Types of Heterotrophic Nutrition

Methods of Feeding1. Saprophytic Nutrition

– feed on dead organic matter, get energy from it, and recycle it back into the environment.

• decomposers.

2. Parasitism– organism (parasite) feeds off of another (host) at the expense of the

host.

3. Predation– - organism (predator) hunts, kills, and eats another organism

(prey). 

4. Scavenging– feed on organisms killed by something else.

What are Bacteria?• Bacteria are PROKARYOTES

– The smallest known living cells

They are found

everywhere!!

Bacteria onhead of a pin Starr, 317

Bacteria in dental plaque microbeworld.org

Did you know? There are over 80 species of bacteria in your mouth!

Obtaining Energy

• Autotrophs (make energy)– Photoautotrophs- capture energy from

light• Ex- cyabobacteria

– Chemoautotrophs- obtain energy from chemical reactions with inorganic molecules (ammonia, hydrogen sulfide, nitrites, sulfur, Iron)• make glucose using energy from

chemical compounds• Ex. Ocean vent bacteria

Cyanobacteria bloom

Obtaining Energy cont…

• Heterotrophs- most bacteria obtain their energy from organic molecules– These bacteria are often feeding in, on and around

us…

• Some bacteria are photoheterotrophs– Capture sunlight and digest organic molecules

Releasing Energy

• Bacteria can use both cell respiration and fermentation

• Many bacteria have different oxygen requirements:– Obligate aerobes- must have oxygen for respiration– Facultative anaerobes- can function with or without

oxygen– Obligate anaerobes- poisoned by oxygen (use

fermentation)

Three basic shapes of Bacteria

• Spherical – coccus

• Rod – bacillus• Coiled - spirillum

Schraer, 633

Shapes of Bacteria

Coccus

• Spheres

• Cocci (plural)

• a variety of arrangements

Diplobacillus (paired)

Bacillus • Cylindrical or rod-shape

• Bacilli (plural)

• Variations in cell arrangement

Spirillium

• Spiral or “squiggle” shaped bacteria

• Vibrio• Spirillum• Spirochete

Simple Colonies

Staphylo = clusters Strepto =

chains

Staphylococcus wisc.edu

Diplo = double

Diplococcus

cat.cc.md.us

Streptobacillus

Bacterial colony shapes have specific names that are used as A prefix that combines with the name of their shape.

Some have flagella - made of rope-like proteins, not microtubules.

Some slide on a slimy secretion.

Many can form dormant

cells called endospores to survive harsh conditions.

Salmonella www.iwate.jp

Streptomyces spores

Many can MOVE

Bacterial Reproduction

• Bacterial cells reproduce asexually through fission which is the splitting of a cell into two new cells.

Bacterial Reproduction cont…• Some bacteria utilize conjugation to

exchange pieces of genetic information to increase variation– *Not considered sexual reproduction- not

complete exchange of DNA, no offspring made

Bacterial Cells

Their Structure

Structure of a Bacterial Cell

http://en.wikipedia.org/wki/Image:Average_prokaryote_cell-_en.svg

Cell Wall

•Outside membrane- maintains cell structure

•May have cell wall + capsule (second wall)

•Protects the cell

•Eubacteria-composed of peptidoglycan, a polymer of sugars and amino acids

Plasma Membrane

•Controls what enters and exits, selectively permeable

•phospholipid bilayer surrounding cell

•contains proteins that play a role in transport of ions, nutrients, and wastes

Flagella (not found in all bacteria)

•tail-like structure used for locomotion

Structure of a Bacterial Cell

Nucleoid

•region DNA is found in prokaryotes

•single double-stranded circular chromosome

•Contains all genetic information

Plasmid (some bacteria)

•small circular chromosome carrying special genes

•may carry an antibiotic resistance gene

•Can be exchanged through conjugation

Ribosomes

•site of protein synthesis (translation)

Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

http://en.wikipedia.org/wiki/Image:Average_prokaryote_cell-_en.svg

Bacterial Structure• Respiratory Enzymes

– Use enzymes in the cytoplasm to undergo respiration

• Cytoplasm– Fluid filling cell

Two Kingdoms of Bacteria

• Kingdom Archaebacteria

- “Ancient”, most primitive earliest known form of life -

•Kingdom Eubacteria - includes bacteria and cyanobacteria (blue-green)

