Cell Structure, Germ Theory, and Immune System Study Guide (Fa24) PDF

Cell Structure, Germ Theory, and the Immune System Cell Organelles Organelle Name Structure and Function Cell Type A barrier that surrounds the cell. All cells Plasma (Cell)...

Cell Structure, Germ Theory, and the Immune System Cell Organelles Organelle Name Structure and Function Cell Type A barrier that surrounds the cell. All cells Plasma (Cell) Made of phospholipids (fats). Membrane Chooses what it allows in and out. Jelly-like fluid fills the inside of the cell. All cells Cytoplasm Mostly made of water. Small proteins that look like dots found in the cytoplasm or All cells Ribosomes attached to the Rough ER. Make proteins for the cell. Nucleoid An area where chromosomes (DNA) gathers in certain cells. Prokaryotes ONLY A membrane structure that contains and protects the Eukaryotes ONLY Nucleus chromosomes (DNA) of certain cells. Nucleolus A dark area inside the nucleus where the ribosomes are made Eukaryotes ONLY A membrane connected to the nucleus with ribosomes on its Eukaryotes ONLY Rough Endoplasmic surface. Reticulum (ER) Makes and processes (edits or changes) proteins. A membrane connected to the rough ER (no ribosomes here) Eukaryotes ONLY Smooth Endoplasmic Where lipids (fats) are made the where the cell detoxifies Reticulum (ER) toxins and other chemicals. A group of membranes that look like a stack of pita bread. Eukaryotes ONLY Act like the post office of the cell Golgi Apparatus Accepts, labels and sends out proteins that come from the Rough ER. Mitochondria Where energy (ATP) is made for the cell from sugars. Eukaryotes ONLY Small membrane spheres (sacs) with acids and digestive Animal Cells enzymes. (Eukaryote) ONLY Lysosome Acts like the stomach or clean-up crew of the cell. Digests food. Breaks down damaged or dead organelles. Protein structures found all over the inside of the cell. Eukaryotes ONLY Cytoskeleton Act as a skeleton, providing structure and support. Act as a super highway to transport materials around the cell. Where photosynthesis occurs in plant cells Plant Cells (Eukaryote) Chloroplast Makes sugar (food) for the cell ONLY Tough rigid structure surrounding the plasma (cell) membrane Plant Cells (Eukaryote) Cell Wall Made of cellulose or chitin ONLY Protects the cell and gives it shape and strength A tail sticking out of the cell Animal Cells Flagella Part of the cytoskeleton (Eukaryote) ONLY Used to move the cell around Little hairs that cover the surface of the cell Animal Cells Cilia Part of the cytoskeleton (Eukaryote) ONLY Used to move the cell around Large membrane sac in the cell Eukaryotes ONLY (but Vacuole Used to store materials like food, water, or waste larger and more important in plant cells) Small circular pieces of DNA that is copied from the Prokaryotes ONLY Plasmid chromosome Cell Types There are two major categories of cells: Prokaryotes and Eukaryotes 1) Prokaryotes are always unicellular. Example: bacteria 2) Eukaryotes can be unicellular or multicellular and are split into two groups: plant or animal cells. Prokaryotes Both – Found in ALL CELLS Eukaryotes 1) Nucleoid 1) Plasma Membrane 1) Nucleus 2) No membrane-bound 2) Cytoplasm 2) Membrane-Bound Organelles organelles 3) DNA (Golgi, ER, mitochondria, etc) 3) Plasmids 4) Ribosomes 3) Multicellular 4) Unicellular Animal Cell Both – Found in all EUKARYOTIC cells Plant Cell 1) Nucleus 6) Plasma Membrane 1) Lysosome 2) Nucleolus 1) Cell wall 7) Cytoplasm 2) Flagella and Cilia 3) Golgi 2) Chloroplast 8) Ribosomes 3) Sometimes Vacuoles 4) Rough ER 3) Vacuole 9) Mitochondria 5) Smooth ER Cell Theory Scientists o Robert Hooke – first to see dead cells (cork); named the cell o Anton van Leeuwenhoek – first to see living cells and bacteria; father of microbiology o Matthias Schleiden – said all plants are made of cells; cofounder of cell theory with Schwann o Theodor Schwann – said all animals are made of cells; cofounder of cell theory with Schleiden o Rudolf Virchow – said all cells come from other cells; final editor of cell theory Spontaneous Generation o Cells appear from the air o Disproven by Francesco Redi (meat and maggot experiment) and Louis Pasteur (bacteria in broth experiment) Parts of the Cell Theory o All living things are made of one or more cells. o The cell is the building block (basic unit) of life. o All cells come from pre-existing cells. Theory of Endosymbiosis o Part 1 – the cell membrane folded inward to create the endomembrane system (nucleus, ER, Golgi, vesicles, lysosome) o Part 2 – some prokaryotic cells engulfed (swallowed) other prokaryotes, allowing them more energy (mitochondria) or the ability to harness sunlight and turn it into food energy (chloroplast) ▪ Evidence for this theory include that the Mitochondria and Chloroplasts Are the same size as prokaryotes Have ribosomes that are more similar to prokaryotic ribosomes than eukaryotic ones Have their OWN UNIQUE DNA!! Can divide separately from the larger cell they are inside of Have at least TWO membranes – the first is their own membrane, the second is the left over membrane from the vesicle that enclosed them when they were engulfed Chloroplasts actually have 3 membranes. Were thought to be engulfed twice! Germ Theory of Disease The discovery that germs (bacteria and viruses) cause some diseases Why is this significant? o We were able to develop antibiotics and vaccines to eradicate or fight off these diseases. o Learned how diseases