Chapter 3

Question 1

What type of chemical reaction occurs when monomers are joined to form polymers?

Answer 1

Polymerization

Question 2

What type of chemical reaction occurs when polymers are broken apart into monomers?

Answer 2

Hydrolysis (water breaks down)

Question 3

In which type of reaction is a water molecule released as a product of the reaction?

Answer 3

A water molecule released as a product of the reaction is dehydration synthesis. This chemical reaction means “to put together while losing water”

Question 4

In which type of reaction is a water molecule broken apart so the reaction can go forward?

Answer 4

Hydrolysis

Question 5

Which of the biological macromolecules is not a polymer?

Answer 5

Lipids

Question 6

What features are shared by all carbohydrates?

Answer 6

1. Carbon
   2.Hydrogen
   3.Oxygen

Question 7

What is the ratio of carbons to hydrogens to oxygens in a carbohydrate molecule?

Answer 7

1:2:1

Question 8

What are three ways in which monosaccharides can differ from one another?

Answer 8

1 the location of the carbonyl group
2 the number of carbon atoms they contain
3 orientations of their hydroxyl groups

Question 9

For each of the following polysaccharides, describe 1) the type of monomer, 2) the type of glyosidic linkage, 3) branching (if any), 4) example organisms that have this type of polysaccharide, and 5) the major functions: starch, glycogen, cellulose, chitin, and peptidoglycan.

Answer 9

1. Starch-plants store sugar as starch, can be broken down into glucose monomers (because it’s sugar), then it makes energy, bonds are easily broken, can be branched or unbranched, alpha glycosidic linkage
2. Glycogen is animals storing sugar, can be broken down into glucose monomers bonds are easily broken, can be branched or unbranched, glycosidic linkage
3. Cellulose- beta glycosidic linkage, polymers are unbranched, this is a structural polymer cell walls, parallel strands connected by hydrogen bonds
4. Chitin- structural in fungi and exoskeletons of insects, parallel strands connected by hydrogen bonds, monomers modified by acetyl- amino acids
5. Peptidoglycan-structural in bacteria cells walls, monomers modified by amino acids, parallel strands connected by peptide bonds

Question 10

What are the four major functions that carbohydrates can perform in cells, and an example of each type?

Answer 10

1. Energy storage- glycogen storage energy or form structures
2. Energy production- glucose used for energy
3. Building macromolecules- cellulose is string of glucose molecules
4. Sparing Proteins - energy for the body

Question 11

Both starch and cellulose are glucose polymers. Why can animals easily degrade starch, but not cellulose?

Answer 11

Animals don’t have the enzymes for it, they have a-glycosidic bonds but not b-glycosidic bonds

Question 12

How can you tell from the molecular formula C6H10O5, that this six-carbon sugar is a disaccharide composed of two trioses and not a hexose?

Answer 12

Because their structure differs, chemically and structurally, they have different arrangements of the structural groups

Question 13

What are some similarities between the structure of peptidoglycans, found in the cell walls of prokaryotes, and chitin, found in the exoskeletons of insects?

Answer 13

Both are for structural support, both are monomers.

Question 14

How does the extensive hydrogen bonding found among parallel glucose polymers of cellulose contribute to its function in plants?

Answer 14

Cellulose holds and maintains the plant cells structure

Question 15

What are the analogous functions of starch and glycogen and where are they stored in plants and animals?

Answer 15

Store energy for later, for plants its plastids, in animals its glycogen in skeletal muscles and liver

Question 16

What are the properties and functions of the three major types of lipids: phospholipids, triglycerides and sterols (give example of each)?

Answer 16

1. Phospholipids- lipid bilayers of a cell membrane
   2.Triglycerides-fats and oils
2. Sterols- hormones like testosterone

Question 17

What are several functions of fats in the body?

Answer 17

1. Energy storage
2. Cushioning and insulation
3. Cell membrane component
4. Precursors for certain vitamins

Question 18

What is the structure of a triglyceride molecule?

Answer 18

There’s a glycerol and fatty acids
1. Fatty acids may contain double bonds
2. Bonds between carbon and unsaturated fats

Question 19

How do saturated and unsaturated fatty acids differ in their structure?

Answer 19

1. Saturated is single bonded
2. Unsaturated is double or more bonds

Question 20

What are some examples of saturated and unsaturated fats that are found in food?

Answer 20

1.Oil
2.Butter
3. Beeswax

Question 21

How do levels of saturated fats and cholesterol in the diet affect a person’s risk of developing cardiovascular disease?

Answer 21

1. High level of trans fat can lead to bad cholesterol
2. Can be lead to heart disease
3. Too much is bad for you

Question 22

What is the molecular structure of phospholipids, and why do they spontaneously form bilayers in water?

Answer 22

Phospholipids safe a plasma membrane, two hydrophobic tails of fatty acids,has two layers (bilayers) make up cell membrane, they form in water because phospholipid head (are water loving) the tails doing because of they’re made up of fatty acids and oils, hydrophobic and hydrophilic interactions, they line up in the interior of the membrane

Question 23

What part of a phospholipid is hydrophilic and what part is hydrophobic?

Answer 23

The tails of a phospholipid is hydrophobic and the heads is hydrophilic.

Question 24

What structural features do all steroids have in common?

Answer 24

All have a four ring structure

Question 25

What are the functions of cholesterol in the body?

Answer 25

Important for plasma membrane and for steroid hormones.

Question 26

What are some examples of protein functions (give an example for each)?

