Chapter 11 The Cell: Basic Unit of Life

Why do we study cells? 2005-2006

Cell Theory All organisms are made up of cells The cell is the basic living unit of organization for all organisms All cells come from pre-existing cells 2005-2006

Activities of life Most everything you think of a whole organism needing to do, must be done at the cellular level… reproduction growth & development energy utilization response to the environment homeostasis

Cell Maintenance Every cell wants to maintain homeostasis Homeostasis- “same state”- it is the condition in which a cell’s (or organism’s) environment remains stable/constant for that particular organism pH, temperature, water concentration, light, etc

Organelles All cells contain smaller parts that have particular jobs to help the cell exist These smaller parts are called organelles “little organs”

Organelles Cell Wall- present only in plant cells Serves as a protective barrier and to aid in the plant’s structure (support)

Organelles Cell membrane Exchange organelle Cell membrane functions as selective barrier allows passage of O2, nutrients & wastes 2005-2006

Organelles Cell Membrane is made up of a lipid bilayer The heads are hydrophilic- “water loving” Located on both the inside and outside of cell The tails are hydrophobic- “water fearing”

Cell Membrane The selectively permeable cell membrane allows the transport of some materials into and out of the cell 2 types of transport Active Transport- this requires the cell to use its own energy to move materials into and out of the cell. This usually occurs with larger particles.

Cell Membrane Passive Transport- this type of cellular transportation does not require the cell to use its own energy to move materials into or out of the cell. Diffusion- the movement of particles from an area of higher concentration to an area of lower concentration *OSMOSIS- diffusion through a semi-permeable membrane- the semi-permeable membrane is the cell membrane

Organelles Cytoplasm: jelly-like fluid inside the cell; surround organelles and aiding in transporting substances through cell

Organelles Mitochondria: the cell’s “power plant” They create all of the energy for the cell Animal cells and plant cells have many

Organelles Endoplasmic Reticulum (ER)- It surrounds the nucleus and connects it to the cell membrane through the cytoplasm. It is the passageways through the cell. 2 types Smooth ER- passageways Rough ER passageways with ribosomes attached to the outside

Organelles Ribosomes- responsible for making proteins, they put proteins together Proteins- are needed by the cell to make DNA, and acts as enzymes to regulate cellular reactions

Organelles Golgi Apparatus- take the proteins made by the ribosomes and pack them up and carry the proteins where they are needed FedEX, UPS, Postal Service (USPS)

Organelles Vacuoles- storage center stores food, water and other nutrients the cell may need to be released as required by the cell Some vacuoles store waste products, some store water Animal cells have several vacuoles (each storing different materials, specialized) Plant cells have one large vacuole (storing mostly water; remember choloroplasts store food and plant cells do not have much waste)

Organelles Lysosome- digestive system of the cell. Breaks down foreign substances and disposes of the waste Breaks down by products of cellular substances that the cell no longer needs and either recycles it to be used again or disposes as waste Break down bacteria and viruses to keep the cell healthy Kill bacteria and viruses

Organelles Chloroplasts- only present in plant cells Responsible for making food for the plant in the form of sugar Photosynthesis- uses water and carbon dioxide with sunlight to make sugar and oxygen Chloroplasts contain chlorophyll- green pigment that stores sunlight energy (solar panels)

Organelles Movement Organelles Cilia- small hair-like organelles responsible for aiding the cell in moving Usually many Flagella- long whip-like organelles responsible for aiding cell in movement Usually 1, maybe 2

Organelles Nucleus- the “brain of the cell” Controls the activities of the cell Contain chromosomes which are composed of DNA and other molecules DNA is the genetic material that gives an organism its characteristics

Plant Vs Animal Cells

2005-2006