Bacteria
Bacteria are small living things that can be found almost everywhere. They live on the ground, in oceans, in the food that we eat and even in our bodies. They have been on earth long before there were any other organisms .Bacteria are so small you can only see them with the help of a microscope. They have only one cell and very simple structures.
Bacteria have outer cell walls that protect the inside. A cell membrane is inside the cell wall. It prevents harmful substances from getting in and out. Inside the membrane is a soft, jelly-like substance called the cytoplasm. It has chemicals that help build the parts of a cell and break down food. Within it is the nucleoid, which contains the DNA. It controls a cell’s growth and other activities
Bacteria appear in different shapes. Spherical bacteria are round or ball-like. Rod-shaped bacteria live in your intestine and formchains. Spiral-shaped bacteria have a twisted form.
Bacteria absorb nutrients and remove waste through their cell walls. They reproduce by splitting themselves in the middle. The two new cells can then split into four cells and so on. In a short time a single bacteria can reproduce billions of times.
Some
bacteria can get inside the human body, reproduce and cause an
infection. These harmful bacteria
are called pathogens. Ourimmune
system is
in charge of fighting off these bacteria. However,
sometimes we need a vaccine to
help fight off these intruders.
Vaccines are weak or dead forms of the bacteria itself. Such
a substance helps
our body fight off bacteria in the future. Some examples
of illnesses caused
by bacterial infections are tuberculosis or pneumonia.
The best way to protect yourself form bacteria is to keep yourself clean and wash your hands. Because bacteria may be transported by air, we should cover our nose and mouth when we sneeze. Vitamins also help strengthen our immune system and fight off bacteria.
Bacteria can be helpful to the human body as well. They live in our stomach and help us digest food. Other bacteria create cheese and yoghurt. Bacteria are at work in the soil and decompose dead plants and animals.
absorb = take in
appear =show
break down = break into very small pieces
cause = lead to
chain = rings that are joined together
decompose = to break down into very small parts
digest = to change food that you have eaten into substances that your body can use
DNA = substance that has the genetic information in the cells of a body
growth = how something grows
harmful = dangerous
however = but
illness = disease
immune system = system in your body that protects it from diseases
intestine = long tube in your body through which food passes after it leaves your stomach
intruder = here: something harmful that gets into your body
jelly = something soft and sticky; it can easily move when you touch it
membrane = very thin layer that covers an object and protects it
nucleoid = region in a cell
nutrient = chemical or food that gives plants and animals what they need to grow
organism = anything that lives
pneumonia = illness that affects your lungs and makes it difficult for you to breathe
prevent = stop, keep away
protect = guard, care for, defend
remove = bring away
reproduce = here: create new bacteria
rod = long and thin
shape = form
single = only one
sneeze = air comes suddenly through your nose with a loud noise
soil = the top layer of the earth, where plants and trees can grow
spherical = round like a ball
strengthen = make stronger
structure = the way something is built
substance = material
transport = travel
tuberculosis = disease that affects your lungs and other parts of your body
twisted = turned, bent
waste = material that we do not need