Biology 1-H Study GuideChapter 5Section 5.1How many cells in the human body?o Greater than 100 trillion 1014 100,000,000,000,000o 30 trillion in the brain, 20 trillion red blood cells All organisms begin as a single cello Some things stay that way bacteria o Most other things grow into 100s, 1000s or millions of cells Cells basic unit of structure and function in living thingso Remember all things must contain cells in order to be alive Cell theory began as curiosity scientists were curious as to what living things were made of and that began to make them look at things more closelyo Used magnifying glasses to enlarge small objects o Used magnifying lenses in combination worked even better o 1600s 2 instruments telescope and microscope changed the way science looked at things 1st Microscope: Anton van Leeuwenhoeko Dutch scientist used his primitive microscope to look at the living things in pond water o Credited with drawing and naming some of the microscopic organisms Other scientists caught on built better microscopesRobert Hooke: Englishman looked at tree and plant stems and corko Looked at cork under his microscope and saw that they were divided into small regular sized compartments o Called them cells because they reminded him of the rooms in a monastery called cells o He observed non-living cells, but what he saw can be adapted to living cells. Theories built on other theoriesBrown: located the nucleus of the cellSchleiden: all plants made of cellsSchwann: all animals made of cellsCell theoryo All living things are composed of cells o Cells are the basic units of structure and function in all living things o All cells come from pre-existing cells Section 5.2Cell sizes varies greatly measured with micrometers10-6 m 1/1000000 of a meter· smallest cell known mycoplasma: .2 um in diameter · large cell giant ameba (Chaos chaos): 1000 um Most cells are 5-50 um in diameterThere are physical limitations on cell sizeLimited by the surface area of a cell in compared to its volume? Why?2 kinds of cells exist: Prokaryotic and EukaryoticProkaryotes: primitive cellso No nucleus o Generally smaller then eukaryotic cells o No organelles (mini organs used to carry out cellular functions) Eukaryotes: advanced/true cellso Membrane bound nucleus o Membrane bound organelles Cell Membraneo Separate cell from its surroundings o Regulates what can come into and out of a cell o Composed of phospholipids o Double membrane bilayer o Within bilayer are proteins and carbohydrates which have special functions act as messengers and channels for passing messages and allowing particles in/out of cell o Pg 91 fig 5-5 is a great picture of what the bilayer looks like Cell Wallo Found only in plants, algae and some bacteria o Very outside of a cell (still have a cell membrane, but the wall is on the outside of it) o Helps to protect and support the cell but has pores which let in and out H2O, O, CO2 etc o Made of two or more layers · 1st layer contains pectin a gluey substance which holds cells together · Primary cell wall is found on the outside of the 1st layer and is made of cellulose · Secondary cell wall is found on the outside of the primary wall and is found only in trees and woody plants is made of cellulose and lignin which gives it much more strength Nucleuso Most visibly noticeable structure in a cell o 1st located by Robert Brown o contains DNA and genetic material o information center of the cell ( like the brain is to the human body) directs all activities which occur in the cell Nuclear Envelopeo 2 membranes surrounding the nucleus o acts as a boundary, but has pores which allows certain things in and out. Nucleoluso Small region inside the nucleus o Made of RNA and proteins o Makes ribosomes Chromosomes: the long threadlike structures of DNA which are in the nucleus. Contains all genetic infoCytoplasm: area between the nucleus and the cell membrane, contains all of the other organelles Section 5.3Organelles: a tiny structure which performs a specialized function in the cell.Mitochondriao Power house of the cell o Convert energy into a form which the cell can use more easily o Made of two membranes an inner and an outer membrane which increases the surface area Chloroplasto Found only in plants and algae o Collects and stores energy for the cell o Trap light energy from the sun and turns it into usable energy chemical energy Ribosomeso Make proteins o Made of RNA and proteins o Can be either be found to a membrane or free in the cytoplasm Endoplasmic Reticulum (ER)o A system of membranes and sacs o Transports materials through the cell o 2 kinds of ER: Smooth and Rough · smooth lacks ribosomes used to make lipids · rough is studded with ribosomes used to synthesize proteins and then transported to the area of the cell where they are needed. Golgi Apparatuso Used to modify, collects, packages and distributes proteins made in the ER o Adds carbohydrates and lipids onto the proteins to enable them to perform other functions o Looks like a flattened stack of membranes (like pancakes) Lysosomeso Clean-up crew of the cell o Contains enzymes to digest certain materials in the cell including organelles which have outlived its usefulness o Cleans up by engulfing the particles within the cell phagocytosis the membrane of the organelle encloses around the particle and takes it into the cell Vacuoles and Plastidso Storage structures store water, food, salts, proteins and anything else that needs to be stored. o In plants have a central vacuole which hold water make the cell rigid and helps it keep its shape. When the cells vacuole loses water what do you think happens? o Plastids are very similar and found only in plants Cytoskeletono The framework of the cell made of a variety of fibers and filaments that support the cell and drive its movement o Microtubules hollow tubes made of proteins help keep the shape of the cell and can move organelles around in the cell. o Microtubules also work outside the cell to build cilia and flagella: whip-like structures which propel the cell in movement (like sperm) and allow things to move over the surface of the cell o Microfilaments: long thin filaments which function in movement and support in the cell. Help to move the cytoplasm inside the cell which helps to move the organelles around Section 5.4Environment of a cell is liquid makes it easier to transport materials across the membrane of a cell.Movement happens in several ways:1. Diffusion: movement of molecules from an area of high concentration to an area of lower concentration until an equilibrium is reached. o Movement is down the concentration gradient o Particles do not stop moving once equilibrium is reached, they just move at equal rates, so the concentration is equal on both sides. o Permeability: the ability of a membrane to allow materials to move through it. Most cells have a selectively permeable membrane they are choosy about what goes across the membrane. 