Water, Lipids, Carbohydrates, and Nucleotides

Question 1

Hydrogen Bonding

Answer 1

Intermolecular bonding between H and F, O, or N. Provides strong cohesive forces between water molecules
Responsible for elevation of boiling point of water

Question 2

Hydrophilic

Answer 2

A characteristic referring to the tendency of molecules to congregate near and dissolve in water.
Ionic compounds’ negatively charged ends are attracted to partial positive charge of water’s hydrogen and positively charged ends are attracted to partial negative charge of water’s oxygen

Question 3

Hydrolysis

Answer 3

Most macromolecules of living cells are broken apart by this process through the addition of water
Hydrolysis of ATP molecules provides the body’s major source of energy

Question 4

Dehydration synthesis

Answer 4

Reverse reaction of hydrolysis. Two molecules are combined to form a larger molecule and water is formed as a byproduct
Allows formation of bonds that make up biological molecules (peptide, ester bonds)

Question 5

ATP Hydrolysis reaction

Answer 5

Water serves as nucleophile and attacks the electrophilic phosphoanhydride bond between the beta and gamma phosphates of the ATP molecule.
Gamma phosphate is freed and can be used by a kinase enzyme

Question 6

Lipids

Answer 6

Low solubility in water and high solubility in nonpolar organic solvents
Nonpolar and hydrophobic

Question 7

Roles of lipids in an organism

Answer 7

1. Energy storage: long carbon chains
2. Cellular organization and structure: fats assemble into barriers separating aqueous environments (hydrophobic)
3. Provision of precursor molecules for vitamins and hormones: can pass easily through cellular membranes

Question 8

Fatty Acids

Answer 8

Lipids that are the building blocks for the most complex lipids
Act as fuel for body, components of cell membranes
Long chains of carbons truncated at one end by carboxylic acid (even Cs, max of 24)
Store more energy than any other molecule (9kcal)

Question 9

Unsaturated Fatty Acid

Answer 9

Contain one or more Carbon-Carbon double bonds

Question 10

Saturated Fatty Acid

Answer 10

Have only single Carbon-Carbon bonds

Question 11

Triacylglycerol

Answer 11

AKA triglycerides or fats and oils
Constructed from 3C backbone called glycerol attached to three fatty acid chains
Function: to store energy, thermal insulation and padding to organism
Found in adipocytes

Question 12

Sphingolipids

Answer 12

Have long chain fatty acid and polar head group, with amino alcohol (Sphingosine) backbone, rather than glycerol
Make up part of cell membrane

Sphingomyelin: phosphate group attached to sphingosine backbone (phospholipid)

Question 13

Phosphatids

Answer 13

Simplest phosphoglycerides.

Glycerol backbone with a phosphate group attached

Question 14

Steroids

Answer 14

Four-ringed structures
Include some hormones, vitamin D, and cholesterol

Cholesterol: maintains membrane stability and fluidity (precursor for steroid hormones)

Question 15

Terpenes

Answer 15

Sixth class of lipids that are often part of pigments in the body

Includes vitamin A

Question 16

Waxes

Answer 16

Formed by ester linkage between a long-chain alcohol and long-chain fatty acid

Water-repellant texture

Question 17

Eicosanoids

Answer 17

12C structures, often considered a fatty acid
Released from cell membrane as local hormones that regulate blood pressure, body temperature, and smooth muscle contraction.

Includes prostaglandins, thromboxanes, and leukotrines.
Aspirin inhibits synthesis of prostaglandins

Question 18

Lipoproteins

Answer 18

Contains a lipid core surrounded by phospholipids and apoproteins
Able to dissolve lipids in hydrophobic core

Move freely in aqueous solutions due to cell

Classified by density; greater ratio of lipid to protein, lower the density

Question 19

Major classes of lipoproteins

Answer 19

Chylomicrons
Very low density lipoproteins (VLDL)
Low density lipoproteins (LDL)
High density lipoproteins (HDL)

Question 20

Major functions of lipids

Answer 20

1. Phospholipids serve as structural component of membranes
2. Triacylglycerols store metabolic energy and provide thermal insulation and padding
3. Steroids regulate metabolic activity
4. Some fatty acids (eicosanoids) serve as local hormones

Question 21

Phospholipids

Answer 21

Lipids with a phosphate group attached
E.g. phosphoglycerides
Glycerol backbone, with polar phosphate group at head and two fatty acids at tail
Amphipathic, suited for cell membrane

Question 22

Glycoliopids

Answer 22

One or more carbohydrates attached to 3C glycerol backbone with two fatty acids at tail
Amphipathic
Found in membranes of myelinated cells in human nervous system

