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Flashcards in Chemistry of Life Deck (54)
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1
Q

pH of life

A

7.2 - 7.4

blood has to be slightly basic to accomodate for carbonic acid

2
Q

What elements is life mostly composed of?

A

Carbon, oxygen, hydrogen, and nitrogen

3
Q

4 macromolecules and function

A

Lipids: membranes, hormones, communication

Nucleic acids: store genetic information (can act as catalysts)

Proteins: structure, function, catalyst

Carbohydrates: store energy, indentification

4
Q

Valence shell

A

Outermost shell of electrons

5
Q

What is the bonding point?

A

Unpaired valence electrons

6
Q

4 main types of bonds

A
  1. Covalent
  2. Polar covalent
  3. Hydrogen
  4. Ionic
7
Q

Covalent bonds

A

Shared electrons

8
Q

A single covalent bond has…

A

2 electrons

9
Q

Nonpolar covalent bonds

A

electrons are shared equally

electrons are halfway between the two atoms

atoms have no charge

10
Q

Polar covalent bonds

A

Electrons are not shared equally due to electronegatively

11
Q

Why is water a polar molecule?

A

Oxygen has high electronegativity that attracts electrons. This gives it a partial negative charge and hydrogen gets a partial positive charge

12
Q

What is CH4?

A

Methane

nonpolar covalent

13
Q

What is NH3?

A

Ammonia

14
Q

Electronegativity

A

chemical property that describes the tendency of an atom to attract electrons

15
Q

What factors affect electronegativity?

A

Atomic number (# of protons)

Greater positive charge will attract more electrons

16
Q

Label the 3 atoms of life in terms of increasing electronegativity

A

H, C, O

17
Q

Strength of bonds

A

Nonpolar covalent are hardest to break (methane, hydrogen)

Polar covalent (water, ammonia)

Ionic bonds (NaCl) are easiest to break

18
Q

Ionic bonds

A

have full charge

19
Q

-OH functional group

A

hydroxyl, probably some type of alcohol

20
Q

What does a functional group with oxygen probably indicate?

A

The molecule is probably polar

This means that it is hydrophilic

21
Q

Hydrophilic substances

A

can interact with water through their charges

if it has a partial or full charge

22
Q

Hydrophobic substances

A

cannot interact with water through these partial charges

Ex: hydrocarbons have no charge

23
Q

What drives protein folding?

A

Interactions between hydrophilic and hydrophobic molecules

24
Q

Where are there hydrogen bonds in the hydrogen atom?

A

Between two different water molecules

polar covalent is actually in the molecule

25
Q

Hydrogen bond

A

an attractive interaction between polar molecules

Hydrogen bonds to atoms with a high electronegativity

26
Q

What does hydrogen bonding lead to?

A

Cohesion

High specific heat

27
Q

Cohesion

A

water can stick to itself

surface tension

28
Q

Why is water’s high specific heat important?

A

It makes a good buffer in temperature which is important for life

29
Q

Adhesion

A

water can stick to other things

capillary action

30
Q

Why does water expand when it freezes?

A

the orientation of hydrogen bonds

water molecules are spaced further apart in ice lattice structure (less dense)

31
Q

Why is water a great solvent?

A

The partial negative and partial positive charges can break apart substances

Ex: Na+Cl-
Na is attracted to negative oxygen
Cl is attracted to positive hydrogen

32
Q

How does water act as a pH buffer?

A

It can dissociate itself into H+ and OH-

33
Q

H+

A

hydronium

34
Q

OH-

A

hydroxide

35
Q

What is the basis of the pH scale?

A

Proton (hydrogen ion) concentration

more hydrogen ions = lower pH

36
Q

Acids

A

molecules that donate H+

makes sense that more hydrogen ions = lower pH, because acids are the ones that donate H+

Ex: HCl

37
Q

Bases

A

molecules that remove H+

raise pH

Ex: NaOH

38
Q

Is water an acid or a base?

A

It can act as both because it can pick up and remove hydrogen ions

39
Q

Veins

A

carry oxygen depleted blood to the heart

40
Q

Arteries

A

carry oxygen rich blood away from the heart

41
Q

Where is CO2 high in the body?

A

Veins and tissues

This reduces the affinity of hemoglobin for oxygen. Hemoglobin will release more oxygen to tissues

42
Q

How is CO2 transported in the body?

A

Dissolved in blood as carbonic acid that water has to buffer

43
Q

What happens when affinity of hemoglobin is lowered?

A

Hemoglobin is more likely to release oxygen, since it cannot carry as much

44
Q

Where is CO2 low in the body?

A

Arteries and lungs

Hemoglobin has a high affinity for oxygen. It does not need to release oxygen in these places. It needs to carry it.

45
Q

What happens when CO2 levels in the blood increase?

A

more H+ is produced from forming carbonic acid

lowers pH

hemoglobin has a lower affinity for oxygen when pH lowers because it indicates high CO2

46
Q

When does hemoglobin’s affinity for oxygen increase?

A

When pH is high

This indicates less H+ ions and correspondingly less CO2

47
Q

Carbonic acid

A

an unstable intermediate molecule that will quickly dissociate into HCO-3 and H+

48
Q

If an atom has 4 electrons in its valence shell what kinds of covalent bonds can it form?

A

single, double, or triple

49
Q

When atoms in a covalent bond have the same electronegativity what type of bond form?

A

Nonpolar covalent

Molecule is not charged

50
Q

How many other water molecules is one water molecule bonded to?

A

4

51
Q

Hydronium ion

A

a water molecule with an extra H+

forms from water gaining a H+ from another water molecule

has a +1 charge

52
Q

Why do all living things need pH buffers?

A

Amino acid side chains have many carboxyl and amino acid groups

53
Q

A solution with a pH 5 has how many more hydrogen ions in it than a solution with pH 7?

A

100x

54
Q

What happens to HCl in water?

A

It is a strong acid, so it dissociates completely and produces lots of H+ which lowers the pH