Presentation on theme: "Chapter 6 and 7 AP Biology. Cells are the basic unit of structural and functional unit of living things. English scientist named Robert Hooke made a simple."— Presentation transcript:
Chapter 6 and 7 AP Biology
Cells are the basic unit of structural and functional unit of living things. English scientist named Robert Hooke made a simple microscope. He observed small, box-shaped structures, called cellulae (meaning small room)
All living things are made of one or more cells. Cells are the basic unit of structure and function in the organization of living things. All cells come from pre-existing cells.
Eukaryotic cells contain DNA in the nucleus. Prokaryotic cells contain DNA in a concentrated region called the nucleoid.
Based on 1 of 2 types of cells Prokaryotic ‘pro’ =before ‘karyon’ = kernel Eukaryotic ‘eu’ = true ‘karyon’ = kernel
Based on 1 of 2 types of cells Prokaryotic Only exist in domains of Bacteria or Archaea Eukaryotic Protists, fungi, animals, and plants
Bound by selective barrier (plasma membrane) Have cytosol (jellylike substance) Where organelles and other components are found Contain chromosomes Carry genes in the form of DNA Have ribosomes
Location of DNA Eukaryotes Most DNA is in nucleus Nucleus is bound by double membrane “true kernel” Prokaryotes DNA is concentrated in region not membrane-enclosed Nucleoid
Cytoplasm Eukaryotes Region between the nucleus and plasma membrane Contains a variety of organelles of specialized form and function Prokaryotes Interior of prokaryotic cell
Organelles Eukaryotes Membrane- bound organelles are Present Specialized form and function Prokaryotes Absence of organelles
Size Eukaryotes Generally Larger than prokaryotes Size relates to function 10 – 100um in diameter Metabolic requirements limit size practicality of cells Prokaryotes Smallest cells known 1 – 5 um in diameter
Acts as a selective barrier Allows sufficient passage of oxygen, nutrients, and wastes to service entire cell
Plasma Membrane- a selective barrier (semipermeable) that allows passage of enough oxygen, nutrients, and wastes to and from the cell. The plasma membrane is a lipid bilayer embedded with diverse proteins.
Fluid Mosaic Model- membrane is a fluid structure with a “mosaic” of various proteins embedded in or attached to a phospholipid bilayer. (lipids and proteins are amphipathic)
Nucleus- contains cellular DNA which includes most of the genes in the cell. The nucleus is surrounded by the nuclear envelope.
Chromosomes- structures that carry genetic information (DNA). Each chromosome contains one long DNA molecule. Each eukaryotic species has a distinct number of chromosomes. Chromatin- the complex of DNA and protein making up chromosomes. Nucleolus- helps synthesize rRNA (ribosomal RNA) and ribosomes.
Ribosomes- made of rRNA and proteins- carry out protein synthesis. Ribosomes exist as either free ribosomes (suspended in cytosol) or bound ribosomes (attached to the Rough ER or nuclear envelope)
Endoplasmic Reticulum- consists of membranous tubules, and sacs, called cisternae. Smooth ER- lacks ribosomes. Functions lipid synthesis, detoxification, and storing calcium ions. Rough ER- has ribosomes on surface. Continuous with the nuclear envelope. Synthesizes glycoproteins and other secretory proteins.
Golgi Apparatus- made of flattened membranous sacs called cisternae. Has 2 sides the cis face (receiving) and the trans face (shipping).
Lysosome- contains hydrolytic enzymes used to digest molecules. Phagocytosis- “cell eating”- lysosome digesting food Autophagy- lysosome breaking down damaged organelles.
Vacuole- functions vary depending on cell type. Food Vacuole Contractile Vacuole Central Vacuole
Mitochondria- site of cellular respiration. Cellular Respiration- the process that uses O 2 to generate ATP by extracting energy from sugars, fats, and other fuels.
Chloroplast- found in plants and algae- the site of photosynthesis. Contain the green pigment chlorophyll. Is a member of the plastid family- a group of plant organelles.
Peroxisomes- contain enzymes that remove hydrogen atoms and transfer them to oxygen, producing hydrogen peroxide (H 2 O 2 ).
Cytos keleton- a network of fibers extending throughout the cytoplasm- plays a major role in organizing the structure and activities of the cells. Motor Proteins- allows for cell movement.
Microtubules- the thickest cytoskeletal fiber, provide a track that organelles with motor proteins can move along. Help separate chromosomes during mitosis. Form flagella and cilia. Centrosome- region where microtubules are organized. Contains a pair of centrioles. Only in animal cells.
Microfilaments- the thinnest fiber. Actin and myosin filaments help muscle cells contract. Aide in pseudopodia movement by converting cytoplasm from a liquid to a gel. Cytoplasmic Streaming- circular flow of cytoplasm within cells. Speeds distribution of cell materials.
Intermediate Filaments- more permanent fixtures, fix the position of organelles and shape of the cell. Include keratin proteins.
Cell Wall- extracellular structure of plant cells. Protects the cell, maintains its shape, and prevents excessive uptake of water. Holds the plant up against gravity. Primary Cell Wall, Middle Lamella, Secondary Cell Wall Plasmodesmata-perforations in the plant cell wall that allows cytoplasm to be continuous between neighboring plant cells.
Passive Transport- moves solute from high to low concentration. DO NOT requires energy.
Diffusion- movement of molecules of any substance until they spread out evenly in the available space. (equilibrium). Diffusion is a spontaneous process, needing no energy input. Rule of Diffusion: in the absence of a force, a substance will diffuse from high concentration to low concentration.
A substance diffuses down its own concentration gradient, unaffected by the concentration of other substances. Diffusion is a form of passive transport- movement that does not require the cell to use energy.
Osmosis- the diffusion of water. Water diffuses from the region of lower solute concentration (higher free water concentration) to the area of higher solute concentration (lower free water concentration)- until equilibrium is reached. Osmosis is a method of passive transport
Tonicity- the ability of a surrounding solution to cause a cell to gain or lose water. Hypertonic- concentration of solution is more than the cell. Cell will lose water, shrivel, and probably die. Hypotonic- concentration of solution is less than the cell. Water will enter the cell and the cell will swell and lyse (burst). Isotonic- concentration of solutions is the same on both sides of the membrane. No net movement of water = stable volume.
Facilitated Diffusion- passive transport aided by proteins. Frequently involves polar molecules. Ion Channels- channel proteins that transport ions down the concentration gradient. No energy required. Gated Channels- open or close in response to a stimulus.
Active Transport- moves solute from low to high concentration. Requires energy (usually ATP). Uses carrier proteins. Active transport allows a cell to have an internal concentration different from its surroundings. Sodium-Potassium Pump- an example of active transport that exchanges Na+ for K+ across the plasma membrane.
Membrane Potential – the difference in voltage across the cell membrane. (ranges from -50 to -200 mV) The inside of the cell is negative relative to the outside. This favors transport of cations into the cell and anions out of the cell. Electrochemical Gradient- the combination of the membrane potential (electrical force) and concentration gradient (chemical force). Ions diffuse not only down their concentration gradient, but down its electrochemical gradient.
Electrogenic Pump- a transport protein that generates voltages across a cell membrane by maintaining a membrane potential. Ex. Sodium-potassium pump in animals and proton pump in plants, fungi and bacteria
Cotransport- active transport driven by a concentration gradient.
Exocytosis- the secretion of large molecules by the fusion of vesicles with the plasma membrane. Requires energy. Endocytosis- cell takes in molecules by forming new vesicles from the plasma membrane. Phagocytosis- cell eating Pinocytosis- cell drinking Receptor-Mediated Endocytosis