Topic 19 Simple Organisms (Prokaryotes) · Photoautotroph, Photoheterotroph (unique to ... describe...

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Topic 19 Simple Organisms (Prokaryotes)

CEB Textbook Chapter 15, pages 294-309

Mastering Biology, Chapter 15

› How did life first arise on Earth?

› To gain insight, scientists have

synthesized from scratch the entire genome of a small bacterium known as Mycoplasma mycoides and

transplanted the artificial genome into the cells of a closely related species called Mycoplasma capricolum.

© 2013 Pearson Education, Inc.

• The newly installed

genome

– took over the recipient cells,

– began cranking out

M. mycoides proteins, and

– reproduced to make more cells containing the synthetic M. mycoides genome.

Biology and Society: Has Life Been Created in the Lab?


› Earth was formed about 4.6

billion years ago.

› Prokaryotes

evolved by about 3.5 billion

years ago,

began oxygen production

about 2.7 billion years ago,

lived alone for more than a

billion years, and

continue in great

abundance today.


Figure 15.1a

Precambrian

Ancestor to all present-day life

Origin of Earth

Earth’s crust solidifies

Oldest prokaryotic fossils

Atmospheric oxygen begins to appear

Millions of years ago

4,500 4,000 3,500 3,000 2,500

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Figure 15.1b


2,000 1,500 1,000

Precambrian

Oldest eukaryotic fossils

Origin of multicellular organisms

Oldest animal fossils

Figure 15.1c


1,000 500 0

Precambrian Paleozoic Cenozoic Meso- zoic

Bacteria

Archaea

Plants

Fungi

Animals Cambrian explosion

Oldest animal fossils

Plants colonize land

Extinction of dinosaurs

First humans

Pro

tists

Pro

karyote

s Eu

karyote

s

Figure 15.UN03

Major episode Millions of years ago

All major animal phyla established

Plants and fungi colonize land

Origin of Earth

First multicellular organisms

Oldest eukaryotic fossils

Accumulation of O2 in atmosphere

Oldest prokaryotic fossils

500

530

1,200

1,800

2,400

3,500

4,600

Figure 15.2

Humans

Origin of solar system and Earth

1 4

2 3

0

What if we

use a clock

analogy to

tick down

all of the

major

events in

the history

of life on

Earth?

› All life today arises by the reproduction of preexisting life, or biogenesis.

› If this is true, how could the first organisms arise?

› From the time of the ancient Greeks until well into the 1800s, it was commonly believed that life regularly arises from nonliving matter, an idea called spontaneous generation.


› Today, most

biologists think it

is possible that

life on early Earth

evolved from

simple cells

produced by

chemical and

physical

processes.

Resolving the Biogenesis Paradox


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› Observation: Modern biological macromolecules are all composed of elements that were present in abundance on early Earth.

› Question: Could biological molecules arise spontaneously under conditions like those on early Earth?


› Hypothesis: A closed

system designed to

simulate early Earth

conditions could produce

biologically important

organic molecules from

inorganic ingredients.

› Prediction: Organic

molecules would form and

accumulate.

The Process of Science: Can Biological Monomers Form Spontaneously?


Figure 15.4

Miller and Urey’s experiment

“Sea”

H2O

Sample for chemical analysis

Cooled water containing organic molecules

Cold water

Condenser

Electrode

“Atmosphere”

Water vapor

CH4

NH3 H2

› Results: After the apparatus had run for a week, an

abundance of organic molecules essential for life had

collected in the “sea,” including amino acids, the

monomers of proteins.

› These laboratory experiments

have been repeated and extended by other scientists

and

support the idea that organic molecules could have

arisen abiotically on early Earth.

The Process of Science: Can Biological Monomers Form Spontaneously?


Figure 15.UN01

Bacteria

Archaea

Prokaryotes

Eukarya

Protists

Plants

Fungi

Animals

› Over millions of years

natural selection

favored the most

efficient pre-cells

and

the first prokaryotic

cells evolved.


