Medical Biochemistry Chapter 2

Question 1

life evocvled in what

Answer 1

water

Question 2

organism typically contain

Answer 2

70tom 90%

Question 3

Water is the perfect way, and what types of reactions occurs in aqueous solutions

Answer 3

solvent and chemical

Question 4

Water has a what heat capacity

Answer 4

high

Question 5

Water acts as a heat buffer to maintain internal temperatures

Answer 5

True

Question 6

Is water more dense than ice?

Answer 6

yes

Question 7

Water is a critical determinant of what?

Answer 7

structure and function of proteins, nucleic acids, and membranes

Question 8

Water has a how many electron pairs and what geometrical shape does it have?

Answer 8

4 and tetrahedral

Question 9

What does the elctronegavity of the oxygen have on water?

Answer 9

water serves as hydrogen bound donor and acceptor

Question 10

Hexagonal ice forms a what lattice

Answer 10

regular

Question 11

What is the entropy of hexagonal ice?

Answer 11

low

Question 12

Why is ice more dense than water?

Answer 12

contains more hydrogen bond per water molecule

Question 13

Ice doesn’t absorbs heat when melting which allows the delta S to be lesser?

Answer 13

False; Ice does absorbs heat when melting which allows the delta S to be greater

Question 14

Water is a good solvent for

Answer 14

polar and charge molecules such as amino acids, peptides, alcohols, carbohydrates, nucleic acids

Question 14

Water is a good solvent for

Answer 14

polar and charge molecules such as amino acids, peptides, alcohols, carbohydrates, nucleic acids

Question 15

Water is a poor solvent for

Answer 15

non polar molecules such as non polar gases, aromatic rings, aliphatic chains, and lipids

Question 15

Water is a poor solvent for

Answer 15

non polar molecules such as non polar gases, aromatic rings, aliphatic chains, and lipids

Question 16

The high dielectric constant of water (ability to screen charges)

Answer 16

reduces the attraction between oppositely-charged ions in salt crystal

Question 17

The stronger electrostatic interactions between the solvated ions and water molecules

Answer 17

lowers the energy of the system

Question 18

What happens to the dissolving of NaCl?

Answer 18

entropy increases, spontaneous, positive enthalpy

Question 19

Dissolved particles affect what?

Answer 19

boiling point. melting point, osmolarity, viscosity, surface tension, taste, and color

Question 20

The cytoplasm of cells have

Answer 20

highly concentrated solutions and high osmotic pressure

Question 21

What happens in hypotonic environments?

Answer 21

Water moves into he cel, stress the plasma membrane, and causes lysis

Question 22

What cells have prevented?

Answer 22

!. Bacteria and plants have rigid cell walls of sufficient strength to resist osmotic pressure
2. Some freshwater protists have an organelle that pumps water out of cell
3. In multicellular animals, blood plasma and interstitial fluid is maintained at as osmolarity close to cytosol. They also pump out ions into interstitial fluid, or pump water directly using aquaporins

Question 23

What does the effect of osmolarity depends on

Answer 23

number of dissolved particles and not their mass

Question 24

When water is a reactant, what happens to reactuons?

Answer 24

produced or consumed in reaction

Question 25

all forms can form

Answer 25

vam dẻ waals (weak bonds)

Question 26

all forms of weak attractions are based on

Answer 26

attraction between electrical charges

Question 27

What are bond measured in?

Answer 27

kJ or kcal

Question 28

Strong covalent bonds

Answer 28

493 kj/mol

Question 29

Weak bonds

Answer 29

4-30 kJ/ mol, broken by thermal energy.

Question 30

Hydrogen bonds

Answer 30

dipole movement of NH/OH molecules

Question 31

Ionic interactions

Answer 31

electrostatic interactions between permeantly charge species, or between the ion and a permanent dipole

Question 32

dipole interactions

Answer 32

electrostatic interactions between uncharged polar molecules

Question 33

Van der Waals interactions

Answer 33

weak interactions between all atoms, regardless of polarity, attractive and repulsive components

Question 34

Hydrophobic effect

Answer 34

the ordering of water molecules around non polar substances

Question 35

What is hydrogen bonds?

Answer 35

strong dipole-dipole or charge-dipole interaction that a rises between an acid and a base

Question 36

hydrogen bonds with neutral atom

Answer 36

2-6

Question 37

hydrogen bonds with one charged atom

Answer 37

12-21 kJ/mol

Question 38

regarding hydrogen bonds, what two most frequent electronegative bonded to?

Answer 38

nitrogen and oxygen

Question 39

When is hydrogen bonds are the most strongest?

Answer 39

when the bonded molecules are oriented to maximize electrostatic interaction

Question 40

In comparison to covalent bonds and hydrogen bonds, which one is weaker?

Answer 40

hydrogen is weaker and have a 2-21 kJ/mol, which indicates that the bond distance is greater with H bonds

Question 41

What is the source of unique properties of water?

Answer 41

H-bonds

Question 42

Why is H bond important?

Answer 42

structure and function of DNA, proteins, lipids, and sugars

Question 43

What is h bond involved in?

Answer 43

enzyme/substrate, hormone/receptors interactions, mRNA with tRNA

Question 44

What can water both serve as

Answer 44

h-bond donor and H-bond acceptor

Question 45

With four h-bonds per water molecules gives water its?

Answer 45

-high boiling -high melting point -large surface tension

Question 46

True or false: Hydrogen bonds between neighboring molecule are weak relative to the H-O covalent bonds

Answer 46

True

Question 47

Ionic bons

Answer 47

opposite charges attract, neutralized oppositely charged groups; 12-17 kJ/mol

Question 48

Where does van Der waals forces arise from?

Answer 48

nonspecific attractive forces that occurs when two atoms come close to each other, induces fluctuating charges caused by the nearness of the molecules

Question 49

Van der Waals radius

Answer 49

attractive and repulsive forces balance at a certain distance which is specific for each atom

Question 50

Organic molecules that tend to form H-bonds are

Answer 50

water soluble

Question 51

The energy of H-bonds is much greater Thant that of Van der Waals interactions

Answer 51

molecules will form H-bonds in preference of van der Waals interaction

Question 52

What cannot form H-bonds H-bonds?

Answer 52

Benzene and oil

Question 53

Nonpolar may seem ordered, however there's a favorable entropy form water's point of view

Answer 53

more self interactions; less clustering

Question 54

Polar molecules form

Answer 54

excellant H bond and soluble in water