1.5 The Origin Of Cells

Question 1

Outline the conclusions that Miller and Urey drew from their experiments.

Answer 1

Organic compounds formed from inorganic compounds. Organic compounds could have existed on pre-biotic earth. Life might have arisen from non-living material.

Question 2

Outline how membranes may have originated in the first cells.

Answer 2

Phospholipids self assemble into double layered structures. Form into spheres capturing fluids. Fluids contain molecules that can replicate.

Question 3

What is the endosymbiotic theory and what does it suggest?

Answer 3

Endosymbiotic theory suggests that mitochondria and chloroplasts developed from free-living organisms.

Question 4

Discuss the endosymbiotic theory.

Answer 4

Explains origin of some organelles. Prok. lack mitochondria/chloroplasts, which may have originated as prok. that were engulfed by larger cell and became symbiotic.

Question 5

Outline the characteristics of the mitochondria and chloroplasts that support the endosymbiotic theory

Answer 5

Have their own DNA, similar to prok. DNA. Have 70S ribosomes like prok. Have double membrane. Similar size to bacteria. Reproduction by binary fission.

Question 6

Outline the methods used my Miller and Urey in their experiments into the origin of organic compounds on Earth.

Answer 6

Apparatus to simulate early Earth conditions. High energy chamber to create lighting. Gases (CH4, NH3, H2O, H2) to form atmosphere. Boiling and condensing to simulate rainfall. Organic molecules created (amino acids)