Transcript Chapter 4
Hey Larry, I think I lost an electron. Are you sure? I’m positive. Chapter 4 Cell Structure and Function The Cell Theory Cells – basic units of structure and function in living things Early scientists that led to the cell theory Anton van Leeuwenhoek (1600s) – given credit for developing the 1st mini microscope, looked at pond water and made detailed drawings Robert Hooke – coined the term “cell” when he looked at slices of cork and dead plant cells Robert Brown (1833) – observed a dark structure near the center of the cell (we now know this is the nucleus) Matthias Schleiden (1838) – stated all plants are made of cells Theodor Schwann (1839) – discovered all animals are made of cells Rudolph Virchow (1855) - stated all cells come from the division of preexisting cells Cell Theory All living things are composed of cells. Cells are the basic units of structure and function in living things. All cells come from preexisting cells. Cell Structure Identify and give the function of the three basic structures of most cells. Distinguish between prokaryotes and eukaryotes. Size of cells Most cells are 5 to 50 micrometers in diameter Humans have #? #? #? #? cells red blood cells brain cells cells per cm2 of skin Size of cells Most cells are 5 to 50 micrometers in diameter Humans have 100 trillion cells #? red blood cells #? brain cells #? cells per cm2 of skin Size of cells Most cells are 5 to 50 micrometers in diameter Humans have 100 trillion cells 20 trillion red blood cells #? brain cells #? cells per cm2 of skin Size of cells Most cells are 5 to 50 micrometers in diameter Humans have 100 trillion cells 20 trillion red blood cells 30 billion brain cells #? cells per cm2 of skin Size of cells Most cells are 5 to 50 micrometers in diameter Humans have 100 trillion cells 20 trillion red blood cells 30 billion brain cells 155,000 cells per cm2 of skin Size of cells The ability of information to flow in and out of cells limits their size http://ed.ted.com/lessons/the-wackyhistory-of-cell-theory Three structures common to most cells Cell Membrane – outer boundary Nucleus – control center Cytoplasm – material between the cell membrane and nucleus Note: Some books list plasma membrane, cytoplasm, chromosomes/DNA, & ribosomes Cell/Plasma Membrane Cell Membrane – outer boundary Structure: Phospholipid bilayer hydrophilic heads, hydrophobic tails Contains lipids (bilayer), proteins (channels), and carbohydrate chains (identification cards) Function: Regulates what enters and leaves the cell Semi-permeable membrane Protection and support Cell Wall Pectin Cell Wall – Only in plants, algae, and some bacteria Lies outside the cell membrane Structure: surrounds the cell membrane 1st layer – contains pectin (gluey substance that helps hold the cells together) 2nd layer – primary cell wall (made of cellulose) 3rd layer (in woody stems) – secondary cell wall (composed of cellulose and lignin to make cellulose more rigid) Function: Helps to protect and support the cell Very porous (water, oxygen, carbon dioxide, etc. can pass through easily) Gives rectangular shape to plant cells Nucleus Nucleus - control center 2 categories of organisms Prokaryotes – organisms whose cells lack nuclei (i.e. bacteria) Eukaryotes – organism whose cells contain nuclei Pro = before Eu = true karyon = kernel (nucleus) Prokaryote vs. Eukaryote Prokaryote vs. Eukaryote 2 Types of Cells Prokaryotic (Pro= before, karyon = kernel) Eukaryotic (Eu=true, karyon = kernel) Found in 2 domains: Archaea and Bacteria (*Kingdom Monera:Archaebacteria/Eubacteria) single celled Found in Domain Eukarya (all other Kingdoms): Animal, Plant, Fungi, Protist No true nucleus; lacks nuclear envelope/membrane True nucleus; bounded by nuclear envelope/membrane Genetic material found in nucleoid region Genetic material found within nucleus Called Prokaryotes Called Eukaryotes Evolved first – 3.5 billion years ago and are very small 1-10um Evolved 1.45 billion years ago and are larger 10-100um No membrane bound organelles – ribosomes are only organelle Contains cytoplasm with cystol and membrane-bound organelles Prokaryote vs. Eukaryote Characteristic Prokaryotic Eukaryotic Cell membrane Cytoplasm Genetic Material Nucleus Organelles Archaea Bacteria Plants, animals, fungi, & protists Only have ribosomes Nucleus - control center Structure: