LIFE SCIENCE 1.2 Microscopes allow us to see inside the cell.

Because cells are very small, in order to measure them we need a new unit. The micrometer (  m)is one millionth of a meter. Cells can range from 1 to 1000 micrometers. It would take 17,000 bacterial cells to line up across a dime.

Light Microscopes bend light and magnify cells up 1000 times. Cells can be treated with dyes to make more visible. Cameras and computers observe movement of cell parts. Can observe living cells.

Scanning Electron Microscope and Transmission Electron Microscope SEM and TEM can view objects as small as micrometers. Can see details inside the cell. Use particles called electrons not light to produce an image. Can magnify objects up to 1 million times. Can not be used to study live specimens.

SEM THE CELL SAMPLE IS COATED WITH A HEAVY METAL SUCH AS GOLD. A BEAM OF ELECTRONS IS RUN BACK AND FORTH OVER THE SURFACE. THE ELECTRONS BOUNCE OFF THE SURFACE AND ARE READ BY A DETECTOR WHICH PRODUCES A 3 D IMAGE OF THE SURFACE

SEM IMAGES Butterfly ProboscisPollen

TEM THE CELL SAMPLE IS SLICED EXTREMELY THIN. ELECTRONS PASS THROUGH A SECTION. IMAGES PRODUCED ARE 2 DIMENSIONAL.

TEM Golgi BodiesMitochondrian

CELLS ARE DIVERSE

EVERY CELL HAS: Cell membrane- separates the cell from its environment. Cytoplasm – gelatin-like material inside the cell, carries on most of the work of the cell.

Two categories of Cells Eukaryotic CellsProkaryotic Cells

Two categories of Cells Prokaryote- pro: before; kary: nucleus  Genetic material contained in a membrane bound structure called a nucleus. Contain other membrane bound structures called organelles.  Usually multicellular organisms. Eukaryote- eu: true; kary: nucleus  Genetic material contained in the cytoplasm does not have membrane bound organelles.  Usually unicellular organisms

Eukaryotic Cells are divided into 2 types Plant CellsAnimal Cells

ORGANELLES: any part of the cell that is enclosed by a membrane. THESE ORGANELLES ARE ONLY FOUND IN PLANT CELLS. Cell Wall  Plant cells have a cell wall.  A tough outer covering that lies just outside the cell membrane.  Supports and protects the cell. Chloroplast  All energy comes from the sun.  Chloroplasts help the plant capture and use the sun’s energy.  Plants convert this energy into sugar and store the excess as starch.

THESE ORGANELLES ARE ONLY FOUND IN PLANT CELLS. Cell WallChloroplast

These organelles are found in all eukaryotic cells…both Plant and Animal Mitochondria  The powerhouse of the cell.  Releases energy from sugar for use by the cell. Endoplasmic Reticulum  A system of twisting and winding membranes, some contain Ribosomes which manufacture proteins.  The ER manufactures parts of the cell membrane.  Part of the cellular transportation system.

These organelles are found in all eukaryotic cells…both Plant and Animal Mitochondria Endoplasmic Reticulum

These organelles are found in all eukaryotic cells…both Plant and Animal Ribosomes  Found attached to the endoplasmic reticulum and floating freely in the cytoplasm.  Manufacture proteins. Golgi Apparatus  ER breaks off and forms Vesicles.  Inside the vesicles are products the cell has made for transport outside of the cell.  The Golgi Apparatus which looks like a stack of pancakes finishes the processing of the products.

These organelles are found in all eukaryotic cells…both Plant and Animal RibosomesGolgi Apparatus

Organelles for storage recycling and waste Vacuole  Enclosed in a membrane  Found in plant and fungus cells.  Can store water, waste and other materials.  Plant cells have one large central vacuole that helps support the plant.  Not found in animal cells. Lysosome  Vesicles that contain chemicals to breakdown materials taken in by the cell as well as old cell parts.  Animals do not make their own food like plants do so must digest or breakdown the food.

Organelles for storage recycling and waste VacuoleLysosome