› Prokaryotes lived

and evolved all

alone on Earth for

about 2 billion

years.

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› Prokaryotes

are found wherever there is life,

have a collective biomass that is at least ten times that of all eukaryotes,

thrive in habitats too cold, too hot, too salty, too acidic, or too alkaline for any eukaryote,

cause about half of all human diseases, and

are more commonly benign or beneficial.


› Compared to eukaryotes,

prokaryotes are

much more abundant

and

typically much smaller.

PROKARYOTES - They’re Everywhere!


Colorized SEM

› Prokaryotic cells

lack a membrane-enclosed

nucleus,

lack other membrane-

enclosed organelles,

typically have cell walls

exterior to their plasma

membranes, but

display an enormous range

of diversity.


Figure 4.4

Plasma membrane Cell wall

Capsule

Prokaryotic flagellum

Ribosomes

Nucleoid

Pili

Co

lori

zed

TEM

› The three most common shapes of prokaryotes

are

1. spherical (cocci),

2. rod-shaped (bacilli), and

3. spiral or curved.

Prokaryotic Forms


Spherical (cocci) Rod-shaped (bacilli) Spiral or Curved

SHAPES OF PROKARYOTIC CELLS

› All prokaryotes are

unicellular.

› Some species

exist as groups of two

or more cells,

exhibit a simple

division of labor

among specialized cell

types, or

are very large,

dwarfing most

eukaryotic cells.

Prokaryotic Forms


(a) Actinomycete

Cyanobacteria Giant Bacterium

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› About half of all prokaryotes are mobile, and many of

these travel using one or more flagella.

Prokaryotic Forms


› In many natural environments, prokaryotes attach to surfaces in a highly organized colony called a biofilm, which

may consist of one or several species of prokaryotes,

may include protists and fungi,

can show a division of labor and defense against invaders, and

Prokaryotic Forms


Biofilm can form on

almost any type of

surface, including

rocks,

metal,

plastic, and

organic material

including teeth.

Prokaryotic Forms


› Most prokaryotes can

reproduce

by dividing in half by binary

fission and

at very high rates if conditions

are favorable.

› Some prokaryotes form

endospores, which are

thick-coated, protective cells

produced when the prokaryote

is exposed to unfavorable

conditions.

Prokaryotic Reproduction


Endospore

Colorized TEM

› Biologists use the phrase “mode of nutrition” to

describe how organisms obtain energy and carbon.

Energy

Phototrophs obtain energy from light.

Chemotrophs obtain energy from environmental chemicals.


Carbon

Autotrophs obtain carbon from carbon dioxide (CO2).

Heterotrophs obtain carbon from at least one organic

nutrient—the sugar glucose, for instance.

› We can group all organisms according to the four

major modes of nutrition if we combine the

energy source (phototroph versus chemotroph) and

carbon source (autotroph versus heterotroph).

Figure 15.12

MODES OF NUTRITION

Light Chemical Chemoautotrophs (Prokaryote Only)

Photoautotrophs

Photoheterotrophs (Prokaryote Only)

Chemoheterotrophs

Energy source

Elodea, an aquatic plant

Rhodopseudomonas Kingfisher with prey

Bacteria from a hot spring

Org

anic

co

mp

ou

nd

s

Car

bo

n s

ou

rce

CO

2

Co

lori

zed

TEM

Co

lori

zed

TEM

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› By comparing diverse

prokaryotes at the

molecular level,

biologists have identified

two major branches of

prokaryotic evolution:

1. Bacteria

2. Archaea (more closely

related to eukaryotes).

© 2013 Pearson Education, Inc. Ar

Plaque forming Bacteria

Archaea Cells

Bacteria

Archaea

Prokaryotes

Eukarya

Protists

Plants

Fungi

Animals

› Some archaea are “extremophiles.”

Halophiles thrive in salty environments.

Thermophiles inhabit very hot water.

Methanogens

inhabit the bottoms of lakes and swamps and

aid digestion in cattle and deer.

