THE CELL The Smallest Unit of Life Alison

THE CELL The Smallest Unit of Life Alison Birkmeyer 1 Copyright 1996 -2001 © Dale Carnegie & Associates, Inc.

THE CELL THEORY • Observations by the following three people formed the cell theory. • Schleiden- plants • Schwann – animals • Virchow - cells come from other cells 2

CELL THEORY 1. All Living Things are made up of one or more cells. 2. Cells are the basic units of structure and function in organisms. 3. All cells arise from preexisting cells 3

Looking at cells • Robert Hooke – 1 st to see cells. (cork) • Anton van Leeuwenhoek – living creatures (animalcules) Two types of microscopes • Compound LIGHT - uses light and two or more lenses. • Electron – uses a beam of electrons. 4

Compound Light • Uses two or more lenses • Uses light • Low magnification • View living or dead specimens • Magnification= ocular lens X objective lens. ex. Ocular = 10 x ; obj. lens = 10 x Total magnification = (10 X 10) = 100 x 5

Electron Microscope • Uses a beam of electrons • Specimens must be placed in a vacuum • Cannot be used to view living things. • Very powerful magnification • Two types of electron microscopes are Transmission and Scanning 6

CELL SIZE • Surface are is an important factor in limiting cell growth because The cell may become too large to take in enough food and to remove enough waste. 7

Common Features of ALL Cells • Cell Membrane • Cytoplasm • Ribosomes • Cytoskeleton • DNA 8

Cell Types • Prokaryote • Eukaryote 9

Prokaryote • Functions are controlled by the DNA Plasmid not the nucleus (NO NUCLEUS) • Modern prokaryotes (most or majority) are generally known as BACTERIA 10

Prokaryote • No internal membrane bound organelles • Do NOT have a nucleus • Oldest cell types –Their evolution preceded that of eukaryotes • Most are unicellular bacteria • Ex. Old Kingdom Monera (BACTERIA) 11

EUKARYOTE • All other organisms (except bacteria) are eukaryotes • The cells of Animals; Plants, Fungus, Protists are Eukaryotic (you are an Eukaryotic) • Specialized structures called organelles that perform a specific function • Only eukaryotic cells have membrane bound organelles 12

EUKARYOTE • A cell with a well defined nucleus surrounded by a nuclear envelope is an EUKARYOTE • EUKARYOTE cells have a system of internal membranes 13

CELL MEMBRANE • Gate keeper- Allows materials to enter and leave • Structure that regulates what enters and leaves the cell • All substances that enter or leave a cell must cross the cell membrane • Is selectively permeable – allows only some things to pass in or out. • Encloses the contents of the cell 14

CYTOSKELETON • Provides the internal framework of a cell • Mesh like network of protein fibers that supports the shape of the cell • Microtubules – highway system • Microfilaments - support structures 15

CYTOPLASM • Gel-like substance found within the cell • Supports the cell • Region of the cell within the membrane that includes the fluid; cytoskeleton; and all of the organelles except the nucleus 16

CELL ORGANELLES (Know ALL of these & functions) 1 Nucleus 2 Ribosomes 3 Endoplasmic Reticulum (rough and smooth) 4 Golgi apparatus 5 Lysosome 9. Chromosomes 6 Mitochondria 10. DNA 7 Vesicle or Vacuole 11. Cell Wall 8 Centrioles 12. Plastids 17

NUCLEUS • The nucleus houses a cell’s DNA, which contains heredity information. • DNA stores information that directs the activities of the cell • Has a double membrane surrounding the nucleus called the nuclear envelope 18

NUCLEUS • Contains chromosomes • Chromosomes are rod shaped structures that are made up of DNA and protein 19

RIBOSOMES • Site of PROTEIN synthesis in a cell • In the cell, proteins are made on the RIBOSOMES • Free (found floating in the cytoplasm • Attached (attached to ER) 20

ENDOPLASMIC RETICULUM • Helps to maintain homeostasis by moving substances from one parts of the cell to another • Rough ER has RIBOSOMES embedded on its surface. • Smooth ER has no ribosomes embedded 21

Golgi Apparatus • Packaging and distribution center of the cell 22

LYSOSOME • Organelle that contains digestive enzymes that breaks down cellular materials (CHO; proteins, nucleoc acids, lipids, etc…) • Referred to as a suicide sac • Waste management system • Digests and recycles cellular components 23

MITOCHONDRIA • POWER HOUSE (ENERGY) • Mitochondria contain DNA • Produces most of the cell’s energy • Stores this energy in cpds called ATP • More energy requirements – more mitochondria • Ex. Muscle cells have more that skin cells 24

CHLOROPLASTS (PLANTS) • Use light energy to make CHO (sugar) Glucose. • The main organelle associated with plant photosynthesis. • Site of Photosynthesis • Contain their own DNA • Thought to be descendants of prokaryotic cells. 25

CELL WALL • NOT FOUND IN ANIMAL CELLS • Support and protection for plants, bacteria, and fungi 26

CILIA and FLAGELLA • Cilia – shorthair like structures that protrude from the surface of a cell and are packed in tight rows (movement) • Flagella – long whip like structure used for movement 27

Major differences between PLANT and ANIMAL cells • PLANT: has the following – Chloroplasts/Chlorophyll – Large central vacuole – Cell Wall = made of cellulose – Plant cells are surrounded by a CELL WALL • PLANT: do NOT have – Centrioles 28

Animal Cells vs Plant cells KNOW • Animal cells do NOT have a cell wall • Animal cells do NOT have Chloroplasts • Animal cells do NOT have a central vacuole – they have smaller vesicles • Animal cells have Centrioles 29

What identifies a cell as an Eukaryote? – The nucleus • Chromosomes are found in the? – NUCLEUS • Recognize an animal cell because(Main Reasons? – NO CELL WALL – NO CHLOROPLAST 30

DRAW and LABLE ANIMAL CELL 1. Nucleus 7. Nuclear Membrane 2. Mitochondria 8. Cytoplasm 3. ER 9. Chromosomes (DNA) 4. Lysosome 10. Ribosomes 5. Golgi Apparatus 6. Cell Membrane 31

DRAW and LABLE PLANT CELL 1. Nucleus 9. Nuclear Membrane 2. Central Vacuole 10. Ribosomes 3. Cell Wall 11. Golgi Body 4. Cell Membrane 5. ER 6. Chloroplast 7. Mitochondria 8. Chromosomes (DNA) 32