could be spread and developed sanitation practices (cleanliness) Scientists o Robert Koch – founder of the germ theory; worked with anthrax bacteria in farm animals o Edward Jenner – created the first vaccine (smallpox) Antibiotic Resistance – What is it? How does it develop? What can we do to stop it? Know the difference between an antibiotic and a vaccine o When do you use antibiotics? o What does a vaccine do? Know the difference between active and passive immunity Immune System Cells recognize foreign invaders by their antigens – chemical markers on the surface of their cell membrane Innate Immunity (Non-Specific) o A set of rapid responses that all cells share (skin as the first line of defense, phagocytosis) o First line of defense: skin and mucous membranes ▪ Skin has low pH, high salt, dry, natural microbiome - help protect against invaders ▪ Mucous is sticky and traps bacteria and other foreign invaders o Second line of defense includes: ▪ Inflammation Purpose is to prevent the spread of invaders and bring immune cells to the area Four Signs: Redness, Swelling, Heat, Pain ▪ Fever ▪ Phagocytes: Macrophages and Neutrophils Cells specially designed to phagocytize (eat) bacteria via endocytosis These cells are drawn toward chemical signals released by the bacteria Adaptive Immunity (Specific) o A form of immunity our cells or body acquires after exposure to a disease; learned immunity o Involves antibodies Antibodies are small proteins that match and bind to specific antigens (identify chemicals) on the surface of bacteria, viruses, or other cells When antibodies bind to antigens it draws phagocytes to eat the invader o T cells and B cells These are specialized immune cells that create our memory for disease and produce antibodies Both types of cells have receptors that recognize antigens B cells make antibodies T Cells target our own cells that aren’t functioning properly (infected by virus, cancer, etc)  Cell Membrane Study Guide Cell Membrane Structure Phospholipids - make up most of the membrane structure Membrane Proteins - make up passageways for materials to move in and out Carbohydrates - sugars that act as signals, name tags, and attachment points Cholesterol - fat that keeps the membrane fluid Phospholipids and the Lipid Bilayer Phospholipids are fats with special characteristics. They have a phosphate group "head" that is polar and hydrophilic (loves water) They have two lipid (fat) "tails" that are nonpolar and hydrophobic (fears water) The hydrophilic heads face the extracellular space (outside of the cell) and the cytoplasm or intracellular space (inside of the cell) because those areas have a lot of water. This creates a lipid bilayer - two layers of phospholipids with the heads outside and tails inside. Membrane Permeability Since the inside of the membrane is made of hydrophobic tails, things that are polar or hydrophilic do not like to pass through this area. This blocks some materials from entering the cell, making the cell semi-permeable. This means it lets some things in, but not other things. Fluid Mosaic Model The phospholipids and the membrane proteins are always moving around in the cell membrane. We use the term fluid to describe this movement. Cholesterol fits in between phospholipids helps keep the parts moving and keeps the membrane fluid. Since the membrane is made of many different types of molecules (many parts) we call it a mosaic. Mosaics are pictures made from many different pieces (like a picture made from many little tiles).  Diffusion, Osmosis, Active Transport There are two ways in which substances can enter or leave a cell: 1) Passive (no energy) a) Simple Diffusion b) Facilitated Diffusion c) Osmosis (water only) 2) Active (requires energy) a) Using a protein b) Bulk Transport (endo/exocytosis) Diffusion Diffusion is the movement of particles (atoms, ions or molecules) from an area of higher concentration (amount) to an area of lower concentration. It continues until the concentration of substances is uniform throughout (equilibrium). This is passive transport and requires no energy! Small, hydrophobic, uncharged molecules can diffuse directly across the membrane. Large, hydrophilic, charged molecules must use membrane proteins to diffuse. Some major examples of diffusion in biology: Gas exchange at the alveoli — oxygen from air to blood, carbon dioxide from blood to air. Gas exchange for photosynthesis — carbon dioxide from air to leaf, oxygen from leaf to air. Osmosis — diffusion of water through a semipermeable membrane. Facilitated Diffusion This is the movement of specific molecules down a concentration gradient (high to low) using a membrane protein. These proteins can be open channels, or they can be very specific and only allow one specific molecule through. Still passive transport and requires no energy. Common molecules entering/leaving cells this way include glucose and amino-acids.  