Archaea


Salt-loving archaea (Halophiles) Heat-loving archaea (Thermophiles)

1) Pathogens

2) Chemical

Recycling/Decomposers

3) Bioremediation

4) Oxygen Revolution

› Bacteria and other organisms that cause disease

are called pathogens.

• Most pathogenic bacteria produce poisons.

Exotoxins are proteins bacterial cells

secrete into their environment.

Endotoxins are

not cell secretions but instead

chemical components of the outer

membrane of certain bacteria.

Figure 15.15

“Bull’s-eye” rash

Tick that carries the Lyme disease bacterium

Spirochete that causes Lyme disease

SEM

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› In October 2001,

endospores of the

bacterium that causes

anthrax were mailed to

members of the news

media and the U.S.

Senate.

› Five people died from this

attack.


› Another bacterium

considered to have

dangerous potential as a

weapon is Clostridium

botulinum, producer of

the exotoxin botulinum,

which

blocks transmission of

nerve signals that

cause muscle

contraction and

is the deadliest poison

on Earth.

Biological Weapons


› The bacterium enterobacteria Yersinia pestis that causes plague

is also a potential biological weapon,

is carried by rodents, and transmitted by fleas,

Infects lymph nodes and produces egg-size swellings called buboes under the skin, and

can be treated with antibiotics if diagnosed early.

Biological Weapons


› Prokaryotes play

essential roles in

chemical cycles in

the environment and

the breakdown of

organic wastes and

dead organisms.


http://en.wikipedia.org/wiki/Enterobacteriaceae

http://en.wikipedia.org/wiki/Yersinia_pestis



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› Bioremediation is the

use of organisms to

remove pollutants from

water,

air, and

soil.

› A familiar example is the

use of prokaryotic

decomposers in sewage

treatment.


› Certain bacteria

can decompose petroleum and

are useful in cleaning up oil spills.

Figure 15.17

Liquid wastes Outflow

Rotating arm spraying liquid wastes

Rock bed coated with aerobic prokaryotes and fungi

Photosynthetic bacteria were most likely responsible for rise in levels of oxygen in the atmosphere 2500 mya which allowed the first respiring eukaryotes to develop

Two main domains – Bacteria and Archaea

Three common shapes – Spherical, Rod, Spiral

Four main modes of nutrition –

Photoautotroph, Photoheterotroph (unique to

prokaryotes), Chemoautotroph (unique to

prokaryotes), Chemoheterotroph

Bacterial impact on life on Earth – Pathogens,

Chemical Recycling, Bioremediation, Oxygen

Revolution

Topic 20 Microbes with Complex Cells

(Eukaryotes)

CEB Textbook Chapter 15 pages 306-311, & Chapter 16, pages 328-332

Mastering Biology, Chapters 15 and 16

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Learning outcomes: After studying this topic you should be able to:

•Explain the fundamental difference

between protists and fungi as compared to

bacteria and archaea.

•List the four main types of protists and briefly describe an example of each type.

•Describe the basic structure of fungi and

explain how they feed and reproduce.

•Describe examples of important impacts

that fungi have in medicine and agriculture.

Figure 15.UN02

Bacteria

Archaea

Prokaryotes

Eukarya

Protists

Plants

Fungi

Animals

› Protists are

eukaryotes that are not

fungi, animals, or plants,

mostly unicellular, and

ancestral to all other

eukaryotes.


› Eukaryotic cells evolved by

the infolding of the plasma

membrane of a prokaryotic

cell to form the

endomembrane system

and

a process known as

endosymbiosis.


› Endosymbiosis

refers to one species living inside another host species

and

is the process by which eukaryotes gained

mitochondria and chloroplasts.

