What was the laurentia and what was it composed of? what happened to it?

Laurentia (North American Craton) is a large continental craton that forms the ancient geological core of the North American continent. Many times in its past, Laurentia has been a separate continent as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and also the northwestern part of Scotland, known as theHebridean Terrane. During other times in its past, Laurentia has been part of larger continents and supercontinents and itself consists of many smaller terranes assembled on a network of Early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambriancraton seen today.

q: compare the parts of a cell and the cell as a whole to another common nonliving system (i.e., a car, a city,

a:

comparing this to the inside of a food building/company.

plasma membrane - building's walls

all cells are surrounded by a plasma membrane, which protects the cell from its environment, keeping toxic substances out of the cell. it regulates which molecules are allowed to enter and exit the cell.

nucleus - the big boss

regulates all cell activity such as cellular metabolism, and growth in addition to storing and maintaining the cell's dna for transcription and replication. determines what proteins to make.

cytoplasm - working areas

contains the organelles; site of most cell activity

endoplasmic reticulum - engineer's work area

the place where ribosomes do their working activity.

ribosomes - engineers

builds the proteins.

golgi apparatus - pickup truck drivers

prepares proteins for use or export.

lysosomes -   investigators

responsible for breaking down and absorbing materials taken in by the cell.

cytoskeleton - renovators

maintains cell shape.

mitochondria/chloroplasts - materials scientist

transforms one form of energy into another.

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