Answer:
In biology, evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection. The theory of evolution is based on the idea that all species? are related and gradually change over time.
Explanation:
Answer: zap70, ITAM.
Explanation:
An antigen is any substance that is capable of stimulating an immune response by activating lymphocytes, which are the body’s infection-fighting white blood cells. Examples of antigens could be proteins that are part of bacteria or viruses or components of serum and red blood cells from other individuals, all of them are foreign antigens originated outside the body. However, there can also be autoantigens (which are self-antigens), originated within the body. In normal conditions, the body is able to distinguish self from nonself. <u>And the antigens that represent a danger induces an immune response by stimulating the lymphocytes to produce antibody or to attack the antigen directly</u>. This is called an antigenic stimulation of the immune system.
ZAP-70 (Zeta-chain-associated protein kinase 70) is a protein that is part of the T cell receptor, thereby it plays a critical role in T-cell signaling. When the TCR (receptor of T cells) is activated by the presentation of the specific antigen through the MHC, a protein called Lck acts to phosphorylate the intracellular CD3 chains and the ζ chains of the TCR complex, allowing the binding of the cytoplasmic tyrosine kinase, ZAP-70. Lck then phosphorylates and activates ZAP-70, which in turn phosphorylates another molecule in the signaling cascade called LAT (short for Linker of Activated T cells), a transmembrane protein that serves as an anchor site for several other proteins. The tyrosine phosphorylation cascade initiated by the Lck culminates in the intracellular mobilization of calcium ion (Ca2+) <u>and the activation of important signaling cascades within the lymphocytes.</u> These include the Ras-MEK-ERK pathway, which is based on activating certain transcription factors such as NFAT, NFκB and AP-1. These transcription factors regulate the production of of certain gene products, most notably cytokines such as interleukin-2 that promote the long-term proliferation and differentiation of activated lymphocytes.
The ITAM motifs (immunoreceptor tyrosine-based activation motif) are sequences of four amino acids present in the intracellular tails of certain proteins that serve as receptors within the immune system. Thus, <u>some receptors such as the TCR have ITAM sequences that, when activated, trigger an intracellular reaction based on consecutive phosphorylations</u>. Kinases are recruited for this purpose.
So, ZAP-70 is a protein tyrosine kinase with a role in T-cell receptor signal transduction. During T-cell activation, ZAP-70 binds to ITAM and becomes tyrosine phosphorylated. The binding of ZAP-70 to the phosphorylated ITAM is able to activate its kinase activity, <u>and relieves the inhibition of the transcription factor which regulates genes that are involved in the immune reaction</u>.
Answer:
Because hemophilia is an X-linked recessive condition.
Explanation:
As the problem states, hemophilia is an X-linked recessive condition.
- Meaning that in Queen Victoria's female descendants (coded XX) which inherited the Queen's one allele, for hemophilia to appear in them it would be necessary to inherit another hemophillia-carrying allele from the father.
- The Queen's male descendants (coded XY) would always manifest hemophilia if they inherited the Queen's hemophilia allele, as they possesed only one X gene.
The organelle is labeled is nucleus, which means, where the chromosomes and one or more nucleoli are located immersed in the nucleoplasm or also karyolymph.
<h3>What is a nucleus organelle?</h3>
The nucleus, generally the largest eukaryotic cell organelle is the region delimited by membrane, where the chromosomes and one or more nucleoli immersed in the nucleoplasm or also karyolymph are located.
The nucleus of an organelle is composed of the karyotheca, chromatin, nucleoplasm and nucleolus.
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