Biological Structure and Aqueous Environment Flashcards

Flashcards covering principles of biological structure, water properties, and acid-base chemistry.

What are some examples of relationships of function to structure?

Enzyme specificity, genetic information, and membrane properties.

What percentage of a human cell is comprised of water?

70%

What is the most abundant intracellular small cation?

Potassium (K+)

What are some intracellular anions?

Chloride (Cl-) and phosphate

What extracellular ions are provided in cell culture to maintain a physiological environment?

Sodium, calcium, chloride, and bicarbonate.

All organic molecules have carbon, sugars, and fatty acids

Sugars (Glucose), Fatty Acids (nervistate & palmitate)

• Contains hydrogen, carbon, and oxygen

What do amino acids and nucleotides contain?

Amino acids: nitrogen

Nucleotides: Sugars, nitrogenous bases, and phosphate.

What are the macromolecules of the cells?

• Proteins: covalently bond to chains of amino acids

• Nucleic acids: Chains of nucleotides

• Polysaccharides: Assembled from sugar units

What happens during a condensation reaction when macromolecules are formed?

A molecule of water is removed.

How does the breakdown of polymers occur?

Hydrolysis, which involves the addition of water.

ie. Digestive enzymes catalyze hydrolysis of macromolecules

What are the four types of non-covalent interactions?

Hydrogen bonds, electrostatic interactions, hydrophobic interactions, and Van der Waals interactions.

ie) DNA

• Nucleotide bases bond covalently to long chains

• Binding of 2 long strabds to each other and joint formation of double helix is mediated by hydrogen bonds

What happens to ionic bonds in aqueous solution?

In aqueous solution, the ionic bonds are greatly weakened and the individual atoms are separated and surrounded by water molecules.

Why are covalent bonds in water molecules highly polar?

Hydrogen bonds form between water molecules due to the polar nature of O-H covalent bonds

The covalent bonds are highly polar because the oxygen has a stronger attraction for the shared electrons.

Between what atoms do hydrogen bonds form in water?

Positively charged hydrogen atom from one water molecule and a negatively charged oxygen from a second water molecule.

What type of molecules can water dissolve well?

Water is good at dissolving charged molecules such as table salt or sodium chloride.

What happens to nonpolar molecules in water?

They are pushed out of the hydrogen-bonded water network.

How do molecules with both hydrophilic and hydrophobic portions tend to aggregate in aqueous solutions?

They form various structures in which the nonpolar portions are internal and the polar portions are associated with the aqueous environment.

What is another name for fats?

Tricylglycerols

Why does ionization of water occur?

Ionization of water occurs because positively charged hydrogen atoms move from one water molecule to another.

What is the concentration of hydrogen ions times hydroxyl ions always equal to?

10 to the minus 14.

What is the pH scale?

The negative logarithm of the hydronium ion or hydrogen ion concentration.

What pH values do acidic solutions have?

Acidic solutions have pH values less than seven.

What solutions have a higher hydroxylion concentration than hydronium ion concentration?

Basic or alkaline solutions have a higher hydroxylion concentration than hydronium ion concentration.

What is the pH of gastric fluid?

Gastric fluid has a pH of one.

What is the pH of lysosomes and what do they do?

Lysosomes are acidic, they have a low pH, they are compartments within the cell where macromolecules are broken down or digested.

What is the tissue culture media pH?

The media is slightly basic, usually has a pH between seven point two and seven point four.

What happens to the color of Phenol red, used as an indicator for pH in culture media?

The color is red at pH 7.4 but it turns yellow with acidity and it turns purple when the pH is more basic.

Give some examples of strong acids and bases

Hydrochloric acid, sodium hydroxide, or sulfuric acid.

What action can weak acids and bases take?

Weak acids and bases can act as buffers by binding excess hydrogen ions or hydroxyl ions and maintain a relatively constant pH or hydrogen ion concentration.

What is Ka?

Ka is the dissociation constant which equals the hydrogen ion concentration times the conjugated base concentration divided by the undissociated acid.

What is the carbon dioxide bicarbonate acid base couple?

The carbon dioxide bicarbonate acid base couple is an effective buffer of blood pH.

What is a major regulator of cytosolic pH?

Inorganic phosphate is a major regulator of cytosolic pH.