Figure 15.19

(a) Origin of the endomembrane system (b) Origin of mitochondria and chloroplasts

Plasma membrane DNA

Cytoplasm

Endoplasmic reticulum

Nucleus

Nuclear envelope

Ancestral prokaryote

Membrane infolding

Cell with nucleus and endomembrane system

Photosynthetic eukaryotic cell

Photosynthetic prokaryote

Aerobic heterotrophic prokaryote

Endosymbiosis

Mitochondrion

Chloroplast

Figure 15.20

(a) An autotroph: Caulerpa, a multicellular alga

(b) A heterotroph: parasitic trypanosome

(c) A mixotroph: Euglena

Co

lori

zed

SEM

LM

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› Protist habitats are diverse and include

oceans, lakes, and ponds,

damp soil and leaf litter, and

the bodies of host organisms with which they share mutually beneficial relationships, such as unicellular algae and reef-

building coral animals, and

cellulose-digesting protists and termites.

The Diversity of Protists


1)Protozoans

2)Slime Molds

3)Algae

4)Seaweed

› Protozoans are protists that live primarily by ingesting

food are called


Figure 15.22

A foram

A flagellate: Giardia

LM

LM

Co

lori

zed

SEM

Co

lori

zed

SEM

Co

lori

zed

TEM

Another flagellate: Trichomonas An amoeba

Red blood cell

Apical complex

TEM

An apicomplexan A ciliate

Cilia

Cell “mouth”

Main Types of Protozoan

a) Flagellates - Protozoans with

flagella

› are typically free-living, but some are

nasty parasites.

Main types of Protozoans

b) Amoebas are characterized by

great flexibility in their body shape

and

the absence of permanent

organelles for locomotion.

› Most species move and feed by

means of pseudopodia (singular,

pseudopodium), temporary

extensions of the cell.

c) Forams – Are protozoans

which have shells.



d) Apicomplexans are

named for a structure at their

apex (tip) that is specialized

for penetrating host cells and

tissues,

all parasitic, and

able to cause serious human

diseases, such as malaria

caused by Plasmodium.

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Figure 15.22e

Red blood cell

Apical complex

TEM

An apicomplexan

› Another apicomplexan is Toxoplasma,

occurring in the digestive tracts of millions of people in the United States but

held in check by the immune system.

› A woman newly infected with Toxoplasma during pregnancy can pass the parasite to her unborn child, who may suffer nervous system damage.



e) Ciliates are protozoans that

are named for their use of

hair-like structures called

cilia to move and sweep

food into their mouths,

are mostly free-living

(nonparasitic), such as the

freshwater ciliate

Paramecium, and

include heterotrophs and

mixotrophs.



Figure 15.22f

LM

A ciliate

Cilia

Cell “mouth”

› Slime molds

resemble fungi in

appearance and lifestyle

due to convergence, but

are more closely related to

amoebas.

› The two main groups of

these protists are

plasmodial slime molds

and

cellular slime molds.


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› Plasmodial slime

molds

are named for the

feeding stage in their

life cycle, an amoeboid

mass called a

plasmodium,

are decomposers on

forest floors, and

can be large.

Types of Slime Molds


› Cellular slime molds have an

interesting and complex life

cycle of successive stages:

a feeding stage of solitary

amoeboid cells,

a swarming stage as a slug-

like colony that can move and

function as a single unit, and

a stage during which they

generate a stalk-like

multicellular reproductive

structure.

Types of Slime Molds


Figure 15.24

Life stages of a cellular slime mold

Slug-like colony

Amoeboid cells

Reproductive structure

LM

1

2

3

› Algae are

photosynthetic protists

whose chloroplasts

support food chains in

freshwater and

marine ecosystems.

› Many unicellular algae

are components of

plankton, the

communities of mostly

microscopic organisms

that drift or swim weakly

in aquatic environments.


• Unicellular algae include

– dinoflagellates, with

– two beating flagella and

– external plates made of

cellulose,

– diatoms, with glassy cell walls containing silica, and

– green algae.

3. Unicellular and Colonial Algae (Protists)


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• Green algae are

– unicellular in most freshwater lakes and

ponds,

– sometimes flagellated,

such as Chlamydomonas, and

– sometimes colonial, forming a hollow ball of flagellated cells as seen

in Volvox.

