Subcellular Organelles and Cell Membranes

Flashcards covering subcellular organelle separation, marker enzymes, metabolic functions, and structural details of the nucleus, endoplasmic reticulum, and Golgi apparatus.

Under what centrifugal conditions is the nucleus pelleted, and what is its marker enzyme?

It forms a pellet at $600\text{--}750 \times g$ for $10\,\text{min}$, and its marker enzyme is DNA.

At what centrifugal force are mitochondria separated, and what is their marker enzyme?

They are pelleted at $10{,}000\text{--}15{,}000 \times g$ for $10\,\text{min}$, and the marker enzyme is ATP synthase (inner membrane).

What are the centrifugal pelleting conditions and marker enzymes for lysosomes?

Pelleted at $18{,}000\text{--}25{,}000 \times g$ for $10\,\text{min}$; marker enzymes are cathepsin and acid phosphatase.

What centrifugal force separates the Golgi complex, and what is its marker enzyme?

It forms a pellet at $35{,}000\text{--}40{,}000 \times g$ for $30\,\text{min}$, and its marker enzyme is galactosyl transferase.

Under what centrifugal conditions are microsomes pelleted, and what is their marker enzyme?

They form a pellet at $75{,}000\text{--}100{,}000 \times g$ for $100\,\text{min}$, and their marker enzyme is glucose-6-phosphatase.

In subcellular fractionation, where is the cytoplasm obtained, and what is its marker enzyme?

It remains in the supernatant, and its marker enzyme is lactate dehydrogenase.

What metabolic functions are attributed to the endoplasmic reticulum in Table 2.2?

Biosynthesis of proteins, glycoproteins, lipoproteins, drug metabolism, ethanol oxidation, and partial synthesis of cholesterol.

What are the metabolic functions of lysosomes according to Table 2.2?

Degradation of proteins, carbohydrates, lipids, and nucleotides.

What metabolic functions and pathways occur in mitochondria according to Table 2.2?

Electron transport chain, ATP generation, TCA cycle, beta-oxidation of fatty acids, ketone body production, and partial synthesis of urea, heme, gluconeogenesis, and pyrimidine.

In which specific cell types does the nucleus occupy most of the available space?

Small lymphocytes and spermatozoa.

How is the nuclear envelope organized, and what is its outer membrane continuous with?

The nucleus is surrounded by two membranes: the inner perinuclear membrane with numerous pores, and an outer membrane that is continuous with the membrane of the endoplasmic reticulum.

What is the nucleolus and what processes take place within it?

A lighter-shaded portion of the nucleus where RNA processing and ribosome synthesis take place; it is prominent in cells actively synthesizing proteins.

What organelle is shown in this diagram, and what are its six labeled components?

The nucleus (Fig. 2.2), showing the endoplasmic reticulum, nucleolus, chromatin, nucleoplasm, nuclear pore, and nuclear envelope.

What are microsomes and how are they formed?

When cells are fractionated, the complex endoplasmic reticulum is disrupted in many places and automatically re-assembles into microsomes.

What characteristic appearance does the endoplasmic reticulum display under an electron microscope?

A railway track appearance.

Which specific enzyme in the endoplasmic reticulum is responsible for drug detoxification?

Microsomal cytochrome P-450, which hydroxylates various drugs.

What accounts for the rough appearance of the rough endoplasmic reticulum?

Ribosomes attached to the cytoplasmic side of the membrane where proteins are being synthesized.

Who first described the Golgi apparatus, in what year, and in which year did he receive the Nobel Prize?

Camillo Golgi (1843–1926) described the structure in 1898 and received the Nobel Prize in 1906.