Cell Structure and Function Lecture 8b

The Cell Theory All living things are composed of cells. All cells are derived from pre- existing cells, i.e., capable of reproduction Cells are the smallest unit of life

Characteristics of All Cells A cell membrane encloses a fluid cytoplasm where most of the chemistry of the cell occurs. DNA is the genetic code. This genetic code is essentially the same for all cells. The basic biological molecules and biochemical pathways are the same in all cells.

Tree of Life Eukaryote Prokaryote

Prokaryotic Cell

Typical Animal Cell Eukaryotic Animal Cell

Typical Plant Cell Eukaryotic Plant Cell

Plasma Membrane

Membrane Functions Enclose cell Surround organelles Provide attachment sites Cell-cell recognition

Membrane Size & Structure Keeps things in/out Large area = more regulatory control Permits compartments Passing membrane may be important

Compartments Isolate materials Concentrate materials Allow concentration gradients Diffusion high concentration low concentration membrane

Membrane Structure Lipid bilayer Highly motile Life measured in hours Embedded proteins Life measured in days

Membrane Structure

Endocytosis

Exocytosis

Nucleus

Rough and Smooth ER

Make proteins

Respiratory center of cell

Package and secrete products

1.Suicide sack 2.Digest food 3.Remove worn organelles

Cell Walls

Chloroplasts

Central Vacuole of a Plant Cell

Endosymbiotic Hypothesis mitochondrion chloroplast

Mitochondria & Chloroplasts Both are membrane bounded Both are relatively large (bacterial size) Endosymbiotic Hypothesis Mutualistic relationship between different “organisms” True?

Mitochondrion Very prominent Most cells have hundreds (plural: mitochondria) Powerhouse of the cell (fuel molecules to ATP)

Mitochondrion Metabolism Glucose (a sugar) to ATP ATP = universal energy “currency” ADP + energy ATP

concentration gradient

Chloroplast Site of photosynthesis Similar to mitochondrion Even larger Produces organic compounds (these store energy)

Animal Plant mitochondria chloroplasts vacuole Vacuole Functions Storage Support Water Regulation Both cell types have membrane-bounded organelles

Endosymbiosis Hypothesis A A prokaryote ingested some aerobic bacteria. The aerobes were protected and produced energy for the prokaryote Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell B C D A N N N N

Endosymbiosis Hypothesis B Over a long period of time the aerobes became mitochondria, no longer able to live on their own A B C D Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell N N N N

Endosymbiosis Hypothesis C Some primitive prokaryotes also ingested cyanobacteria, which contain photosynthetic pigments A B C D Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell N N N N

Endosymbiosis Hypothesis D Cyanobacteria became chloroplasts, unable to live on their own A B C D Chloroplasts Aerobic bacteria Mitochondria Cyanobacteria Prokaryote Animal Cell Plant cell N N N N

1.What is the function of: Mitochondria Nucleus Golgi apparatus Lysozome Ribosomes Smooth and rough ER Cellular Visions: The inner life of a cell (video) Inquiry