Bacteria and Protists• Objectives: 7Sb.3

– Compare the body shapes of bacteria• Detect differences among the shapes• Be able to classify bacteria as spiral, coccus, or bacillus

– Compare the body structures that protists use for food gathering and locomotion

• Detect similarities and differences among the structures of protists used for food obtainment and locomotion

• Identify protits as a euglena, amoeba, or paramecium based on structures for food gathering and locomotion.

Bacteria

• Greatest number of organisms in the world

• Part of the monera kingdom.

• Live almost everywhere on Earth

Properties of Bacteria

• Single-celled organisms- usually very small, seen using a microscope

• Simple organisms-lack organelles• Biologist classify bacteria by their shape.

– Looks – rod, spiral or sphere– Often form long chains or clusters that look

like a bunch of grapes.

Properties of Bacteria

Rod shapeSphere shape Spiral shape

Life Activities of Bacteria

• Each bacterial cell carries out all of the basic life functions– Ex. Break down dead organisms, some use

sunlight to make food• Many need oxygen to carry out respiration:

aerobe but some are poisoned by oxygen.

Methane Bubbles

• These bacteria live where oxygen is not present such as the bottom of swamps.

• Anerobe: can live without oxygen• They produce methane- a gas produced

by bacteria from hydrogen and carbon dioxide.

Methane bubbles out of the water as marsh gas.

Methane producing Bacteria

Binary Fission

• Bacteria reproduces by a process called binary fission.

• Binary Fission is where the bacterial cell divides into 2 cells that look the same as the original cell. Can reproduce every 20 minutes.

Helpful Bacteria

Many are helpful in two ways.1. Recycle nutrients such as carbon and

nitrogen. They breakdown dead organisms or waster.

• Organisms that do this are called saprophytes. • Some of the broken-down nutrients are returned to

the soil and plants use them. Animals eat the plants to get the nutrients.

Helpful Bacteria

• 2. Help plants to get nitrogen. – Nitrogen is plentiful in the atmosphere but

plants cannot absorb it from the air. – The nitrogen must be changed to ammonia.

Some bacteria lives inside the roots of plants and change the nitrogen to ammonia. In return the plants provide food for the bacteria.

Symbolic Relationships

• Mutualism- A closeness in which two organisms live together and help each other. – Example- bacteria that

turns nitrogen into ammonia and the plant provides food for the bacteria.

• Commensalism- A relationship in which one organism benefits and the other is not affected. – Ex. Barnacles on

whales.

• Mutualism

• Commensalism

Useful to humans

• 1. Bacteria help to produce some food.– Example- cheese, sour cream, yogurt, pickle

• 2. Bacteria can produce many different materials that are helpful. – Chemical companies use bacteria to make

vitamins. And some bacteria make antibiotics to kill other kinds of bacteria.

Harmful Bacteria

• Some cause food to spoil– Ex. Cause mild to spoil-

refrigerating food helps to prevent spoiling because bacteria grow slowly at low temps.

– Food that looks or tastes bad should be thrown away.

FYI

• Doctors prescribe antibiotics such as penicillin to fight bacterial disease.

• Bacteria often develops ways to resist the antibiotic.

• Many household products contain antibacterial agents- dish soap– They also cause bacteria to become resistant.– As more bacteria becomes resistant, scientists must

search for new ways to kill the bacteria.

Harmful Bacteria• Some cause disease. • Ex. Botulism, gonorrhea, strep throat• Some harm the body by producing

poisons called- toxins. • A single gram of botulism can kill a

million people. • Botulism is food poisoning.

– The bacteria can be inside canned food. It produces toxins.

– Eating the contaminated food causes botulism.

– Do not eat out of Expired cans or cans that show bacterial growth like the one to the left

Notice can expanding as the Bacteria grows.

Protists

• Is a kingdom• Contains over 6,000 species• Have many features like those of plants,

animals or fungi. • Are single-celled• Have organelles inside their cell.

Algae

• Plant-like protist are known as algae• Use sunlight to make food• Most are aquatic• Important in 3 ways:

– 1. Produce nearly half the world’s carbohydrates– 2. Provide food for other organisms– 3. Release oxygen as they make food- about half the

world’s oxygen that enters the atmosphere comes from algae.

Euglena• Euglena is a type of protist• Has chloroplasts.• Live in freshwater and moves with

a long, whiplike tail called a flagellum.

• Has unique characteristics of both a plant and a animal• Contains chloroplasts that

photosynthesize• Can consume other organisms as well.

