5Prokaryotic and Eukaryotic Cells Prokaryotic cells have:DNACell wall and plasma membraneCytoplasm and ribosomesProkaryotic cells DO NOT have:A nucleusCompartmentalized specialized structures (organelles)
7Prokaryotic and Eukaryotic Cells Bacteria are prokaryotic cells and are generally much smaller than eukaryotic cellsFigure 2.15 Bacterial cell being engulfed by a human immune system cell.Prokaryotic cells are much smaller than eukaryotic cells, as this electron micrograph demonstrates.
8Prokaryotic and Eukaryotic Cells Eukaryotic cells include cells ofPlantsProtozoa and AlgaeFungiAnimalsEukaryotic cells haveA plasma membraneRibosomesDNA enclosed in a nucleusCompartmentalized specialized structures (organelles)
9Cell StructureAll cells are enclosed by a structure called a plasma membraneThe function of the plasma membrane is to control what enters and leaves the cell
10Cell StructureAll membranes in a cell have similar structural components: phospholipids and proteinsThe phospholipids arrange themselves to form phospholipid bilayers with water both on the inside and the outside of the bilayer
11Cell StructureSince the phospholipids have two hydrophobic tails at one end and a hydrophilic head at the other end, they tend to gather in a specific arrangementTwo layers with the hydrophilic heads pointing out and the hydrophobic tails on the inside.
13A Fluid Mosaic of Lipids and Proteins Because lipids and proteins can move about laterally within the membrane, the membrane is a fluid mosaic of lipids and proteins
14A Fluid Mosaic of Lipids and Proteins Cell membranes are semipermeableAllow some things through but not othersWater freely crosses the membranesThis can be a problemIf too much water enters the cell, it may swell or burstIf too much water leaves the cell, it may shrinkAll organisms have ways of regulating how much water is in their cells.In most animals (except some simple marine invertebrates) the water content of tissues is regulated by the kidneys, so this isn’t normally a problem.
15A Fluid Mosaic of Lipids and Proteins Cell membranes are semipermeableAllow some things through but not othersGases such as oxygen and carbon dioxide pass freelyBut substances such as glucose and proteins require the help of the proteins in the cell membrane in order to enter the cell.
16A Fluid Mosaic of Lipids and Proteins Some cells (like plant cells and fungal cells) have a cell wall outside of the plasma membrane that give the cell structure and protect against water damageThe cell wall is purely structural and has no control over what enters or leaves the cell
31Mitochondria are organelles that carry out the process of aerobic respiration, which converts food energy to ATP, the type of energy a cell can use.Table 2.1 Cell components.Illustrations and descriptions of cell components and their functions.
35The nucleus is a membrane bound structure that encloses the DNA Table 2.1 Cell components.Illustrations and descriptions of cell components and their functions.
36Cytosol and CytoplasmThe cytoplasm is made up of the watery mixture inside the cell (called the cytosol) and the organellesThe cytoplasm is contained by the plasma membrane.Organelles are membrane bound structures that carry out specific jobs for the cells.Cellular functions are more efficient when the work is compartmentalized in organelles.
37Chloroplasts are organelles found in plant cells Chloroplasts are organelles found in plant cells. Chloroplasts can convert sunlight energy into chemical energy stored in the chemical bonds of glucose.
38Lysosomes are small membrane sacs that contain digestive enzymes which break down food and other materials for the cell.
39Ribosomes are small structures that act like workbenches Ribosomes are small structures that act like workbenches. Proteins are assembled at the ribosomes. Some ribosomes are free in the cytoplasm and some are bound to a structure called the endoplasmic reticulum.
40Some subcellular structures help cells divide and maintain their shape Some subcellular structures help cells divide and maintain their shape. Centrioles are involved in moving genetic material around when a cell divides
41Figure: 03-01aTitle:A eukaryotic cell.Caption:Eukaryotic cells, such as (a) the generalized animal cell shown here, have internal membrane-bound organelles.
42Figure: 03-14tTitle:Endoplasmic reticulum.Caption:Top: The endoplasmic reticulum in a cell.
43Figure: 03-01aTitle:A eukaryotic cell.Caption:Eukaryotic cells, such as (a) the generalized animal cell shown here, have internal membrane-bound organelles.