Answer:
Proteins and lipids exist as separate but loosely attached molecules that can move around
Explanation:
Cell membranes are mainly composed of lipids, proteins, and also carbohydrates. Phospholipids are the most abundant type of lipid and the main constituent of the cell membranes. Membrane proteins are divided into two types according to their interactions with the cell membrane: 1-integral (intrinsic) and peripheral (extrinsic) proteins. These peripheral proteins are loosely attached by ionic bonds or calcium bridges with the phosphate heads of the phospholipids; whereas integral membrane proteins contain side chains that interact with fatty acyl groups of the phospholipids. Cell membrane fluidity indicates how easily lipids (e.g., phospholipids and cholesterol) and proteins (e.g., intrinsic proteins) diffuse laterally in the cell membrane. This fluidity is affected by the amount of cholesterol, temperature, and the ratio of unsaturated to saturated fatty acids. Saturated fatty acids have no double bonds in the hydrocarbon chain, whereas unsaturated fatty acids have at least one double bond (these double bonds increase fluidity). Moreover, higher temperatures increase membrane fluidity, whereas cholesterol molecules function to regulate membrane fluidity: at high temperatures cholesterol molecules stabilize the membrane, whereas at low temperatures intercalate between phospholipids, thereby preventing them from clustering together.
The answer to the question is true
In terms of parasites vs hosts, it is an organism in which the parasite resides and normally feeds + reproduces.
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Answer:
The option 'All cells contain a nucleus' is not a part of the cell theory.
Explanation:
The cell theory proposed by scientists illustrates that every organism whether prokaryotic or eukaryotic is made up of a cell or different kinds of cells. It also that explains that cells are made from living things. According to the cell theory, cells are termed as the basic unit of life, without which life is not possible.
The cell theory does not claim that every cell must have a nucleus because many cells like cells of prokaryotes lack nucleus. Their genetic material is dispersed in the cytoplasm.
