More About Cells

The cell was discovered by Robert Hooke in 1665 He examined very thin slices of cork and saw a multitude of tiny pores that he remarked looked like the walled compartments a monk would live in. Because of this association, Hooke called them "cells". Cell Theory refers to the idea that cells are the basic unit of structure in every living thing. Development of this theory during the mid 17th century was made possible by advances in microscopy. This is the basis for biology. The theory says that new cells are formed from other existing cells, and that the cell is a fundamental unit of structure, function and organization in all living organisms.

The generally accepted parts of Modern Cell Theory include: 1. All known living things are made up of one or more cells. 2. All living cells arise from pre-existing cells by division. 3. The cell is the fundamental unit of structure and function in all living organisms. 4. The activity of an organism depends on the total activity of independent cells. 5. Energy flow occurs within cells 6. Cells contain hereditary information (DNA) which is passed from cell to cell during cell division. 7. All cells are basically the same in chemical composition in organisms of similar species. Why is this referred to as a "theory"?

All cells require Free energy to survive and reproduce. We could even go far enough to say that the goal of life is to produce ATP. ATP – Adenosine Tri-Phosphate is essentially sugar and a phosphate group. ATP transports chemical energy within cells and even helps with the replication of DNA. There are two strategies to obtain and store this energy on our planet (depending on what type of organism you are.) Autotrophs Make their food Heterotrophs Eat their food How exactly does this happen?

This includes plants, algae, and even some bacteria! Most Autotrophs rely on Photosynthesis to make food. Photo = Light Synthesis = To build This includes plants, algae, and even some bacteria! What: This process takes energy from sunlight, combined with carbon dioxide and water to make sugars and release oxygen gas as a waste product. Chemical energy is thus stored in the bonds of the sugar (glucose) molecule. How: ("Light Reaction") Thylakoid Stacks convert light energy into chemical energy called ATP. ("Dark Reaction") This energy ATP energy is then utilized to make the necessary conversions you see in the above equation. 6CO2 + 6H2O (photons) C6H12O6 + 6O2

Where: Organelles in Plant leaves called chloroplasts collect the reactants: Water is brought up from roots through the plant’s vascular system while sunlight is absorbed within the green pigment called chlorophyll. CO2 gas enters through tiny pores called stomata. Why: Plants do not carry out this process for you. It is a method to store energy for later plant functions – growth, reproduction, etc.. Did you know? Are Autotrophs without a light source out of luck? No, In fact, a small group of autotrophs use chemosynthesis to make energy. These tubes worm get the energy they need from hydrothermal vents in the deep dark sea floor.

Heterotrophs (like you) can't make their own food – they have to eat! Cellular Respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Glucose Energy C6 H12O6 + 6O2 6CO2 + 6H2O + ATP Aerobic Respiration Why: Energy stored in ATP can be used in both small and large scale movements – from transporting molecules in blood, to running a marathon! Where: The cytoplasm and mitochondria play key roles in this process. Some organisms can carry out cell respiration without the presence of oxygen. This is referred to as Fermentation. Did you know?

Q: What specific branch of science does this involve? Biochemistry Q: How are Photosynthesis and Cellular Respiration importantly related? A: The organic compounds created by photosynthesis are required to carry out cellular respiration.