Question 23

Adipocytes

Answer 23

Specialized cells whose cytoplasm contains almost nothing but triglycerides

Question 24

Types of lipids

Answer 24

Fatty acids, Triacylglycerols, Phospholipids, Glycolipids, Sphingolipids, Steroids, Terpenes, and Waxes

Question 25

Carbohydrates

Answer 25

Carbon and water fixed in a one-to-one ratio: C_n (H_2O)_n Useful for storing energy and providing easily accessible energy to the body Store up to 4 kcal of energy in C-H bonds Consistent structure allows stacking in cell

Question 26

Polysaccharides

Answer 26

Long chains of carbohydrates formed from linkage of many monosaccharides Useful for energy storage Dehydration: forms polysaccharides Hydrolysis: Breaks down polysaccharides to monosaccharides through addition of water

Question 27

Glucose

Answer 27

Most commonly occurring six carbon carbohydrate (hexose) Accounts for ~80% of carbohydrates absorbed by humans. Almost all digested C converted to glucose by liver or enterocytes (intestinal cells) Glucose polymerized to polysaccharide, glycogen, or converted to fat when sufficient energy available

Question 28

Glycogen

Answer 28

Branched glucose polymer with alpha linkages Found in all animal cells, but large quantities in muscle and liver cells Liver can break down glycogen to glucose when needed (regulate blood glucose level)

Question 29

Absorption of glucose

Answer 29

Most cells absorb glucose via facilitated diffusion - Insulin increases this ability Epithelial cells in digestive tract and proximal tubule of kidney are capable of absorbing glucose against concentration gradient - secondary active transport down gradient of sodium

Question 30

What happens to glucose absorption without insulin?

Answer 30

As insulin increases rate of facilitated diffusion of glucose, affects the uptake of glucose and blood glucose level Only neural and hepatic cells are capable of absorbing sufficient amounts of glucose via the facilitated transport system

Question 31

Starch

Answer 31

Polysaccharides present in animals Can be amylose or amylopectin Amylose: branched or unbranched and has same alpha linkages as glycogen Amylopectin: resembles glycogen, but has different branching structure

Question 32

Cellulose

Answer 32

Structural material in plants (polysaccharide) formed from glucose Composed of beta linkages, stable for plant cell walls Humans have enzymes to digest alpha linkages, but not cellulose- fiber Bacteria break beta linkages

Question 33

Nucleotides

Answer 33

Important class of molecules, building blocks of genetic material, involved in cell’s usage of energy

Question 34

Three components of Nucleotides

Answer 34

1. Five carbon (pentose) sugar 2. Nitrogenous base 3. Phosphate group Highly stable sugar with phosphate group can link together to form stable and organized backbone (polar and hydrophilic) Nitrogenous bases form weak H bonds to stabilize double helix, but can be separated

Question 35

Four Nitrogenous Bases

Answer 35

Adenosine, Thymine, Guanine, and Cytosine Two H-bonds form between A and T Three H-bonds form between C and G

Question 36

Purines

Answer 36

Guanine (G), and Adenine (A) Two ring nitrogenous base structure

Question 37

Nucleoside

Answer 37

Pentose sugar attached to nitrogenous base Form nucleotide with addition of one or more phosphate groups to nucleoside

Question 38

Nucleic Acids

Answer 38

Polymers of nucleotides Known as DNA or RNA Specify production of proteins to allow for expression of genetic traits Formed by phosphodiester bonds between phosphate group of one nucleotide and 3rd C of pentose sugar of next nucleotide

Question 39

Sugar Phosphate Backbone

Answer 39

Formed by phosphodiester bonds between nucleotides

Question 40

In what direction are strands of nucleotides synthesized?

Answer 40

Synthesized by DNA polymerase in 5’ to 3’ direction

Question 41

Watson-Crick Model of DNA

Answer 41

B Form of DNA: Two strands of DNA lie side by side in opposite 3’ to 5’ direction (antiparallel) bound together by H-bonds between nitrogenous bases, forming double-stranded structure One spiral for every 10 nitrogenous bases

Question 42

Complementary Strands

Answer 42

DNA strands whose bases match up in the correct order

Question 43

RNA

Answer 43

Ribonucleic Acid: 1. Carbon number 2 on pentose is not deoxygenated (hydroxyl attached) 2. Almost always single stranded 3. Contains pyrimidine uracil (U) instead of thymine (T) Can move through nuclear pores

Question 44

Three types of RNA

Answer 44

``` Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA) ```

Question 45

Important Nucleotides beside DNA

Answer 45

ATP (adenosine triphosphate) for energy Cyclic AMP (cAMP) important component in secondary messenger systems NADH, FADH are coenzymes involved in Krebs Cycle and electron transport chain

Question 46

Pyrimidines

Answer 46

Cytosine (C) and Thimine (T) One ring nitrogenous base structure