CELL STRUCTURE & FUNCTION Professor Andrea Garrison Biology 11 Illustrations ©2010 Pearson Education, Inc.

Cell Theory Cells : – Most basic unit of living system – Arise by cell division from existing cell – Make up all living organisms All living things composed of one or more cells & cell products Cell Structure and Function2

Basic cell structure Nucleus Contains genetic material; controls cell activities Cell membrane Separates cell from environment and regulates passage in/out of cell Cytoplasm 80% water, organelles Cell Structure and Function3

How tiny are cells, anyway? Cell Structure and Function4

How tiny are cells, anyway? Very, very tiny Cell Structure and Function5

Resolution of lenses Cell Structure and Function6 µm

Electron Microscope Used to see things smaller than 0.1 mm (= 100 μm) Uses beam of electrons to “see” structures Scanning EM used to study surface of object Transmission EM used to internal structure Cell Structure and Function7

Light microscope SEM TEM Cell Structure and Function8

Categories of Cells Based on how they feed – Autotrophs vs. Heterotrophs Based on cell structure – Prokaryotes vs. Eukaryotes Cell Structure and Function9

Categories of Cells Autotrophs make their own food Heterotrophs eat another organism Cell Structure and Function10

Categories of Cells Prokaryotes lack organelles Eukaryotes have organelles Cell Structure and Function11

Organelles – Internal membrane-bound structures For example, nucleus & chloroplasts Cell Structure and Function12

Organelles – Internal membrane-bound structures For example, nucleus & chloroplasts – Perform specific functions Nucleus contains DNA, transcribes genetic code into messages that control cell activities Chloroplasts site of photosynthesis Cell Structure and Function13

Prokaryote--no organelles Cell Structure and Function14

Eukaryote--organelles Cell Structure and Function15

Eukaryotic Cell Structure Variety of organelles present Cell structure related to cell function – Not all organelles present in all cells – Abundance of organelles differs between cells Cell Structure and Function16

Plant vs. Animal Cells Plant cells Animal cells Cell Structure and Function17

Plant vs. Animal Cells Plant cells – Cell wall Animal cells – None Cell Structure and Function18

Plant vs. Animal Cells Plant cells – Cell wall – Chloroplasts for P/S Animal cells – None Cell Structure and Function19

Plant vs. Animal Cells Plant cells – Cell wall – Chloroplasts for P/S – Central vacuole Animal cells – None Cell Structure and Function20

Plant vs. Animal Cells Plant cells – Cell wall – Chloroplasts for P/S – Central vacuole – None Animal cells – None – Lysosomes Cell Structure and Function21

Plant vs. Animal Cells Plant cells – Cell wall – Chloroplasts for P/S – Central vacuole – None Animal cells – None – Lysosomes – Centrioles to assist with cell division Cell Structure and Function22

Plant vs. Animal Cells Cell Structure and Function23

Plant vs. Animal Cells Cell Structure and Function24

Nucleus Functions: Holds genetic material (DNA) Controls cell activities Cell Structure and Function25

Nucleus Nuclear Envelope: 2-layered membrane Pores allow chemical communication Inside Nucleus: Chromatin = DNA + protein Nucleolus – makes ribosomal RNA (rRNA) Cell Structure and Function26

Nucleus Ribosomes: Made of rRNA Not organelles Present in cytoplasm & on membrane outside nucleus Function in making proteins Cell Structure and Function27

Nucleus Inside nucleus: DNA  messenger RNA Outside nucleus: Ribosomes use mRNA to make proteins to be used in cell functions Cell Structure and Function28

Ribosomes Cell Structure and Function29

Endomembrane System Membrane made around nucleus Cell Structure and Function30

Endomembrane System Membrane made around nucleus Membrane moves from nucleus to outer plasma membrane – Moves through various organelles on the way – Different function with each new organelle Cell Structure and Function31

Endomembrane System Cell Structure and Function32

Endomembrane System Cell Structure and Function33

Endomembrane System Cell Structure and Function34

Endomembrane System Cell Structure and Function35

Endomembrane System Cell Structure and Function36

Endomembrane System Cell Structure and Function37

Endomembrane System Cell Structure and Function38

Organelles of Endomembrane System Cell Structure and Function39

Organelles of Endomembrane System: Nuclear Envelope Membrane made around the nucleus Moves into Endoplasmic Reticulum Cell Structure and Function40

Organelles of Endomembrane System: Endoplasmic Reticulum Rough ER: Has ribosomes Surface area Makes proteins Cell Structure and Function41

Organelles of Endomembrane System: Endoplasmic Reticulum Rough ER: Has ribosomes Surface area Makes proteins Smooth ER: No ribosomes, has enzymes Surface area Makes lipids Breaks down drugs, etc. Cell Structure and Function42

