Organ Systems

PEER Life Science Cells Are Us Levels of Organization Notes Outline Key Introduction ● A cell is the smallest unit of life. ● The human body is composed of trillions of cells. Their size and shape depends on their function. ● Name three functions of cells: ○ Provide structure for the body ○ Take in nutrients and convert them into energy ○ Carry out specialized functions like reproduction ● Each cell contains the body’s hereditary material that is passed on to our offspring. Why It Matters ● Each cell in our body has a role that helps our body stay well and survive. ○ When our cells are healthy, our body is healthy/sick. ○ When our cells are sick, our body is healthy/sick. ● Name four situations that can cause cells to lose or change their function. ○ Disease/sickness ○ Exposure to radiation ○ Substance abuse ○ Aging ○ Natural causes ○ New cells not replacing dying cells ○ Cells replace themselves too much What We Know ● The basic structural, functional, and biological unit of all living organisms is a cell. ○ This is similar to a brick that makes up buildings in a city. ● A group of cells with similar functions joining together makes up tissues. ○ This is similar to walls of buildings in a city. ● Groups of different tissues working together make up organs. ○ This is similar to buildings in a city. ● Groups of organs working together for a shared function makes up organ systems. ○ This is similar to a city district, like a medical district. ● Different organ systems work together to make up an entire organism. ○ This level is like the entire city. ● Specialized structures that perform various jobs in cells are called organelles. They function within the cell similarly to how organs function in the body. ● Mitochondria are organelles that obtain usable energy for the cell. This is kind of like part of the digestive system in the body. ● The nucleus is a cellular organelle that stores DNA and is the command and control center of the cell. It’s similar to the brain in the body. ● The cell membrane is a barrier around the cell that controls what enters and leaves the cells and interacts with the world outside of the cell. It’s similar to the skin in the body. ● The cytoplasm is a gel-like fluid in which the cell’s organelles are suspended and that transports materials within the cell. It’s analogous to the circulatory system in the body. ● The endoplasmic reticulum transports materials from one part of the cell to another, like the circulatory system in the body. ● Ribosomes manufacture proteins and send them to parts of the cell where they are needed. They have similarities to the digestive system. ● The golgi body packages and sends out proteins similar to how the digestive system breaks down and repackages food for the body. ● Lysosomes break down cell parts and remove cellular waste. Vacuoles store waste, water, and necessary materials. They function similarly to the excretory system. ● Label the organelles in the diagram below. ● Cells can have many/few different structures. Cell shape and structure is determined by their function. ● Most cells are naturally transparent, but we can use stains to see the different parts. How We Know ● Most cells are microscopic. ● To study cells and how they work, scientists often grow them as a culture. A cell culture is a growth of a large group of cells in the laboratory. ● Name two things that cell cultures can be used for. ○ Diagnose infections ○ Test new drugs ○ Cell research ● In order for cells to stay alive in a culture they need: ○ A sample of the type of cells needed that are healthy and can divide. ○ A culture media that supplies the cells with energy, amino acids, and vitamins. ○ Oxygen ○ Warm temperature ○ Removal of waste gas ● The warm temperature is provided by a machine called an incubator. ● When looking at a tissue cut from an organ under a microscope, that organ may have several types of cells. Each cell has even smaller structures called organelles. ● Organelles can be visualized with powerful microscopes like electron microscopes. Common Hazards