lecture 3 part 2

Question 1

non covalent bonds`

Answer 1

keep atoms close together without sharing electrons

Question 2

what are biologically important non covalent bonds

Answer 2

-hydrogen bonds
-ionic bonds
-van der waals forces (occur due to hydrophobic interactions)

Question 3

are non covalent bonds individually weaker than covalent bonds

Answer 3

yes

Question 4

what are hydorgen bonds and ionic bonds due to

Answer 4

due to the attraction of opposite charges

Question 5

where do hydorgen bonds exists

Answer 5

exist between two atoms with opposite partial charges
-water is not required but it frequently forms hydrogen bonds)
-the partial charge is on a hydrogen atom
-partial negative charge is usually on a N or O atom

Question 6

what do hydrogen bonds give water

Answer 6

its special properties important for life
-surface tension (cohesive forces)

Question 7

can water form hydrogen bonds with other polar molecules

Answer 7

yes
-glucose
-ammonia

Question 8

hydroxyl group

Answer 8

OH

Question 9

Hydrogen bonds are a type of _____ _______ bond and are due to the attractions of _______ charges (no sharing electrons)

Answer 9

non covalent; opposite

Question 10

ionic bonds

Answer 10

hold together two ions with opposite charges (number of protons doe snot equal number of electrons)

Question 11

ionic bonds in different environments

Answer 11

they are strong in dry environments and weak in aqueous environemnts
-in many aq solutions ionic bonds dissocoaute (why salt dissolves in water)

Question 12

water forms ________ _____ around ions

Answer 12

hydration shell
-several water moleqs surround the ion
-opp charges on water oriented towards the ion

Question 13

uncharged polar molecules and ions interact well with ______ and are called ________ molecules

Answer 13

water; hydrophillic

Question 14

ions often ______ in water but they dont form __ ______ with water

Answer 14

dissolve; Hydrogen bonds

Question 15

do no polar molecules interact well with water and what are they called

Answer 15

no and they are called hydrophobic molecules

Question 16

what do non polar molecules do in water

Answer 16

they group together in water because water molecules for H bonds with on another

Question 17

hydrophobic interactions

Answer 17

association of non polar molecules (or non polar regions w/in a molecule)
-lessens interactions with water and other polar moleqs (or polar regions w/in moleq)

Question 18

van der waals forces

Answer 18

weak attractive forces between adjacent moleqs due to transient fluctuations in electrical charges

Question 19

what type of force stabilizes hydrophobic interactions

Answer 19

wan der waals forces

Question 20

do avn der waals forces initiate hydrophobic interactions

Answer 20

no hydrophobic interactions do

Question 21

what are critical for the 3D structure of many macromolecules

Answer 21

non covalent bonding

Question 22

what type of bond stabilizes the double stranded DNA struvture

Answer 22

hydorgen bonds

Question 23

non covalent bonds are necessary for what

Answer 23

proteins to be in their correct 3D shape (so they can function properly)

Question 24

structure determines what

Answer 24

fucntion

Question 25

what can stabilize the loop structure in protein

Answer 25

non covalent bond

Question 26

what are important for intermolecular interactions

Answer 26

non polar covalent bonds

Question 27

intermolecular interactions is between ____ moleqs

Answer 27

2

Question 28

exampels of intermolecular interactions

Answer 28

-hormone binding to receptor
-body binding to pathogen
-enzyme binding to substance
-transcription factor binding to DNA to regulate gene expression

Question 29

what are some non covalent bonds important points

Answer 29

-individually much weaker than covalent bonds (because they don’t share e-)
-collectively exhibit strength in proportion to their numbers
-changes in environment conditions can cause them to break and molecules to denature or dissociate

Question 30

what can disrupt non covalent bond

Answer 30

higher than optimum temperatures

Question 31

what happens to non covalent bonds in higher than optimum temps

Answer 31

cause the molecules to denature (unfold) or dissociate
-proteins
-nucleic acids
-lipids with hydrophobic tails

Question 32

what can disrupt hydorgen and ionic bonding

Answer 32

salt concentration and pH