Untitled Quiz

Molecular Building Blocks of Life

• All matter is made up of atoms and molecules
• Four biological elements account for 96% of living matter: carbon, oxygen, hydrogen, and nitrogen
• These four elements combine to create the four major macromolecules of life: carbohydrates, fats (polymers of fatty acids), proteins (polymers of amino acids), and nucleic acids (polymerize to form DNA and RNA)
• Most macromolecules are polymers
• Made by stringing together many smaller molecules called monomers, bonded by dehydration reactions
• Broken down by hydrolysis

Dehydration Synthesis and Hydrolysis

• Monomers are joined by removing a hydroxyl group (OH) from one monomer and a hydrogen (H) atom from another, releasing a water molecule (H₂O)
• Monomers are released by adding a water molecule (adding OH to one monomer and H to the other)

Biological Macromolecules

• Carbohydrates:

  • Include polysaccharides, disaccharides, and monosaccharides
  • Monosaccharides are single-sugar units: glucose, fructose, galactose
  • Disaccharides are double-sugar units: sucrose, lactose, maltose
  • Polysaccharides are multi-sugar polymers: glycogen, starch, cellulose

• Lipids:

  • Biological compounds containing hydrocarbons
  • Not soluble in water (hydrophobic)
  • Examples: fats, waxes, oils, sterols, triglycerides, phospholipids
  • Importance: major structural component of cell membranes, major class of chemical messengers (e.g., steroid hormones), major store of energy (triglycerides), major source of energy (fatty acids), major solvent for certain vitamins (A, D, E, and K), major functional barriers (e.g., skin oils), major source of insulation/cushioning of vital organs
  • Relevant Types:
    • Fatty acids: long hydrocarbon chains with a carboxyl group
      • Saturated: straight chains, solid at room temperature
      • Unsaturated: kinked chains, liquid at room temperature
    • Triglycerides: three fatty acids bonded to a glycerol through dehydration (ester linkage)
    • Steroids: any fatty substances containing four carbon rings; cholesterol is the base steroid from which your body produces other steroids (sex hormones)

• Proteins:

  • Biological polymers of linked amino acid monomers (via a peptide bond)
  • The most complex and functionally diverse molecules of living organisms
  • Importance: protein enzymes, protein hormones, carrier proteins, cellular receptor proteins, membrane transporter proteins, contractile proteins, structural proteins, storage proteins, defensive proteins, sensory proteins, gene regulatory proteins
  • Amino Acids:
    • Consist of a central carbon covalently bonded to 4 partners: an amino group, a carboxyl group, and a side group (variable among 20 amino acid types)
    • Joined by dehydration reactions forming peptide bonds
    • 20 relevant amino acids; some are essential (must be consumed in food), others are non-essential (body can synthesize them)
  • Protein Shape/Structures:
    • Primary: multiple peptide bonds (polypeptide chains)
    • Secondary: local folding of the protein chain
    • Tertiary: three-dimensional structure of a single polypeptide chain
    • Quaternary: structure formed by multiple polypeptide chains

• Nucleic Acids:

  • Family of biopolymers named for their role in the cell nucleus
  • Composed of chains of monomeric nucleotides (bases):
    • Adenine (A), Guanine (G), Thymine (T), Cytosine (C)
    • In DNA, Uracil is replaced by thymine in RNA
  • Joined by a sugar-phosphate backbone
  • Importance: provide the directions for building all proteins necessary for life, encode phenotypes/traits in all animals, central to the success of evolution
  • Types:
    • DNA: deoxyribonucleic acid, stable genetic code
    • RNA: ribonucleic acid, translates genetic information from DNA into proteins, acts as a messenger, uses Uracil instead of Thymine

Homeostasis

• The body maintains a stable internal environment
• Negative feedback mechanisms detect deviations from a set point, initiate responses that return the system to normal
  • Components: stimulus, sensor, control center, effector, response
• Positive feedback mechanisms amplify changes that increase the response, for example, in blood clotting and childbirth.

Body Organization

• Composed of cells
• Cells of similar function are organized into tissues: muscle, nervous, epithelial, connective.

Anatomical Planes and Positions

• Anatomical position: standing erect, facing forward, feet together, arms hanging at sides with palms facing forward
• Planes: sagittal (divides body left/right), coronal (divides body front/back), and transverse (divides body upper/lower)

Body Cavities

• Dorsal body cavity: cranial cavity (brain) and vertebral canal (spinal cord).
• Ventral body cavity: thoracic (heart, lungs) and abdominopelvic (stomach, intestines, liver).

Neural and Endocrine Regulation

• Regulation by nervous and endocrine systems
• Nervous: controls secretions, some hormones affect nervous system
• Endocrine: achieves regulation by hormone secretions into blood to stimulate target organs.

Positive and Negative Feedback Loops

• Negative: reverses deviations from set point. (e.g., blood pressure, temperature)

• Positive: amplifies initial stimulus. (e.g., blood clotting, childbirth)