Cyanobacteria and Endosymbiosis

Objectives

– Students will be able to:

• Assess the magnitude of lake polution.• Describe endosymbiosis and provide evidence

for the theory. • Recognize the social impacts of mitochondrial

DNA.

Thought Question

•Before there were plants, how did oxygen enter the atmosphere?

Cyanobacteria

• Photosynthetic Prokaryotes.

• Produced most of the first oxygen in the atmosphere.

What happens to all of the chemical runoff that is dumped into the sea or

lakes?

• It becomes food for algae and cyanobacteria.

What happens to all of the chemical runoff that is dumped into the sea or

lakes?

Satellite image of the Gulf of Mexico

Dangerous cyanobacteria

• Large amounts of cyanobacteria destroy the wildlife around them. – How?• Block sunlight• Take up too many

resources.

Which organelle might have been able to survive by itself?

Mitochondria! Chloroplast!

Endosymbiosis

• Theory proposes that mitochondria and chloroplast are the descendants of bacteria.

Why?• Size and structure– Mitochondria (Mt) and chloroplasts (Chl) are

about the same size as most bacteria

Why?• Size and structureMitochondria (Mt) and chloroplasts (Chl) are about

the same size as most bacteria

• Genetic MaterialMt and Chl have unique DNA to that found in the

nucleus of the host cell.

Why?• Size and structureMitochondria (Mt) and chloroplasts (Chl) are

about the same size as most bacteria

• Genetic MaterialMt and Chl have unique DNA to that found in the

nucleus of the host cell.

Why?• Size and structureMitochondria (Mt) and chloroplasts (Chl) are about

the same size as most bacteria

• Genetic MaterialMt and Chl have unique DNA to that found in the

nucleus of the host cell. • Reproduction-Mt and Chl reproduce by simple fission.

How might this have happened?

How might this have happened?

• Prokaryotes entered the larger cells either as parasites or undigested prey.

• Instead of being digested, the bacteria began to live inside the host cell.

• OPTIONAL: VIDEO

How is mitochondrial DNA passed on?

• mtDNA is only passed down through the maternal line.

• Egg cell contains mitochondrial DNA.

Argentine Dirty war

• Between 1976-1983 Argentina was governed by a military dictatorship.

• Many who were deemed the opposition were kidnapped and tortured.

Argentine mothers

• Kidnapped pregnant women were taken to secret detention centers to have their babies but were then tortured and killed.

• Babies were adopted by military personnel.

Mothers of La Plaza de Mayo

• Grandmothers of the kidnapped children wanted vengeance.

• They used mtDNA to prove that they in fact were the grandmothers of the kidnapped children.

Vengeance accomplished.

• Mothers of La Plaza de Mayo proved the identity of 59 children.

• 31 children were returned to their biological families.