NUCLEAR ENVELOPE – double membrane around the nucleus that contains pores, allows molecules to move in and out of the nucleus, and protects the nucleus NUCLEAR PORES – allows passage of materials into or out of nucleus (RNA, ribosomes) NUCLEOLUS – a small, darkened region in the nucleus that is made up of RNA and proteins, this is where ribosomes are made CHROMOSOMES – large structures formed from DNA that contain the genetic info Function: Information center of the cell Contains DNA (chromatin vs. chromosomes) Directs cell activities Nucleus - control center Cytoplasm Material between the cell membrane and the nucleus Contains the organelles of the cell Who Am I? Robert Hooke! I stated all plants are made of cells I stated all cells come from the division of preexisting cells I coined the term “cell” when he looked at slices of cork and dead plant cells I given credit for developing the 1st mini microscope, looked at pond water and made detailed drawings I discovered all animals are made of cells I observed a dark structure near the center of the cell (we now know this is the nucleus) Group Activity Each group will be assigned one organelle You must answer the following questions: What does it look like? (What is its structure?) What does it do? (What is its function?) Is it found in prokaryotic cells? Is it found in eukaryotic cells? In plants? In animals? Group Activity Group Group Group Group Group Group #1 – mitochondria #2 – chloroplasts #3 – ribosomes #4 – endoplasmic reticulum #5 – Golgi apparatus #6 – lysosomes Organelle Analogies Mitochondria and Chloroplasts: Power Stations Ribosomes: Protein Factories Endoplasmic Reticulum & Golgi Apparatus: Manufacturers and Shippers Lysosomes: Cleanup Crews Vacuoles and Plastids: Storage Tanks Cytoskeleton: Framework Mitochondria Mitochondria Structure: Double membrane Cristae - inner folds, increase surface area Outer membrane for protection of cell Function: “Powerhouse” of the cell Able to self-replicate ( # in cells with high energy need) Converts sugars into energy for cells Chloroplast Chloroplast Structure: Double membrane Elaborate structure inside Function: Another power station Found in plant cells only Conversion of light energy (sun) into chemical energy (glucose) Ribosomes Ribosomes Structure: Small ball-like structures Found free-floating in cytoplasm or attached to rough endoplasmic reticulum Composed of RNA and protein Function: Synthesis of proteins (where proteins are made) Endoplasmic Reticulum (ER) Endoplasmic Reticulum Structure: Network of flattened sacs Can be rough (w/ ribosomes) or smooth (w/o) Function: Transport materials within or out of cell Synthesis of macromolecules Rough - proteins, lipids, carbs Smooth - lipids Golgi Apparatus vesicle Golgi Apparatus Structure: Flattened stacks of membranes Vesicles attached to top and bottom Function: Collection, modification, packaging of proteins and other substances Vesicles attach, deposit materials GA modifies materials based on needs Vesicles attach to membrane and distribute modified substances Lysosome Lysosome Structure: Small, circular structures Found only in animal cells Contain digestive enzymes Function: Digestion of: Worn out organelles Debris Large ingested particles Lysosomes are responsible for your hands not being webbed!! Vacuole Vacuole Structure: Large, central structure in plants Many, small, circular structures in animal cells Filled with liquid Function: Storage of water, salts, proteins, carbohydrates, waste products Pressure system for plants, prevents wilting Special case: contractile vacuole - prevents excess water intake, leading to cell-bursting Plastid Plastid Structure: Differ based on type of plastid (chloroplast is one example) Found only in plants Function: Leukoplasts: Store food/starch Chromoplasts: Store pigments (give color to fruits & veggies) Cytoskeleton Cytoskeleton Structure: Microtubules - hollow tubes of proteins Examples: cilia, flagella, centrioles Function: Framework Provide cell with support, structure and shape Movement (cilia, flagella) Microfillaments - allow movement of cytoplasm within the cell (cytoplasmic streaming) Plant vs. Animal Cell Animal Cell Plant Cell Please . . . List 3 organelles you learned about today. Describe the function of each of the organelles you listed. Yes, you should write your name on the paper