levels of biological organization and unicellular...

Levels of biological

organization and unicellular

organisms

8th grade science

Levels of Biological Organization.

Atom Molecule Cell

Organelle

Tissue

System

Organism

“I’m Jimmy Carter, 39th President”

“I am made of an enormous number of atoms”

“Which come together to create molecules”

“Which can organize to create cell organelles”

“Many organelles can form a living cell.”

“Many specialized cells form tissues.”

“Specialized tissues can form organs.”

“Many organs can form an organ system.”

“Many organ systems working together can form

organisms.”

Cell Theory

Well researched ideas that all scientists believe to be true about cells:

1. Cells are the basic unit of life.

2. All living things are made of cells.

3. New cells are produced from existing cells.

beforenucleus

truenucleus

Eukaryotes

1. Ex: animals, plants, fungi

2. Has a nucleus with a nuclear envelope

3. Have membrane bound Organelles

(golgi, ER, lysosomes…etc)

4. Bigger and more complex than prokaryotes

5. Can be unicellular OR multicellular

organisms

Multicellular eukaryotes

• Whole cells can be specialized for one job

• Cells can work together as tissues

• Tissues can work together as organs

Examples of specialized euk.

• liver cell:

specialized to

detoxify blood and

store glucose as

glycogen.

• Mesophyll cell– inside leaves

– specialized to

capture as much

light as possible

Eukaryotes are bigger and more

complex

• Have organelles

• Have multiple strands of DNA

• can be multicellular

• Includes all animal and plant cells

Prokaryotes

1. Ex: bacteria and archaea

2. NO nucleus

3. NO membrane bound organelles

4. ALL are unicellular

5. Much smaller than eukaryotic cells

6. Predate eukaryotic cells (were around long before)

Prokaryote cells are simply built

Three layers on the

outside

• capsule: slimy outer

coating to protect the

• cell wall: tougher

middle layer

• cell membrane: delicate

inner skin

Prokaryote cells are simply built

• Cytoplasm, cytoskeleton,

ribosomes

• One strand of DNA

arranged in a big loop

• pilli: fibers made by the

cell, used for sticking to

things

• flagella: whip-like tail used

for swimming

E. coli bacteria

on the head of

a steel pin.

Prokaryote food sources

• Photosynthetic: get their energy from

sunlight

• Heterotrophic: feed on living things

• Decomposers: feed on dead things

Prokaryote lifestyle

• unicellular: all alone

• colony: forms a thin film of

cells that help protect one

another, kind of like a

community.

• Filamentous/clusters: forms

chains/small groups of cells

that help each other out.

Prokaryote vs

eukaryote size

White blood cell

Red blood cell

Bacteria Cell

Not Living

Prokaryote levels of Biological Organization.

Atom MoleculeCell

Multicellular organisms Organism is made up of many cells

Cells are specialized to perform different functions

Individual cells don’t have to perform every life function

Death or injury of some cells won’t doom the organism as a whole

The organism can attain a large size by increasing the number of cells

Generally long lifespan and slower reproduction

Only outer cells are exposed to the environment

Unicellular organisms

Organism is made up of one cell

A single cell carries out all functions

Injuries to the cell are serious and often deadly

Very limited on organism size due to the limitations of diffusion

The entire organism is exposed to the environment

Short lifespan and fast reproduction

Which cell has a nucleus (Eukaryotic), and

which is a bacteria (Prokaryotic)?

Cell with a nucleus,

Eukaryotic

Cell without nucleus

Prokaryotic (Bacteria)

• Which is prokaryotic?

BacteriaArchaea

Protists

Major groups

of unicellular

organisms

• Archaea are inhabitants of some of the most

extreme environments on the planet.

Like these deep-sea

geothermal vents

• An acidic mine drain filled with Archaea.

• Archaea also thrive in mud, they are one

reason swamps are usually smelly.

• Archaea are prokaryotes, meaning….

• Archaea are prokaryotes, meaning….No

nucleus or membrane bound organelles.

• Types of Archaea

– Methanogens: Produce methane gas as a waste

product of their digestion.

– Halophiles: Live in extremely salty environments.

– Thermophiles: Live in extremely hot temperatures.

– Psychrophiles: Live in unusually cold

temperatures.

