Chedrese 4.0-4.3

Question 1

What are the seven characteristics or properties of life?

Answer 1

Display order, harness and utilize energy, reproduce, respond to stimuli, exhibit homeostasis, grow and develop, and evolve

Question 2

Are viruses a form of life?

Answer 2

Viruses are not considered to be alive because they need to use the translational machinery of the infected cell. Therefore virus does not fit in any of the attributes of life

Question 3

Where and when did the first forms of life, based on RNA rather than DNA, originate?

Answer 3

Approximately 3.8 billion years ago in undersea alkaline vents

Question 4

What are the two ancestral groups of life?

Answer 4

Bacteria and Archaea

Question 5

Earths atmosphere initially consisted mostly of _______. Thus considered a highly reducing environment

Answer 5

Hydrogen

Question 6

Describe the Oparin-Haldene hypothesis

Answer 6

Essential organic molecules formed in the atmosphere of primordial earth around 4 to 3.7 billion years ago. The early atmosphere was a reducing atmosphere because of the presence of large concentrations of molecules such as hydrogen, methane, and ammonia. These molecules contain an abundance of electrons and would have entered into reactions with one another that would’ve yielded larger and more complex organic molecules. The lack of oxygen meant there was no ozone layer. Without the ozone layer energetics you file was able to reach the lower atmosphere and provide energy needed to drive the formation of biologically important molecules

Question 7

What is today’s atmosphere classified as?

Answer 7

Oxidizing atmosphere; the presence of high levels of oxygen prevents complex, electron rich molecules from being formed because oxygen is a particularly strong oxidizing molecule and would itself except electrons from organic molecules and be reduced to water.

Question 8

Describe the miller-urey experiment

Answer 8

Created an artificial reducing environment in a close system that was exposed to energy in the form of electrodes. After what week of continuous functioning the apparatus produced a large assortment of organic compounds

Question 9

Describe the clay hypothesis

Answer 9

Complex organic molecules of rose gradually on surfaces of silicate crystals in solution. Clays provided the environment for polymerization. Short nucleic acid and poly peptide’s can be synthesized on surface of clay

Question 10

A possible origin of the cell membrane?

Answer 10

Lipid spheres

Note: liposomes can swell and contract depending on the osmotic conditions of their environment

Question 11

What is a Protobiont?

Answer 11

A group of abiotically produced organic molecules that are surrounded by a membrane or membrane like structure.
Early type of protobiont could’ve been like a liposome that is in an artificial lipid vesicle

Question 12

True or false? Clay also accelerates the formation of lipid vesicles.

Answer 12

True.

Question 13

Describe the RNA world.

Answer 13

Hypothetical stage where self replicating RNA molecules proliferated before the evolution of a system based on DNA and proteins. Ribozymes are RNA molecules that have the ability to catalyze specific bio chemical reactions: including storage of genetic material and catalyst like a protein enzyme. Thus RNA can replicate its own genetic material

Question 14

Describe the possible scenario for the development of today’s system of information transfer.
Hint RNA world to DNA

Answer 14

RNA self replicate by ribosomal RNA polymerase activity. A short polypeptide reverse transcribes RNA into DNA. DNA self replicates and RNA is replaced by DNA for information storage. DNA start transcription by mRNA. mRNA are translated into polypeptides. RNA is replaced by proteins for catalysis.

Question 15

What are the advantages of DNA over RNA?

Answer 15

DNA is more resilient and more easily repaired. DNA is stable while RNA is very liable.

Question 16

Why are protein enzymes more versatile than ribozymes.

Answer 16

Much greater power (higher rate of catalyst) and greater numbers (many different kinds of proteins). Lastly amino acids can interact chemically with each other in bonding arrangements that are not possible between nucleotides

Question 17

What is anaerobic metabolism?

Answer 17

In bacteria, a light driven membrane proton pump, termed bacteriorhodopsin, synthesizes ATP by creating a gradient the is chemically converted to energy

Question 18

Explain the earliest evidence of life on earth.

Hint stromatolites

Answer 18

Stromatolites are layered sedimentary formations that are created by photosynthesis cyanobacteria prokaryotic micro organisms that possess a sophisticated metabolism. Cyanobacteria produced adhesive compounds that cement sand and other rocky materials to form mineral Microbial mats that build up on layers gradually growing overtime. Today found as fossils

Question 19

The ability to ______ means that cyanobacteria could thrive almost anywhere on the planet where there was sunlight

Answer 19

Oxidize water

Question 20

Where did atmospheric oxygen come from?

Answer 20

Cyanobacteria uses water as an electron donor for photosynthesis and the oxidation of water releases electrons and molecular oxygen

Question 21

What caused the near extinction of anaerobic organisms?

Answer 21

By producing molecular oxygen cyanobacteria change the composition of life forms on earth by stimulating biodiversity. Favouring the growth of aerobic micro organisms like aerobic bacteria

Question 22

What is LUCA (last universal common ancestor)?

Answer 22

LUCA is not thought to be the first life on earth but rather the only type of organism of its time to still have living descendants. LUCA is the original life form from which all Archaea bacteria and eukaryotes have decended.
LUCA was anaerobic and autotrophic; it didn’t breathe air and made it sound food from the dark metal rich environment. It’s metabolism depended upon hydrogen carbon dioxide and nitrogen turning them into organic compounds such as ammonia

Question 23

Compare and contrast archaea and bacteria

Answer 23

Generally similar in size and shape and reproduce by binary fission. Lack cell nuclei and therefore prokaryotes and both single celled organisms. Despite the similarities archaea possesses genes and several metabolic pathways that are more closely related to those of eukaryotes

Question 24

How did Endosymbiosis Solving energy crisis that lead to eukaryotes?

Answer 24

To become more complex cells may have to sort out a limitation imposed by not having sufficient energy. These obstacles were overcome on a cell engulfed some bacteria and started using them as power generators giving origin to the first mitochondria

Question 25

Describe the theory of Endo symbiosis

Answer 25

Mitochondria and plastids and eucaryotic cells were once independent prokaryotic cells. Cells in golfed respiration cells to be able to make useful energy and for the synthetic cells to confirm the energy from the sun into stored chemical energy.