Unit 1.1: Cell Theory

Giant algae

Unicellular, single nucleated organisms with cells as long as 10mm (its large size makes us question cell theory)

Aseptate fungal hyphae

Multinucleated, elongated cells with continuous cytoplasm without any partitions or defined cells (multinucleated makes us question cell theory)

Rate of metabolism

________ is determined by the SA: V ratio.

surface area

As a cell grows, volume increases faster than ________.

Cells

________ need to exchange materials with the environment to survive.

Cells

________ can only arise from pre- existing ________.

Cells

The structural and functional unit of life.

Striated muscle cells

Multinucleated, long cells that can be up to 300mm long (its size and multinucleated characteristics makes us question cell theory)

Aseptate hyphae

long, multinucleated fibers without partitioning and have complete cytoplasm

rate of metabolism is determined by the SA

V ratio

Small SA

V ratio

Large SA

V ratio

therefore, cells must stay as small as possible to keep the SA

V ratio high

Cellular Organization

organisms --> organ systems --> organs --> tissues --> cells --> organelles

MRHGREN

Metabolism, Reproduction, Homeostasis, Growth, Response, Excretion, Nutrition

Cell Theory Postulates

Living organisms are composed of cells
The cell is the smallest unit of life
Cells can only arise from pre-existing cells

Why are cells small?

Because of their SA:V ratio, which requires them to have a large rate of diffusion to metabolism.

Metabolism

The organic processes that are necessary for life (ex. ATP production)

Homeostasis

The maintenance and regulation of internal cell conditions (ex. water and pH)

Emergent properties

Individual cells can join together to form functions in multicellular organisms

Specialized cells

Cells that have differentiated in order to perform a more specific function (as cells get more specialized they have a harder time reproducing)

Stem cells

Cells which all other cells with specialized functions are generated

Totipotent

Stem cells that can differentiate into any type of cell

Pluripotent

Stem cells that can differentiate into many types of cells

Multipotent

Stem cells that can differentiate into a few related types of cells

Unipotent

Stem cells that can regerate, but only into specific associated cell types

Embryonic Stem Cells

Stem cells gathered from embryos in the early stages of development

Umbilical Cord Stem Cells

Stem cells gathered from the ubmilical cord (easy to collect and store for future use)

Adult Stem Cells

Obtained from adult tissues such as bone marrow (difficult to obtain and limited capacity to differentiate but are fully compatible with other adults)