Water and Macromolecules Flashcards
1
Q
What is the cell theory?
A
- The cell is the smallest living unit in all organisms.
- All living organisms are composed of cells.
- All cells come from pre-existing cells.
2
Q
Why is water important?
A
- Serves as the universal solvent in biological systems (living organisms)
- Makes up 70% or more of the weight of most cells
- Creates an aqueous extracellular environment for organisms and cells to survive
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)
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.
5
Q
Why are hydrogen bonds important?
A
Crucial in maintaining the structure and function of biological molecules. (Eg. Carbohydrates, proteins, nucleic acids)
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