Cells

1) ALL living things are composed of cells

2) Some organisms are unicellular (one cell), others are multicellular

3) Each cell carries on all of the life functions

Cell Theory

1) A MAJOR theory in Biology

2) States that:1) Every organism is made of one or more

cells

2) The cell is the basic unit of structure and function in living things

3) All cells come from previously existing cells

Development of Cell Theory

1) Cell Theory was developed by a number of scientists:

1) 1632-1723 Anton van Leeuwenhoek made simple MS to see bacteria

2) 1635-1703 Robert Hooke made 1st CMS, used term “cells” to describe what was seen in a piece of cork

Development (cont)

1) 1831 Robert Brown 1st to see nucleus

2) 1838 Matthias Schleiden – all plants were made of cells

3) 1839 Theodor Schwann – all animals were made of cells

4) 1855 Rudolf Virchow – all cells arise from preexisting cells

Exceptions to Cell Theory

1) Mitochondria and chloroplasts (parts of cells) have DNA and can duplicate themselves within a cell

2) A virus (a DNA core encased in protein) can reproduce inside of a host cell

3) The 1st living things must have come from non-cellular matter (not from preexisting cells)

Cell Structure

1) ALL cells have specialized structures called organelles (little organs)

2) Organelles perform the life functions for the cell

Organelles of Animal Cell

1) Cell Membrane – protect cell, controls what enters and exits

2) Cytoplasm – fluid inside cell, transports materials

3) Nucleus – contains DNA (used to make proteins/enzymes to control cell)

4) Nucleolus – dark area inside nucleus, makes ribosomes

Organelles (cont)

1) Endoplasmic Reticulum – paths for transport of material (smooth and rough)

2) Ribosomes – protein synthesis, found in cytoplasm or rough ER

3) Mitochondria – site of respiration, releases energy for the cell in form of ATP (adenosine tri-phosphate). ATP is turned into ADP (di-phosphate) when energy is needed

Organelles (cont)

1) Golgi Body – synthesis, packaging & storage of cell parts and products

2) Lysosome – sacs w/ digestive enzymes (break down foods)

3) Vacuole – storage of cell waste / food4) Centriole – line up chromosomes

during cell division5) Cytoskeleton – maintains shape or

movement of cell6) Cell Models: An Interactive Animation

Plant Cell Organelles

1) Same organelles as animal except:1) No centrioles

2) Cell Wall – protects the cell, gives cell shape

3) Chloroplast – makes food for cell, photosynthesis

2) Cell Models: An Interactive Animation

Cell Membrane

1) Selectively controls the entry and exit of materials

2) This aids in the cell maintaining homeostasis

3) Cell Membrane also maintains cell’s shape

4) Does NOT protect it from “bad” substances (viruses, bacteria, etc)

Membrane Structure1) Membrane is made up mainly of lipids

and proteins, with some cholesterol and carbohydrate molecules

2) Membrane is a double layer of lipids with protein molecules that “float” within the layers

3) Proteins in membrane serve as:1) Transport Proteins – move molecules

across the membrane2) Receptor Proteins – binding sites on the

membrane for hormones, chemicals, etc.

Membrane Structure (cont)

1) Cholesterol makes membrane less “fluid”

2) Carbohydrates (on the outside layer) serve as identification for the cell

3) Cell Membrane Animation

Functions of Cell Membrane

1) Membrane gives shape to the cell2) Regulates the passage of materials

into and out of the cell (selectively permeable membrane)

3) Two types of transport across membrane

1) Passive Transport2) Active Transport

Passive Transport

1) Molecules flow from High to Low concentration

2) Does NOT need energy

3) Three Types:1) Diffusion

2) Osmosis

3) Facilitated Diffusion

Diffusion1) Solid or dissolved particle moving

across a membrane from H to L2) In the cell, small (non polar) particles

such as O2 and CO2 can diffuse across the membrane (High to Low)

3) Basic Diffusion4) Animation: How Diffusion Works5) NYS: Diffusion Lab6) Plasmolysis (Red Onion)

Osmosis

1) Water moving from H to L

2) In the cell, water can move slowly across the membrane on its own.

3) Multiple Diffusion/Osmosis

Facilitated Diffusion

1) Molecules moving from H to L by going through a “tunnel” in the membrane.

2) In the cell, larger molecules, or polar molecules, can go from H to L across the membrane by Carrier Proteins that act as a “tunnel” through the membrane

3) Passive Transport Overview

Active Transport

1) Movement of molecules from Low to High concentration

2) Requires ENERGY (in the form of ATP)

3) Three types1) Ion pumps

2) Co-transport

3) Endocytosis

Ion Pumps

1) Moving Ions (charged atoms) from Low to High concentration

2) Makes an electrochemical charge

3) The resulting energy is used to fuel other processes (muscle contractions, nerve impulses)

Co-Transport

1) An ion will be expelled from the cell (from L to H). That ion will attach to another membrane protein and alter its shape allowing it to move another molecule into the cell (from L to H)

Endocytosis

1) Membrane “folds in” on itself to create a vesicle (small vacuole) to bring in materials

2) Two Types1) Phagocytosis – cell eating (solids)

2) Pinocytosis – cell drinking (liquids)

3) Active Transport Overview