Cytology

What is the cell theory?

The cell theory is a unifying concept in biology that states all living things are composed of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

What happens when a cell gets too large?

When a cell gets too large, its volume increases faster than its surface area, making it less efficient at transporting nutrients and waste products across the cell membrane. This can lead to a nutrient deficiency or accumulation of waste products, ultimately hindering cell function and survival.

Why is there a limit to how big cells can get?

The limit to cell size is primarily due to the surface area-to-volume ratio. As a cell grows, its volume increases much faster than its surface area. The surface area (cell membrane) is responsible for exchanging materials with the environment, while the volume dictates the metabolic needs. A low surface area-to-volume ratio makes transport inefficient, limiting how large a cell can grow.

What nutrients go into a cell?

Common nutrients that go into a cell include glucose (sugar), amino acids, fatty acids, vitamins, minerals, water, and oxygen.

What waste products come out of a cell?

Waste products that come out of a cell include carbon dioxide, urea, ammonia, and excess water.

What is the surface area of a cell?

The surface area of a cell refers to the total area of its outer boundary, which is typically the cell membrane (or cell wall in plants/bacteria). It is the region responsible for interacting with the external environment and facilitating transport of substances into and out of the cell.

What is the volume of a cell?

The volume of a cell refers to the total amount of space it occupies, which primarily consists of the cytoplasm and internal organelles.

What are prokaryotic cells?

Prokaryotic cells are simple, single-celled organisms that lack a membrane-bound nucleus and other membrane-bound organelles. Examples include bacteria and archaea.

What are eukaryotic cells?

Eukaryotic cells are more complex cells that have a membrane-bound nucleus and various membrane-bound organelles, such as mitochondria, endoplasmic reticulum, and Golgi apparatus. These cells make up animals, plants, fungi, and protists.

What does karyo- mean?

Karyo-" is a Greek prefix meaning "nut" or "kernel," referring to the nucleus of a cell.

What are bacterial cell walls made up of?

Bacterial cell walls are primarily made up of peptidoglycan, a polymer consisting of sugars and amino acids.

What is the cytoplasm made up of?

The cytoplasm is made up of cytosol (a jelly-like substance primarily composed of water, salts, and organic molecules) and the various organelles suspended within it.

What shape is the chromosome inside of bacterial cells?

The chromosome inside of bacterial cells is typically a single, circular shape.

What is the cell membrane?

The cell membrane (or plasma membrane) is a flexible barrier that surrounds the cytoplasm of a cell, separating its internal environment from the outside world. It controls which substances can enter and exit the cell.

What does semi-permeable mean?

Semi-permeable (or selectively permeable) means that a membrane allows certain molecules or ions to pass through it by means of active or passive transport, while preventing others from passing.

What is the bilayer made up of?

The bilayer (specifically the phospholipid bilayer of the cell membrane) is made up of two layers of phospholipid molecules, each having a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail.

What do all living cells need to be surrounded by?

All living cells need to be surrounded by a cell membrane.

What are embedded in the cell membrane?

Various proteins, cholesterol, and carbohydrates are embedded in or associated with the cell membrane.

What are enzymes?

Enzymes are proteins that act as biological catalysts, speeding up specific chemical reactions within the cell without being consumed in the process.

What are ion channels?

Ion channels are pore-forming proteins embedded in the cell membrane that allow specific ions (such as sodium, potassium, or calcium) to pass through.

What are transporter proteins?

Transporter proteins (or carrier proteins) are membrane proteins that move specific substances across the cell membrane, often by changing their shape.

What are receptor site proteins?

Receptor site proteins are cell surface proteins that bind to specific signaling molecules (like hormones or neurotransmitters), initiating a response within the cell.

What are recognition site proteins?

Recognition site proteins (often glycoproteins or glycolipids) are involved in cell-to-cell recognition, helping the body's immune system distinguish its own cells from foreign invaders.

What are immunosuppressant drugs?

mmunosuppressant drugs are medications that suppress or reduce the strength of the body's immune system, often used to prevent the rejection of transplanted organs or to treat autoimmune diseases.

What are autoimmune diseases?

Autoimmune diseases are conditions in which the body's immune system mistakenly attacks its own healthy tissues and cells

What is diffusion?

Diffusion is the net passive movement of molecules or particles from a region of higher concentration to a region of lower concentration, down a concentration gradient.

What are the four factors that affect the rate of diffusion?

The four primary factors that affect the rate of diffusion are temperature, concentration gradient, surface area, and the size/mass of the diffusing particles.