Cellular Level of Organization

These flashcards cover core concepts related to cell structure, function, transport mechanisms, and genetic information as discussed in the lecture on the cellular level of organization.

What does the cell theory state?

All organisms are composed of cells, the cell is the simplest unit of life, an organism's structure and functions arise from cellular activities, and cells arise only from preexisting cells.

What is the approximate size of most human cells?

Most human cells are approximately 10–15 micrometers in diameter.

What is the significance of cell size limitations?

An overly large cell cannot support itself and may rupture; as diameter increases, volume increases more than surface area.

What are the basic components of a cell?

Plasma membrane, cytoplasm (organelles, cytoskeleton, inclusions, cytosol), and extracellular fluid.

What is the primary function of the plasma membrane?

It defines the cell's boundaries, governs interactions with other cells, and controls the passage of materials in and out of the cell.

What are phospholipids and their role in the membrane?

Phospholipids make up 75% of membrane lipids, forming a bilayer where hydrophilic heads face water and hydrophobic tails face inward.

What is membrane permeability?

Plasma membranes are selectively permeable, allowing some substances to cross while prohibitively blocking others.

What are the types of transport processes across the cell membrane?

Passive processes (like diffusion, facilitated diffusion, osmosis) and active processes (like active transport and vesicular transport).

What is the difference between active and passive transport?

Passive transport does not require energy as substances move down their concentration gradient, whereas active transport requires energy to move substances against their gradient.

What is endocytosis?

Endocytosis is the process of bringing material into the cell through vesicular transport.

What does the cytoskeleton do?

It provides structural support, helps in cell movement, and maintains cell shape and organization.

What is the function of ribosomes?

Ribosomes are the site of protein synthesis, translating mRNA into proteins.

What role does the Golgi apparatus play in the cell?

It modifies, packages, and sorts proteins and lipids for secretion or use within the cell.

What are the functions of lysosomes?

Lysosomes are involved in digestion and recycling of cellular waste and can cause autolysis in case of cell injury.

What is the chemical makeup of DNA?

DNA consists of nucleotides, made up of a phosphate group, a sugar (deoxyribose), and nitrogenous bases (adenine, thymine, cytosine, guanine).

What is transcription?

Transcription is the process of copying a segment of DNA into RNA, specifically mRNA.

What is the difference between mRNA and tRNA?

mRNA carries genetic information from DNA to ribosomes, while tRNA transports amino acids to ribosomes for protein synthesis.