Osmosis Osmosis is a special example of diffusion. It is the diffusion of water through a semi-permeable membrane down the water's concentration gradient (high to low). Water uses special membrane proteins called aquaporins to move in and out of the cell quickly. Semi-Permeable Membranes (like the cell membrane) allow some things to pass through but not other things. Note: diffusion and osmosis are both passive so energy not used. Some major examples of osmosis Absorption of water by plant roots. Re-absorption of water by the proximal and distal convoluted tubules of the nephron. Re-absorption of tissue fluid into the venule ends of the blood capillaries. Absorption of water by the alimentary canal — stomach, small intestine and the colon. Hypotonic Isotonic Hypertonic  Active Transport Active transport is the transfer of a substance across a cell membrane against its concentration gradient (from lower concentration to higher concentration) requiring the use of energy. Special proteins within the cell membrane act as specific protein ‘carriers’. The energy for active transport comes from ATP made by the mitochondria. Two Types of Active Transport 1) Specific Transport Using a Membrane Protein 2) Bulk Transport (Endocytosis and Exocytosis) Endocytosis and Exocytosis This is the movement of very large molecules, many large molecules at once, or even cells like bacteria across the cell membrane. It involves transport vesicles that contain the materials being transported in or out of the cell. Endocytosis is the process of taking material INTO the cell. Exocytosis is the process of releasing (or secreting) materials OUT of the cell. Homeostasis How the cell/body regulates itself – maintains a steady state for things like temperature, water content Negative Feedback o A signal that causes the cell to stop something or to counteract something undesirable o Examples: ▪ Temperature – Body temperature drops too low so we start to shiver, shivering generates heat and restores raises the temperature back to normal levels. The opposite also occurs where we get too hot and our bodies trigger the sweating response to cool us and lower our temperature. ▪ Blood Glucose – insulin (pancreatic beta cells), glucagon (pancreatic alpha cells and liver cells), epinephrine (fight or flight response neurotransmitter) ▪ Testosterone and Estrogen – When these hormones reach a certain level in our blood, they bind to receptors on the brain. This causes the brain to stop producing hormones that stimulate the ovary or teste to cease estrogen/testosterone production. Positive Feedback o A signal that causes the body to continue an action or make a stimulus stronger o Examples: ▪ Childbirth – Baby grows so big it starts to push on the cervix. Pressure on the cervix sends a signal to the brain to release a hormone called oxytocin. Oxytocin travels to the uterine muscle cells, binds to their receptors, and causes muscle contractions. These contractions cause the baby to push harder on the cervix, which sends a stronger signal to the brain. Ends when the baby is out of the body and there is no longer pressure on the cervix. ▪ Lactation – Baby suckling sends a signal to the brain to release prolactin and oxytocin which stimulate mammary glands to produce milk. As long as the baby suckles, milk will be produced. As soon as the baby stops suckling for a long period of time milk production will slow and eventually stop. ▪ Fruit Ripening – Ethylene is a gas signal molecule that binds to surface receptors and triggers ripening genes in the fruit to turn on. One of these genes produces ethylene, which then binds to more receptors to produce more ethylene and ripen the fruit more. Ethylene can also cause nearby fruit to ripen, so as all the fruit on a tree ripen they trigger more ripening to occur. ▪ Quorum Sensing – Bacteria receive signals when they are in groups to start or stop certain activities. In particular, glowing or producing virulence factors that increase pathogenicity (ability to cause disease). The Nervous System Central Nervous System o Contains the brain and spinal cord only Peripheral Nervous System o Contains all the nerves of the body Neurons o Brain cells that send signals throughout the body o Know the structure of the neuron (cell body, axon, dendrites, myelin sheath) o Dendrites: send signals TO the neuron cell body o Axon: sends signals AWAY from the neuron cell body o Myelin Sheaths: fatty cells that cover the axon; make the signal travel faster and protect the neuron Action Potentials o How the neuron sends a signal o Trigger from a stimulus causes the cell to open its membrane channel proteins and let Sodium ions (Na+) into the cell – makes the cell more positive o The positive charge then triggers the next part of the membrane to open its membrane channel proteins to let sodium ion in – this continues down the axon o The signal jumps over the fatty myelin sheath cells and only transmits where the axon is exposed o The sodium-potassium pump resets the voltage of the membrane after the signal has passed Neurotransmitters o There is a gap between the end of the axon and the next cell called a synapse o When the action potential reaches the end of the axon it triggers vesicles filled with neurotransmitters to be released into the synapse (exocytosis) o These neurotransmitters bind to the next cell and continue the signal from the brain Endocrine System Works with the nervous system to send long-distance chemical signals around the body Hormones o Long-distance signal molecules that travel through the bloodstream to the target cell o All hormones trigger a change in how the DNA makes proteins for the cell o Steroid (Lipid) Hormones ▪ Can cross the membrane and bind to proteins inside the cell o Non-Steroidal (Hydrophilic) Hormones ▪ Cannot cross the membrane so they bind to membrane proteins ▪ The membrane protein sends a signal to other proteins inside the cell ▪ Signal gets passed from protein to protein until it reaches the final protein or enzyme