A cell biologist compared the properties of rough endoplasmic reticulum (ER) and smooth ER. She found that one type of ER is used for protein synthesis, and the other is used for lipid synthesis. What accounts for this difference?

Explanation:

The structure of the two endoplasmic reticulum makes the difference.

Endoplasmic reticulum (ER) is located in the cytoplasm membrane in the eukaryotes and its divided into two the rough and smooth endoplasmic reticulum.

Rough ER has ribosomes which gives it the name rough because of its appearance. The ribosomes on rough ER helps it to specialize in the synthesis of proteins. proteins in a cell, are synthesize by it. The smooth endoplasmic reticulum lacks ribosome in its structure and cannot synthesize protein but lipids.

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle