Chapter 2 Cells: The Basic Unit Of Life A Joke Why did the chicken cross the playground? To get to the other slide!! 1
Can you name the world s largest cell???? It s the yolk of the ostrich egg. It s the size of a softball! 3 Think about it. Can you feel the flurry of activity within your cells that keep you alive? (yes? Or no?) NO!!!! WELL, HOW DO YOU KNOW YOUR CELLS ARE WORKING? BECAUSE YOU CAN BREATHE, DIGEST YOUR FOOD, AND MOVE, SILLY!!! PLANTS AND ANIMALS ARE ONLY ABLE TO DO THESE THINGS SIMPLY BECAUSE OF ITS CELLS. 4 2
Target Objectives: I Can: -- describe the difference between unicellular organisms and multicellular organisms, --describe the difference between prokaryotic cells and eukaryotic cells. Chapter 2 3
Cell Theory Confirmed discoveries that all scientists believe to be true about cells: 1. All living things are made of cells 2. Cells are basic units of life 3. All cells are made from other cells Why Cells are Important What happens inside cells causes us to be who we are. (Genes) All growth and life starts from a single cell. All diseases start at the level of the cell. 4
It s a Small World A cell is the smallest unit that is capable of performing life functions. It is the basic unit of all living things. If it s living, it is made of cells! Cells come in many shapes and sizes Most are too small to be seen without a microscope *electron microscope is best Cells are US!! Believe it or not, YOU also began as just one cell! Not All Cells Are Created Equal We have about 200 different cells in our body, and about 100 trillion in all. Each type is specialized to do a particular job. The size & shape of a cell relates to its function. (Examples include: (Bone cells, blood cells, skin cells, muscle cells) 5
Other examples of cells include: white blood cell red blood cell Amoeba cheek cells sperm nerve cell muscle cell Paramecium 11 Organisms and Their Environment Any living thing is known as an organism including bacteria. Organisms can be grouped as either: Unicellular- one cell Multicellular- more than one cell Most cells cannot live on their own They must be in a group to survive. EX: If you scrape your knee on the sidewalk, the cells that are left on the sidewalk won t survive on their own!! 6
Cells are either Prokaryotic or Eukaryotic (each type has is own characteristics) 13 The Discovery of Cells before nucleus true nucleus 7
1. Prokaryotic Cells (proh KARY ah tick) Small, Simple, primitive cells All are unicellular Lack a nucleus: circular genetic material floats free in cell Lack membrane-bound organelles ( little organs ) Example: Bacteria 2. Eukaryotic Cells (yew KARY ah tick) Unicellular or multicellular DO HAVE: nucleus (with DNA) membrane-bound organelles Complex internal structure Compartments allow many different chemical reactions to take place simultaneously Ex: protists, fungi, plant & animal cells. 8
Eukaryotic Cells - Contain 3 basic cell structures: 1) Nucleus 2) Cell Membrane 3) Cytoplasm with organelles *add this to your notes 17 CAN T STRESS IT ENOUGH Cells are the basic units of of all living organisms Most cells can only be observed under a microscope Basic types of cells: Animal Cell Plant Cell Bacterial Cell 18 9
Inside All Cells 19 All Cells have : No matter what type of cell it may be (prokaryotic, eukaryotic), ALL cells have the following: CELL MEMBRANE RIBOSOMES CYTOPLASM & ORGANELLES Add this to your notes!!! DNA (Heredity Material) 10
All Cells Have a Cell Membrane (also called plasma membrane) It is the thin protective layer around cells that is made up of phospholipids & proteins. Acts as a barrier between the inside of the cell and the cell s external environment Controls the passage of materials into and out of the cell. That s why it is known as selectively permeable Ex: Water & oxygen molecules, food molecules, and waste products Found just inside the outer cell wall in plant cells Plasma/Cell Membrane Cell membrane 11
All Cells Also Contain Cytoplasm, Organelles & DNA Cytoplasm- the gel-like sea of fluid that all of the cell s organelles float in. *constantly moving ORGANelles- contain all the chemicals and structures that enable cells to live, grow, and reproduce *just like your organs!! * They are located in the cell s constantly moving cytoplasm All cells have organelles, but not necessarily the same kind (bacteria, plant cells and animal cells differ) Some organelles are surrounded by a membrane, and some are not. Ex: ribosomes All cells have DNA contains instructions for the cell s activities. Lesson 2-2 The Organelles of the Cell Animal cell 12
