Chapter 4 - Cell Structure and Function 4.1 What is the Cell Theory? 4.2 What are the basic attributes of cells? 4.3 What are the major features of eukaryotic cells? 4.4 What are the major features of prokaryotic cells?

4.1 What is the Cell Theory? Every living organisms is made up of one or more cells The smallest living organisms are single cells, and cells are the functional units of multicellular organisms All cells arise from preexisting cells

frog embryo most eukaryotic cells mitochondrion most bacteria virus proteins diameter of DNA double helix chicken egg adult human tallest trees atoms 1 centimeter (cm) = 1/100 m 1 millimeter (mm) = 1/1000 m Units of measurement: 1 meter (m) = inches Diameter visible with conventional electron microscope visible with special electron microscopes visible with llight microscope visible with unaided human eye 1 micrometer (µm) = 1/1,000,000 m 1 nanometer (nm) = 1/1,000,000,000 m 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm 0.1 nm 1 mm 1 cm 10 cm 100 m 10 m 1 m

17th century microscope In 1665, English scientist and inventor observed cork and called the boxes “cells” because they looked like tiny rooms or cells occupied by monks This is one of his drawings and the type of microscope he used

blood cells photographed through Leeuwenhoek's microscope Leeuwenhoek's microscope 1670s specimen location of lens focusing knob Dutch microscopist Antoni Leeuwenhoek observed living cells, like blood, sperms and eggs of small insects This created a huge stir because people believed (strongly) in spontaneous generation (like fleas just emerge from dust)

The Search for the Cell In 1830, German zoologist Theodor Schwann noted cells in animals exactly like the ones in plants In 1839 he published his cell theory In mid-1800s, German botanist Matthias Schleiden said “It is... easy to perceive that the vital process of the individual cells must form the absolutely indispensable basis [of life]”

Electron microscope – 3D image of specimen’s surface

50 micrometers cilianucleus contractile vacuole Paramecium Light microscope

cilia 0.5 micrometers mitochondrion Transmission electron microscope

Scanning electron microscope 10 micrometers

5 micrometers mitochondria Scanning electron microscope

4.2 What Are the Basic Attributes of Cells? There Are Two Basic Types of Cells: –Prokaryotic “before the nucleus” –Eukaryotic “true nucleus” Evidence supports that eukaryotic cells evolved from prokaryotic cells – endosymbiotic hypothesis

4.2 What Are the Basic Attributes of Cells? Cell function limits cell size Many nutrients & wastes move in and out of cells through diffusion Diffusion is a slow process and requires no part of the cell to be too far from the outside

distance to center (r) surface area (4  r 2 ) volume (4/3  r 3 ) area/volume r r r

4.2 What Are the Basic Attributes of Cells? All cells have a plasma membrane –Isolates the cell’s contents from outside –Regulates flow of material –Allows interaction with other cells and outside

4.2 What Are the Basic Attributes of Cells? All cells –Have a plasma membrane –Contain cytoplasm –Use DNA and RNA as hereditary material –Obtain energy & nutrients from their environment

mitochondrion vesicle cytoplasm flagellum lysosome centriole Golgi complex vesicle nuclear pore nuclear envelope chromatin (DNA) nucleolus nucleus ribosome free ribosome microtubules rough endoplasmic reticulum Smooth endoplasmic reticulum plasma membrane intermediate filaments

central vacuole plastid mitochondrion vesicle plasmodesma cell wall plasma membrane intermediate filaments free ribosome ribosomes nucleus nucleolus nuclear pore chromatin nuclear envelope Golgi complex chloroplast Microtubules (part of cytoskeleton) smooth endoplasmic reticulum rough endoplasmic reticulum

4.3 What Are the Major Features of Eukaryotic Cells? Eurkaryotic cells are: –Usually bigger than prokaryotic –Have lots of organelles –Have a cytoskeleton –Have a nucleus, nucleolus and nuclear envelope The nuclear envelope allows selective exchange of materials

nuclear envelope nuclear pores nucleolus chromatin

nucleus nuclear pores Yeast cell

4.3 What Are the Major Features of Eukaryotic Cells? Some Cells Are Supported by Cell Walls –Bacteria, plants, fungi and some protists –Plant cell walls are made of polysaccarides and cellulose –Plants secrete cellulose through the plasma membranes to make the primary and secondary cell walls –Cell walls need to be strong but are often porous

Copyright © 2005 Pearson Prentice Hall, Inc. primary cell wall secondary cell wall plasma membrane cytoplasm middle lamella

