(a) Draw the structure of choline and explain why it needs a transport protein in order to enter cells. (b) Cells must transport choline from outside the cell (where it is relatively rare) to the inside of the cell (where it is relatively abundant). The diagram below represents a cell with a choline transporter (labeled T). Draw a solid arrow through the transporter to show the direction in which choline travels (into or out of the cell). (c) Is T an active or passive transport protein for choline? (d) For every choline molecule that moves through T, a sodium ion moves through the same transport protein at the same time. The sodium ion moves down its gradient. Add a dashed arrow to the diagram in part (b) to show the direction of movement of sodium. (e) Is T an active or passive transport protein for sodium?
Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
The molecule that condensed with a phosphate group to form the head group of the lipid shown in the first image (picture 6) is choline, an essential component of many cellular molecules.
(a) Draw the structure of choline and explain why it needs a transport protein in order to enter cells.
(b) Cells must transport choline from outside the cell (where it is relatively rare) to the inside of the cell (where it is relatively abundant). The diagram below represents a cell with a choline transporter (labeled T). Draw a solid arrow through the transporter to show the direction in which choline travels (into or out of the cell).
(c) Is T an active or passive transport protein for choline?
(d) For every choline molecule that moves through T, a sodium ion moves through the same transport protein at the same time. The sodium ion moves down its gradient. Add a dashed arrow to the diagram in part (b) to show the direction of movement of sodium.
(e) Is T an active or passive transport protein for sodium?
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