Cell Structure Function Life is Cellular A little

Cell Structure & Function

Life is Cellular

A little history… § 1600 s: 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

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 semipermeable. § 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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