3. Unicellular and Colonial Algae (Protists)


Figure 15.25

(a) A dinoflagellate, with its wall of protective plates

LM

LM

SEM

C

olo

rize

d S

EM

(b) A sample of diverse diatoms, which have glassy walls

(c) Chlamydomonas, a unicellular green alga with a pair of flagella

(d) Volvox, a colonial green alga

› Seaweeds

are large, multicellular marine

algae,

grow on or near rocky

shores,

are only similar to plants

because of convergent

evolution,

are most closely related to

unicellular algae, and

are often edible.


› Seaweeds are classified

into three different

groups, based partly on

the types of pigments

present in their

chloroplasts:

1. green algae,

2. red algae, and

3. brown algae (including

kelp).

Seaweeds


Brown algae Red algae Green algae

› Multicellular organisms have specialized cells that are dependent on each other and

perform different functions, such as feeding,

waste disposal,

gas exchange, and

protection.


› Colonial protists likely formed the

evolutionary links between

unicellular and

multicellular organisms.

› The colonial green alga Volvox

demonstrates one level of specialization

and cooperation.

http://www.youtube.com/watc

h?v=He9FSeGRi3A

16/10/2013

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Figure 15.27-1

Unicellular protist

An ancestral colony may have formed when a cell divided and remained attached to its offspring.

Figure 15.27-2

Unicellular protist

Locomotor cells

Food- synthesizing cells

Cells in the colony may have become specialized and interdependent.


Figure 15.27-3

Unicellular protist

Locomotor cells

Food- synthesizing cells Somatic

cells

Gamete

Additional specialization may have led to sex cells (gametes) and nonreproductive cells (somatic cells).

Cells in the colony may have become specialized and interdependent.


Any Eukaryote that is not a fungi, animal or

plant!

Four main types

1) Protozoans (flagellates, amoebas,

apicomplexans, and ciliates) – aquatic and

ingest their food

2) Slime moulds –decomposers, resemble fungi

but not closely related

3) Algae – (dinoflagellates, diatoms, unicellular

green algae) – photosynthetic, support food

chains in fresh water and marine ecosystems

4) Seaweed – (green, red and brown algae) –

large multicellular marine algae

› Fungi are

eukaryotes,

typically multicellular, and

more closely related to animals

than plants, arising from a

common ancestor about 1.5

billion years ago.

FUNGI


come in many shapes and sizes and

represent more than 100,000 species.

› Fungi have unique

structures and

forms of nutrition.

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Figure 16.22

Orange fungi

Mold

Predatory fungus

Budding yeast A “fairy ring”

Bud

Roundworm Body of fungus

Co

lori

zed

SEM

Co

lori

zed

SEM

C

olo

rize

d S

EM

› The bodies of most fungi are

constructed of threadlike filaments

called hyphae.

› Hyphae are minute threads of

cytoplasm surrounded by

a plasma membrane and

cell walls mainly composed of

chitin (not cellulose like in plants!).


› Hyphae branch repeatedly,

forming an interwoven network

called a mycelium (plural,

mycelia), the feeding structure of

the fungus.

› Fungi

are chemoheterotrophs

and

acquire their nutrients by

absorption.

› A fungus is a decomposer

digests food outside its

body by secreting

powerful digestive

enzymes to break down

the food and

absorbs the simpler food

compounds.


Figure 16.23

Reproductive structure

Mycelium

Hyphae Spore-producing structures

› Mushrooms

arise from an

underground mycelium

and

mainly function in

reproduction.

› Fungi reproduce by

releasing haploid spores

that are produced either

sexually or

asexually.

Fungal Reproduction

© 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.

Animation: Fungal Reproduction and

Nutrition

Right click slide / select “Play”

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› Fungi and bacteria

are the principal decomposers of ecosystems and

keep ecosystems stocked with the inorganic nutrients

necessary for plant growth.

› Without decomposers, carbon, nitrogen, and other

elements would accumulate in nonliving organic

matter.


› Fungi have

an enormous ecological impact and

many interactions with humans.

