Cells: The Basic Unit of Life PDF

Cells: The Basic Unit of Life 1 Outline Cell Basics and History Cell Types Cell Parts (Organelles) Evolution of Eukaryotes 2 Cell basics Cells are the basic building blocks of life. Some organ...

Cells: The Basic Unit of Life 1 Outline Cell Basics and History Cell Types Cell Parts (Organelles) Evolution of Eukaryotes 2 Cell basics Cells are the basic building blocks of life. Some organisms are composed of a single cell. Others are multicellular! Multicellular are organized into levels: 1. Cells make up tissues. 2. Tissues make up organs. 3. Organs make up organ systems. 4. All of which compose the organism! 3  Cell Theory 1. All living things are made of cells. 2. Cells are the basic unit of structure and function in an organism 3. Cells come from the reproduction of existing cells (cell division). 4  5 https://ed.ted.com/lessons/the-wacky-history-of-cell-theory History of Cell Discovery: Hooke In 1665, Robert Hooke used a primitive microscope to examine thin piece of cork Here’s what he saw: 6 History of Cell Discovery: Hooke Hooke named these unexpected compartments: cells Why? – They looked like small rooms that monks lived in, which were called ‘cells’ 7  History of Cell Discovery: Leeuwenhoek In 1673, Anton van Leeuwenhoek was the first to view a live cell. He looked at a pond water sample with a simple, handheld microscope. (He also looked at scrapings from his teeth…) 8  History of Cell Discovery: Schleiden & Schwann In 1838, a German botanist, In 1839, a German zoologist, Matthias Schleiden concluded Theodore Schwann that all plants were made of concluded that all animals cells were made of cells 9 History of Cell Discovery: Virchow…or Remak? In 1855, Dr. Rudolph Virchow observed cells dividing (using a microscope, of course) Historians argue that Robert Remak actually made this observation… Virchow “borrowed” without permission Led to the hypothesis that all cells come from other pre-existing cells. 10  Cell Theory (Review) 1. All living things are made of cells. 2. Cells are the basic unit of structure and function in an organism 3. Cells come from the reproduction of existing cells (cell division). 11 Outline Cell Basics and History Cell Types Cell Parts (Organelles) Evolution of Eukaryotes 12 Cell types and characteristics 13  Life is organized into two basic groups. Prokaryotes Eukaryotes 14  Life is organized into two basic groups. Prokaryotes Eukaryotes No membrane-bound organelles Have membrane- Not even a nucleus! bound organelles Bacteria cell 15 Prokaryotes Lack a nucleus and other membrane-bound organelles Simplest type of cell First to evolve! Single circular chromosome 16  Structure of prokaryotic cells Nucleoid region (center) contains the DNA Surrounded by cell membrane & cell wall Contain ribosomes (no membrane) in their cytoplasm to make proteins 17  Eukaryotic cells More complex than prokaryotic cells Have a nucleus and other membrane-bound organelles Includes protists, fungi, plants, animals, and a few other interesting characters 18  Structure of eukaryotic cells Contain 3 basic cell structures: 1. Nucleus 2. Cell Membrane 3. Cytoplasm with organelles 19 We will focus on these two eukaryotic cell types… Plant Cell Animal Cell 20  Variation in size Cell size varies Bacteria: 0.1 – 5 µm Animal: 10 – 30 µm Plant: 10 – 100 µm Prokaryotes Eukaryotes < < Bacteria Animal Plant 21 Variation in size Cell size varies Bacteria: 0.1 – 5 µm Animal: 10 – 30 µm Plant: 10 – 100 µm 22 Variation in size 23 Why are cells small? Nutrients, gases, and waste are exchanged at the cell’s membrane. As the cell grows, volume increases faster than surface area. Change from 1 to 3 µm 9x 27.3x If cell volume becomes too large, the relatively smaller surface area cannot transport enough nutrients in and waste out! So, cell size is limited by the ratio of surface area to volume! 24 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. 25 Multicellular organisms Cells in multicellular organisms often specialize (take on different shapes & functions) 26  Cell specialization Cells in a multi-cellular organism become specialized by turning different genes on and off This is known as DIFFERENTIATION 27 Specialized Animal Cells Muscle cells Red blood cells Cheek cells 28  Specialized Plant cells Guard Cells (For gas exchange) Pollen Xylem cells (Moves water and dissolved nutrients upward) 29 Outline Cell Basics and History Cell Types Cell Parts (Organelles) Evolution of Eukaryotes 30 Cell parts 31 What are organelles? Specialized structures within a living cell Perform various specialized functions Found in cytoplasm 32 What are organelles? Specialized structures within a living cell Perform various specialized functions The nucleus is surrounded by a membrane. Found in cytoplasm May or may not be membrane-bound The ribosome has no membrane. 