7.1 Life is Cellular

The Cell Theory  All living things are composed of cells.  Cells are the basic unit of structure and function in living things.  New cells are produced from existing cells.

Discovery of the Cell  England- In1665, Robert Hooke observed the first cork cells under the microscope Reminded him of a monastery's tiny rooms  Holland- In 1674, Anton van Leeuwenhoek observed microorganisms in pond water

Exploring the Cell  Variety of shapes & sizes From tiny bacteria (0.2 μm) to large amoeba (1,000 μm)  All are surrounded by a cell membrane and contain DNA

Prokaryotes & Eukaryotes  Nucleus- large membrane- enclosed structure that contains the cell’s genetic material (DNA) Prokaryotes- do not contain nuclei Eukaryotes- contain nuclei

Prokaryotes  Genetic material not contained in the nucleus  Carry out every activity associated with living things Grow, reproduce, respond to stimuli

Eukaryotes  Genetic material is separated into nucleus  Generally more complex and larger than prokaryotic cells  Examples: Plants, animals, fungi, and protists

7.2 Eukaryotic Cell Structure

Comparing the Cell to a Factory  Organelles- “little organs”; specialized functions  Two Major Parts: Nucleus Cytoplasm- portion of the cell outside the nucleus

Nucleus  Control center; “office”  Nuclear envelope  Chromatin- protein bound DNA  Chromosomes- condensed chromatin  Nucleolus- assembly of ribosomes

Ribosomes  Protein synthesizing “machine”  Makes proteins using coded instructions from the nucleus  Found throughout the cytoplasm

Endoplasmic Reticulum  Internal membrane system; “transport”  Lipid components of the cell membrane are assembled  Rough ER- ribosomes on surface; produce proteins for export  Smooth ER- contains enzymes responsible for cell detox

Golgi Apparatus  Modifies, sorts, and packages proteins made in the Rough ER  Like a “customization shop” preparing proteins for shipment

Lysosomes  Recycles worn out cellular products; “Clean Up Crew”  Small organelles filled with enzymes  Breaks down lipids, carbs, and proteins for use elsewhere in the cell

Vacuoles  Saclike structures; Cell “storage”  Assists in maintaining homeostasis inside the cell

Mitochondria & Chloroplast  Produce energy for the cell; “powerhouse”  Contain their own DNA  Mitochondria- convert chemical energy stored in food into compounds the cell can use  Chloroplast- capture energy from sunlight and transform it into chemical energy photosynthesis

Cytoskeleton  Supports the cell; maintains shape  Network of protein filaments  Also involved in movement Microfilaments ○ Cilia ○ Flagella  Microtubules Centrioles- aid in cell division in animal cells

7.3 Cell Boundaries

The Cell Membrane  Regulates what enters and leaves the cell  Provides protection and support  Semipermeable  Made up of a lipid bilayer

Lipid Bilayer  Lipids are made up of 2 parts: 1. Hydrophobic layer 2. Hydrophilic layer  Contains proteins throughout  Carbohydrate molecule chains attached to the proteins

Types of Transport  Passive Transport  Does NOT require energy  Types: 1. Diffusion 2. Facilitated Diffusion  Active Transport  DOES require energy

Diffusion  Causes many substances to move across a cell membrane but does not require the cell to use energy  Solutions move from high concentration to low concentration

Special Type of Diffusion: Osmosis  The diffusion of water through a selectively permeable membrane

Osmosis – Isotonic Solution

Osmosis – Hypotonic Solution

Osmosis – Hypertonic Solution

Osmosis

Facilitated Diffusion  Molecules move from high concentration to low concentration through proteins in the cell membrane

Active Transport  Materials move from low concentration to high concentration

Active Transport - Endocytosis  The process of taking large amounts of material into the cell by means of infoldings, or pockets, of the cell membrane

Active Transport – Endocytosis: Phagocytosis A form of endocytosis in which large particles are taken in to the cell

Active Transport - Exocytosis  The removal of large amounts of material from a cell

7.4 The Diversity of Cellular Life

Unicellular Organisms  Sometimes a cell IS an organism.  They do everything an organism would do Grow Respond Transform energy Reproduce  Dominant form of life on Earth

Multicellular Organisms  Animals and Plants Cell Specialization- c ells develop in different ways to perform different tasks

Levels of Organization  In order of increasing complexity Cells Tissues Organs Organ Systems

Levels of Organization  Tissues- g roup of similar cells that perform a particular function  Types in Animals Muscle Epithelial Nervous Connective

Levels of Organization  Organs- groups of tissues that work together to perform closely related functions

Levels of Organization  Organ Systems- group of organs that work together to perform a specific function