› Molds can destroy

fruit,

grains,

wood, and

human-made material.

Fungi as Decomposers


› Parasitic fungi absorb nutrients from the cells or body fluids of living hosts.

› Can cause serious economic losses in agriculture

› Of the 100,000 known species of fungi, about 30% make their living as parasites, including

Dutch elm disease and

deadly ergot, which infests grain.

Potato blight


(a) An American elm tree killed by

Dutch elm

disease fungus

Figure 16.24b

(b) Ergots

› About 50 species of fungi are

known to be parasitic in

humans and other animals,

causing

lung and vaginal yeast

infections such as thrush

athlete’s foot

facial eczema

Parasitic Fungi


› Observation: In 1692, eight young

girls were accused of being witches

and had symptoms consistent with

ergot poisoning.

› Question: Did an ergot outbreak

cause the witch hunt?

› Hypothesis: The girls’ symptoms

were the result of ergot poisoning.

› Prediction: The historical facts would

be consistent with this hypothesis.


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› Results: Agricultural records

from 1691, before the symptoms appeared, indicated a particularly warm and wet year, in which ergot thrives.

Records from the following year, when accusations of witchcraft died down, indicate a dry year consistent with an ergot die-off.

This correlation is consistent with the hypothesis but not conclusive.

The Process of Science: Did a Fungus Lead to the Salem Witch Hunt?


› Fungi are commercially

important. Humans eat them

and use them to

produce medicines such as

penicillin (the first ever

antibiotic!),

decompose wastes, and

produce bread (yeast),

beer, wine, and cheeses.

Mushrooms and Truffles

are grown for food


Figure 16.26

Chicken of the woods

Giant puffball

Chanterelle mushrooms

Figure 16.27

Penicillium Zone of inhibited growth

Staphylococcus

› Mutually beneficial

symbiotic relationships

between plants and fungi


› Examples include

Mycorrhizae, a fungi which

increases the surface area of plant

roots allowing them to absorb more

minerals and water from the soil,

and

Lichens, the association of fungi

and algae. Algae can create sugars

by photosynthesis which feeds

both. Fungi increases surface area

allowing more water absorption.

Figure 16.28

Algal cell

Lichens: symbiotic associations of fungi and algae

Co

lori

zed

SEM

Fungal hyphae

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18

Unicellular or multicellular eukaryotes

Chemoheterotrophs – Digest their food externally and absorb nutrients, more closely related to animals than

plants

Consist of threadlike hyphae, forming a mycelium

Reproduce by releasing spores

Ecological Impact of Fungi

Principal decomposers of ecosystems

Parasites of people and other animals and plants. Beneficial to some plants to increase root surface

area.

Important in manufacture of food (bread, beer, wine,

mushrooms, truffles) and antibiotics

Symbiotic Relationship with plants – Fungi live on roots

of plants (gets nutrients) and increase surface area of plant roots (plant can absorb more water/minerals

Homework Prokaryotes and Eukaryotes

1) Unit Assessment Topic 19 and 20

2) Mastering Biology Assignment Prokaryotes and Eukaryotes

3) Mastering Biology activities:

Prokaryotic Cell Structure and

Function, Classification of

Prokaryotes

4) Complete the tables in study notes for Topic 19 and 20

5) Fill in Key Terms tables for Topic 19

and 20

VIDEOS Crash course in Fungi

http://www.youtube.com/watch?v=m4DUZhnNo4s

Fungi Lesson

http://www.youtube.com/watch?v=dj9m7Oc36wM

Crash course Archaea, Bacteria (Prokaryotes) and Protists (Unicellular

Eukaryotes) http://www.youtube.com/watch?v=vAR47-g6tlA

Bacteria Lesson

http://www.youtube.com/watch?v=h-z9-9OOWC4

http://www.youtube.com/watch?v=m4DUZhnNo4s

http://www.youtube.com/watch?v=dj9m7Oc36wM

http://www.youtube.com/watch?v=vAR47-g6tlA








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