33  Animal cell organelles Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Rough Smooth endoplasmic endoplasmic reticulum reticulum Centrioles Golgi apparatus 34 Plant cell organelles 35  Organelle index: Basic function Organelles Structure Cell membrane, cell wall, cytoplasm, cytoskeleton It’s all in the genes Nucleus (nuclear envelope, nucleolus), centrioles Energy Mitochondria, chloroplasts Manufacturing, distribution, Endoplasmic reticulum, ribosome, Golgi and breakdown apparatus, lysosomes, vacuoles Movement Cilia, flagella 36  Cell membrane A cell’s membrane or surrounding layer Remember the phospholipid bilayer! Acts as gateway to the cell (creates balance or homeostasis) 37 Cell junctions (connections between cells) “Watertight seal” Plasma membranes of neighboring cells are connected firmly by proteins Flexible seal Held together by protein fibers in the cytoplasm, allow for some water/small molecules to pass through Communication stations Protein channels that allow small molecules to pass from cell to cell 38  Cell Wall Cell wall Nonliving layer, found outside of the cell membrane Supports and protects the cell Found in plants, fungi, & bacteria Made of Cellulose in plants Peptidoglycan in bacteria Chitin in Fungi 39  Cytoplasm Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place Contains organelles Found in ALL cells 40  Cytoskeleton Helps cell maintain cell shape Also helps move organelles around Made of proteins Three basic types: 41  Organelle index: Basic function Organelles Structure Cell membrane, cell wall, cytoplasm, cytoskeleton It’s all in the genes Nucleus (nuclear envelope, nucleolus), centrioles Energy Mitochondria, chloroplasts Manufacturing, distribution, Endoplasmic reticulum, ribosome, Golgi and breakdown apparatus, lysosomes, vacuoles Movement Cilia, flagella 42 The Nucleus: The Control Organelle Bounded by nuclear envelope (membrane) with pores Contains DNA in chromosomes Each cell has a fixed number of chromosomes that carry genes Controls normal activities of the cell Genes control cell characteristics 43 Nuclear Envelope Double membrane surrounding nucleus Also called nuclear membrane Contains nuclear pores for materials to enter & leave nucleus Connected to the rough endoplasmic reticulum (ER) Nuclear pores 44 Inside the Nucleus… The genetic material (DNA) is found DNA is spread out DNA is condensed & wrapped And appears as CHROMATIN around proteins forming in non-dividing cells as CHROMOSOMES in dividing cells 45 What Does DNA do? DNA is the hereditary material of the cell Genes that make up the DNA molecule code for different proteins 46  Nucleolus Inside nucleus Cell may have 1 to 3 nucleoli Disappears when cell divides Makes ribosomes AKA protein-making machines 47 48 Centrioles Found only in animal cells Paired structures near nucleus Made of bundle of microtubules Appear during cell division Help to pull chromosome pairs apart to opposite ends of the cell 49 50  Organelle index: Basic function Organelles Structure Cell membrane, cell wall, cytoplasm, cytoskeleton It’s all in the genes Nucleus (nuclear envelope, nucleolus), centrioles Energy Mitochondria, chloroplasts Manufacturing, distribution, Endoplasmic reticulum, ribosome, Golgi and breakdown apparatus, lysosomes, vacuoles Movement Cilia, flagella 51  Mitochondrion (plural = mitochondria) Power plant of the cell Generates cellular energy (ATP) by breaking down glucose Process is called cellular respiration 52  Mitochondrion (plural = mitochondria) Power plant of the cell Generates cellular energy (ATP) by breaking down glucose Process is called cellular respiration More active cells like muscle cells have MORE mitochondria Both plants & animal cells have mitochondria 53 Structure of mitochondria Surrounded by a double membrane Contain their own DNA Folded inner membrane, called cristae Increases surface area for chemical reactions Interior is called the matrix 54 Fun Fact: Mitochondria come from cytoplasm in the EGG cell during fertilization Therefore … You inherit your mitochondria from your mother! 