Chapter 7 Cell Structure and Function

Cell Theory All living things are made of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells

How do we see cells? The microscope: Light microscope Produce magnified images by focusing visible light rays Magnifies up to 1,500 X using visible light Electron microscope Produce magnified images by focusing beams of electrons Magnifies up to 1,500,000 X using electrons Traditionally require a vacuum to operate, cannot see living cells

How Big are Cells? Cells come in a large variety of shapes and sizes Most are between 5 and 50 micrometers

Two Major Cell Types Prokaryotes Very small cells WITHOUT a nucleus Bacteria

Two Major Cell Types Eukaryotes Larger more complex cells with one or more nuclei Everything not bacteria

Two Major Cell Types

Parts of the Cell Cytoplasm Nucleus Ribosomes Endoplasmic reticulum (ER)- rough and smooth Golgi apparatus Lysosomes (and vacuoles) Mitochondria Cytoskeleton and Centrioles Cell membrane and cell wall Specialized parts (chloroplasts, cilia, flaggella)

The Parts of the Cell Organelles are the membrane bound structure in a eukaryote that carries out some function for the cell. Ex. nucleus and mitochondria Cytoplasm is the gel-like substance outside the nucleus

The Nucleus A large membrane-enclosed structure containing DNA

The Nucleus DNA appears granular most of the time and is called chromatin; it condenses to form chromosomes during cell division Two major parts of the nucleus Nuclear envelope is a double membrane with pores that surrounds the nucleus Nucleolus is the dense region of the nucleus where ribosomes are made (most nuclei have a nucleolus)

Ribosomes Ribosomes are the small particles of RNA and protein where proteins are made in the cell

The Endoplasmic Reticulum (ER) The ER is the site where lipid parts of the cell membrane are assembled, as well as proteins and other materials that are exported from the cell Two types: Rough ER has ribosomes and functions in protein production (synthesis) Smooth ER has no ribosomes and functions in lipid production or detoxification

The Endoplasmic Reticulum (ER)

The Golgi Apparatus The Golgi functions to modify, sort, and package proteins and other materials for storage in the cell or secretion from the cell

The Golgi Apparatus

Mitochondria Mitochondria helps convert food energy into cellular energy

Lysosomes and Vacuoles Lysosomes are enzyme filled organelles that function to digest food for the cell and to get rid of old organelles Vacuoles are important in storage (water, salts, proteins, carbs)

Chloroplasts Chloroplasts capture energy from sunlight and convert it into chemical energy

Cytoskeleton and Centrioles Cytoskeleton is the network of protein filaments that maintain the cell’s shape and aid in movement Centrioles help organize cell division (not found in plants)

Cilia and Flagella Cilia are short projections made from the microtubules that function in movement Flagella are long projections from the microtubules that function in movement

Cell Wall Provides support and protection in bacteria, plants, fungi, and some Protists (Not Animals) Made of cellulose in plants

Cell Wall

Cell Membrane (Plasma membrane) The cell membrane regulates what enters and leaves the cell and also provides protection and support Found in all cells and made of phospholipids

Diffusion and the Cell Membrane Diffusion is the movement of particles from an area of higher concentration to lower concentration Requires NO energy

Diffusion and the Cell Membrane Concentration is the mass divided by the volume (mass/volume) grams/mL, or g/cm3 Osmosis is the diffusion of water through a selectively permeable membrane

Diffusion and the Cell Membrane

Diffusion and the Cell Membrane Isotonic solution is one that the concentrations are the same on both sides of the membrane Hypertonic solution is the more concentrated solution (more sugar molecules) Hypotonic solution is the less concentrated solution (less sugar molecules) Water will net diffuse to the side that is more concentrated

Diffusion and the Cell Membrane

Diffusion and the Cell Membrane

Diffusion and the Cell Membrane Facilitated diffusion is the diffusion through protein channels without using energy

Diffusion and the Cell Membrane Active transport is the movement of particles that requires energy Passive transport is the movement of particles without using energy

Diffusion and the Cell Membrane

Diffusion and the Cell Membrane Endocytosis takes material into a cell by engulfment (requires energy); a vacuole forms on the inside of the cell after engulfment Phagocytosis takes food or solid particles into the cell Pinocytosis takes liquid into the cell Exocytosis releases material from a cell (requires energy)

Diffusion and the Cell Membrane

Unicellular vs. Multicellular Unicellular organisms is an organism made of one cell. Examples: Bacteria and many Protists Multicellular organisms is an organism made of many cells that are specialized

Cell Differentiation (Specialization) Cell differentiation occurs when cells develop in alternative ways to perform different tasks Go Go Stem Cells Example: Red blood cells are specialized to transport oxygen. Pancreatic cells produce certain proteins. Guard cells in plants open and close the stomata Stem cell animation

Organization of Life Cell- collection of living matter enclosed by a barrier; basic unit of life Tissues- group of similar cells that perform a particular function Organ- many group of tissues that work together to function as an organ Organ system- a group of organs that work together perform a specific function, like digestion

Organization of Life