Water and Macromolecules Flashcards

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1
Q

What is the cell theory?

A
  1. The cell is the smallest living unit in all organisms.
  2. All living organisms are composed of cells.
  3. All cells come from pre-existing cells.
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2
Q

Why is water important?

A
  1. Serves as the universal solvent in biological systems (living organisms)
  2. Makes up 70% or more of the weight of most cells
  3. Creates an aqueous extracellular environment for organisms and cells to survive
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3
Q

What is the molecular structure of water?

A
  • Two hydrogen atoms in water are covalently bonded to the one oxygen atom at an angle of 104.5°
  • Electronegativity (O is strongly electronegative (attracts e-), H is electropositive (donates e-))
  • Unequal distribution of charges; water molecule as a whole is uncharged (O has δ−, H has δ+)
  • Polar molecule (two ends of molecule have opposite charges)
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4
Q

What is a hydrogen bond?

A

A bond formed between a hydrogen atom and an electronegative atom (F,O,N) that belongs to another chemical group.

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5
Q

Why are hydrogen bonds important?

A

Crucial in maintaining the structure and function of biological molecules. (Eg. Carbohydrates, proteins, nucleic acids)

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6
Q

Properties of hydrogen bonding.

A
  • δ+ region of one molecule comes close to δ− region of another molecule, electrical attraction between them result in a weak bond
  • hydrogen bonding is much weaker than covalent bonds, but combined effort of many weak bonds is highly significant
  • occurrence of hydrogen bonding is not unique to water; it can be found in other biological molecules
  • 1 water molecule
  • each oxygen atom can form hydrogen bond to two hydrogen atoms
  • both hydrogen atoms can form hydrogen bonding with oxygen atoms of adjacent molecules
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