Building a cell

Question 1

Atom

Answer 1

The smallest part of an element

Question 2

The Hydrogen atom

Answer 2

• simplest element
• no neutron
• 1 electron = unstable
• 1 proton

Question 3

Protons

Answer 3

• In nucleus
• has mass
• positive charge

Question 4

Neutrons

Answer 4

• has mass
• no charge
• what defines isotopes

Question 5

Electrons

Answer 5

• has mass
• negative charge
• in orbital/energy shell/volume

Question 6

What do energy shells do

Answer 6

overcome electrons’ attractions to protons in the nucleus

Question 7

how to electrons move to higher shells

Answer 7

absorb energy

Question 8

how do electrons move to lower shells

Answer 8

emit energy

Question 9

how do electrons leave atoms

Answer 9

collisions

Question 10

Molecules

Answer 10

• Form when at least 2 atoms are chemically bonded (by valence electrons)

Question 11

Covalent bond

Answer 11

• Shared valence electrons
  -> Ex. Hydrocarbons
• Strong
• Only break in water at boiling point (100)

Question 12

Ionic bond

Answer 12

• More electronegative (receiving) atom steals an electron
• Easily broken in water
• Easily formed in water

Question 13

Polar Covalent Bonds

Answer 13

• Unequal sharing of electrons between H and O atoms
• O atoms are more electronegative/negative pole (electrons are repulsed by O and attracted to H)

Question 14

H-bonds

Answer 14

• Sharing of an H atoms between polar molecules
• Forms btw a Hydrogen and a more electronegative atom (O)

Question 15

Properties of H-bonds

Answer 15

• Weak individually
  -> Gives big molecules the ability to break apart (Ex. rungs of DNA) can break and replicate
  -> Allow things like enzymes to change shape
• Collectively strong
• Require less energy transfer than COVALENT bonds
• H-bonds form hexagonal lattice (ice) that is less dense than water (although it is strong)

Question 16

Hydrophillic

Answer 16

Polar likes polar

• helps water-soluble molecules and ions dissolve and interact with watery environment (ex. inside and outside cells)

Question 17

Hydrophobic

Answer 17

Non-polar likes non-polar

• Drives organization of cell membranes (phase separation)
  -> Phase separation forms liquid bilayers
  -> If phases mix, big oil droplet

Question 18

Bond Energy

Answer 18

• Amount of energy needed to separate 2 bonded atoms

Question 19

What determines the state of water?

Answer 19

H-bonds

• Why water is not a gas all the time: cold slows down atoms and forms ice (solid)
• Add heat = atoms move faster = turns into liquid or gas
• As a liquid, H-bonds break continuously but randomly

Question 20

Properties of water

Answer 20

• Water is a solvent
  -> Ionic bonds break easily in water bc of the charges surrounding it (water is a polar molecule that has + and - ends)
• The attraction of water molecules to ions helps facilitate the movement of ions in and out of neurons
  -> Contributing to electrical signaling
• Liquid water is cohesive (things float on it)
  -> Hydrophobic
• Liquid water is adhesive (straw sucks up water)
  -> Hydrophilic
• Water has a high heat of vaporization
• Water has high heat capacity