Mitochondria and Smooth Endoplasmic Reticulum- Basics of their Function and Structure
- 1. MITOCHONDRIA AND SMOOTH ENDOPLASMIC RETICULUM Sarah, Olivia, Anna and Jonti
- 2. Where are they located in the cell? • Mitochondria used to be single- celled organisms 2 billion years ago but are now freely suspended in the cytoplasm of cells often near a cell’s flagella if the cell is particularly active. Although most DNA is within the nucleus, mitochondria also have a small amount of their own DNA, known as mitochondrial DNA or mtDNA. • Smooth Endoplasmic Reticulum, SER, unlike RER, is not integrated into the membrane of the nucleus but is instead held in the cytoplasm, but with one end still near to the nucleus, or sometimes even connected to the RER.
- 3. The Structure of a Mitochondrion • Christae, projections of the inner membrane, extend into the matrix of the cell. Giving the inner membrane a larger surface area, the christae increase the rate of ATP’s synthesis. • Mitochondria have a double membrane structure, each membrane 6nm in thickness. The outer membrane is much smoother and has an abundance of ‘porin’ transport proteins that pass through the outer membrane, allowing for more passive diffusion. The inner layer is much more rough but still highly permeable. A higher concentration of protons (H+ ions) outside the inner membrane of the mitochondria than inside the inner membrane, creating a gradient, drives the formation of ATP. • The matrix of the mitochondria contains the enzymes, ATP synthase, that are involved in the synthesis of ATP. • ATP synthase is an enzyme that synthesizes the reaction between ADP and a phosphate to create ATP. It uses the movement of H+ ions across the membrane to carry out the reaction.
- 4. What is the function of a mitochondrion? The function of the mitochondria is to create adenosine triphosphate, chemical energy, from adenosine diphosphate and a phosphate.Through the membranes, the ATP can then be released to the rest of the cell, where it is needed. Some functions of ATP in the cell include: • ActiveTransport- moving substances across cell membranes. • ‘Mechanical Work’- releasing the energy needed for muscle contraction. • ‘Chemical Work’- supplying the energy needed to synthesize the molecules that the cell requires. • ATP is also used to control chemical reactions and to send messages across the cell.
- 5. Which Cells require an abundance of Mitochondria? The Heart’s Muscle Cells Sperm Cells Brain Cells
- 6. The Structure of SER • Smooth ER is more tubular than RER and is formed of a long network of a folded, hollow membrane. It can be thought of as a pipe with a lot of twists and turns. Like in vessels the inside of the SER is called the lumen, which is enclosed by a phospholipid membrane, just like the membrane around the entire cell.The number of smooth ER units in a cell depends on the type of cell and also it purpose.
- 7. What is the function of SER? • The main function of SER is to act as a storage organelle. It’s important in the creation and storage of lipid molecules and steroids Most SER in both plant and animal cells makes lipids, however, and so cells involved in the manufacture of lipids contain more SER than others. . Cells in your body that release oils also have more SER than most cells, for example. Additionally, the testes have lots of SER, as do the ovaries, as they need to make testosterone (in men and women) and oestrogen (women). Steroids are organic compounds that are made up of four rings of carbon atoms. Steroids are a type of organic molecule used for many purposes in an organism. For example, the hormones testosterone and oestrogen are steroids.