55 56  Chloroplasts Found only in organisms that photosynthesize (e.g. plants, algae) Use energy from sunlight to make own food (glucose) = PHOTOSYNTHESIS Energy from sun stored in the chemical bonds of sugars Contain their own DNA Contain pigments and enzymes required for photosynthesis 57  Chloroplast structure Surrounded by DOUBLE membrane Smooth outer membrane Inner membrane modified into sacs called Thylakoids Thylakoids are arranged in stacks of interconnected grana Stroma = gel-like material surrounding thylakoids 58 59  Organelle index: Basic function Organelles Structure Cell membrane, cell wall, cytoplasm, cytoskeleton It’s all in the genes Nucleus (nuclear envelope, nucleolus), centrioles Energy Mitochondria, chloroplasts Manufacturing, distribution, Endoplasmic reticulum, ribosome, Golgi and breakdown apparatus, lysosomes, vacuoles Movement Cilia, flagella 60 Endoplasmic Reticulum (ER) Network of hollow membrane tubules Connects to nuclear envelope and cell membrane Functions: Synthesis and transport of cell products (e.g. proteins, lipids) Two types: Rough ER and Smooth ER 61 Rough Endoplasmic Reticulum (ER) Has ribosomes on its surface After production by ribosomes, proteins enter the Rough ER to be modified and transported 62 63 Smooth Endoplasmic Reticulum (ER) Smooth ER lacks ribosomes on its surface Is attached to the ends of rough ER Makes cell products that are used inside the cell Functions of the smooth ER: Synthesis of lipids Regulates calcium (muscle cells) Destroys toxic substances (liver cells) 64 65 Ribosomes Made of PROTEINS and rRNA (ribosomal RNA) “Protein factories” for cell Join amino acids to make proteins Process called protein synthesis 66  Ribosome location Can be attached to Rough ER Be free in the cytoplasm Produce proteins that are OR Produce proteins that are used in exported from the cell the cell 67 68  Golgi Apparatus CIS Stacks of flattened sacs (think pancakes!) The cell’s packaging plant Modifies, sorts, and packages molecules from the ER for storage or TRANS for transport out of the cell Transport vesicle Has a receiving side (cis face) and a shipping side (trans face) Transport vesicles with modified proteins pinch off the ends 69  Golgi Apparatus Animation Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES 70 71  Lysosomes: The cell’s recycling centers Membrane-enclosed sacs of digestive enzymes Break down food, bacteria, and worn out cell parts for cells Lyse (break open), fuse with a vesicle or vacuole, and release enzymes to break down food or recycle cell parts Figure 4.10 72  Vacuoles Fluid filled sacks for storage Large vacuoles found in plant cells Small or absent in animal cells (e.g. food vacuoles) No vacuoles in bacterial cells Store “cell sap” Sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes 73 74 Endomembrane System Series of membranes, which aid in the transport, modification, and storage of molecules Includes nuclear envelope, ER, Golgi apparatus, vesicles, cell membrane, lysosomes, and vacuoles Knowledge checkpoint: Can you describe the pathway of a protein made inside the cell? 75  Organelle index: Basic function Organelles Structure Cell membrane, cell wall, cytoplasm, cytoskeleton It’s all in the genes Nucleus (nuclear envelope, nucleolus), centrioles Energy Mitochondria, chloroplasts Manufacturing, distribution, Endoplasmic reticulum, ribosome, Golgi and breakdown apparatus, lysosomes, vacuoles Movement Cilia, flagella 76 Cilia & Flagella: The cell’s wiggly bits Cilia: short and numerous Flagella: long with only 1 – 3 found on cell Made of protein tubes called microtubules Functions: Cell locomotion (movement) and moving small particles across cell’s surface 77 Cell Movement with Cilia & Flagella 78 Example: Cilia Moving Away Dust Particles from the Lungs 79  Organelle index: Basic function Organelles Structure Cell membrane, cell wall, cytoplasm, cytoskeleton It’s all in the genes Nucleus (nuclear envelope, nucleolus), centrioles Energy Mitochondria, chloroplasts Production, modification, Endoplasmic reticulum, ribosome, Golgi and transport apparatus, lysosomes, vacuoles Movement Cilia, flagella 80 Outline Cell Basics and History Cell Types Cell Parts (Organelles) Evolution of Eukaryotes 81 One more thing… How did we evolve from here? 82  Let’s talk about evolution…. The first life on earth was a unicellular prokaryote. Now, we have multicellular eukaryotes with membrane-bound organelles and specialized functions. 83  Endosymbiosis Endosymbiotic theory explains the origin of membrane-bound organelles, particularly mitochondria and chloroplasts 84 Endosymbiosis 85