Water Properties and Cell Structure

Flashcards covering the properties and structure of water, electron microscopy, resolution, magnification, and cell staining.

Water content in cells

Takes up $80\text{ percent}$ of a cell's contents.

Hydrolysis

A chemical reaction in which water acts as a reactant.

Solvent

A liquid in which most biological reactions take place in solution.

Transport molecules in organisms

Glucose and oxygen are transported in blood, while minerals are transported in the xylem vessel in plants.

Temperature control in water

Helped by water's high specific heat capacity and high latent heat of evaporation, which also makes water a habitat for many organisms.

Structure of water

Consists of two hydrogen atoms covalently bonded to one oxygen atom, where each hydrogen shares a pair of electrons with the oxygen.

Polarity of water

Occurs because oxygen has a greater affinity for electrons than hydrogen, pulling electrons closer; this and unshared electrons make oxygen slightly negative $-$ and hydrogens slightly positive $+$.

Resolution

The ability to distinguish $2$ separate points that are very close together.

Magnification

Making an image larger.

Electron microscope resolution

Electrons have a shorter wavelength than light and can pass between close objects more easily, resulting in higher resolving power.

Electron microscope limitations

Specimens must be viewed in a vacuum because electrons are easily blocked by atoms/molecules in air; cannot view colors and can only view dead organisms.

Scanning Electron Microscope (SEM)

A type of electron microscope that shows the surface of a tissue, cell, or organelle.

Transmission Electron Microscope (TEM)

A high-resolution electron microscope that produces $2\text{D}$ images showing internal structures of tissues, cells, or organelles.

Staining

A technique used on samples to increase the contrast between different structures.

Methylene blue

A stain used for animal cells to increase contrast.

Iodine in KI solution

A stain used for plant tissues that specifically stains starch.