Cell Structure Discovery of the Cell Scientists did

Cell Structure

Discovery of the Cell Scientists did not start using simple compound microscopes until the mid 1600’s. n Robert Hooke used an early compound microscope to look at slices of cork. n http: //www. smithlifescience. com/cork 2. GIF n n Hooke named the ‘seemingly empty’ chambers ‘cells. ’ Around the same time, Anton von Leeuwenhoek was using a single-lens microscope to observe unicellular organisms in pond water for the first time.

Cell Theory n Additional observations of cells in other living things led scientists to 3 basic conclusions, known as the cell theory. n Cell Theory states: – All living things are composed of cells. – Cells are the basic units of structure and function in living things. – New cells are produced from existing cells.

There are two categories of cells…… n Prokaryotes – No nucleus – Few organelles (no membranebound organelles) – Small in size http: //www. cod. edu/people/faculty/fancher/Prokaryotic. Cell. jpg – Ex: Bacteria n Eukaryotes – Nucleus – Many membranebound organelles – Large in size – Ex: Humans, plants, fungi, etc. http: //www. cod. edu/people/faculty/fancher/Eukaryotic. Cell. jpg

Cell Structure n All cells, both prokaryotes and eukaryotes, have DNA and a cell membrane. n Cells also contain organelles – specialized structures within the cell that perform certain tasks. n These organelles float around in the cell’s cytoplasm, which is mostly made of water.

Prokaryotes……. they’re simple. n Prokaryotes only have a few basic structures: – DNA – Cell/plasma membrane – Cell wall – Ribosomes – Some use structures like pili, cilia, and flagellum to move in aquatic environments. n …. but they come in many varieties. http: //scienceblogs. com/clock/2006/11/cell_structure. php

Eukaryotes are more complex. n Eukaryotes can be multicellular or unicellular. n Eukaryotes contain many organelles…….

Cell Organelles?

Cell (plasma) membrane n Regulates what enters and leaves the cell.

Nucleus n Controls most cell processes and contains nearly all of the cell’s DNA

Ribosomes n assemble proteins. – Some are free floating while others are attached to the endoplasmic reticulum.

Endoplasmic Reticulum (ER) n There are two types: – Rough – chemically modifies proteins that are produced by the ribosomes on its surface. – Smooth – contains specialized enzymes and makes lipid components for the cell membrane.

Golgi apparatus n Sorts, modifies, and packages proteins and other materials from the ER for storage or secretion from the cell.

Lysosomes and peroxisomes Lysosomes contain enzymes that are specialized to digest lipids, carbs, proteins so they can be reused n Peroxisomes contain enzymes that are specialized to digest toxic substances n

Cytoskeleton http: //scienceblogs. com/clock/2006/11/cell_structure. php n A network of protein filaments (microtubules and microfilaments) that help the cell move and maintain its shape

Mitochondria n Provides the cell with usable chemical energy – It is the site of cellular respiration.

Mitochondria Cont. n Contains many folds which increase surface area for cellular respiration reactions

How are Cells different? http: //staff. tuhsd. k 12. az. us/gfoster/standard/BCELL 1_files/image 005. jpg http: //scienceblogs. com/clock/2006/11/cell_structure. php

Plant cells have special features…. . n Plants contain: – Chloroplasts – create and store usable energy through the process of photosynthesis. – Cell wall – provides the cell with rigid structure. – No Lysosomes – One large vacuole – used for the storage of water and some other materials § Animal cells usually have many small vacuoles

Plant Cell

Animal Cell

http: //micro. magnet. fsu. edu/cells/chloroplasts/images/chloroplastsfigure 1. jpg http: //en. citizendium. org/images/c/c 7/Mitochondria. SMALL 2. jpg