4.3 What Are the Major Features of Eukaryotic Cells? The cytoskeleton provides shape, support and movement –Cell shape –Cell movement –Organelle movement

microfilaments mitochondrion ribosomes microtubule vesicle plasma membrane intermediate filaments endoplasmic reticulum The Cytoskeleton Provides Shape, Support, and Movement

microtubules (red) nucleus microfilaments (blue)

Paramecium 0.1 micrometer cilium plasma membrane basal body x-section of cilium (9+2 arrangement) x-section of basal body (9+0 arrangement) central unfused pair of microtubules fused pair of microtubules Protein "arms" 0.1 micrometer

return stroke Cilium plasma membrane power stroke propulsion of fluid Cilia and Flagella Move the Cell Through Fluid or Move Fluid Past the Cell

return stroke cilia lining trachea flagellum of human sperm Cilium continuous propulsion plasma membrane direction of locomotion power stroke Flagellum propulsion of fluid Propulsion of fluid

4.3 What Are the Major Features of Eukaryotic Cells? Chromatin contains DNA, which codes for the synthesis of proteins DNA is copied onto messenger RNA (mRNA) and taken out of the nucleus mRNA uses ribosomal RNA to help make proteins

chromatin chromosome

4.3 What Are the Major Features of Eukaryotic Cells? The nucleolus is the site of ribosome synthesis (plural is nucleoli) Ribosomes help make proteins (they are the “workbench”) They can be found on the rough endoplasmic reticulum, the cytoplasm, along the membrane of the nuclear envelope

Copyright © 2005 Pearson Prentice Hall, Inc. nuclear envelope nuclear pores nucleolus chromatin

0.05 micrometers mRNA ribosomes

vesicles

rough endoplasmic reticulum ribosomes 0.5 micrometer

smooth endoplasmic reticulum vesicles 0.5 micrometer

5.3 What Are the Major Features of Eukaryotic Cells? Eukaryotic Cells Contain a Complex System of Membranes –The endoplasmic reticulum (both types) forms membrane-enclosed channels within the cytoplasm –They contain enzymes which can make various lipids – like phospholipids and cholesterol –The Golgi complex sorts, chemically alters, and packages important molecules

Golgi complex vesicles from ER vesicles leaving Golgi complex

5.3 What Are the Major Features of Eukaryotic Cells? Lysosomes serve as the cell’s digestive system

smooth endoplasmic reticulum nuclear envelope Golgi complex exocytosis plasma membrane phagocytosis lysosome fused with food vacuole food vacuole rough endoplasmic reticulum

5.3 What Are the Major Features of Eukaryotic Cells? Membrane synthesized in the endoplasmic reticulum flows through the membrane system of the cell Vacuoles serve many functions, including water regulation, support, and storage

contractile vacuole central reservoir pore collecting ducts Freshwater Microorganisms Have Contractile Vacuoles

cytoplasm central vacuole cell wall plasma membrane The central vacuole and turgor pressure in plant cells

5.3 What Are the Major Features of Eukaryotic Cells? Mitochondria extract energy from food molecules (endosymbiotic hypothesis again) Chloroplasts capture solar energy with photosynthesis

outer membrane inner membrane intermembrane compartment matrix cristae 0.2 micrometer Mitochondria extract energy from food and make ATP

outer membrane inner membrane stroma thylakoid channel interconnecting thylakoids granum (stack of thylakoids) 1 micrometer Chloroplasts extract energy from the sun and make glucose

starch globules plastid 0.5 micrometer Plants Use Plastids for Storage

5.2 What Are the Major Features of Prokaryotic Cells? Prokaryotic Cells Are Small and Possess Specialized Surface Features Prokaryotic Cells Have Fewer Specialized Structures Within Their Cytoplasm

chromosome (nucleoid region) pili ribosomes food granule prokaryotic flagellum capsule or slime layer cell wall plasma membrane cytoplasm plasmid (DNA)

mitochondrion vesicle cytoplasm flagellum lysosome centriole Golgi complex vesicle nuclear pore nuclear envelope chromatin (DNA) nucleolus nucleus ribosome free ribosome microtubules rough endoplasmic reticulum Smooth endoplasmic reticulum plasma membrane intermediate filaments

central vacuole plastid mitochondrion vesicle plasmodesma cell wall plasma membrane intermediate filaments free ribosome ribosomes nucleus nucleolus nuclear pore chromatin nuclear envelope Golgi complex chloroplast Microtubules (part of cytoskeleton) smooth endoplasmic reticulum rough endoplasmic reticulum