IB Bio Cell biology 1.1

What does Cell Theory state?

1. All living organisms are composed of cells.
2. Cells are the smallest units of life
3. Cells only arise from pre-existing cells

Exceptions to Cell Theory

Muscle fibers- very long and contain multiple nuclei
2. Giant algae - is composed of one cell but is huge in size (Large organisms can only be build up by multiple cells)

What are all the functions of life?

Metabolism
Excretion
Sensitivity
Homeostasis
Reproduction
Nutrition
Growth

Why is a single skin cell considered to be alive?

It carries out every function of life as growth, reproduction and responsiveness and other.

What is surface area to volume ratio? Why is it important in limitation of cell size?

If a cell gets too large, surface area becomes too small to support the internal volume. Cells have to be small to be able to carry out their processes and still move freely

How is magnification measured?

Magnification= I(image size, measured with a ruler)/A (actual size)

Describe why it would be impossible for one cell to be a full adult human size.

Due to surface area to volume ratio, the cell would not be able to support the functions of internal volume so the cell will die.

How do multicellular organisms arise?

Through cell differentiation.

What is cellular differentiation?

Cell differentiation is a process by which new when dividing, cells change their functions and phenotypical type.

What are stem cells?

Stem cells are cells that have not yet gone through differentiation process therefore are able to become any type of cell (cardiac(heart*), fat, muscle, neutron, epithelial (skin*) etc.)

What are stem cells used for?

Therapeutic (creating new tissues of cells to replace the damaged tissue)

How are the stem cells What are the ethical issues of using stem cells?

Some stem cells are cultivated from adult tissues, whereas others are taken/extracted from a developed human embryo. Those extracted from human embryo has ethical issues, since to access those cells the embryo is being destroyed, killing a human.

An example of disease and its cure with the use of stem cells.

Stargardt's disease, an inheritable disease caused by gene mutation. It impairs photoreceptors found in the eye eventually leading to blindness.
Stem cells are used to create a tissue with working photoreceptors to replace damaged photoreceptors.