Cell Structure & Function
Life is Cellular
A little history… 1600s: van Leeuwenhoek used microscope to study nature 1665: Hooke used microscope to look at plant tissue & cork; called them “cells” 1838: Schleiden concluded that all plants were made of cells 1839: Schwann concluded that animals are made of cells 1855: Virchow studied cell reproduction and concluded that cells come from cells
The basic unit of ALL living organisms. What is a cell? The basic unit of ALL living organisms. Scale of Life
Cell Theory All living things are composed of cells. Cells are the basic units of structure & function in living things. New cells are made from existing cells.
Types of cells: Prokaryotes Eukaryotes
Prokaryotes Unicellular No nucleus Asexual reproduction Example: bacteria
Eukaryotes Unicellular or multicellular Nucleus present Organelles present Sexual reproduction Examples: plants, animals, people
Prokaryotes & Eukaryotes have: Cell membrane Cytoplasm Ribosomes Cell wall (plants only for Eukaryotes)
Cell membrane The “skin” of the cell. Protects cell from outside environment. Regulates flow of water, nutrients & waste.
Cytoplasm Material inside the membrane (not including the nucleus). Contains many important structures.
Other cell parts to know: Cell Wall Found outside cell membrane Supports & protects cell Plant cells & some bacteria Cytoskeleton Maintains shape Movement Nucleus Organelles
Nucleus The “brain” of the cell. Controls cell functions. Contains DNA. Surrounded by nuclear envelope.
Organelles ”Little organs” Specialized parts of the cell. Examples: ribosomes, mitochondria, chloroplasts, vacuoles
Cell Transport
Cell Membrane Functions: Provides protection and support. Regulates what enters and leaves the cell. Takes in food and water. Eliminates waste. Allows the cell to maintain homeostasis.
The cell membrane is semi-permeable. Some substances can pass through it, while others cannot. Most biological membranes are semi-permeable.
Parts of the Cell Membrane Phosopholipid bilayer: the core of the membrane; forms a strong barrier between the cell and the outside Protein channels: form pumps to move material through membrane Carbohydrates: identify the cell; on the outside
Concentration How many molecules are in a given volume. (How crowded the molecules are.) Concentration = Amount of solute Volume of Solution Every cell is surrounded by liquid and has a liquid interior (cytoplasm) that are solutions of many different substances. High Concentration Low Concentration
Passive Transport: movement from an area of high concentration to areas of lower concentration (getting less crowded); does not require energy Diffusion Facilitated Diffusion: molecules that are too large to pass through the cell membrane go through protein channels Osmosis: the diffusion of water
Osmosis in Cells
Active Transport: movement from an area of low concentration to areas of higher concentration (getting more crowded); requires energy Exocytosis: when a vesicle fuses with the cell membrane to take material out Endocytosis: brings material into the cell when a pocket in the membrane breaks off, forming a vesicle
Homeostasis & Cells
Cell Specialization Cells in multicellular organisms are interdependent. Cells in multicellular organisms are specialized to perform particular functions in the organism.
Cells – Tissues- Organs- Organ Systems- Organism
Cell The basic unit of life.
Tissue A group of cells that perform a particular function. Four types: Connective Epithelial Muscle Nervous
Organs A group of tissues working together to perform a particular function. Examples: Heart Stomach Lungs
Organ System A group of organs working together. Examples: Nervous system Circulatory system Digestive system
Organism Any living thing.
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