Fluorescent micrograph of an archaeon microbeworld.org

Eubacteria

EUBACTERIAEUBACTERIAthe the ““truetrue”” bacteria- more common bacteria- more common

Cell Walls

• eubacterial cells have two different cell wall structures. A technique called gram staining can distinguish between:– Gram-positive: cell wall containing mainly

peptidoglycan- stains purple– Gram-negative: bacterial cell has a second,

outer layer of lipids and carbs- stains pink

Kingdom Eubacteria

Photosynthetic – 2 groups 1) cyanobacteria (aerobes)

–Have chlorophyll a and phycocyanin (blue)–Other colors, too–Most live in fresh water–Others live in salt water, soil and lichens

Starr, 315NostocSchraer, 637

More photosynthetics

2) green-sulfur and purple bacteria - anaerobic

- colors range from pink to black - photosynthesize without

water - make no oxygen - live in pond and sea mud

CyanobacteriaThis is a group of bacteria that includes some that are single cells and some that are chains of cells. You may have seen them as "green slime" in your aquarium or in a pond.

Cyanobacteria can do "modern photosynthesis", which is the kind that makes oxygen from water. All plants do this kind of photosynthesis and inherited the ability from the cyanobacteria.

Cyanobacteria were the first organisms on Cyanobacteria were the first organisms on Earth to do modern photosynthesis and they Earth to do modern photosynthesis and they made the first oxygen in the Earth's made the first oxygen in the Earth's atmosphereatmosphere..

Biologic Importance of Bacteria

1) Essential to nutrient cycling2) Decomposers – in soil, inside

animals3) Enterobacteria – live inside us,

break down waste, make vitamins • vitamin K is essential to blood clot formation.

4) Process foods – cheese, yogurt etc..5) Some MAKE antibiotics

(streptomyacin)

Bacterial uses cont.6) Help with sewage treatment

– Break down wastes

7) Can be utilized in genetic engineering, molecular research…– Insert foreign genes into new organism– Can be used to make specialized products like

insulin

8) Indicate pollution levels– Provide visual clue to presence of pollution

9) Nitrogen Fixation– Still other Bacteria live

on the roots of certain plants, converting atmospheric nitrogen into a usable form.

Some cause diseaseWe call these “pathogens”

Anthrax, as seen by Koch microbeworld.org

But most are beneficial

Bacteria ferment cheese Schraer, 641

Kingdom Archaebacteria

Why a separate kingdom? Archae differ chemically from other bacteria. 1) cell wall - different amino acids and sugars.

Eubacteria have peptidoglycanArchaebacteria have varied polysaccharides

but not peptidoglycan. 2) unique membrane lipids3) ribosomes4) enzymes - - - - - - - - - - - - >5) gene sequences . . . And MORE

RNA polymerase

ArchaebacteriaArchaebacteria• Lack important Lack important

carbohydrate found in carbohydrate found in cell wallscell walls

• Have different lipids in Have different lipids in their cell membranetheir cell membrane

• Different types of Different types of ribosomesribosomes

• Very different gene Very different gene sequencessequences

• Archaebacteria can Archaebacteria can live in extremely harsh live in extremely harsh environmentsenvironments

• They do not require They do not require oxygen and can live in oxygen and can live in extremely salty extremely salty environments as well environments as well as extremely hot as extremely hot environments.environments.

Archae are extremophiles

Live in habitats like early earth Too harsh for most organisms

1) methanogens – decomposers, live in intestines, swamps & bogs

sewage treatment

2) Halophiles – “love salt” Great Salt Lake, Dead Sea

3) Thermophiles – hot springs, geysers

4) Acidophiles – acidic environments

Starr,635

ArchaeaArchaea, , the the ““extremophilesextremophiles””methanogens, thermophiles, halophilesmethanogens, thermophiles, halophiles

Nitrogen-fixing Fix nitrogen in special cells called heterocysts

Chemosynthetic make glucose using energy

from chemical compounds

**Mostly archae

Starr, 745

Legume roots – nodules contain nitrogen-fixing bacteria

Tube worms at ocean vent Fed by chemoautotrophs

Starr, 314

Eubacteria and Archaebacteria