The freezing point of water is zero degrees Celsius.
The difference between the concentration of a substance between two areas is called the concentration gradient. This concentration gradient between a cell and its environment shows a difference resulting in the simplest form of transport called the passive transport. It is the movement of substances from a region of its higher concentration to a region of its lower concentration along with the concentration gradient across a semi permeable membrane.
Passive transport includes diffusion, facilitated diffusion, osmosis and filtration. All these processes are involved in various metabolic activities of the cell. Some of the examples are the movement of water molecules, nutrients, elimination of waste substances, exchange of gases and important life processes like digestion, respiration, excretion, transmission of nerve impulses and others depend on different types of passive transport. On elimination of concentration gradient between a cell and its environment, all the metabolic activities of the cell are inhibited and the cell dies.
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
Learn more about APC here,
brainly.com/question/13588471
# SPJ4
It is true that all GAL structural genes have UAS elements in their enhancer regions.
UAS elements can be found in the enhancer regions of every GAL structural gene. An enhancer is a short portion of DNA (50–1500 bp) that can be bound by proteins (activators) to increase the likelihood of a particular gene being transcribed.
The GAL4-UAS system is a biochemical technique used to investigate gene expression and function in fruit flies. Two parts make up the system: the Gal4 protein, which is an activator of transcription in yeast, and the UAS (Upstream Activation Sequence), which is an enhancer to which GAL4 binds specifically to initiate transcription.
know more about GAL structural genes here: brainly.com/question/29674603
#SPJ4
The first one and the fourth one
