Cells and How They Work By: dave wedzina

Cells are the basic unit of life. Cells are made up of many parts, each with an important role. Here they are.

In both plant and animal cells there are these ten organelles.

Cell Membrane - The cell membrane is like the gatekeeper of the cell. This is the organelle that allows what goes into the cell and what comes out of the cell. The cell membrane is also called the Phospholipid Bilayer. The cell membrane is made up of lipids and proteins.

Nucleus - The nucleus is like the control center of the cell. This organelle has codes to guide all the other organelles around. It is in charge of cell division and makes ribosomes.

Nucleolus - The nucleolus is located inside the nucleus. The nucleolus job is to transcribe rRNA and combine it with proteins to form incomplete ribosomes.

Cytoplasm - The cytoplasm is what holds all of the organelles together. It is a jellylike substance that covers all the whole cell’s spaces.

Ribosomes - The ribosomes are all over the cell. They are what make proteins. The ribosomes will come out of the nucleus, go to the rough ER, then get in a vesicle and go to the golgi apparatus.

Rough ER - The rough ER is a weblike organelle that surrounds the nucleus. Ribosomes can stick onto it to start making their proteins.

Smooth ER - The smooth ER is also a weblike organelle that surrounds the nucleus. But, unlike the rough ER, the smooth ER does NOT have ribosomes on its surface. It’s job is to make lipids and help remove molecules from the cell.

Vesicles - The vesicles are what surrounds the ribosomes when they are being transported. You will mostly find vesicles transporting ribosomes to the golgi apparatus.

Golgi Apparatus - The golgi apparatus is what packages the protein. When the ribosomes are made in the nucleus, they are transported to the rough ER where they start the proteins production. After that, a vesicle takes the ribosome over to the golgi apparatus where it packages that protein.

Mitochondria - The mitochondria is like the powerhouse of a cell. This is the organelle that makes the energy. To make its energy, it takes food molecules and turns those into its energy.

In plant cells there are these four organelles plus the above organelles.

Cell Wall - The cell wall is only in plant cells. This is the organelle that forms the cell. You may ask, does the cell wall also act like the cell membrane. The answer, is no because the cell wall is just outside the cell membrane. All plant cells still have a cell membrane.

Chlorophyll - This organelle is what makes food for plant. It also traps light for the plant.

Vacuole (only one) - The vacuole is like the storage area of a cell. People ask questions like don’t plant and animal cells have vacuoles? Well, yes indeed they do. But, plant cells only have one vacuole that takes up to as much as 90% of the cell.

Lysosome (some plant cells) - The lysosome is like the garbage dump. This is where all the unused or not able to operate organelles go to decompose.

In animal cells there are all of the above organelles plus these two

Lysosome (in all animal cells) - Lysosome, again? Wait, shouldn’t it be in both animal and plant cells? Yes, but no. The lysosome is only in some plant cells. Not all, some. In animal cells, however, they are guaranteed that each and every cell, has a lysosome.

Vacuole (more than one) - The vacuole in an animal cell is also the storage area. But instead of having one big vacuole, the animal cells have more than one vacuole but they are smaller..

How do cells transport materials?

There are many ways of transporting materials. There are Passive Transports, Active transports, Diffusion, Facilitated Diffusion, Osmosis, and many more. You can tell what they mean a little by there names but not a lot so I’ll tell you their real definitions soon. First off, we’ll start with passive transports.

A passive transport is the movement of substances through a cell membrane without using the cell’s energy. If inside the membrane there are 2 oxygen molecules and outside the membrane there are 4, a passive transport can take place because the oxygen molecule is small enough that it can go right through the membrane. Passive transports are always transporting substances to make the rate equal. In this case, 1 oxygen molecule from outside the membrane will make a passive transport through the membrane and into the cell to even out the molecule rate from the outside to the inside of the cell.

Diffusion is the movement of substances from an area of higher concentration to an area of lower concentration. When a substance is in an area of higher concentration, diffusion will take place until the area of higher concentration and lower concentration are equal. When the substances keep going to the different areas, the substance is in equilibrium.

Osmosis is the diffusion of water molecules only through a membrane. The water molecules will always continue to transport until equilibrium occurs. It is also going from an area of higher concentration to an area of lower concentration.

