Cell biology 1: the cell (Dr. Whitmore)

Question 1

What is the range of cellular dimensions ?

Answer 1

Mammalian nerve cell: ~100μm 
Paramecium: ~25μm 
Single-celled green algae: ~10μm 
Budding yeast cell: ~5μm 
Helicobacter bacterium: ~1μm

Question 2

Who set forth a modification to the “cell theory” in 1860 ?

What does this modification say ?

Answer 2

Louis Pasteur –> new cells form by growth and division of existing cells.

Question 3

Who first stated the “central Dogma” of molecular biology and when ?

Answer 3

Francis Crick in 1956.

Question 4

How big is an epithelial cell ?
A mitochondrion ?
A ribosome ?
An atom ?

Answer 4

Epthelial cell: 10-15μm
Mitochondrion: 2μm
Ribosome: 20nm
Atom: 0.2nm

Question 5

what are the characteristics of a bacterium ?

Answer 5

• genome (DNA) lies freely in cell
• no internal compartmentalisation
• 0.1-1 μm in size
• organo-, photo, or litotrophic (feeding on rock)
• flagellum (often)
• cell wall (often)

Question 6

Give an example of lithotrophic bacteria.

Answer 6

Beggiatoa is a sulfur bacteria –> it gets NRG from H2S.

Question 7

What are the major features of eukaryotic cells ?

Answer 7

• 10-100μm diameter
• nucleolus
• nucleus
• SER
• RER
• mitochondria
• lysosomes
• vesicles
• nuclear enveloppe
• nuclear pore
• extracellular matrix
• chromatin (DNA)
• centrosome with pair of centrioles
• microtubules
• actin filaments
• peroxisomes
• ribosomes in cytosol
• Golgi apparatus
• intermediate filaments
• larger than prokaryotic cells

Question 8

What is the function of the nucleolus ?

Answer 8

rRNA genes, rRNA, ribosomal proteins, ribosome subunit assembly

Question 9

What is the function of the nucleus ?

Answer 9

• contains genome, site of DNA and RNA synthesis

- surrounded by nuclear envelope

Question 10

What is the function of the cytoplasm ?

Answer 10

Contains organelles and cytosol

Question 11

What is the function of the cytosol ?

Answer 11

Place for many essential chemical reactions and protein synthesis

Question 12

What is the function of the ER ?

Answer 12

• membrane enclosed labyrinthine space
• RER contains ribosomes for protein synthesis
• ER also produces lipids and functions as Ca2+ store

Question 13

What is the function of the Golgi apparatus ?

Answer 13

Stacks of flattened membrane, receives lipids and proteins from ER, modifies them and dispatches them to other parts or the exterior of the cell

Question 14

What is the function of the mitochondria and chloroplasts ?

Answer 14

Main place of energy (ATP) production in animal and plant cells, respectively

Question 15

What is the function of the endosomes ?

Answer 15

Endocytosed material must pass through endosomes before being delivered to lysosomes.

Question 16

What is the function of the lysosomes ?

Answer 16

• contain digestive enzymes to degrade defunct organelles, macromolecules, as well as particles taken up from the outside of the cell via endocytosis
• release nutrients from break down of food particles

Question 17

What is the function of the peroxisomes ?

Answer 17

Contain enzymes used in various oxidative reactions involving hydrogen peroxide (H202)

Question 18

What are likely explanations that could explain the presence of chloroplasts and mitochondria ?

Answer 18

Mitochondria most likely evolved from engulfed bacteria and chloroplasts almost certainly evolved from engulfed photosynthetic bacteria.