Cells...

Cell

The smallest unit

of life that can

perform all life processes.

The Cell Theory -17th Century

1. All organisms are made of one or more cells.

2. The cell is the basic unit of all living things.

3. All cells come from pre-existing cells

Theodor Schwann (zoologist)

Matthias Schleiden (botonist)

Robert Hooke (first observed cells under microscope)

“little wretched beasties” Antonie van Leeuwenhoek (1632-1723) – first to observe single celled organisms

Structure and Function

2 types of cells

prokaryote eukaryote

Cells that DO NOT have a cell membrane around their nucleus.

Example – Bacteria

Cells that have a membrane around their nucleus.

Plant and Animal Cells

Eukaryote cells usually 10X larger than Prokaryote cells.

prokaryote

eukaryotic cells

Plant Cell Animal Cell

A Panoramic View of the Cell

Cell Membrane

Cytoplasm

Nucleus

DNA/Chromosomes

Ribosomes

Endomembrane System

Golgi Apparatus

Lysosomes

Peroxisomes

Vacuoles

Mitochondria

Chloroplasts

Cytoskeleton

the plasma membrane (cell membrane)

A double layer of phospholipids (bilayer) with embedded proteins **more to come on this structure**

Found in both eukaryotic and prokaryotic cells

Cell membrane

Cytoplasm gel-like substance residing within the cell membrane holding all the cell’s organelles (outside of the nucleus) -eukaryotic

Also all the contents within the cell membrane of a prokaryotic cell

Cytoplasm

cell wall – in plant cells, not animal

• Found outside cell membrane • Helps maintains cell shape • Protects plant from

excess water uptake

• Found in bacteria, fungi cells as well as plant cells

cell wall

Nucleus – contains most of the genes in the eukaryotic cell

Nucleus

No nucleus in prokaryotic cells

the nucleus

contains the genetic material

Chromosomes

DNA coiled up

The genetic material of cells

In unwound state is called chromatin

Both eukaryotic and prokaryotic cells have chromosomes

Ribosomes site of protein synthesis – the protein factories

Both eukaryotic and prokaryotic cells have ribosomes

Ribosomes (dots)

Endomembrane System (eukaryotic cells only) –Smooth and Rough ER

Rough Endoplasmic Reticulum

•folds proteins into more complex shapes (tertiary structures)

• involved in protein synthesis

Rough Endoplasmic Reticulum

smooth ER

• metabolizes carbohydrates

• detoxification of poisons

• where fats (lipids) and steroids are made

Smooth ER

golgi apparatus

• receives proteins

from ER

•Not found in prokaryotic cells

• Sorts, packages and sends proteins to where ever they need to go

Golgi apparatus

Lysosomes –

found in both eukaryotic cells

contain enzymes that work to break down (digest) large

macromolecules

Work best in acidic environment

Digest excess or worn-out organelles, food particles, and engulf viruses or bacteria

Lysosomes

peroxisomes

• the most common vesicle in

cells

•Eukaryotic cells only

• contain enzymes to rid the cell of hydrogen peroxide

(convert the hydrogen peroxide to water)

• some detoxify alcohol and other harmful compounds

central vacuole (plants ONLY)

Maintaining internal pressure or turgor within the cell

Mitochondria - site of cellular respiration eukaryotic cells only

Mitochondria

Chloroplasts – site of photosynthesis (plant cells only)

Cytoskeleton: microtubules & microfilaments

Recently found in prokaryotic cells as well as eukaryotic cells

Microtubules •Provide shape and support for the cell •Found in cytoplasm, cilia, flagella, and cytoskeleton

Cilia and flagella help propel cell

Microfilaments

Helps support cell’s shape

Makes up part of cytoskeleton

Assist in cell contraction (muscle cells)

Microfilaments

The Inner Life of a Cell...