Thursday, Oct. 30- Cells - Cellular Respiration
Objective: Understand that while plants make their own food, animals cannot, which leads to the process of cellular respiration.
Plants get their energy from photosynthesis. Animals can’t make food so they eat plants and animals. Cells have to release the energy stored in food. Cellular respiration breaks down glucose and molecules to release energy.
Most of cellular respiration happens in the mitochondria, which stores the enzymes you need for cellular respiration.
Steps of cellular respiration:
- Glycolysis – two molecules of ATP provide energy to break up glucose. This makes a different sugar (pyruvate) and two molecules of ATP, which is a molecule for storing energy. Glycolysis can break up proteins, carbohydrates and fats.
- Kreb’s Cycle – Oxygen bring pyruvate into the mitochondria. It’s changed into acetyle coenzyme A and enters Kreb’s cycle – a long string of chemical reactions that produces carbon dioxide and energy.
- Oxidative Phosphorylation –Hydrogen atoms produced in Kreb’s cycle have lots of energy. They are broken down and provide energy to produce ATP and then oxygen and water are the waste products.
When you don’t have oxygen for cellular respiration you end up with fermentation – beer, yogurt, etc.
MITOSIS AND MEIOSIS
Cells can grow, but eventually they divide – this is cell division/cell reproduction.
Prokaryotic cells (no nucleus) are very simple. Copy the DNA and divide.
Eukaryotic cells (nucleus) go through the cell cycle.
- Cell grows
- Cell copies DNA
- Cell grows again producing extra organelles and cytoplasm for cell division
- Mitosis – Nucleus divides into two nuclei. Divides the genetic material.
- Cytokinesis – Cell divides
Cells have checkpoints to make sure it moves on to the next stage.
Chromosomes – Genes – Mitosis
- Prophase – Chromosomes group together
- Metaphase – Chromosomes line up
- Anaphase – Chromatids start moving
- Telophase – Cell divides
Meiosis – Cell divides twice to cut the number of chromosomes in half – This happens during sexual reproduction. Result is 4 cells instead of two.