Cell Biology Overview

Cell Biology Terminology

• Differentiated cells have specialized functions and characteristics essential for various roles in an organism.
• Major components of a cell include the nucleus, cytoplasm, and cell membrane, each with distinct functions.

Nucleus and DNA

• The nucleus houses DNA, which directs cellular functions and processes.
• DNA provides the instructions required for growth, development, and reproduction of cells.

Cytoplasm Components

• Cytosol is the fluid matrix within the cytoplasm that supports cellular structures.
• The cytoplasm maintains cell shape and supports internal structures.

Cell Membrane Properties

• The cell membrane is selectively permeable, allowing specific substances to pass while restricting others.
• Membrane proteins play multiple roles, including message reception, pore formation, and chemical reaction facilitation.

Cell Structure and Organelles

• Cytoskeleton provides structural support and shape to the cell through protein rods and tubules.
• Ribosomes are composed of protein and RNA, crucial for protein synthesis.
• The endoplasmic reticulum consists of membrane-bound sacs aiding in synthesis and transport.
• Organelles are specific cell structures housing biochemical reactions for distinct functions.
• Vesicles are membranous sacs that store or transport materials within the cell.

Specific Organelles

• Golgi apparatus modifies and packages proteins.
• Mitochondria are energy-producing organelles, responsible for ATP generation.
• Lysosomes function as the cell's waste disposal system, breaking down debris.
• Peroxisomes resemble lysosomes and are involved in lipid metabolism.

Cytoskeletal Elements

• Centrosomes are responsible for organizing microtubules during cell division.
• Cilia and flagella are motile structures aiding in cell movement.
• Microfilaments and microtubules contribute to the cell's structural integrity.

Nuclear Structures

• The nuclear envelope is a double membrane separating the nucleus from the cytoplasm.
• Nuclear pores allow selective passage of molecules in and out of the nucleus.
• The nucleolus synthesizes ribosomal RNA, important for protein synthesis.
• Chromatin, composed of DNA and proteins, condenses into chromosomes during cell division.

Transport Mechanisms

• Diffusion allows movement of particles from higher to lower concentration areas.
• Osmosis is the diffusion of water across a selectively permeable membrane.
• Active transport involves moving substances against their concentration gradient.
• Endocytosis incorporates materials into the cell via vesicles, including pinocytosis (liquids) and phagocytosis (solids).
• Receptor-mediated endocytosis selectively transports specific particles.

Cellular Processes

• Exocytosis transports substances out of the cell through vesicle fusion with the membrane.
• The cell cycle encompasses all cellular changes from formation to division, including interphase (cell growth) and mitosis (cell division).

Mitosis Stages

• Prophase: Chromosomes become visible.
• Metaphase: Chromosomes align in the cell center.
• Anaphase: Chromatids separate and move to opposite poles.
• Telophase: Cells begin to split apart to form two daughter cells.

Cancer Biology

• Tumors arise from uncontrolled cell division due to genetic mutations in oncogenes and tumor suppressor genes, leading to cancer.
• Oncogenes promote excessive cell division, while tumor suppressor genes normally inhibit it.

Cell Differentiation and Types

• Differentiation results in specialized cell types from stem cells for specific functions.
• Stem cells are undifferentiated and can become other cell types; progenitor cells are lineage-restricted daughter cells.
• Totipotent cells can become any cell type, while pluripotent cells can become several specialized types.

Cell Death

• Apoptosis is a programmed cell death process essential for development and tissue homeostasis.