Human Anatomy - Chapter 2: The Cell

Comprehensive question-and-answer flashcards covering cell anatomy, organelles, membrane transport mechanisms, cell junctions, and the cell life cycle based on Chapter 2.

What are the three fundamental propositions about cells presented in the introduction?

Cells are the structural "building blocks" of all plants and animals, cells are produced by the division of pre-existing cells, and cells are the smallest structural units that perform all vital functions.

What are the two major categories of cells in the human body?

Sex cells (germ cells or reproductive cells, which are sperm in males and oocytes in females) and somatic cells (all other cells in the body).

What is cytology, and what three common microscopy techniques are used to study cells?

Cytology is the study of cells. The three common methods are light microscopy, transmission electron microscopy, and scanning electron microscopy.

What are the four major functions of the plasmalemma (cell membrane)?

Physical isolation, regulation of exchange with the environment, sensitivity, and structural support.

According to Table 2.1, what percentage of the ATP required by the cell is produced by mitochondria?

$95\text{ percent}$ of the ATP required by the cell.

What is the structural difference between microvilli and cilia as described in Table 2.1?

Microvilli are membrane extensions containing microfilaments, whereas cilia are membrane extensions containing microtubule doublets in a $9 + 2$ array.

Which specific ions are regularly moved across the plasmalemma by active transport?

$\text{Na}^+$, $\text{Ca}^{2+}$, $\text{Mg}^{2+}$, and $\text{K}^+$.

What is an exchange pump in active transport?

An ion pump that moves two ions simultaneously in opposite directions.

What factors affect the rate of exocytosis and what substances are required?

Exocytosis requires ATP and calcium ions, with its stimulus and mechanism being incompletely understood. It involves fluids and wastes.

What is the chemical composition of ribosomes?

Ribosomes are composed of $60\%$ RNA and $40\%$ protein.

How do centrioles, cilia, and flagella compare in terms of microtubule organization according to Table 2.3?

Centrioles consist of nine groups of microtubule triplets forming a short cylinder. Cilia and flagella both consist of nine groups of long microtubule doublets forming a cylinder around a central pair.

What are the four major functions of the endoplasmic reticulum (ER)?

Synthesis of all classes of macromolecules, storage of manufactured molecules, transport of substances from one area of the cell to another, and detoxification provided by enzymes in the lumen.

What are the three main functions of the Golgi apparatus?

Synthesis and packaging of secretions, packaging of enzymes for use in the cytosol, and renewal and modification of the cell plasmalemma.

What are the three ways in which lysosomes function in a cell?

Lysosomes fuse with phagosomes to digest solid materials, fuse with and recycle damaged organelles, and break down (autolysis) following cell injury or death to liberate digestive enzymes.

What functions do peroxisomes perform, and in which cell type are they abundant?

Peroxisomes digest fats and toxins and convert hydrogen peroxide to water; they are abundant in liver cells.

What is membrane flow?

The continual movement and recycling of the plasmalemma driven by the ER, Golgi apparatus, and vesicles.

What are the three major types of cell junctions?

Tight junctions, communicating junctions, and anchoring junctions.

Based on the provided cell cycle diagram, what are the durations of the $G_1$, S, and $G_2$ phases of Interphase?

The $G_1$ phase lasts $8\text{ or more hours}$, the S phase lasts $6\text{ to }8\text{ hours}$, and the $G_2$ phase lasts $2\text{ to }5\text{ hours}$.

What are the four stages of mitosis in sequential order?

Prophase, metaphase, anaphase, and telophase.

How is DNA structured within a chromosome?

DNA forms a double helix wrapped around proteins called histones to form nucleosomes, which assemble into chromatin in non-dividing cells and condense into supercoiled visible chromosomes prepared for division.