Introductory Biology

3.2 Cell Features

Today we started to talk about the cell theory and bacteria. EVERYTHING has a certain relationship in how its shaped and what it does. Robert Hook first found cells when he sliced a piece of cork and looked under it with an microscope. Cells are the basic units of life in both form and structure in organisms, and make up EVERYTHING that is living. Cells come from pre-exisiting cells, as well.

Cell sizes do matter in order for each one to stay alive. Cells must be small but cannot be smaller than 1 micrometer. The bigger the cell is, the smaller the surface area over volume ratio. Big cells cannot get things in the middle nor can they get rid of things in the middle of the cell so they either die from starvation or lacked to get rid of its wastes.If the cube is 1, the surface area is 6x1x1cm2 = 6cm2 and the volume is 1x1x1cm3 = 1cm3. The surface area over volume ration is 6/1 =6   or 6 Larger cubes with a side of 2, will have an surface area is 6x2x2 cm2= 24cm2 and its volume is 2x2x2 = 8cm3. The surface area over volume ratio is 24/8 = 3  or 3:1. As you can see from the measurements up above, volume increases faster than the surface area. Smaller cells with small metabolic needs are easier to be fed than larger cells with greater metabolic need. Therefore, multi-celluar organisms are produced of many small cells than large cells.  Moving the cytoplasm around and changing the shape of the cells  are some forms to meeting functions of meeting metabolic demands.

Prokaryote, or bacteria, is everywhere and they basically “control the world”. They do not have a membrane nor a nucleus. Bacterias contain ribosomes, cytoplasm, and DNA. They keep things simple and reproduce easily in 20 minutes, as for us humans, it takes us 20 years. Some prokaryote need oxygen and others do not. Every spoonful of yogurt contains a million of bacteria! One of the prokaryotes structure is the cell wall. The cell walls keeps itself from exploding and are made from peptidoglycan (sugar) with amino acids. Enzymes are the main type of protein that controls the metabolism. Mesosome controls things that come in and out of the bacteria. The flagella helps move the prokaryote around. The pili help stick the prokaryote onto things. For example, bacteria is able to stick onto your teeth with the help of pili. Those bacteria that stick onto your teeth are having sex, exchanging DNA, in your mouth. Bacteria has specialized functions each within its own form. There are lots of membranes in the inside and not only the outside of the bacteria. (This relates to the unit question)

These are some common features of cells: the cell membrane, cytoplasm, cytoskeleton, DNA and ribosomes. DNA -> RNA -> Ribosome -> Protein.

Phospholipids creates a boundary concentrating what is required and getting rid of any wastes. They have 2 personalities in one and are made of 2 fatty acids, glycerol, phosphate, and chorine. They have non polar/hydrophobic tails, electrons are equally shared and polar/hydrophilic, ionic, heads.   If there are enough of them, they can make a phospholipid bilayer, the fluid mosaic phospholipid bilayer. Bubbles are produced to make a separate environment in the inside and the outside.

Eukaryotic cells contain many organelles, including the nuclei. The most important organelles are; ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria and cytoskeleton.

The marker proteins/ glycoprotein are little flags and identify cell types. They stick together with other same proteins and make tissues. The receptor proteins listen for its corresponding messages (insulin) to do its job. The protein receive the insulin and takes the glycogen and puts it into the blood. * All features of being a women is caused by estrogen. Estrogen is a lipid /non polar and it can go through the membrane. Transport proteins have little channels and these proteins can specifically move molecules that cannot move into the phospholipid biolayer. There are also proteins in the membrane that act as channels and enzymes.


One thought on “3.2 Cell Features

  1. Yurika,

    Good blog for 3.2 on the limits of size in cells. Your entry is well-organized and thorough. Keep up the good work!

    Mr. F.

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