2. Osmosis: diffusion of water across a semi-permeable membrane. Water can move relatively freely across membranes. o Water moves down the concentration gradient like many other substances do but it isnt as easy to figure out the direction of the concentration gradient of water. o High solute concentration ( a lot of things are dissolved in the water) is a low water concentration o Low solute concentration (few things dissolved in the water) is a high water concentration. o Therefore, water travels from a weak solution to a stronger solution until both solutions are equal in concentration. o Water moving across the cell membrane creates osmotic pressure against the cell wall only felt when water is moving. o Most cells have more sugar and salt than a sample of fresh water. So when cells are placed in an environment of fresh water, they swell up and eventually burst. o Opposite can happen when the cell is placed in a strong salt solution, the water will rush out of the cell causing the cell to shrink and die. 3. Facilitated diffusion: materials are carried across the cell membrane by another molecule, usually a protein. o Still moves down the concentration gradient, but it is carried instead of moving itself. o It does not require energy to move it sort of hitchhikes it way into the cell. But it only works if the concentration gradient exists things must be moving in that direction anyway. 4. Active transport: process which uses energy to move materials against the concentration gradient. o Moving from an area of high concentration to an area of low concentration. o Usually used when moving ions: Na+, Cl-, K+, Ca2+ Look up the definitions of endocytosis, exocytosis, phagocytosis, and pinocytosis Section 5.5Cells are uniquely suited to perform particular functions within an organism.o Specialized cells are usually different in their structure form other kinds of specialized cells. Pancreas: organ which specializes in producing digestive enzymes.If enzymes are made, what organelles are most important in this type of cell?o Rough ER o Ribosomes o Golgi apparatus The cell will contain all of the organelles needed to function, but there will be a large amount of these organelles which have a special role in protein formation.Eye Cell: eye cells are light sensitive which makes up our vision.o Eye cells have two different and distinct parts: o Lower part: has 4-5X the mitochondria of a regular cell. Uses a great deal of energy. o Upper part: light sensitive flattened membranes which contain the pigment rhodopsin absorbs light and sends out signals which make up our vision. Mucus cells: line our nasal passages and our throat which make and release a combination of water, carbohydrates and salts (mucus).o The mucus traps dirt, dust, smoke and small bacteria and sweeps them away to keep our passage ways clear. Section 5.6Multicellular organisms are organized very systematically into levels: cells, tissues, organs and organ systems.Tissues: cells are organized into specialized clusters which together perform specialized functions.o Four main types of tissues: muscle, epithelial, nerve and connective tissue. Organs: a collection of specialized tissues which work together to perform certain functions.Organ systems: groups of organs which work together to carry out major life processes.The four major levels of organization allow for a division of labor which allows all life processes to get done. Biology 1-H Study Guide Chapter 6 Section 6.3 Gylcolysis and respiration are part of a large process called cellular respiration. Gylcolysis is the beginning of the process and finishes with respiration, if oxygen is present. Review gylcolysis: o Breaks down glucose to make ATP o ATP is not the only final product of the process o The 6-C glucose is broken down to make 2 3-C compounds. These compounds are processed allowing the cell to make 2 ATP molecules and 2 NADH molecules o The final product is a 3-C compound called pyruvic acid. Review respiration: o Breaks down the pyruvic acid made in glycolysis to make energy if oxygen is present. o Aerobic process requires oxygen o Krebs cycle: continuous series of reactions with no final end product. o Refer to page 126 Fig 6 16 in your book for the complete listing of the steps of the Krebs cycle o Briefly: pyruvic acid (3-C) is broken down into a 2-C compound and CO2 is released. o The 2-C compound is cycled thru the system, with many additions and subtractions happening to the molecule. o Along the way, NADH and FADH2 are used as storage molecules for energy. They hold energy in the form of highly excited electrons. o These electrons are passed down an electron transport chain to the bottom step, where oxygen accepts the elections and makes H2O as a byproduct. Traveling down the chain produces more energy (like in photosynthesis). o Additional ATP is made using a similar system of pumping electrons across the membrane of the mitochondria. Figure 6-18 on page 128 outlines the total amount of energy produced in each step of the process. Section 6.4 Most cellular energy made is produced by respiration in the presence of oxygen. Can energy still be made is oxygen is not present? Glycolysis happens without the input of oxygen, but as we saw it wasnt a very efficient way of making energy (only 2 ATP and 2 NADH were produced compared to the 30 ATP of respiration). The byproducts of glycolysis were pyruvic acid, ATP and NADH. In order to complete the cycle of energy production, the NADH needs to be converted back to NAD+ - which is the usual role of respiration. Fermentation is an anaerobic process (no oxygen needed) which can change the NADH into NAD+ in order to make more energy. NADH NAD+ happened by the removal of an electron and it is donated to an organic compound which is produced as the product of the reaction. Lactic Acid Fermentation: o Pyruvic acid is converted into lactic acid while making NAD+ o Happens in muscle cells when not enough oxygen is present for respiration to occur. o Happens during rapid exercise when the supply of oxygen to muscle tissue is quickly used up. Muscles still need energy and fermentation can produce energy quickly by making lactic acid. The lactic acid buildup in muscle tissue causes burning and soreness. Alcoholic Fermentation: o Pyruvic acid is broken down to make alcohol and CO2. Also makes NAD+ during the reaction. o Done by yeast and many microorganisms o CO2 produced as a byproduct is what makes bread rise and the bubbles in beer and champagne. o Alcohol is toxic to the yeast cells and the cells will die if the alcohol content is greater than 12%. Therefore, alcoholic beverages which have a higher percent alcohol content must be specially processed.
