Objectives List scientists who contributed to the cell theory List the components of the cell theory Compare prokaryote and eukaryote cells Label a plant and an animal cell Know the functions of cell organelles

Early Contributions Anton van Leeuwenhoek – Made 1 st microscope Observed living cells called "animalcules“ Robert Hooke - Observed tiny units in cork and named them “cells”

Theodore Schwann - zoologist who observed tissues of animals had cells (1839) Mattias Schleiden - botanist, observed tissues of plants contained cells ( 1845)

The Cell Theory 1. Every living organism is made of one or more cells. 2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions. 3. All cells arise from pre- existing cells.

The cell is the Basic Unit of Life Cell is basic unit of life Unicellular organisms are made of one cell only The cells of multicellular organisms are specialized to perform different functions

Common Cell Features ALL CELLS have these parts Ribosomes – make protein for use by the organism Cytoplasm – fluid material within cell DNA – genetic material Cytoskeleton – internal framework of cell Cell Membrane – outer boundary, some things can cross the cell membrane

Prokaryote Cells The first cells to inhabit the earth Smallest and simplest cells Always a single–celled organism Bacteria These cells do NOT have a nucleus, lack internal compartments / organelles, their DNA is circular and floats in the cytoplasm Have a cell wall Many have flagella – long, threadlike structures that protrude from the cell’s surface and enable movement (whip-like tail) A capsule surrounds some bacteria and helps them avoid the body’s immune system and cling to almost anything (teeth, skin, and food)

Prokaryotic Cell

Bacteria Images Bacteria that causes Anthrax

Eukaryotic Cells Cells found in plants, animals, protists, and fungi The cell is composed of 4 main parts: 1.Cell membrane 2.Cytoplasm 3.Nucleus – “control center” of cell, houses DNA 4.Organelles – small structures that carry out specific functions (“little organs”)

Eukaryotic Cell

CELL MEMBRANE Selectively permeable Regulates what comes into the cell and what leaves the cell It is composed of a double layer of phospholipids with proteins embedded throughout

CELL WALL only animal cells and some protists lack cell walls Provides structure and support Helps maintain shape, protects from damage, and connects it with adjacent cells Composed of proteins and carbohydrates Rigid Prokaryotic made up of strands of plysaccharides connected by short chains of amino acids Fungi made up of chitin, a polysacccharide found in the hard outer covering of insects Plants made up of proteins and the polysaccharide cellulose

*Jelly-like substance enclosed by cell membrane *Provides a medium for chemical reactions to take place *Contains organelles Cytoplasm

Ribosomes Small spherical shaped Protein factories – cells make proteins on ribosomes Made in the nucleolus Found on the Rough ER and throughout the cytoplasm Made up of dozens of different proteins as well as RNA

Organelles “Little Organs” Have specific functions Found throughout cytoplasm Very small size Can only be observed under a microscope Examples: golgi body, endoplasmic reticulum, nucleolus

Nucleus Usually found at center of cell in animal cells and near the cell membrane and wall of plant cells Has a nuclear membrane & nuclear pores Contains cell’s DNA in one of 2 forms o chromatin - DNA bound to protein (non-dividing cell) o chromosomes - condensed structures seen in dividing cell Also contains an organelle called nucleolus - which makes the cell’s ribosomes

Cell Organelles: Mitochondria Mitochondria – cell’s energy center *Turns food into a chemical energy called ATP *Called the “powerhouse” of the cell *Site of Cellular Respiration *Active cells like muscles have more mitochondria * Contains DNA independent of nuclear DNA

Cell Organelles: Golgi Apparatus Golgi Apparatus – post office of the cell *processes, packages and secretes proteins *Stacks of flattened sacs *Have shipping side and receiving side *A vesicle forms with Golgi to transport substances outside cell. Transport vesicle

More Cell Organelles Lysosome – Contains digestive enzymes, breaks things down; garbage can of the cell Endoplasmic Reticulum – Transport, "intracellular highway" Found by nucleus -Rough ER contains many ribosomes -Smooth ER ribosomes not found on surface

Cell Organelles Cytoskeleton – Helps cell maintain support & shape; movement a. microtubules-hollow structures; also help build cilia flagella b. microfilaments-threadlike c. centrioles-only in animal cells; used during cell division (paired structures near nucleus) Vacuole – storage area for water and other substances, plant cells have a large central vacuole

THE ANIMAL CELL

Different kinds of animal / animal like cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium

Plant Cells Have additional structures: CELL WALL – surrounds membrane & provides additional support Also found in prokaryotes (bacteria) & Fungi CHLOROPLASTS – contain green pigment, function in photosynthesis CENTRAL VACUOLE – large water container in center of cell

PLANT CELL Vacuole Cell wall Chloroplast

26 Different kinds of plant cells Onion Epidermal Cells Root Hair Cell root hair Guard Cells

Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both are eukaryotic (have a nucleus) Both contain mitochondria

Differences between plant cells and animal cells Animal cellsPlant cells Relatively smaller in size Irregular shape No cell wall Relatively larger in size Regular shape Cell wall present

Animal cellsPlant cells Vacuole small or absent Glycogen as food storage Nucleus at the center Large central vacuole Cellulose in the cell wall Nucleus near cell wall Differences between Plant Cells and Animal Cells

Organelles With DNA Mitochondria and chloroplasts have their own DNA (separate from the nucleus) This supports the ENDOSYMBIOSIS THEORY which states that eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells.

Levels of Organization  CELLS (muscle cells, nerve cells)  TISSUES (muscle, epithelium)  ORGANS (heart, lungs, stomach)  SYSTEMS (circulatory system)  ORGANISM (human)

Microscope Microscope Instrument for observing small objects Magnification – making an image appear larger Resolution – a measure of clarity of an image Hold one hand on the arm and one on the base when carrying the microscope!

Total Magnification Take the ocular lens (10x) times the objective lens(4x, 10x, 40x, 100x) = total magnification Example: If you are looking at something on low power than the image is magnified 40x.

Eyepiece (ocular lens) Fine adjustment Arm Stage Base Body tube Coarse adjustment Diaphragm Revolving nosepiece Objective Stage Clip Mirror / Light source Parts of a Microscope

Steps in using the microscope (1) Adjust the stage so that it is all the way down (2) Make sure the objective is on the lowest power (3) Using the coarse adjustment knob bring the stage up until you can see the image (4) You can now change objective lens to a higher power (5) Use the fine adjustment knob to focus