Organelles: Are very small, specialized structures in cells which operate like organs by carrying out specific tasks Can only be observed under a microscope * Have specific function (job) * Found floating throughout the cytoplasm 25 The Need for Protein Protein is a very important substance in the cell because it takes part in nearly every cell activity Needed for chemical reactions that take place in the cytoplasm Also part of cell membrane Ribosomes are also important because they produce these proteins - are not covered by a membrane, so they can also be found in prokaryotic cells as well as animal cells - some float freely in the cytoplasm of animal cells, and some are attached to the endoplasmic reticulum - ribosomes are produced in the nucleolus 13
Endoplasmic Reticulum (ER) - Extends from the nucleus to the cell membrane - Breaks down drugs and certain other chemicals that could damage the cell - it s known as the Internal delivery system.meaning that Substances can move from one place to another (thru tunnels) - Looks like a cloth folded back and forth *folds make tunnels - - 2 types: rough and smooth 27 Rough and Smooth Rough ER- has ribosomes attached to it (The Proteins made by the ribosomes pass into the ER and are later released to be used elsewhere in the cell) Smooth ER- lacks ribosomes, but acts as a storage organelle Makes lipids and other materials for use inside and outside of the cell 14
Golgi Complex/Bodies Looks like ER, but it is located closer to the cell membrane It is made up of Stacks of flattened sacs Have a shipping side & a receiving side mainly for packaging Primary job: to receive, modify and ship lipids & proteins made by ER!! 29 The Golgi complex moves materials to other parts of the cell by way of transport vesicles. Golgi Complex/Bodies How?? Part of the membrane pinches off to form a small compartment This small compartment transports its contents (such as cellular substances) to be delivered to other parts of the cell. Transport vesicle *It also carries cellular substances to the cell membrane where they are released to the outside of the cell 30 15
Lysosomes Contain digestive enzymes that help break down food molecules, cell wastes, and worn-out cell parts Lysosomes are known as the clean up crew 31 Interesting Fact Did you know that before you were born, lysosomes caused the destruction of cells that formed the webbing between your fingers? Yep! They say they also contribute to the aging process in us L 16
Mitochondria Powerhouse of the Cell Mitochondria Rod shaped with a folded membrane inside - Site of Cellular respiration 33 In Animal Cells: Mitochondria What is Cellular Respiration? This is where food is broken down into carbon dioxide and water to produce energy Active cells like muscles have more mitochondria In other words Burn sugars to produce energy (ATP) Adenosine Triphosphate 34 17
Mitochondria Most of the ATP (energy used by the cell) is made in the inner membrane Can work only if they have oxygen The reason you breathe air Lots found in active cells, such as muscles, the heart, and liver because they need more energy! Nucleus Control Center Nucleus - Usually the Largest organelle - Directs all cell activities - Contains instructions for everything the cell does - These instructions are found on hereditary material called DNA 36 18
NUCLEAR MEMBRANE Nucleus is surrounded by the nuclear membrane Nuclear membrane separates nucleus from cytoplasm This membrane controls movement of materials in & out of nucleus NUCLEOLUS AKA little nucleus Found Inside nucleus Disappears when cell divides Ribosomes that make the proteins are produced here 19
So, let s recap the function of each organelle - - Target Objectives: I Can: -- describe the functions of each organelle in a plant and animal cell. 20
Target Objectives: I Can: -- describe the difference between a plant and animal cell. Two Main Types of Eukaryotic Cells Plant Cell Animal Cell 42 21
Cell Wall Cell wall - Dead layer - Gives structure and shape to plant and bacterial cells 43 Cell wall Plant Cell Made of cellulose which forms very thin fibers It s strong and rigid 44 22
Plant Cell Cell wall Function is to: a) Protect and support the cell b) Resist entry of excess water into the cell c) Gives shape to the cell 45 How is Cell Wall is important to the Cell Membrane? - The cell wall provides strength and support to the cell membrane (by keeping it from tearing). - Cell Membrane- keeps the cytoplasm inside and allows nutrients in and waste products out 23
Chloroplast Plant Cell Organelles Contain the green pigment chlorophyll Traps sunlight to help make sugars (food) Process called photosynthesis 47 Plant Cell Organelles Vacuole - Have a large central vacuole - Stores sugars, proteins, minerals, wastes, & pigments - Because of this Plant cells DO NOT HAVE LYSOSOMES! - Contains cell sap - Juice in fruits are here 48 24
BREAKING NEWS!!! - REMEMBER: - Plant cells have a large central vacuole - Stores sugars, proteins, minerals, wastes, & pigments - Because of this Plant cells DO NOT HAVE LYSOSOMES! 49 The vacuoles in grapes hold so much juice. Did you know???? That they must dry in the sun for several weeks before they become raisins. A grape loses about ¾ of its original weight in the process. 50 25
