BIO 315: Exam 1

Question 1

What is the definition of life?

Answer 1

A self-organizing, self-replicating, non-equilibrium system.

Question 2

What are the macromolecules needed for life, and in what percentage?

Answer 2

Polypeptides = 50 - 55%, Deoxyribonucleotides = 2 - 5%, Ribonucleotides = 15 - 20%, Lipids = 10%, Polysaccharides = 6 - 7%

Question 3

What are microbes? Name some examples.

Answer 3

These are forms of LIFE that are too small to be seen with the naked eye. Examples: Fungi, Algae, Protists.

Question 4

Before the three-domain classification was invented, how were groups of life separated?

Answer 4

Into Prokaryotes & Eukaryotes

Question 5

What do prokaryotes lack that eukaryotes have?

Answer 5

Membrane-bound organelles, including a true nucleus.

Question 6

What are the three domains of life?

Answer 6

Bacteria, Archaea and Eukarya

Question 7

How were the three domains of life discovered?

Answer 7

By sequencing and then comparing the small subunit ribosomal RNA genes of different organisms.

Question 8

We aligned and concatenated a set of __ ribosomal protein sequences from each organism to give the three domain tree.

Fill in the blank

Answer 8

16

Question 9

Archaea are more similar to which of the other two domains

Answer 9

Eukarya

Question 10

To which domain do viruses belong?

Answer 10

None! Viruses are not microbes, and technically, they are not living things. They require a host cell to replicate, and they have minimal biochemical activity outside of their host cell.

Question 11

Are viruses smaller or larger than bacteria, in general?

Answer 11

Viruses are MUCH SMALLER than bacteria.

Question 12

What are viruses composed of?

Answer 12

Viruses are composed of DNA OR RNA particles, surrounded by a capsid. This capsid may have proteins on it, called capsomeres, and the capsid may be covered by an envelope.

Question 13

What are viral envelopes made out of?

Answer 13

They’re made out of lipids and proteins.

Question 14

What is an example of an envelope virus?

Answer 14

The flu virus is an example of an envelope virus.

Question 15

Most bacterial cells have how many chromosomes?

Answer 15

1

Question 16

How many ybp have microbial organisms existed?

Answer 16

3.5 billion ybp.

Question 17

Who were the two scientists that discovered the microbial soup that was similar to life on primitive earth.

Answer 17

Stanley Miller & Harold Urey

Question 18

What did iron-containing surfaces do to provide the right environment in primordial life?

Answer 18

They helped “stick” molecules to their surfaces.

Question 19

What molecule served as both a genetic information storer AND as an enzyme?

Answer 19

Ribozymes! They contain both RNA and an enzyme.

Question 20

What was the original primordial form of plasma membrane?

Answer 20

A single lipid layer known as the micelle, where the hydrophobic tails are on the inside, and the hydrophilic head groups are all on the outside.

Question 21

Why did cells switch from single stranded RNA to double stranded DNA for storing genetic information?

Answer 21

Because the double strand provides a back up and DNA is more stable than RNA.

Question 22

What is Endosymbiotic Theory

Answer 22

Endosymbiotic theory described the possible way eukaryotic cells were formed: Prokaryotic microbes ingested other prokaryotic microbes. If the ingested microbes could use oxygen for energy they became mitochondria.
If the ingested microbes could use carbon-dioxide to make organic molecules using light energy, they became chloroplasts.