Biology Chapter 2 Flashcards

Atomic Structure and Properties

• Atomic number indicates the number of protons in the nucleus of an atom.
• The atomic number of hydrogen is 1; it contains 1 proton, 1 electron, and 0 neutrons.
• Carbon's atomic number is 6, meaning its nucleus must have 6 protons.

Water Properties

• Cohesion refers to the tendency of water molecules to stick together, facilitated by hydrogen bonds.
• Unique properties of water crucial for life include cohesion, large heat capacity, low density when solid, and its effectiveness as a solvent.
• Hydrogen bonds between oxygen in one water molecule and hydrogen in another account for its cohesive properties.

Organic Molecules

• Cellulose is indigestible by humans due to its molecular structure, despite being similar to starch.
• Triglycerides are fats consisting of three fatty acids linked to a glycerol molecule.
• Lipids are made of long hydrocarbon chains and are insoluble in water due to their non-polar nature.
• Polysaccharides, which are polymers, consist of three or more sugar molecules linked together.

Amino Acids and Proteins

• Peptide bonds are covalent bonds that connect amino acids, essential for protein formation.
• Essential amino acids must be obtained from the diet, while others can be synthesized by the body.

Nucleic Acids

• RNA contains carbon, nitrogen, oxygen, hydrogen, and phosphate, with uracil as its unique base (it does not contain thymine).

Chemical Bonds and Reactions

• The second orbital shell of an atom can hold up to 8 electrons, influencing its bonding behavior.
• A decrease in pH from 7 to 5 in a lake indicates a 100-fold increase in H+ ion concentration due to acid rain.

Triglycerides and Structural Properties

• The number of double bonds in a triglyceride affects its structure; more double bonds result in more "kinks" in the hydrocarbon tails, making it a liquid at room temperature.