The Living Cell

The Living Cell

“Cell”– Named by Robert Hooke who used

microscope to look at cork (1663)– Described by Anton van

Leeuwenhoek who designed his own microscope to look at living cells (1676)

– “Cell Theory” developed by Schleiden & Schwann (1838)

The Living Cell

Cell Theory

– All living things are composed of cells

– The cell is the fundamental unit of life

– All cells arise from previous cells

The Living Cell

Cell membrane– Separates the “inside” from the

“outside”– Made from a bilayer of phospholipid

molecules– Allows certain certain molecules to

pass through – Has protein protein receptors to

assist other molecules – May be surrounded by a cell wall (in

plants)

The Living Cell

Nucleus– Present in eukaryotes– Controls the cell’s heredity and

chemistry– Contains DNA in chromosome pairs– “mitosis” results in 2 daughter cells

with same DNA as original cell– “meiosis” results in the production of

egg and sperm cells with ½ DNA as original cell

The Living Cell

Energy organelles– Chloroplasts

• Contains chlorophyll which absorbs energy from sunlight

• Site of photosynthesis• Found in green plants

– Mitochondria• Site of respiration• Release energy from food by

metabolism• Found in both plants and animals

The Living Cell

Photosynthesis vs. Respiration

– Photosynthesis produces energy rich glucose

– CO2 + H2O C6H12O6 + O2

(carbon dioxide + water = glucose + oxygen)

– Respiration releases energy from glucose

– C6H12O6 + O2 CO2 + H2O + energy

sunlight

The Living Cell

Energy generation in cell

Glycolysis is 1st step – breaks down glucose and produces ATP

Followed by• Respiration, in presence of oxygen• Fermentation, in absence of oxygen

The Living Cell

Other organelles– Endoplasmic reticulum

• Smooth• Rough

– Ribosomes– Nucleoli– Golgi apparatus– Lysosomes– Vesicles and vacuoles– Cytoskeleton– Centrioles

The Living Cell

Differences between plant and animal cells– Plant

• Cell wall• Large central vacuole• Chloroplasts

– Animal• None of the above• Centrioles