Cell & Molecular Bio L1

emergent properties

properties and rules that emerge in a given level of organization that cannot be predicted from an understanding of the level below

Properties of living systems

• Contains chemical instructions for structure and function (DNA, RNA)

• Engages in metabolic activities (cellular respiration)

• Energy and matter flow through living systems (metabolism)

• Compensate for changes in their environment (signal transduction)

• Reproduce (cell division)

• Change from one generation to the next (mutation and evolution)

Cell Theory Principles

1. All organisms are composed of one of more cells

1. The cell is the basic structural and function unit of all living things

2. Cells arise only from the division of preexisting cells

Defining features of prokaryotes

1. Prokaryotic size is constrained by surface area to volume ratio (small sizes)

2. One chamber, no internal membrane bound structures

3. Heritable material is held in the nucleotide (no nucleus)

Gram positive bacteria

thick peptidoglycan wall

• peptidoglycan is made up of a sugar/amino acid polymer

Binds to gram stain (ex. Crystal violet)

Gram negative bacteria

characterized by a thin peptidoglycan layer, outer membrane, and capsule

• capsule is made up of sugar polymer

Other physical features in prokaryotes (5)

1. DNA

2. Ribosomes (protein synthesis)

3. Glycocalyx (polysaccharide coat on gram negative bacteria)

   1. Ex. Capsule

4. Motor Protein complex (movement)

   1. Ex. Flagella

5. Pili (rigid, hairlike shafts)

How can bacteria differ?

1. Shape

   1. Sphere, rod, corkscrew

2. Environmental niches they occupy

3. Metabolic requirements and outputs