Microbial Evolution and Systematics (lec 11)

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Questions and Answers

Which of the following is NOT a component of the prebiotic soup?

Nitrogen bases (correct)

Lipids

Amino acids

Sugars

What is the most likely origin of the first self-replicating systems?

Lipids

DNA

Proteins

RNA (correct)

Which of the following is a component of certain essential cofactors and molecules?

Ribonucleotides (correct)

RNA

DNA

Proteins

What is the primary function of RNA in early cellular life?

Catalytic activity of proteins, small molecules and ribonuleotides Signup and view all the answers

What was the major source of carbon for the earliest life on Earth?

CO2 Signup and view all the answers

What event led to the accumulation of O2 in the Earth's atmosphere?

Photosynthesis Signup and view all the answers

What criteria are currently used to determine how closely related to organisms are?

the use of 16S rRNA and its similarities Signup and view all the answers

When is cellular life believed to have evolved?

4 billion years ago Signup and view all the answers

What were the early geological evidences of life mentioned in the text?

Stromatolites Signup and view all the answers

What is the subsurface origin hypothesis?

The hypothesis that life originated from hydrothermal springs on the ocean floor Signup and view all the answers

What is the main function of compartments in the origin of life, according to the text?

They allow coupling of energetic reactions to molecular replication Signup and view all the answers

What are stromatolites?

Precipitates of clay, metal sulfides, silica, and carbonates Signup and view all the answers

What are the hostile conditions on Earth's surface during the origin of life?

Anoxic, extremely hot, and high levels of UV radiation Signup and view all the answers

Which of the following is a characteristic of molecular clocks?

They assume that mutations occur at a constant rate per generation. Signup and view all the answers

What is the best type of sequence to compare when using molecular clocks?

Gene for small subunit rRNA Signup and view all the answers

Which of the following is a characteristic of 16S rRNA genes?

They are found in the genomes of all organisms. Signup and view all the answers

What does a phylogenetic distance map from the 16S ribosomal RNA sequence show?

Evolutionary distance as non-identical nucleotides Signup and view all the answers

Which of the following is a characteristic of horizontal gene transfer?

The acquisition of DNA from another cell Signup and view all the answers

What is the purpose of multilocus sequence typing (MLST) in distinguishing between strains?

Is utilized when stains of orangism are to similar through 16S rRNA. Signup and view all the answers

Which of the following is Not true about the core genome?

Concise of pan genome Signup and view all the answers

What is the selective advantage of a reduced genome size?

Increased efficiency in DNA replication Signup and view all the answers

Which of the following is an example of mutualism?

Rhizobium and mutualist plant hosts Signup and view all the answers

What is the endosymbiotic hypothesis?

The symbiotic association of prokaryotes with anther type of cell Signup and view all the answers

Which organelles have their own circular genomes?

Mitochondria and chloroplasts Signup and view all the answers

What is the function of chloroplasts?

Photosynthesis Signup and view all the answers

What is the function of mitochondria?

Respiration Signup and view all the answers

Who was the man that revolutionized the organization system from domains from microbial organisms?

Carl Woese Signup and view all the answers

What types of prokaryotes are believed to endosymbiosis for the origin of Eukaryotes? choose the most correct answer.

Proteobacterium and cyanobacterium Signup and view all the answers

Study Notes

Origin of Life

Prebiotic soup did not contain life forms, but it did contain organic compounds, water, and energy sources.
The most likely origin of the first self-replicating systems is the RNA world hypothesis.
Phosphorus is a component of certain essential cofactors and molecules.
The primary function of RNA in early cellular life was to store and transmit genetic information.
The major source of carbon for the earliest life on Earth was carbon dioxide.
The event that led to the accumulation of O2 in the Earth's atmosphere was oxygenic photosynthesis.
The criteria currently used to determine how closely related organisms are include comparative morphology, comparative embryology, and molecular biology.

Early Life on Earth

Cellular life is believed to have evolved around 3.5-4.5 billion years ago.
Early geological evidences of life include fossilized stromatolites, which are layered structures created by ancient bacteria.
The subsurface origin hypothesis suggests that life originated deep in the Earth's crust.
The main function of compartments in the origin of life was to provide a protected environment for chemical reactions.

Molecular Biology

Molecular clocks are characterized by a constant rate of mutation over time.
The best type of sequence to compare when using molecular clocks is a highly conserved sequence.
16S rRNA genes are characterized by a high degree of conservation and are often used in molecular clocks.
A phylogenetic distance map from the 16S ribosomal RNA sequence shows the evolutionary relationships between organisms.
Horizontal gene transfer is characterized by the transfer of genes between organisms other than by vertical inheritance.
The purpose of multilocus sequence typing (MLST) in distinguishing between strains is to compare multiple genetic loci.

Genomics and Genome Evolution

The core genome refers to the set of genes shared by all members of a species.
The selective advantage of a reduced genome size is increased efficiency and reduced energy requirements.
The endosymbiotic hypothesis suggests that mitochondria and chloroplasts originated from ancient bacteria.
Mitochondria and chloroplasts have their own circular genomes.
The function of chloroplasts is to carry out photosynthesis.
The function of mitochondria is to generate energy for the cell through cellular respiration.
Carl Woese revolutionized the organization system of domains from microbial organisms.

Symbiosis

Mutualism is an example of symbiosis, in which both organisms benefit.
Endosymbiosis is a type of symbiosis in which one organism lives inside another.
Alpha-proteobacteria are believed to have undergone endosymbiosis to originate Eukaryotes.

Studying That Suits You

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Description

Test your knowledge of molecular clocks and choosing the right chronometer in microbiology with this quiz. Explore concepts such as neutral mutations, sequence differences, conserved sequences, and the gene for small subunit rRNA. Challenge yourself with questions on the steady accumulation of mutations and the importance of conservation for function.