- Slides: 71
Cell Structure and Function Plant Cell Animal Cell
ENGAGE: WHAT IS A CELL?
EXPLORE: CELLS WEBQUEST
EXPLAIN: First View of Cells • In 1665, Englishman Robert Hooke used a microscope to examine a thin slice of cork (dead cell of oak bark). • In cork, he observed small geometric shapes that seemed to be made of tiny, empty chambers.
CELL THEORY • All organisms are made of one or more cells. • Cells are the basic unit of structure and function in an organism. • New cells come from preexisting cells.
Number of Cells Although ALL living things are made of cells, organisms may be: • Unicellular – composed of one cell • Multicellular- composed of many cells that may organize into tissues, etc.
CELL SIZE Typical cells range from 5 – 50 micrometers in diameter
Cell Specialization Red blood cells Cells in multicellular organisms develop in different ways to perform different task. This is known as cell specialization. Guard cells Muscle cells Xylem cells
Cell Specialization • Nearly all cells contain the same chromosomes and DNA. • Cells in a multi-cellular organism become specialized by turning different genes on and off. • This is known as DIFFERENTIATION
Simple or Complex Cells
Prokaryotes • • • Primitive Live in a wide variety of environments Unicellular Cells that lack a nucleus or membrane bound organelles Smaller and simplier Single, circular chromosome (plasmids) Contains DNA & RNA Surrounded by cell membrane & cell wall Contain ribosomes in their cytoplasm to make proteins Divide by binary fission (bacteria only) Bacteria
Eukaryotes • Cells contain a nucleus and membrane-bound organelles (specialized structures) • Contain DNA and RNA • Larger and more complex type of cells • Can be unicellular or multicellular • Includes plants, animals, protists, and fungi, • Divide by mitosis or meiosis • Some have cilia Plant Cell Animal Cell
ELABORATE: VENN DIAGRAM
EVALUATE Which is a characteristic of prokayotic cells? a. Prokaryotic cells contain DNA enclosed in a nuclear membrane. a. Prokaryotic cells are complex cells containing membrane-bound organelles. a. Prokayotic cells are simple cells containing no membrane-bound organelles. a. Prokaryotic cells synthesize proteins at ribosomes found on the endoplasmic reticulum.
EVALUATE Which organisms are best described as prokayotic cells? a. bacteria a. protists a. plants a. fungi
EVALUATE Which list of organelles could be found in both eukaryotic and prokaryotic cells? a. mitochondria, cytoplasm, nucleus a. ribosome, cytoplasm, mitochondria a. cytoplasm, plasma membrane, ribosomes a. cytoplasm, chloroplasts, plasma membrane
ENGAGE EDPUZZLE: INTRO INTO THE CELL
EXPLORE CELL WEBQUEST
Organelles • Very small, specialized structures • Found in the cytoplasm • May or may not be membrane-bound
Cytoplasm of a Cell (Eukaryotes and Prokaryotes) cytoplasm Location? • Material inside the cell membrane but not including the nucleus • Contains many structures called organelles Function? • Establishes living condition to supply and transport materials for cell activities
Ribosomes (Eukaryotes and Prokaryotes) Location? • In cytoplasm, and Rough E. R. Function? • Produce proteins following coded instruction that come from the nucleus (protein synthesis)
Cell/Plasma Membrane (Eukaryotes and Prokaryotes) Composed of phospholipid bilayer Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Semipermeable • Transport proteins act as gates into/out of the c ell • • Location? • Surrounds outside of ALL cells Function? • Regulates what enters and leaves • Balances internal condition of cells (homeostasis/equilibrium)
Semipermeable Membrane Small molecules and larger hydrophobic molecules move through easily (O 2, CO 2, H 2 O). Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own.
