33 terms

Chapter 7: Cell Structure and Function

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Cell
basic unit of life, made up of organic (carbon) molecules, and they are all not alike.
Cell Theory
these discoveries, confirmed by many biologists are summarized in this fundamental concept of biology:
1. All living things are made up of cells.
2. Cells are the basic unit of structure and function in living things.
3. New cells are produced from existing cells.
Cell Membrane
all cells are surrounded by this thin flexible barrier that regulates what enters and leaves the cell.
Nucleus
this is a large membrane enclosed structure that contains genetic material in the form of DNA and controls many of the cells activities.
Eukaryote
cells that enclose their DNA in a nucleus.
Prokaryote
also known as bacteria, cells that don't enclose their DNA in nuclei.
Cytoplasm
the portion of the cell outside of the nucleus. In prokaryotic cells, this is all the content of the cell.
Organelle
"little organs" these are structures that act like specialized organs.
Vacuole
large saclike, membrane-enclosed structures that store materials like water, salts, proteins, and carbohydrates.
Lysosome
small organelles filled with enzymes. Lysosomes break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell. They are also involved in breaking downs organelles that have outlived their usefulness.
Cytoskeleton
Eukaryotic cells are given their shape and internal organization by a network of protein filaments known as the cytoskeleton. Certain parts of the cytoskeleton also help transport materials between different parts of the cell. The cytoskeleton helps the cell maintain its shape and is also involved in movement
Centriole
Organelles found in animal cells that formed from tubulins. Centrioles are located in the nucleus and help organize cell division. Centrioles are not found in plant cells.
Ribosomes
proteins are assembled on ribosomes. One of the most important jobs carried out in the cell nuclear factory is making proteins. They are small pieces of RNA and protein found throughout the cytoplasm of a cell.
Endoplasmic Reticulum
Eukaryotic cells contain an internal membrane system known as the endoplasmic reticulum or ER. The ER is where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell. Proteins made on the rough ER include those that will be released, secreted from the cell.
Golgi Apparatus
proteins produced in the rough ER move next into an organelle called the Golgi apparatus. The Golgi apparatus modifies, sorts, and packages proteins and other materials from the ER from storage in the cell or release outside the cell.
Chloroplast
the biological equivalents of solar power plants. They capture the energy from the sunlight and convert it into food that contains chemical into a process called photosynthesis. Two membranes surround chloroplast. Inside the organelle are large stacks of other membranes, which contain the green pigment chlorophyll.
Mitochondria
nearly all eukaryotic cells. They are the power plants of the cell. Mitochondria convert the chemical energy stored in food into compounds that are more convenient for the cell to use.
Cell Wall
a strong supporting layer around the membrane produced by many cells including prokaryotes. The main functions are to support, shape, and protect the cell. Most prokaryotes and many eukaryotes have these, but animal cells do not.
Lipid Bilayer
gives cell membranes a flexible structure that forms a stronger barrier between the cell and its surroundings.
Selectively Permeable
means that some substances can pass across them and others cannot, also called semipermeable membranes. Most biological membranes are this.
Diffusion
the process by which particles move from an area of high concentration to an area of lower concentration. The driving force behind the movement of many substances across the cell membrane.
Facilitated Diffusion
the process in which molecules that cannot directly diffuse across the membrane pass through special protein channels. Its fast and specific, but its still diffusion, so it doesn't require any additional use of the cell's energy.
Aquaporin
many cells contain these water channel proteins that allow water to pass right through them.
Osmosis
the diffusion of water through a selectively permeable membrane. In this, as in other forms of diffusion, molecules move form an area of concentration to an area of lower concentration.
Isotonic
means "same strength." For example, when the concentrations of water and sugar are the same on both sides of the membrane. "strength" refers to the amount of solute not water.
Hypertonic
means "above strength." When a substance in more concentrated on one side than the other.
Hypotonic
noting a solution of lower osmotic pressure than another solution. (below strength)
Osmotic Pressure
the force that is produced when the net movement of water out of or into his cell. Can cause an animal cell in a hypertonic solution to shrink, and one in a hypertonic solution to swell. Because cells contain salts sugars proteins and other dissolved molecules, they're almost always hypertonic to freshwater.
Homeostasis
living things that are unicellular maintain this. Relatively constant internal and chemical conditions. To maintain homeostasis unicellular organisms grow, respond to the environment, transform energy, and reproduce.
Tissue
a group of similar cells that perform a particular function. The specialized cells of multicellular organisms are organized into tissues, then into organs and finally into organ systems.
Organ
when many groups of tissues work together. For example, each muscle on your body is an individual organ. Within a muscle, however, there is much more than muscle tissue. There are nervous tissues and connective tissues too.
Organ System
A group of organs that work together to form a specific function. For example, the stomach, pancreas, in the intestines were together as the digestive system.
Receptor
where the signaling molecule can bind. Some receptors are on the cell membrane; receptors for other types of signals are inside the cytoplasm.
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