Post on 21-May-2020
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