Answer 26

1. Catalyst : speeds up chemical reactions (ex: enzymes) 2.Signaling : signal and receptor proteins exchange information (ex: testosterone, progesterone) 3. Transport : Motor proteins transport materials around the cell; membrane proteins regulate what goes in/out of cell (ex: GLUT1, calcium ATPase) 4. Gene Regulation : transcription regulator proteins bind to DNA to control gene expression (ex: activator proteins bind to regulatory sites) 5. Fluid balance : serum proteins regulate distribution of fluid between blood and tissues (ex: Albumin and Globulin proteins) 6. Structure : Cytoskeletal proteins define cell shape (ex: keratin, collagen) 7. Movement : Motor and contractile proteins move the cell (ex: muscle protein Myosin motors the contraction of muscle fibers in animals)

Question 27

What structural features all amino acids have in common, and how are each of the 20 amino acids different from one another?

Answer 27

Amino acid R groups can be grouped into four general types: Acidic, basic, Uncharged Polar and Nonpolar. They differ based on the R group attached to the central carbon.

Question 28

What is an ionized amino acid, and where are you likely to find proteins with ionized amino acids?

Answer 28

Amino acids ionize in solutions such as water or bodily fluids; ionization results in the loss or gain of one electron, the molecule becomes electrically charged and more reactive with other molecules

Question 29

What are the features of a peptide bond, and what parts of amino acids are involved in making this bond?

Answer 29

A peptide bond is a condensation reaction (chemically joins two molecules together) that bonds the carboxyl group of one amino acid to the amino group of another amino acid.

Question 30

How do the amino acid side chains (R-groups) affect the biochemical properties of each amino acid?

Answer 30

The side chains affect the folding of the protein because it changes the unique sequence of amino acids in its primary structure, which ultimately determines its function

Question 31

Which are the biochemical characteristics of the amino acids that are in the following groups: nonpolar, polar uncharged, charged (acidic and basic)?

Answer 31

Non polar - hydrocarbon side chains are generally built from carbon and hydrogen, which have little electromagnetic difference; their results in bonds that are not polarized, or nonpolar Polar uncharged - the hydroxyl group on Ser normally does not ionize, so it is not charged in proteins (it remains neutral)

Question 32

How do you identify the N-terminus and the C-terminus of a protein, and how are the amino acids in a protein numbered?

Answer 32

The N-terminus is part of the amino group and found at the start of the protein while the C-terminus is part of the Carboxyl group and found at the end of a protein. The amino acids are numbered based on its primary structure and the order of the peptide bonds found in the DNA sequence

Question 33

What are the four levels of protein structure?

Answer 33

1. Primary - unique sequence of amino acids 2. Secondary - formed by hydrogen bonds in the backbone of amino acid 3. Tertiary - interactions between R groups and peptide backbone, which causes the 3D folding 4. Quaternary - bonding of two or more distinct polypeptide units

Question 34

What biochemical characteristics of amino acids (carbon skeleton or side-groups) are important for the formation of protein secondary and tertiary structure?

Answer 34

1. Secondary - Hydrogen bonds occur between the backbone of the carbonyl group of one amino acid and amino group of another 2. Tertiary - R group interactions involved in protein folding include hydrogen bonds, hydrophobic interactions 3. Covalent disulfide bonds, ionic bonds and Van der Waals interactions

Question 35

1. What are the three basic parts of a nucleotide?

Answer 35

1. Phosphates group 2. Sugar 3.Nitrogen base

Question 36

What is the importance of the 2’, 3’, and 5’ carbons of the sugar in the nucleotide?

Answer 36

Hydroxyl groups for on 3 and 5 carbons making a dna backbone (they link to a phosphate group)

Question 37

Which purines and pyrimidines are present in DNA and RNA?

Answer 37

Adenine, Guanine is the purines, the pyrimidines are Uracil (RNA) and Thymine (DNA).

Question 38

How do purines and pyrimidines hydrogen bond to each other to form complementary base pairs?

Answer 38

The shape allows them to bond together

Question 39

What is a nucleic acid, and what bond type connects nucleotides to one another within a nucleic acid strand?

Answer 39

Nucleic acid is the genetic blueprint, it carries the instruction so things can function

Question 40

What is meant by the 5’ end and the 3’ end of a DNA or RNA strand?

Answer 40

5 and 3 is the number of carbon atoms in deoxyribose sugar- a phosphate group bonds

Question 41

What is Chargaff’s rule for the ratios of nucleotides in a DNA sample, and how did this information help in solving the structure of the DNA molecule? If a sample of DNA has 30% guanine, how much adenine, thymine and cytosine does it have?

Answer 41

Chargaff rules was 2 empirical rules, one states purines= pyrimidines (A+G=C+T), and the second rule states A=T and C=G, this helped determine the structure because it showed that everything was in paris. Cytosine has 30, A=20 G=30 C=20 T=20.

Question 42

What are the primary and secondary structures of DNA?

Answer 42

Primary is ribose, secondary is polynucleic chains

Question 43

What are the primary, secondary, tertiary, and quaternary structures of RNA?

Answer 43

Primary=uracil, secondary= single stranded, has a loop like a bobby-pin,fold into complex shapes, tertiary= 3D, folds, building blocks, quaternary= multiple polypeptide chains

Question 44

How do DNA and RNA differ in their functions as information storage molecules in living organisms?

Answer 44

DNA stores the information, RNA is the messenger, under alkaline condition DNA is fine RNA is not