01_Intro to Cell Bio

Question 1

What are three components of cell theory?

Answer 1

1) All organisms are composed of one or more cells.
2) Cells are the structural units of life.
3) Cells arise from pre-existing cells through the process of cell division.

Question 2

What are the three domains of life? Which are prokaryotes?

Answer 2

Eukaryotes, Archaea, Bacteria; the latter two are prokaryotes.

Question 3

Which came first: eukaryotic cells or prokaryotic cells?

Answer 3

Prokaryotic

Question 4

Describe endosymbiotic theory in 1 sentence.

Answer 4

Prokaryotic cells arose first, and organelles in eukaryotic cells (mitochondria & chloroplasts) evolved from smaller prokaryotic cells.

Question 5

What evidence is there in support of endosymbiotic theory? (6 points)

Answer 5

• Eukaryotic cell organelles (mitochondria & chloroplasts) contain their own DNA.
• Ribosomal RNA sequences in eukaryotes are highly conserved, and resemble that of prokaryotic cells.
• Organelles duplicate independent of the nucleus.
• There is an absence of any intermediary evolutionary step containing eukaryotic cells with organelles.
• Mitochondria/chloroplasts possess a DOUBLE lipid bilayer (inner membrane is prokaryote-like; outer membrane eukaryote-like – BUT this simplification is controversial)
• There exist many symbiotic relationships between organisms.

Question 6

What is the proposed origin for the mitochondrion, chloroplast, and the “parent” cell?

Answer 6

aerobic bacterium, photosynthetic cyanobacterium, and anaerobic heteretrophic prokaryote (respectively).

Question 7

What is the point of controversy in endosymbiotic theory?

Answer 7

Appearance of the nuclear envelope and the ER

Question 8

How many genes were present in LUCA? What does this suggest?

Answer 8

4133; suggests this ancestor was surprisingly complex