BIOL 071 Human Anatomy Lecture 2: The Cell

These flashcards cover the basic unit of structure and function in the cell, detailing the composition of the plasma membrane, transport mechanisms, and the functions of membrane-bound and non-membrane-bound organelles based on Chapter 2 of the Human Anatomy lecture.

What is the plasma membrane?

The outer barrier separating the internal contents of the cell from the external environment.

How is the cytoplasm defined in a cell?

The cellular contents located inside of the cell.

What are the four primary functions of the plasma membrane?

1. Physical barrier: Establishes a flexible boundary and protects cellular contents. 2. Selective permeability: Regulates entry and exit of ions, nutrients, and waste. 3. Electrochemical gradients: Establishes and maintains an electrical charge difference. 4. Communication: Contains receptors that recognize and respond to molecular signals.

What are the three main types of lipids found in the plasma membrane?

Phospholipids, cholesterols, and glycolipids.

What are glycoproteins?

Proteins that have carbohydrates attached to them.

What is the difference between integral and peripheral proteins?

Integral proteins are fully embedded into the plasma membrane, while peripheral proteins are attached loosely to either the external or internal surface.

What are the six functions of proteins in the plasma membrane?

1. Transport 2. Intercellular connection 3. Anchorage for the cytoskeleton 4. Enzyme activity 5. Cell-cell recognition 6. Signal transduction.

What is the difference between passive and active transport?

Passive transport is the movement of substances with the concentration gradient, while active transport is the movement of substances against the concentration gradient.

Define diffusion.

The movement of molecules from an area of higher concentration to an area of lower concentration until the gradient is eliminated.

Give an example of diffusion in a cell.

When the concentration of $CO_2$ inside a cell is greater than outside, $CO_2$ diffuses out of the cell and into the extracellular fluid.

What occurs during facilitated diffusion?

Solutes like glucose and amino acids are passively transported across a plasma membrane by a carrier protein following the concentration gradient.

What is osmosis?

The diffusion of water molecules (rather than solutes) across a selectively permeable membrane toward an area of higher solute concentration.

What are the two main types of active transport?

Ion pumps and bulk transport.

Describe the function of the $Na^+/K^+$ pump.

A type of ion pump that uses energy from ATP breakdown to transport three sodium ions ($3 Na^+$) out of the cell and two potassium ions ($2 K^+$) into the cell.

What is the difference between exocytosis and endocytosis?

Exocytosis is the transport of large molecules outside of the cell, whereas endocytosis is the transport of large molecules inside of the cell.

What are the three types of endocytosis?

(a) Phagocytosis, (b) Pinocytosis, and (c) Receptor-mediated endocytosis.

What are the two primary functions of the nucleus?

1. Cellular regulation: Houses genetic material to direct cellular activities and regulate structure. 2. Production: Produces ribosomal subunits in the nucleolus and exports them for assembly.

Contrast the functions of the Smooth ER and the Rough ER.

Smooth ER is the site of lipid synthesis, carbohydrate metabolism, and detoxification of drugs, alcohol, and poisons. Rough ER synthesizes proteins for secretion, the plasma membrane, and lysosomes.

What are the three main functions of the Golgi apparatus?

Modification, packaging, and sorting of materials for lysosomes, secretion, or the plasma membrane.

What are the three functional roles of lysosomes?

1. Digestion of materials entering by endocytosis. 2. Removal of worn-out organelles (autophagy). 3. Self-destruction of remains after cellular death (autolysis).

What is the function of peroxisomes?

Detoxification of harmful substances, converting hydrogen peroxide to water, and breaking down fatty acid molecules.

Why are mitochondria called the 'powerhouses' of the cell?

Because they harvest energy by producing ATP through cellular respiration for the energy needs of the cell.

What is the functional difference between free and bound ribosomes?

Free ribosomes synthesize proteins for use within the cell; bound ribosomes synthesize proteins destined for the plasma membrane, export from the cell, or lysosomes.

What are the three primary functions of the cytoskeleton?

1. Structural support and organization. 2. Cell division (separating chromosomes and splitting daughter cells). 3. Movement (cytoplasmic streaming, vesicle movement, and muscle contraction).

What are the roles of centrosomes and centrioles?

They organize microtubules and support their growth in nondividing cells, and direct the formation of spindle fibers in dividing cells.