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

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

All cells have:  Cell membrane  Cytoplasm  Ribosomes  Cell wall (plants only)

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 only!!! Cytoskeleton  Maintains shape  Movement NucleusOrganelles

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, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles

Cell Transport

Cell Membrane  Functions: Provides protection and support. Provides protection and support. Regulates what enters Regulates what enters and leaves the cell. Takes in food and water. Takes in food and water. Eliminates waste. Eliminates waste. Allows the cell to maintain homeostasis. Allows the cell to maintain homeostasis.

Parts of the Cell Membrane

Concentration  How many molecules are in a given volume. (How crowded the molecules are.)  Concentration = Amount of solute Volume of Solution Volume of Solution  Every cell is surrounded by liquid and has a liquid interior (cytoplasm) that are solutions of many different substances. High ConcentrationLow Concentration

Osmosis in Cells  Hypotonic: the solution outside has a lower solute concentration that inside the cell.  Isotonic: the concentration of solutes is the same both in and out of the cell  Hypertonic: the solution outside has a higher solute concentration than inside the cell

Homeostasis & Cells

Cell Specialization

Cells – Tissues- Organs- Organ Systems- Organism

 The basic unit of life. Cell

 A group of cells that perform a particular function.  Four types:  Connective  Epithelial  Muscle  Nervous Tissue

 A group of tissues working together to perform a particular function.  Examples:  Heart  Stomach  Lungs Organs

 A group of organs working together.  Examples:  Nervous system  Circulatory system  Digestive system Organ System

 Any living thing. Organism

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