Cell Structure and Function Chapter 7 Cell Structure and Function

What does it mean to be alive? Ability to grow and develop Ability to reproduce Ability to adapt to the environment Have structure Chapter 1 review

Components of 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 already existing cells

Microscopes First microscopes were single lens (think of glasses) Compound microscope (multiple lenses) Limited on detail and resolution because light is scattered as it passes through matter Electron Microscope – beam of electrons is aimed at the cell Electrons are not easily scattered 1000x resolution of best light microscope Limitation – subject can’t be alive since it is done in a vacuum

Two Types of Cells Prokaryote Eukaryote

Prokaryote Bacteria and other simple cell organisms Very basic cells with no membrane bound organelles DNA is not separate from the rest of the cell Maximum size of bacteria is about 0.001 mm (1 m)

Eukaryote Complex unicellular organisms and all multicellular organisms Cells that contain membrane bound organelles The DNA is separated from the rest of the cell by a nucleus Maximum size is 0.1 mm (100 m)  larger than prokaryotes

Quick Check Classify each as eukaryotic or prokaryotic Human Bacteria Algae Mold Virus

Cell Structure and Function

Organelle Translates to mean “little organ” A structure inside a cell that has a specialized function Machinery of a cell Ex: Nucleus, chloroplast, cell wall

Cell Membrane Found in plant and animal cells Function: Protection Allows molecules to pass through Semipermeable: only certain molecules can pass through

Cell Wall Made of cellulose or chitin Found only in plants, fungus, bacteria, and some protists. Function: Provide support

Cytoplasm Fluid that surrounds the organelles and fills the cell Function: Provide a medium for chemical reactions to occur

Nucleus “Brain” of the cell Function: Found in Nucleus: Control the activity of the cell Store genetic information (DNA) Found in Nucleus: Chromatin – structure of DNA DNA/Genes – the genetic message used to make proteins

Nucleolus Function: Found within the nucleus Where the ribosomes are made

Ribosomes One of the few organelles also found in prokaryotic cells Not membrane bound Function: Makes proteins according to RNA RNA (ribonucleic acid) – carries the instructions for making protein from DNA in nucleus to the ribosome

Mitochondria The “powerhouse” of the cell Present in all eukaryotic cells Function: Site of cellular respiration Production of energy for cell Glucose  CO2 + water + energy

Chloroplast Found only in plant cells and some protists Contain green pigment called chlorophyll Function: Site of photosynthesis Produces sugar from carbon dioxide, water, and light energy

Endoplasmic Reticulum Two types – rough and smooth Rough E.R.: Has “bumpy” look because of the presence of ribosomes Function: produce and transport proteins Smooth E.R.: Looks smooth, no ribosomes Function: produce and transports lipids

Golgi Apparatus Flattened membrane sacs Function: Packages, modifies, and transports the protein for specific uses Produces vesicles (transport) and lysosomes (contains enzymes)

Vacuole Plants have large permanent vacuoles Animals have smaller temporary vacuoles Function: Storage of materials such as water, salts, proteins, lipids, carbohydrates, and waste products.

Lysosomes Sacs containing enzymes Function: Digest food and old cell parts When the cell gets worn out the lysosome will burst and digest the whole cell

Cytoskeleton Made up of microtubules and microfilaments Function: Helps maintain cell shape Responsible for many forms of cell movement including organelle movement

Movement Cilia: Flagella Short, hairlike structures that move the cell Ex. Paramecium Flagella A long threadlike structure used to propel the cell Ex. Sperm, Euglena

Levels of Organization within and Organism Cell – basic unit of life Tissue – a collection of cells that work together for a common purpose Organ – two or more tissues acting together Organ system – a group of organs that work together in a system

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