7.1 The discovery of cells?

Do Now: Copy the following in chronological order _1838-Matthias Schleiden- observed plant cells _1650s Anton van Leewenhoek started observing water with primitive Microscopes _1858- Rudolf Virchow studied cell reproduction _1660 Robert Hooke observed cork cells _1839 Theodor Schwann- observed animal cells

Dust Mite Under the Microscope

Types of Microscopes Light Microscope (LM)- an optical instrument w/ lenses that refracts light to magnify images. Dissecting Microscope- low magnification but has a work space Micrograph- a photograph taken through a microscope. Magnification- an increase in the apparent size of an object. (Zoom) Resolving Power- a measure of the clarity of an image; the ability to show two objects as separate. (High Def. TV)

Electron Microscopes Electron Microscope (EM)- an instrument that focuses an electron beam through or onto the surface of a specimen. *1000X greater resolving power than a LM. *One problem they cannot be used to study living specimens, because they would have to be placed in a vacuum chamber. SEM or Scanning electron microscope: Surface of cells TEM or transmission electron microscope: structures within STM or Scanning Tunnel Microscope: atoms on a molecule

Cell Theory All organisms are made of cells The cell is the smallest unit of life All cells come from pre-existing cells

Eukaryotic vs. Prokaryotic

Prokaryotic cells Bacterial cells Much smaller and simpler than eukaryotic cells Organelles include only – a plasma membrane – cell wall – capsule: extra protective layer outside the cell wall – ribosomes – single loop of DNA free in the cytoplasm in nucleiod region – sometimes has pili: small hairs on the outside of the cell used for movement – sometimes has flagella

Eukaryotic cells – Plants, animals, fungi, protistans (single Celled) – Membrane-bound nucleus & organelles

7.2 Plasma Membrane

Objectives: -Understand the structure of the cell membrane -Understand how the properties of the cell membrane make it ideal for it’s function -Does the membrane have any flaws?

Do Now: List three substances that enter the cells in your body List three substances that leave the cells of your body

The Plasma Membrane controls what enters and leaves the cell maintains homeostasis (balance in the cell) – Allows water, oxygen, and glucose to enter when there’s not enough – Allows water, carbon dioxide, and waste to leave when there’s too much selective permeability: the membrane allows some molecules, but not all, to pass through Made up of a molecule called a phospholipid – lipid with a phosphate group

Plasma membrane is a phospholipid bilayer – 2 layers of phospholipids back-to-back – Polar heads face the water inside and outside the cell – Nonpolar tails hide from water inside the membrane In between the phospholipids in the plasma membrane, there are – proteins transport proteins: move needed materials or waste across the cell membrane – cholesterol – carbohydrates

Fluid mosaic model of the plasma membrane – the membrane is fluid because the phospholipids are constantly moving over the cell – the proteins in the membrane are carried around by the phospholipids, forming different mosaics (patterns) – Types of proteins

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Organelle Cards

Cell Wall Plants Only Outside plasma membrane Support and protects

Nucleus Control Center Contains chromatin (DNA) Controls protein production Contains nucleolus

Nucleolus Produces ribosomes

Ribosomes Produces proteins Found on RER and in cytoplasm

Cytoplasm Clear jelly inside cell

Rough Endoplasmic Reticulum Chemical Reactions Modifies Proteins

Smooth ER Chemical reactions Production of lipids

Golgi Postal Service Sorts and transports proteins

Vacuoles Storage for enzymes, food and other materials Large in plants Small in animals

Lysosome Digestive enzymes breakdown food, bacteria, and old organelles Recycling Center Animals only

Chloroplast Contains chlorophyll Photosynthesis : Sunlight is used to make sugar Plants only

Mitochondria Converts sugar into usable form of energy ATP

Cytoskeleton Support structure Microtubules: small hollow tubes Microfilaments: thin solid fibers

Centrioles Help cell division Animals only

Cilia Short hairs used for movement Animals only

Flagella Long tail used for movement Animals only