By Richard Gaspar and Keith Salgado Biology 4 Honors Mitochondria By Richard Gaspar and Keith Salgado Biology 4 Honors

Origins of Mitochondria Mitochondria displays similarities to bacteria which has led to the endosymbiont theory. The theory states that an early ancestor of eukaryotic cells engulfed an oxygen-using non photosynthetic prokaryotic cell. The two formed an endosymbiotic relationship. Over the course of evolution the two merged and became a single organism. It is believed a chloroplast did the same with a photosynthetic prokaryote. Mitochondria are found in nearly all eukaryotic cells, including those of plants, animals, fungi, and most unicellular eukaryotes. Not found in prokaryotes.

Evidence of Symbiosis Membranes — Mitochondria have their own cell membranes, just like a prokaryotic cell does. DNA — Each mitochondrion has its own circular DNA genome, like a bacteria's genome, but much smaller. This DNA is passed from a mitochondrion to its offspring and is separate from the "host" cell's genome in the nucleus. Reproduction — Mitochondria multiply by pinching in half — the same process used by bacteria. Every new mitochondrion must be produced from a parent mitochondrion in this way; if a cell's mitochondria are removed, it can't build new ones from scratch.

Evolution of Mitochondria & Chloroplast

Structure & Appearance/Properties Mitochondria is known as the powerhouse. This is an organelle within a cell where cellular respiration occurs which releases energy for the cell to use. It is bound by 2 membranes; an outer and inner membrane Mitochondria also possess their own ribosomes as well as multiple circular DNA molecules associated with their inner membranes. The DNA in these organelles programs the synthesis of some organelle proteins on ribosomes that have been synthesized and assembled there as well. They are also somewhat independent organelles that grow and reproduce within the cell. Found in nearly all eukaryotic cells. They range in size and cells can have anywhere from hundreds to even thousands of mitochondria. The quantity is determined based on a cells metabolic activity For example, cells that move or contract such as muscle cells have proportionally more mitochondria per volume than less active cells. (skin cells) Each of the two membranes consists of a phospholipid bilayer with a unique collection of embedded proteins. The outer membrane is smooth while the inner membrane has many folds which helps increase its surface area. The folds are called cristae The inner membrane divides the mitochondria into two internal compartments. The first is the intermembrane space which is between the outer membrane and the inner membrane The second compartment is known as the mitochondrial matrix. The matrix contains different enzymes, mitochondrial DNA and ribosomes. They range from 1 to 10 micrometers long.

Structure of Mitochondria

Mitochondrion Functions The function of the mitochondria is to produce ATP (Energy) through the process of aerobic cellular respiration (anaerobic occurs in the cytoplasm) ATP is used to drive cellular work. Organic Compounds (Food) + Oxygen (Breathing) —> Carbon Dioxide + Water + Energy + Heat Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. It’s he metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels. Similar function is done by chloroplasts in plants, through photosynthesis Mitochondria also receive broken down fatty acids supplied by peroxisomes which it then uses as fuel for cellular respiration

Cellular Respiration