Diatoms

• Diatoms are other kinds of protist• Found in freshwater and in the ocean. • Have hard shells that contain silica.• As diatoms die, their shells build up in

deposits at the bottom of lakes and sea. These deposits are mined to make metal polish and soaps.

Seaweed

• Is many celled. • Also called sea

lettuce. • Giant seaweed is

called kelp- is harvested and used to thicken foods.

Kelp

Protozoans

• Animal like protist• Protozoan means first animal• Live in water, on land or inside other

organisms. • Cannot make their own food- eat bacteria

or other protists or dead organisms.• Divided into 4 groups based on how they

move

Amoebas• Move by pushing out

parts of the of their cell called a pseudopod, means “false foot.”

• Amoebas change their shape

• Use pseudoposd to surround and trap other protists.

• Live on rocks and on plants in ponds.

Paramecium

• Move with short, hairlike structures known as cilia.

• Cilia moves like oars. When they move back, the paramecium moves forward.

• Often found in ponds.

Flegella

• Flegella- push or pull the protozoan• Example is Giardia lamblia- is a parasite in the

intestines of animals.• Get from water that contains waste from infected

animals. Causes tiredness, weight loss, but not usually fatal.

• Ex. Sleeping sickness is more serious caused by trypanosomes- a protozoan that is a parasite and lives in blood. Spread by the bite of tsetse flies which only live in Africa.

No means of moving

• Protozoans that reproduce by forming spores.

• Called sporozonas. – a protozoan that is a parasite and lives in blood, may cause malaria

• All sporozonas are parasites

• Live in the blood of their host

Malaria• Sporozoan Plasmodium causes

malaria.• Mosquitoes spread malaria

when they draw blood from an infected person. The sporozoan enters the mosquito and reproduces. The mosquito transfers the sporozoans when it bites another person.

• Malaria can be deadly and it affects ½ billion people every year.

• It kills 1 –3 million a year.

Protists

• Carry out all of the basic life activities.• Most are single-celled, but not simple• Cells must perform the duties of tissues

and organs in a plant or an animal.

Getting and Digesting Food

• Algae makes their own food• Protozoans do not• Euglena does both• Amoebas trap other protists• Paramecia use their cilia to sweep food

particles over their surface. – The food moves into an opening called the

gullet on the paramecium’s side. The gullet is like the mouth of an animal

Dinner time for an Amoeba

Paramecium eating1. Enters gullet2. The gullet encloses the food within a bubble like

structure called a food vacuole3. Small packets of food travel all through the

paramecium and chemicals in the food vacuole break down the food.

4. The food leaves the food vacuole to be used by the paramecium.

5. Food that is not digested leaves the paramecium through an opening called the anal pore.

Amoebas and other protozoan's also digest food inside the food vacuoles.

Paramecium

Maintaining Water Balance

• Most protist live in a watery environment• Water moves easily through the cell

membrane which causes a problem• Think of a dry sponge. What happens to

the sponge as it gets wet?• This is what happens to protists if they can

not control the water intake

Osmosis

• The water molecules outside the protists are more concentrated and the chemical molecules and water inside the protists are not as concentrated.

• This difference in concentration causes water to move into the protist from the outside.

• Osmosis is the movement of water through a cell membrane.

Passive Transport

• Water molecules move from an area of high concentration to an area of low concentration.

• This is a type of passive transport, or movement, that doesn’t use cellular energy.

Cell’s burst• Too much water causes a

protist to burst like a water balloon.

• To avoid bursting, protists release water that is not needed.

• Structures called contractible vacuoles collect water. They contract or pull together to squeeze the water out of the protist.

• Contractile vacuoles carry out the same functions as your kidneys when you drink too much water.

Sensing and Reacting

• All organisms must be able to sense and react to signals in their environment.

• Many protists have an eyespot, which can sense changes in the brightness of light.

• Eyespots allow algae to move to areas where the light is brighter. With brighter light they can make food more quickly.

Paramecium

                                                                                             

Sensing and Reacting

• Protozoans can sense food in their environment and move toward it.

• Protozoans can sense harmful chemicals and move away from it.

• Can move away from objects in it’s way.• Paramecium’s that bump into an object,

reverse by using their cilia.

Reproduction• Single-celled protist reproduce by dividing

into 2 cells. The result is 2 protists that look the same as the original cell and is an example of asexual reproduction.

• Some reproduce in pairs. Each member of the pair gives some hereditary material to the offspring. The offspring is different from either parent. This is an example of sexual reproduction.

Asexual reproduction