Presentation on theme: "If all living things need water to survive…"— Presentation transcript:
1If all living things need water to survive… Why do you think the runner reacted so negatively when given water during her marathon?
27.1 Life is CellularThe key to how organisms live and function is found in cells.Let’s see what you remember or already know about cells…
3Pre-Test … What do you know? The smallest unit considered “alive” is…T / F: All cells contain genetic material called DNADNA is found in this centralized structure within a cell called the ______________All cells are surrounded by a thin, flexible barrier called __________________________Scientists didn’t know about cells until (THIS) was invented in the late 1500’s.
46. T / F: All cells have the same basic structure and function 7 6. T / F: All cells have the same basic structure and function 7. T / F: Most plants and animals are multi-cellular (made of many cells) 8. An example of a unicellular (one-celled) organism is _________________.
5Pre-Test Answers Anyone get 100% ? A cell True Nucleus Cell membrane MicroscopeFalseBacteriaAnyone get 100% ?
6CELLS The building blocks of living things Some organisms are made of 1 cellUnicellular (bacteria)Some organisms are made of many cellsMulti-cellular (plants, animals)
7Discovery of the CellInvention of microscope led to discovery of cells!1665 – Robert Hooke, Englishman – used microscope to observe piece of corkMade of many tiny compartments, like rooms in a monastery called “cells”Anton van Leeuwenhoek - using a microscope, found organisms in pond water, drinking water, and even his mouth
8Types of Microscopes (p.192) Light microscopes – can see cells and cell structures – use stainsCan be magnified up to 500xElectron microscopes (2 types)Scanning electron microscope – produces dramatic 3D images- Have 3750x magnification2. Transmission electron microscope – samples are cut in thin slices, making a flat 2D image- Have 4375x magnification
9Transmission Electron Microscope (TEM) Light MicroscopeTransmission Electron Microscope (TEM)Scanning Electron Microscope (SEM)Light microscopes use stains to add color to cellsElectron microscopes use the computer to add color
10What do all cells have in common? Cells are many different shapes and sizesBut all cells have a _______________ – thin, flexible barrier that surrounds the cell-All living things are made of cellsCells are the basic unit of structure and function of living thingsNew cells are produced from existing cellscell membraneThe Cell Theory
11How are cells different? Cells fall into 2 broad categories,based on the presence or absence of a __________________ = large, membrane-enclosed structure that contains genetic material called DNAProkaryotes (bacteria)Eukaryotes (animals, plants)nucleusNucleus
122 Categories of Cell Types ProkaryotesEukaryotesNo nucleus (DNA floats freely)UnicellularSmall and simpleSome swim or glide along surfacesNucleus (contains DNA)Multi-cellularLarge and complex
13Is a virus a cell? Is it alive? No, it is not a cell, and it is not aliveViruses are nonliving particlesMade of proteins, nucleic acids (DNA or RNA), and sometimes lipids (fats)Can ONLY reproduce by infecting living cells (remember cell theory?)
14Structure of VirusesMany shapes and sizes – All very small – need what type of microscope …?Viruses have a protein coat called a capsidBacteriophages – virus that infects bacteriaOnce inside bacteria, it makes many copies of itselfBreaks open and infects other cells