Download bacteria

BACTERIA
1
Characteristics of Bacteria
Did you know that billions of tiny organisms too small to be seen
surround you? These organisms, called bacteria are microscopic
prokaryotes. You might recall that a prokaryote is a unicellular
organism that does not have a nucleus or other membrane-bound
organelles.
Bacteria live in almost every habitat on Earth, including the air,
glaciers, the ocean floor and in soil. A teaspoon of soil can
contain between 100 million and 1 billion bacteria. Bacteria also
live in or on almost every organism, both living and dead.
Hundreds of species of bacteria live on your skin. In face, your
body contains more bacterial cells than human cells! The
bacteria in your body outnumber human cells by 10 to 1!
From textbook page 253
2
BACTERIA
 Bacteria like a warm, dark, and moist
environments.
 They are found almost everywhere:
-water
-air
-soil
-food
-skin
-inside the body
-on most objects
3
How do bacteria get in the body?
•
•
•
•
•
Air
– Droplets containing microbes fly into the air when people sneeze or cough. The microbes they
contain get into other people if breathed in.
– Chicken pox, colds, flu, measles and tuberculosis are spread like this.
Animals
– Animals may carry harmful microbes. The microbes can get into a person who is scratched or
bitten by such an animal. Malaria is a tropical disease spread by a tiny fly called a mosquito.
Food
– Food can have harmful microbes in and on it. The microbes get into the body when the food is
eaten, causing food poisoning. Thorough cooking kills most microbes, but they can survive
under-cooking. Careless handling of food increases the risk from harmful microbes.
Touch
– Microbes can be passed from one person to another when people touch each other, or when
they touch something an infected person has handled. Athlete's foot is spread like this.
– Bacteria on the skin can be killed by antiseptics, and bacteria on surfaces can be killed by
disinfectants. Washing your hands reduces the chance of spreading microbes.
Water
– Water can have harmful microbes in it. The microbes get into the body when the water is
swallowed. Cholera is a disease caused by a bacterium that spreads like this. Thorough boiling
or adding chlorine to the water can reduce the chance of spreading microbes in this way
4
3 Shapes of Bacteria
Rod-shaped
Round or Sphere-shaped
Spiral-shaped
5
7 Major Structures of a Bacteria Cell
•Capsule
•Cell wall
•Ribosomes
•Nucleoid
•Flagella
•Pilli
•Cytoplasm
6
7 Major Structures of a Bacteria Cell
Capsule
 keeps the cell
from drying out
and helps it
stick to food or
other cells
7
7 Major Structures of a Bacteria Cell
Cell wall
Thick outer
covering that
maintains the
overall shape of
the bacterial
cell
8
7 Major Structures of a Bacteria Cell
Ribosomes
 cell part where
proteins are made
 Ribosomes give
the cytoplasm of
bacteria a granular
appearance in
electron
micrographs
9
7 Major Structures of a Bacteria Cell
Nucleoid
 a ring made
up of DNA
10
7 Major Structures of a Bacteria Cell
Flagella
 a whip-like
tail that some
bacteria have
for locomotion
11
7 Major Structures of a Bacteria Cell
Pilli
 hollow hair-like
structures made
of protein
allows bacteria
to attach to
other cells.
Pilli-singular
Pillus-plural
12
7 Major Structures of a Bacteria Cell
Cytoplasm
 clear jelly-like
material that
makes up most
of the cell
13
Reproduction of Bacteria
Asexual reproductionreproduction of a living
thing from only one
parent
Fission- Type of asexual
reproduction. Cell division
that forms two genetically
identical cells.
14
Harmful Bacteria
Human tooth with accumulation of bacterial
plaque (smooth areas) and calcified tartar
(rough areas)
15
Harmful Bacteria
 Bacteria can also cause
infections such as
tuberculosis, pneumonia,
meningitis and strep throat.
 Eating food that is
contaminated by some
bacteria can cause
food poisoning.
16
Helpful Bacteria
•Decomposers help recycle nutrients into the
soil for other organisms to grow
•Bacteria grow in the stomach of a cow to
break down grass and hay
•Most are used to make antibiotics
•Some bacteria help make insulin
•Used to make industrial chemicals
17
Helpful Bacteria
E.coli on small intestines
18
Helpful Bacteria
•Used to treat sewage
Organic waste is consumed by the bacteria,
used as nutrients by the bacteria, and is no
longer present to produce odors, sludge,
pollution, or unsightly mess.
•foods like yogurt, cottage & Swiss cheese,
sour cream, buttermilk
are made from
bacteria that grows
in milk
19
BLUE-GREEN BACTERIA
Autotrophs – make their own food
through photosynthesis
larger than most bacterial cells
commonly grow on water and surfaces that
stay wet…such as rivers, creeks and dams
Some live in salt water, snow, and acid
water of hot springs
food source for animals that live in the
20
water
BLUE-GREEN BACTERIA
can be toxic to humans and animals
Blooms- occur when the
bacteria multiplies in great
numbers and form scum on
the top of the water
21
22