expressed in any genotype.

Half of the progeny are blue and half of the possible genotypes contain the blue allele meaning that blue is expressed in all genotypes. This means that blue is the most dominant.

The only alleles left are yellow and orange. We can deduce that yellow is more dominant than orange because one of the parent frogs is yellow and contains the genes for yellow and orange.

As a result blue is the most dominant, yellow is the second most dominant, orange is the third most dominant and red is the least dominant.

7 0
2 years ago
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