Organelles of Endomembrane System: Endoplasmic Reticulum Cell Structure and Function43

Organelles of Endomembrane System: Transport Vesicles Flattened sacs pinched off ER or other organelles Transport – to Golgi apparatus – to other areas of cell – to outside of cell Cell Structure and Function44

Organelles of Endomembrane System: Transport Vesicles Flattened sacs pinched off ER or other organelles Transport – to Golgi apparatus – to other areas of cell – to outside of cell Cell Structure and Function45

Organelles of Endomembrane System: Golgi Apparatus Flattened sacs pinched off Rough ER Receives proteins from rough ER via transport vesicles Modifies proteins Packages proteins for transport Cell Structure and Function46

Organelles of Endomembrane System: Golgi Apparatus Cell Structure and Function47

Organelles of Endomembrane System: Transport Vesicles Flattened sacs pinched off ER or other organelles Transport – to Golgi apparatus – to other areas of cell – to outside of cell Cell Structure and Function48

Organelles of Endomembrane System: Lysosomes Sac pinched off from Golgi membrane Contains digestive enzymes Intracellular digestion – Food vacuoles to digest food – Damaged organelles – Cell destruction after death Cell Structure and Function49

Organelles of Endomembrane System: Lysosomes Cell Structure and Function50

Organelles of Endomembrane System: Vacuoles Sacs pinched off from internal membrane or plasma membrane Variety of types with different functions – Contractile vacuoles in Protista – Central vacuole in plants Cell Structure and Function51

Organelles of Endomembrane System: Vacuoles Contractile vacuole Absorbs excess water in cytoplasm Contracts to expel excess water Cell Structure and Function52

Organelles of Endomembrane System: Vacuoles Central vacuole Storage – Water – Nutrients – Wastes – Toxins – Pigments Cell Structure and Function53

Other Organelles & Structures Not Associated with Endomembrane System Cell Structure and Function54

Organelles associated with energy Chloroplasts and mitochondria – Provide cellular energy – Contain their own DNA Feature not found in other organelles Encodes some of their proteins Still require nuclear DNA for full function Considered evidence that these organelles evolved form free-living prokaryotes Cell Structure and Function55

Organelles associated with energy Chloroplasts Found in photosynthetic cells – plants and some protistans Site of P/S Cell Structure and Function56

Chloroplasts Grana – Surface area to trap light – Contains chlorophyll Stroma – fluid – Site of sugar production Cell Structure and Function57

Organelles associated with energy Mitochondria Found in all eukaryotes Site of ATP production Cell Structure and Function58

Mitochondrion Cristae – Surface area for ATP production Matrix – Fluid – Site of sugar breakdown Cell Structure and Function59

Non-membrane bound structures Found in prokaryotes or eukaryotes May or may not be found in all cells Cell Structure and Function60

Non-membrane bound structures Cytoskeleton Network of fibers – Microtubules Associated with cell movement – Intermediate filaments – Microfilaments Function – Support – Movement Cell Structure and Function61

Non-membrane bound structures Cytoskeleton Support – Maintains cell shape – Holds organelles in place Cell Structure and Function62

Non-membrane bound structures Cytoskeleton Movement – Network of fibers constantly dissolving and reforming in new arrangements Allows cell to change shapes Pulls chromosomes apart during cell division Cell Structure and Function63

Non-membrane bound structures Flagella & Cilia Hair-like structures that aid in movement Core of microtubules creates beating motion Move cells through liquid Create currents past non-moving cells Cell Structure and Function64

Non-membrane bound structures Flagella Long whipping “tails” Usually 1-3 per cell Propel cell forward Found in many protists Found in human sperm Cell Structure and Function65

Non-membrane bound structures Cilia Short hair-like structures Usually many on cell surface Beat in synchrony Found in many protists Found in human tissues Cell Structure and Function66

Non-membrane bound structures Cell Structure and Function67

Non-membrane bound structures Cell Wall Found in variety of cells – Bacteria – Protistans – Plants – Fungus Protective structure outside plasma membrane Porous to water, salts Cell Structure and Function Cell wall 68

Cell Junctions Cell Structure and Function Connections between cells – Proteins tie cells together 69

Cell Junctions Cell Structure and Function Types – Tight junctions Seal cells together so molecules cannot slip between cells – i.e., cells lining intestine – Adhering junctions (desmosomes) Strengthen attachment so cells won’t tear apart – i.e., skin – Gap junctions Channels allow movement of molecules between cell – i.e., heart muscle 70

Cell Junctions Cell Structure and Function ions.html ions.html 71