FLUID MOSAIC MODEL FLUID- individual phospholipids and proteins can move side-to-side within the layer, like a fluid. MOSAIC- pattern produced by the scattered protein molecules
Cell Wall Location? • Found in plants, algae, fungi, & bacteria • Made of cellulose in plants • Made of peptidoglycan in bacteria • Made of chitin in Fungi • Lie outside the cell membrane Function? Provides support and protection for the cell. Cell wall
The Control Organelle - Nucleus Location? • In all cells but bacteria cells • Often most prominent structure in center of cell Function? • Controls cell processes • Stores hereditary information of DNA • Codes for protein synthesis (making of proteins most important role of cell)
Inside the Nucleus The genetic material (DNA) is found DNA is spread out And appears as CHROMATIN in non-dividing cells DNA is condensed & wrapped around proteins forming as CHROMOSOMES in dividing cells
Nucleolus Location? • Inside nucleus • Cell may have 1 to 3 nucleoli • Disappears when cell divides Function? • Makes ribosomes that make proteins
Mitochondria Location? • Throughout the cytoplasm • More numerous in cells that have high energy requirements (muscle cells, sperm cells) Function? “Powerhouse” of the cell • Release energy in the form of ATP from stored food molecules (glucose) • Site of Cellular Respiration Note: Mitochondria contain some of their own genetic info or DNA that is essential to the function of the mitochondrion.
MITOCHONDRIA Surrounded by a DOUBLE membrane Folded inner membrane called CRISTAE (increases surface area for more chemical Reactions) Interior called MATRIX
Vacuoles Location? • Saclike structure in the cytoplasm • Plant cells – Single, large central vacuole • Small or absent in animals Function? • Store materials such as water, salts, proteins and carbohydrates • Pressure in plant vacuole aid in support of plant cell (lack of water – wilting)
Chloroplasts Location? • Found in cytoplasm of plants Function? • Use energy from sunlight to make energy-rich food molecules (glucose). • Site of Photosynthesis Note: Chloroplasts contain some of their own genetic info or DNA that is essential to the function of the chloroplast.
Centrioles • Made of bundle of microtubules Location? • Only in animal cells • Found near the nucleus and appear during cell division forming mitotic spindle Function? • Help to separate chromosome pairs and pull to opposite ends of the cell
Endoplasmic Reticulum - ER • Internal membrane system Location? • Attaches to nuclear envelope & cell membrane Function? • Site where lipid components of the cell membrane are assembled. Two kinds of ER – Smooth and Rough
Rough Endoplasmic Reticulum (Rough ER) • Has ribosomes on its surface Location? ● Attached to the nuclear envelope Function? • Makes many membrane proteins and proteins for EXPORT out of cell. • They are then threaded into the interior of the Rough ER to be modified and transported by the Golgi Apparatus
Smooth Endoplasmic Reticulum • Lacks ribosomes on its surface Location? • Attached to the ends of rough ER Function? • Makes cell products that are USED INSIDE the cell
Golgi Apparatus • Flattened stack of tubular membranes Location? ● In the cytoplasm near the rough ER. Function? • Modifies, sorts, and packages proteins and other materials from the ER for cell storage or secretion outside the cell
Lysosomes ● Small organelle filled with enzymes. Location? ● Found in animal cells scattered throughout the cytoplasm Function? ● Digest, or breakdown of food, bacteria, and worn out cell parts for cells
Cytoskeleton ● Network of protein filaments Location? ● Throughout the cytoplasm Function? ● Helps cell maintain cell shape and helps move organelles around
Specific Cell Adaptations
Contractile Vacuole • Found in unicellular organisms like paramecia • Pumps out excess water and keeps the cell from bursting Contractile vacuole animation
Cilia & Flagella • Function in moving cells, in moving fluids, or in small particles across the cell • Cilia are shorter and more numerous on cells • Flagella are longer and fewer on cells
• Pseudopod – allows movement (fake foot)
Eyespot light-sensitive pigmented spot on the bodies of invertebrate animals such as flatworms, starfishes, and microscopic crustaceans, and also in some unicellular organisms.
