Cell Biology Key Terms and Concepts Explained
Key Cell Biology Terms
Active transport: The movement of substances across a cell membrane using energy, usually ATP. It often moves substances against their concentration gradient.
Centrioles: Structures that help organize microtubules and the spindle during cell division.
Channel proteins: Membrane proteins that form passageways for specific substances to cross the cell membrane.
Cilia: Short, hairlike projections that help move a cell or substances along its surface.
Cytokinesis: The division of the cytoplasm at the end of cell division, forming two daughter cells.
Cytoplasm: The material inside the cell but outside the nucleus. It includes the cytosol and the organelles.
Cytoskeleton: A network of fibers that supports the cell, gives it shape, and helps the cell and its parts move.
Diffusion: The movement of particles from an area of higher concentration to an area of lower concentration. It does not require cellular energy.
Endocytosis: The process of bringing materials into a cell by surrounding them with the cell membrane and forming a vesicle.
Endoplasmic reticulum (ER): A membrane network that makes and transports materials. Rough ER has ribosomes and helps make proteins. Smooth ER makes lipids and helps process certain substances.
Exocytosis: The process of releasing materials from a cell when a vesicle joins the cell membrane.
Extracellular fluid: The fluid found outside the cells.
Extracellular matrix: A network of materials outside the cells that supports them and helps keep them organized.
Glycolysis: The first step in breaking down glucose to release energy. It takes place in the cytoplasm.
Glycoproteins: Proteins with carbohydrate chains attached. In the cell membrane, they help with cell recognition and communication.
Golgi apparatus: The organelle that modifies, sorts, and packages proteins and lipids for transport.
Messenger RNA (mRNA): RNA that carries a copy of DNA instructions from the nucleus to the ribosomes.
Microvilli: Small projections that increase a cell’s surface area and help it absorb more substances.
Mitochondria: Organelles where most cellular respiration takes place and ATP is produced.
Mitosis: The division of the nucleus that separates the chromosomes into two new nuclei.
Nucleus: The organelle that contains most of the cell’s DNA and directs many cell activities.
Passive transport: The movement of substances across a cell membrane without using cellular energy.
Plasma membrane: The boundary around a cell that controls what enters and leaves.
Ribosomes: Structures that make proteins by following instructions from mRNA.
Transcription: The process of copying information from DNA into RNA, usually mRNA.
Transfer RNA (tRNA): RNA that carries amino acids to the ribosome during protein production.
Common Word Parts in Cell Biology
cyt- = cell. Example: cytoplasm.
exo- = outside. Example: exocytosis releases materials from a cell.
trans- = across or to the other side. Example: transcription copies information.
• -lysis = breaking down. Example: glycolysis breaks down glucose.
• -some = body. Example: ribosome.
• mit- = thread. Example: mitosis involves chromosomes during cell division.
Key Differences Between Cell Processes
• Active transport and passive transport: Active transport uses energy. Passive transport does not.
• Diffusion: Particles move from higher concentration to lower concentration. Diffusion is a type of passive transport.
• Endocytosis and exocytosis: Endocytosis brings materials into the cell. Exocytosis releases materials from the cell.
• Mitosis and cytokinesis: Mitosis divides the nucleus. Cytokinesis divides the cytoplasm.
• Cilia and microvilli: Cilia help move a cell or substances. Microvilli increase surface area for absorption.
• Cytoplasm and cytoskeleton: Cytoplasm is the material inside the cell. The cytoskeleton is the internal fiber network that supports the cell.
• mRNA and tRNA: mRNA carries instructions. tRNA carries amino acids to the ribosome.
• Transcription and glycolysis: Transcription copies DNA information into RNA. Glycolysis starts breaking down glucose for energy.
• Extracellular fluid and extracellular matrix: Extracellular fluid is liquid outside the cells. The extracellular matrix is a support network outside the cells.