Cell Structure and Function Chapter 7 Cell Structure and Function

The History of the Cell Theory and Microscopes Section 7-1 The History of the Cell Theory and Microscopes

Historical View of the Cell Theory As science improves, so do improvements in scientific instruments, and improved scientific instruments lead to new discoveries.

1590 – Zacharias Janssen Built first simple microscope (one set of lenses)

1670’s Anton Van Leeuwenhoek Made improvements 270x magnification Saw bacteria, protozoa, sperm cells, red blood cells and yeast cells

1665 – Robert Hooke Produced a compound microscope Saw hollow boxes and named them “cells”

1665 – Robert Hooke

1831 – Robert Brown Saw central structure in plant cells, called this structure a nucleus

1838 – Theodore Schwann Concluded that all animals are made of cells

1838 – Matthias Schleiden Concluded that all plants are made of cells

1839 – Johannes Purkinje Stated that “the cell is the unit of function of life”

1858 – Rudolf Virchow Concluded that “ cells come only from previously existing cells”

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

Prokaryotes and Eukaryotes Section 3-2 Prokaryotes and Eukaryotes

Eukaryotes Have a nucleus and membrane covered organelles

Prokaryotes Don’t have a nucleus and membrane covered organelles

Eukaryotic Cell Structures

Plasma Membrane Separates the cell from its environment Controls the transport of materials in and out Allows some materials but not others to pass through this is called… Selectively permeable

Endoplasmic Reticulum Extensive network of tube-like structures that forms a passageway that functions in the transport of materials throughout the cells

Ribosomes Site of protein synthesis Attached to the walls of the ER or move freely in the cytoplasm

Golgi Bodies Stack of tiny, flattened sac-like tubes used in secretion Package protein molecules in a membrane and send the package to the cells surface

Mitochondria Where cellular respiration takes place to release energy “Mighty Mitochondria” Powerhouse of the cell

Microtubules Tubes that serve as support for the cell

Microfilaments Thin threads attached to the cell membranes, play a role in movement

Lysosomes Vesicles that contain enzymes used in digestion Fuses with food vacuoles to digest food into smaller pieces Digest old cell structures to dispose of them or even entire cells

Nucleus Regulates all the cells activities

Chromosomes Long coiled fibers that carry the material of heredity Made of protein and DNA

Nucleolus Composed of RNA Involved in the passage of RNA into the cytoplasm

Centrioles Small cylinders in the cytoplasm that play a role in cell division

Cilia

Flagella

Chloroplasts Organelle found only in plants, used to make food

Vacuoles Spherical, bubble-like storage sacs Plant cells have very large vacuoles compared to animal cells

Cell Wall Rigid structure that surrounds the cell membrane Made of cellulose Permits most things to pass through Cell Wall

Section 3-3 Cellular Processes

The Big Idea Cells need to regulate the movement of dissolved molecules on either side of the membrane

Cell membrane Regulates what enters and leaves the cell and also provides protection and support Outside of cell Inside (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains

Cell membrane Made of a double layered sheet called a lipid bilayer Outside of cell Inside (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains

Cell Wall Provide support and protection for cell Found in more than just plants Contrary to popular belief, not selectively permeable

Cell Walls

Diffusion Through Cell Boundaries One of the more important functions of the cell membrane is to regulate the movement of dissolved molecules from one side of a membrane to the other

Concentration The mass of solute in a given volume of solution Mass/volume

What is the concentration of 12 grams of salt in 3 liters of water?

In a solution, particles move constantly

Diffusion Process by which molecules of a substance move from areas of high concentration to areas of low concentration

Diffusion

Diffusion

Equilibrium When the concentration of the solute is the same throughout a system

Because diffusion depends on random particle movements, substances diffuse across membranes without energy being used Even during equilibrium, particles still move, but there is no net change in concentration

Osmosis The diffusion of water

Osmosis

Isotonic The concentration of solutes is the same inside and outside the cell

Hypertonic Solution has a higher solute concentration than the cell

Hypotonic Solution has a lower solute concentration than the cell

Facilitated Diffusion Movement of specific molecules across cell membranes through protein channels Only go from high concentrations to low concentrations Does not require energy Glucose molecules High Concentration Cell Membrane Low Concentration Protein channel

Types of Active Transport Sometimes cells must move materials in the opposite direction Low concentrations to high concentrations

Active Transport Energy requiring process that moves materials across a cell membrane against a concentration gradient

Active Transport Molecule to be carried Molecule being carried Energy

Molecular transport Small molecules and ions are actively transported

Carrier proteins Proteins that act like pumps

Endocytosis The process of taking material into the cell by means of infolding of the membrane Forms a vacuole Food particle engulfing

Phagocytosis Cell eating White blood cells do this

Pinocytosis Cell drinking

Exocytosis Forces contents out of the cell Endocytosis in reverse

The Diversity of Cellular life Section 3-4 The Diversity of Cellular life

Unicellular Organism Single celled Do everything a living organism does

Multicellular Organism Many celled Depend on communication and cooperation among specialized cells

Specialization When cells develop in different ways to perform different tasks

Red Blood Cells Transport oxygen

Pancreatic Cells Make proteins Packed with ribosomes

Skeletal Muscle Generate force Packed with mitochondria Overdeveloped cytoskeleton

Nerve Cell Send messages

Guard Cells Open and close the stomata

Levels of Organization Cells Tissues Organs Organ Systems

Tissues Group of similar cells that perform specific function Ex.) smooth muscle

Organ Group of tissues that work together to perform a specific function Ex.) stomach

Organ System Group of organs that work together to perform a specific function Ex.) digestive system This organization creates a division of labor that makes multicellular life possible

Biological Organization