ANIMAL CELL PLANT CELL BACTERIA Eukaryotes Prokaryotes Cell membrane Mitochondria NO cell wall Cell wall made of CELLULOSE Cell wall made of PEPTIDOGLYCAN Has ribosomes DNA in multiple chromosomes DNA is a single circular ring (plasmid) Small vacuoles Really big vacuole NO vacuoles NO chloroplasts Chloroplasts NO chloroplasts SMALLER SMALLEST NO mitochondria
ELABORATE MAKE A CELL ACTIVITY
EVALUATE Which cell organelle is correctly paired with its function? a. vacuole - protein synthesis b. mitochondria - photosynthesis c. chloroplast - cellular respiration d. nucleus - directs cellular activities
EVALUATE Which organelles are most helpful in distinguishing between plant and animal cells? a. nucleus and chloroplast b. chloroplast and cell wall c. cell membrane and nucleus d. cell membrane and cell wall
EVALUATE Which best describes the function of a ribosome? a. Ribosomes use RNA to synthesize proteins. b. Ribosomes use lipids to synthesize nucleic acids. c. Ribosomes use RNA to synthesize carbohydrates. d. Ribosomes use lipids to synthesize carbohydrates.
EVALUATE CELL ANALOGY
ENGAGE EDPUZZLE - CELL MEMBRANE
EXPLORE DIFFUSION/OSMOSIS EGG LAB
Transport Across the Plasma Membrane 54
Passive Transport Diffusion • Molecules move from area of HIGH to LOW concentration • Requires the cell to use no energy. ▪ Ex: Oxygen diffusing into a cell and carbon dioxide diffusing out.
Diffusion in a Liquid
Osmosis • Diffusion of water across a selectively permeable membrane • Moves from HIGH water potential (low solute) to LOW water potential (high solute) • • Solute – dissolved material Solvent - Water
10% Na. CL 90% H 2 O ENVIRONMENT CELL 10% Na. CL 90% H 2 O NO NET MOVEMENT What is the direction of water movement?
10% Na. CL 90% H 2 O CELL 20% Na. CL 80% H 2 O What is the direction of water movement?
15% Na. CL 85% H 2 O ENVIRONMENT CELL 5% Na. CL 95% H 2 O What is the direction of water movement?
Effects of Osmosis on Cells
Passive Transport Facilitated diffusion ❖Uses transport proteins to move high to low concentration ❖Doesn’t require energy ❖Ex: Glucose or amino acids moving from blood into a cell.
Active Transport ❖Requires energy or ATP ❖Moves materials from LOW to HIGH concentration AGAINST their concentration gradient ❖Generally carried out by transport proteins or “pumps” found in cell membrane
Transport of the Large Molecules Large molecules move materials into the cell by endocytosis.
Transport of the Large Molecules Exocytosis – expulsion or secretion of materials from a cell. EX: removal of water by contractile vacuole
Na+ - K+ Pump ● Sodium is pumped (energy) out. ● Potassium comes through as a byproduct.
ELABORATE OSMOSIS/DIFFUSION WORKSHEET
EVALUATE Single-celled organisms move substances from low concentrations to high concentrations to maintain homeostasis. What is this process called? a. passive transport b. active transport c. osmosis d. diffusion
EVALUATE Which will most likely happen if a freshwater plant is placed in a beaker of salt water for an hour? a. It will swell and burst. b. It will lose water and shrink. c. It will reach a state of equilibrium. d. It will use energy and pump.
Evaluate This diagram shows a cell placed in a solution containing a higher concentration of dissolved substances. The membrane is permeable to water but NOT dissolved substances. How will this affect the cell? a. Water will exit the cell to maintain homeostasis. b. Water will enter the cell to maintain homeostasis. c. Dissolved substances will exit the cell by diffusion. d. It will not affect the cell because it is in an isotonic solution.