Facilitated Diffusion is when molecules pass through the cell membrane using transport proteins. Facilitated diffusion does not need to use energy along with diffusion and osmosis. There are two types of transport proteins. One is the channel protein and the other is the carrier protein. Carrier proteins carry more massive molecules through the membrane. On the other hand, channel proteins form pores or holes that go through the membrane. Atomic particles pass through the cell membrane by using channel proteins.

Active Transport is the movement of substances through the cell’s membrane only by using the cell’s energy. Instead of active transports moving substances from higher concentrations to lower concentrations, they actually do the opposite. Active transports move substances from lower concentrations to higher concentrations. Cells can take in the nutrients they need from the surrounding environment when the concentration is lower there.

Endocytosis and Exocytosis are just opposites. Endocytosis is when a cell takes in a substance or group of substances that is too big for facilitated diffusion and surrounds it with the membrane. Lots of cells use Endocytosis and Exocytosis. Exocytosis is like I said, the opposite of endocytosis. This is when it takes the substance(s) that has a membrane around it and pushes it out of the cell while the membrane around the substance, comes back and connects to the cell membrane.

Growth and Repair

The cell cycle consists of two phases. The Interphase and the Mitotic phase. In the interphase, the cell starts to grow, replicate organelles, and store energy for later processes. The mitotic phase is the phase in which the nucleus and its contents divide. It is made up of the prophase, metaphase, anaphase, telophase and cytokinesis. The prophase is when the nuclear membrane and the nucleolus disappear and spindle fibers form. In the metaphase, the chromosomes line up in single file in the middle of the cell. The spindle fiber then attach to the chromosomes at the centromere. During the anaphase the chromosomes separate into two sister chromatids. They are split by the spindle fibers. The telophase is the second to last stage of the mitotic phase. This is where the sister chromatids get brought to opposite sides of the cell. Cytokinesis is the last step of the Mitotic Phase. This is where the cytoplasm splits and the Parent cell is turned into two new daughter cells. The end result of the cell cycle is two daughter cells. The parent cell has disappeared because its original organelles have been used in the daughter cells. The cell cycle has to do with making energy because it needs energy for each processes of Mitosis. It will make energy in the Mitochondria which is the location of the second part in Cellular Respiration.

Energy Usage in Cells

Cellular Respiration is the process of converting food and oxygen into energy called ATP, carbon dioxide (waste product), and water(waste product). Cellular Respiration takes place in two places. During the first part in Cellular Respiration, the glucose is broken down into smaller molecules in the cytoplasm. The second part of Cellular Respiration is when the glucose and the oxygen react in the mitochondria and make the energy (ATP), water, and carbon dioxide. The cell makes the energy by first having the food come to them. As you eat, some sugar is used for cell energy. This sugar is called glucose. The glucose has to pass through using a carrier protein no matter what because of its size. This will either be a passive or active transport depending on if there’s a higher or lower concentration in the cell. The oxygen comes into the cells when you breathe. Now that the oxygen and glucose are in the cells, the glucose is broken down into smaller pieces in the cytoplasm. These smaller pieces go from the cytoplasm into the mitochondria with the oxygen to turn into three things. Water, carbon dioxide, and energy called ATP. We call the water and carbon dioxide, waste products because we don’t need them in the cell but we need the energy so the cell can divide. This “process” happens in both plant and animal cells, but not in the same way. In animal cells, the cell uses oxygen and glucose to make water, ATP and carbon dioxide. In plant cells, however, the cell uses carbon dioxide, water and uses the sun’s energy to make glucose and oxygen. The two processes are named differently. In animal cells, it is called cellular respiration and in plant cells it is called photosynthesis. The difference in the way plant and animal cells get their energy is simple. Animal cells get their energy from the sugars in foods and the oxygen you breathe. Plant cells however, get their energy through the sun. You may ask, where does the plant keep all this sun energy? The answer, is the chlorophyll. The chlorophyll’s job in a plant cell is to trap light and store it. Making energy has to do with transporting materials into and out of the cell from its needs to make the energy. The glucose has to come in from some way right? Glucose needs to get into the cell by Facilitated diffusion. This is like diffusion, but using the proteins in the cell membrane instead of through the membrane itself. During the process, the glucose reaches the carrier protein and enters it. In the carrier protein, the glucose changes form and is moved into the cytoplasm of the cell.

Created By
David Wedzina
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Created with images by skeeze - "cancer cells cells scan"

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