Archaea are rather pretty in large numbers

• Bacteria are single celled organisms that are

much more common than archaea and live

almost everywhere.

• Bacteria are prokaryotic no nucleus and

no membrane bound organelles.

• Bacterial shapes

– Sphere (Round) Shaped: Cocci

• Rod shaped: Bacillus

• Spiral shaped: Spirilla

• Mycoplasma bacteria: Smallest known life form

(jagged and random).

• Mycoplasma are oddly shaped because

they don’t have a cell wall.

• Many bacteria grow as colonies of millions,

billions, or even trillions of individual cells

living next to one another.

Bacterial reproduction

– Bacteria under the right conditions (enough food

and water, the correct temperature, and absence

of inhibiting chemicals) can reproduce very

quickly.

– Bacterial cells reproduce by a process called

binary fission where one bacterial cell will divide to

form two identical offspring.

– Binary fission is a form of asexual reproduction.

Meaning that there is only one parent and the

offspring are genetically identical to the parent.

• Cyanobacteria.

– They’re photosynthetic bacteria (get energy from

• Heterotrophic bacteria

– Bacteria that get their energy from other living

things.

• Currently living things

• Dead things

• Materials produced by other living things (ex:

• Many species of bacteria live in or on our body.

– Mutualistic: We provide a place to live and food,

while the bacteria attack harmful microbes and

digest food.

– Commensalistic: Most bacteria in our body, they

benefit but don’t cause us harm.

– Parasitic: Harmful bacteria that eat tissue and

release toxins.

• A few positives of bacteria.

– They are used in many food products.

– Symbiotic relationships with plants.

– They decompose wastes and dead things.

– Help us digest food and absorb nutrients.

– They recycle nutrients in

the environment.

– They destroy pollution.

• A few negatives of bacteria

– They can kill us by the millions.

– They can destroy food and property.

– They can make life generally unpleasant: bad

breath, odors, acne, etc.

• The name Protista means "the very first",

and there are thousands and thousands of

different species of the most basic

eukaryotes.

• Animals, Plants, and Fungi are all

descended from primitive Protists.

• Protists are like the junk drawer of

eukaryotes.

– If it’s a eukaryote and not a plant, animal,

fungus, or bacteria it just goes in the kingdom

Protista.

• Protists are very diverse and can use

sunlight, eats things, or decompose things to

get nutrients.

• Protists are mostly single celled organisms,

some are very simple multicellular

organisms. Protists are thought to be the link

between the two groups.

• Protists do not form tissues.

• Remember, Protists lack tissues.

– Which specimen below is a protist, and which

is an animal?

Answer! Protists do not have eyes because

they are unicellular organisms.

• Which specimen below is a protist, and

which is an animal?

• Answer A. Protists are unicellular so

they don’t have tissues and organs.

• Is this a protist? Why or why not?

• Answer! No, because the specimen has

tissues such as eyes, and some sort of

digestive tract.

• Algae (Autrophs)

• Algae can be found as bacteria, protists,

and plants.

• Algae produce the majority of the oxygen

on Earth.

• Diatoms

– Organisms that make glass shells to protect

themselves.

• Diatoms produce more oxygen for the

planet than all of the forests combined.

– About ¼ of all the oxygen on Earth comes

from diatoms.

• Diatoms use silicon to make their glass

shells using a process called

biomineralization.

• Dinoflagellates (Flagella)

• Euglena

• Ciliates

–Cilia

• Cilia: Hairlike projections from the surface

of a cell and used to move the cell.

• Paramecium are ciliates.

• Amoebas

• The slime molds and water molds of protists

used to be in the Kingdom Fungi but have

been switched to the protists.

• Brown Algae

• Red Algae

Bacterial spores

– Sometimes conditions in a

bacteria’s environment

would be deadly to the

organism.

– Some bacteria can combat

this by forming endospores;

small, round, tough, mostly

dormant, cells that preserve

the bacteria’s DNA.

Bacterial spores

– Endospores can resist heating, freezing, harsh

chemicals, and drying for many, many years.

Waiting until conditions are right for the cell to

start growing again.

• Cyanobacteria are thought to have led to

the plants.

– The chloroplasts that help plants make food

using sunlight is thought to be an ancient

cyanobacterium living within plant cells.

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