Biology Chapter 7 Cell Structure & Function

Cell Structure and Function

• A cell is the fundamental structural and functional unit of all living organisms.
• The cell theory identifies cells as the basic building blocks of life.

Types of Organisms

• Eukaryotes have complex cells with a nucleus and organelles, found in multicellular organisms.
• Prokaryotes are unicellular organisms without a nucleus, including bacteria.

Cell Components

• The nucleus contains DNA and RNA, essential for cell growth and reproduction.
• Organelles are specialized structures within cells that perform specific functions.
• Cytoplasm is a jellylike fluid that suspends organelles within the cell.
• The nuclear envelope surrounds the nucleus, made of two membranes.
• Chromatin is a form of DNA tightly coiled around proteins, found in the nucleus.
• Chromosomes are structures made of DNA and protein; prokaryotes contain a single ring of DNA.
• The nucleolus is responsible for synthesizing and assembling ribosomes.

Protein Production and Processing

• Ribosomes are particles where proteins are assembled, formed from RNA and proteins.
• The endoplasmic reticulum (ER) is a membrane system where cell membrane components and proteins are constructed.
• The Golgi apparatus modifies, sorts, and packages proteins received from the ER.

Energy and Nutrition

• Mitochondria are known as the powerhouse of the cell, producing ATP, the energy currency.
• Chloroplasts are found in plant cells, utilizing chlorophyll to convert sunlight into chemical energy.
• Lysosomes contain enzymes for digesting waste materials within the cell.
• Vacuoles store substances like water, salts, and carbohydrates.

Cell Structure and Transport Mechanisms

• The cell membrane is a flexible barrier regulating the movement of substances in and out of the cell.
• The cell wall provides structural support, found in plants, algae, and some bacteria.
• The lipid bilayer forms the core of cell membranes, composed of two layers of phospholipids.

Transport Processes

• Diffusion involves the movement of molecules from high to low concentration.
• Osmosis is the diffusion of water through a selectively permeable membrane.
• Solutions can be isotonic, hypertonic, or hypotonic, affecting cell behavior.
• Facilitated diffusion utilizes protein channels for the movement of specific molecules.
• Active transport requires energy to move substances against their concentration gradient.
• Processes like endocytosis, phagocytosis, and pinocytosis involve the cell engulfing substances to bring them inside.
• Exocytosis is the release of substances from the cell using vesicles.

Cell Specialization

• Cell specialization allows different cells to perform unique functions within an organism.
• Tissues consist of groups of similar cells performing specific tasks.
• An organ is a structurally and functionally differentiated unit made up of tissues.
• An organ system is a group of organs that collaborate to perform a particular function.

Cytoskeletal Structures

• The cytoskeleton is a network of protein filaments providing shape and support to cells.
• Microtubules are hollow rods in the cytoskeleton, critical for cell shape, movement, and structure, found in cilia and flagella.