Different kinds of plant cells Onion Epidermal Cells root hair Guard Cells Root Hair Cell 51 vacuole cytoplasm Animal cell mitochondrion nucleus - Unlike plant cells, animal cells have no cell wall or chloroplasts glycogen granule cell membrane 52 26
Animal Cell Organelles Centrioles are located near the nucleus of a cell. Comes in paired structures Help cell divide 53 Different kinds of animal cells white blood cell red blood cell Amoeba cheek cells sperm nerve cell muscle cell Paramecium 54 27
Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria 55 Differences between plant cells and animal cells Animal cells Plant cells Relatively smaller in size Irregular shape No cell wall No Chloroplasts Relatively larger in size Regular shape Cell wall present Chloroplasts 56 28
Differences between Plant Cells and Animal Cells Animal cells Vacuole small or absent Nucleus at the center Plant cells Large central vacuole Nucleus near cell wall 57 WHAT ARE THE LONGEST CELLS IN YOUR BODY? The LONGEST cell in your body.. Are nerve cells in your brain called Neurons. They can be more than 1m long (~ 3 ft.) 58 29
Target Objectives: I Can: -- describe the difference between cells, tissues, organs, and organ systems. Organization of Life The Building Blocks of Life!!!!! Life is Organized on Several Levels " Cells life starts here " Tissues " Organs " Organ Systems " Organism " Populations " Communities " Ecosystems 60 30
Levels of organization Cells are grouped together and work as a whole to perform special functions 61 Tissues A tissue is a group of cells that perform a particular function. Also includes the material between and around your cells (Fat cells, blood cells, and muscle cells) 31
What are some ways you use your muscles? It s not just by riding your bike, walking, riding, swimming, or even throwing or kicking a ball. You are using your muscles (tissue) even when you: Swallow your food (tongue) Digest your food (stomach) Blink your eyes (eyelid) and even so much as breathe!!! (diaphragm) 63 Did you know. An elephant s trunk is constructed of 300lbs of hair, skin, connective tissue, nerves, and muscles. Its muscle tissue is composed of 150,000 subunits that allow the elephant to drink, breathe, grab and greet friends. 64 32
Organs Organs consist of at least 2 different types of tissue functioning together for a common purpose. Examples: stomach, intestines, heart, lungs, skin, liver, kidneys Organs Depend On Each Other The organs in an organ system depend on each other If one fails, other organs are affected Failure of one organ system can affect other organ systems If your digestive system stopped converting food to energy, then none of the other systems would have energy to function 33
What is the largest organ of the human body? Your skin is the largest organ of the human body. In your life time, you will shed about 40lbs of dead skin cells. The Bad news: You ll spend a lot of time washing the ring from around the tub! Ha! Ha! The good news! Cells are constantly being formed and replacing dead cells. 67 More about your skin Hair and fingernails Are composed of specialized skin cells. Why doesn t it hurt when you cut them??? Even though they grow continuously, both are composed of dead cells along with a protein called keratin. If they were alive and contained nerves: haircuts and manicures would be quite painful. 68 34
Organ Systems Are composed of two or more different organs that work together to provide a common function Examples: Digestive, nervous, circulatory, respiratory System Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way Human : digestive, respiratory, excretory, circulatory and reproductive systems Plant : root and shoot systems 70 35
Human Body Systems Examples of systems : Digestive System Respiratory System Circulatory System Nervous System 71 Digestive System Job: Breakdown and absorb nutrients that are necessary for growth and maintenance Major Organs: Mouth, esophagus, stomach, small and large intestines. 36
Nervous Job: sends electrical impulses throughout the body; directs behavior of all other body activities Major Organs: Brain, spinal cord and nerves Circulatory Job: transport nutrients, gases (such as oxygen and CO2), hormones and wastes through the body Major Organs: Heart, blood vessels blood, and spleen 37
Respiratory Job: provide gas exchange between the blood and the environment Major Organs: Nose, trachea and lungs, mouth, diaphragm The Human Body (according to Amoeba Sisters) The 11 Systems of the Human Body 38
Small Size Remember: Almost all cells are too small to be seen without a microscope. It would take 50 of your cells to cover up this period. An electron microscope is used when things are too small to be viewed with other microscopes. 39