Topic 8 Molecules of life (1)

Question 1

Everything is made of

Answer 1

matter

Question 2

Life is organized into fundamental units, cells

What maintains it and what opposes this organization

Answer 2

energy is needed to maintain this, if not, entropy would cause the system to fall apart

Question 3

Atoms and molecules

Answer 3

Everything is made of matter

Matter is made of elements
Elements are different types of atoms
Two or more join to make a molecule

Question 4

What is life based on

Answer 4

Carbon based

Carbon
Oxygen
Hydrogen
Nitrogen

Elements that form the building blocks of molecules that are essential for life

Question 5

Atomic mass

Answer 5

Mass of protons and neutrons

bottom right on periodic table

Question 6

Atomic number

Answer 6

Number of protons

Top left in periodic table

Question 7

Atomic structure

Answer 7

Protons and electron numbers are equal

Electrons are organized into shells. In reality these are clouds where they are likely to be found at a given time

Question 8

Isoforms

Answer 8

Atomic number is the same but additional (or fewer) neutrons = isoform

Question 9

Carbon dating

Answer 9

Nitrogen-14 decays to carbon-14 in the atmosphere due its loss of a proton and gain of a neutron using energy from cosmic rays in the atmosphere.

Organisms take in carbon-14 from the atmosphere ion proportion to its presence

This stops when an organism dies

C-14 > N-14 with t 1/2 5730

By comparing c-14 to n-14 in the body, the time since death can be calculated

Carbon-14 decays with a half life of

Question 10

You believe an organism died 12000 years ago. Estimate the amount of c-14 you expect to find relative to the starting amount

Answer 10

12000 is appx 2x5730

Therefore 2 half lives

Hence 25% remaining

Question 11

The bohr model and the octet rule

Answer 11

Reactivity of an atom is determined by the number of electrons in its last or valent shell

2,8,8

Tries to have a full outer shell by either losing, gaining or sharing electrons

Question 12

Covalent bond

Answer 12

Shares a valent electron to form the bond

Question 13

Ionic bond

Answer 13

Donates one (or more) valent electrons. Both atoms become charged.

Stay together by electrostatic forces

Question 14

Bond types (5 things)

Answer 14

Covalent- share an electron pair - strong

Hydrogen - share an H atom - semi strong

Ionic - attraction of opposite charges via electron donation - semi strong

Hydrophobic interaction - interaction of nonpolar substances in the presence of polar substances - weak

Vaan der Waals attraction - interaction of electrons of nonpolar substances - very weak

Question 15

Chemical reactions are based on random collisions

Answer 15

Increase temp or relative concentration you increase the probability of a collision happening with enough energy for a reaction

-273 degrees, no energy, absolute zero, no reactions

Question 16

Irreversible reaction

Answer 16

One way (essentially)

One arrow

Question 17

Reversible

Answer 17

two way, reaches and maintains an equilibrium

If you alter the amount of a product, you may drive the equilibrium in one way eg blood buffering

Question 18

Covalent bond

Answer 18

Each atom shares electrons

In biological substances, up to 6 atoms are shared (in 3 pairs)

The strength of the bond increases with each pair

This also changes how much an atom may rotate around a bond and has a major effect on the molecules shape

Question 19

Polar molecules have polar covalent bonds

Answer 19

When bonds form, sometimes the electrons stay closer to one atom of the molecule. This creates charged areas.

This may result in polar parts of a molecule

Question 20

Covalent bond shape

Answer 20

Polar covalent bonds have unequal charge between atoms within a molecule because the covalent bond has resulted in electrons closer to one atom

If this does not happen it may be neutral, or non polar

Double bonds prevent rotation, single allow it

Question 21

Ionic bonds

Answer 21

The more electronegative steals electrons from the donor atom. Then they stay electrostatically attracted to one another. These are often interrupted by water eg NaCl

Question 22

Polar covalent and hydrogen bonds

Answer 22

Water makes polar covalent bonds within itself.

H+ areas of water are attracted to O- areas of others

This causes HYDROGEN BONDS

Breaking these turns ice to water and water to steam

Question 23

Hydrocarbons

Answer 23

are composed of hydrogen and carbon

Question 24

Water is special

Answer 24

as it is a liquid over livable temperatures

H bonds

Question 25

Hydrophilic/phobic interactions

Answer 25

Phyllic between polar and polar

phobic between non polar and non polar

Means polar molecules are attracted to water and non polar ones are more to each other than water

Lipid bilayer

Question 26

High heat capacity

Answer 26

Very important

Has the highest heat capacity of a liquid on earth
Takes a lot of energy to heat it

Takes a lot of energy to vaporize it

Stays as a liquid over a large range of temperatures

Question 27

Great solvent

Answer 27

Water is a great solvent

Ions unstably bound by ionic bonds will be split up and form stable hydrated states with water molecules surrounding it

Question 28

Water is cohesive and adhesive

Answer 28

Objects can float

Capillary action allows plants to draw water from the soil to leaves

Question 29

Water as a heat sink

Answer 29

Oceans absorb all heat

Controls climate of earth

getting hotter

there is a limit to how much energy will be absorbed Water will expand as H bonds break and melt from ice

There will be less oxygen dissolved in water. More energy needed to maintain temp. Mess up habitats and food chains