1.1 Cell Theory
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Cell Theory States
• All living things are composed of cells • The cell is the smallest unit of life • Cells only arise from pre-existing cells
Essential Idea cell theory unit
The evolution of multicellular organisms allowed cell specialization and cell replacement
Totipotent cell
Unspecialized cell that can become any kind of specialized cell
Advantage of multi-cellular organization
Cell death does not equal organism death
Cells only arise from pre-existing cells
Cells multiply through division, all life evolved from simpler ancestors
Examples of atypical cells that defy cell theory
• Striated muscle cells • Asepate fungal hypnate • Giant algae
Functions of life
Metabolism, Response, Homeostasis, Growth, Reproduction, Excretion, Nutrition
Polyploidy
To have many sets of chromosomes
Haploid
To have one set of chromosomes (gametes)
Diploid
To have two sets of chromosomes
Surface area to volume ratio
Units of membrane bear unit of volume in a cell
Larger SA:Volume ratio
More efficient rate of material exchange
Diffusion distance
Space between nucleus and membrane
Examples where large SA: Vol ratio is undesirable
• Warm blooded small animals that lose heat to quickly 2. Desert plants that would lose more water
SA:Vol Ratio purposes
• Increase efficiency of material exchange 2. Signal time for cell division
Cell compartmentalization
The use of membranes (organelles) to separate cells into specific areas with specific functions
Rate of cell metabolism is a function of
SA: Vol ratio
Faster increase throughout cell growth
Volume
Death due to metabolic rate occurs when
Cell metabolism is faster than rate of exchange
Cell division occurs when
The surface area to volume ratio has favored volume to the point that the cells metabolic rate is faster than it’s rate of exchange
Cells specialized for material exchange do what to increase efficiency
Increase their surface are through folds e.g mitochondria, lung cells, digestive tract
Emergent properties
Properties that arise from interaction of components that were not present in the individual components
Emergence in multi-cellular organisms
Multicellular organisms have properties that arise form the interactions of their cellular components
Differentiation
• The process of cells expressing some genes and not others within the genome in order to specialize for a particular function with a distinct structure. Active genes instruct which proteins should be synthesized. Active genes more loosely coiled.