A nonfunctional CD4 protein on a helper T cell would result in the helper T cell being unable to interact with a class II MHC-antigen complex
Importance of Class II MHC-Antigen complex
- CD4+ T cell-dependent immunological responses need antigen presentation restricted to MHC class II.
Professional antigen-presenting cells (APCs) perform a range of functions that are essential for the generation of an effective and specific immune response.
- Dendritic cells (DCs) investigate their surroundings and gather foreign antigens, such as those derived from bacteria or viruses, before activating CD4+ and CD8+ T cells to initiate adaptive immune responses against these antigens.
- The thymus' DCs and epithelial cells express (and also capture) a diverse set of self-proteins that contribute to both central and peripheral tolerance.
Recognizing the processes involved in the creation (and stability) of peptide-MHC class II complexes in APCs provides crucial information about T cellular metabolism including both normal and pathological settings.
Hence, the correct answer is option D
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Answer: It helps to regulate circadian rhythm
Exposure to natural light during the day helps regulate the circadian
rhythm, which improves sleep pattern. The term circadian rhythm refers to our
biochemical, physiological and behavioral processes in approximately 1 full day
cycle. Circadian rhythm plays an
important role in
controlling when we fall asleep and when we wake up.
During day light, the secretion of melatonin or sleep hormone is
suppress by melanopsin that keeps people awake and alert. Nevertheless, during nighttime,
melanopsin stimulates the release of melatonin to signal sleeping time. Therefore,
this hormone works the entire day and has direct effect on the circadian
rhythm, which acts as a regulator of our biological clock.
The correct answer is: 2.5%
The vast majority of the human genome (97.5%) is comprised of non-coding DNA with different functions. Non-coding DNA includes telomeres, introns, non-coding RNA genes and gene regulatory sequences.
• Telomeres-ends of DNA with protective role (prevents shortening of DNA),
• Non-coding RNA genes-e.g. genes for tRNA,
• Gene regulatory sequences such as promoter, enhancers and silencers.
Because the radiation can cause skin cancer!!! hope this helps wear sunscreen