Exam 1 Flashcards Flashcards by Unknown Unknown

Identify the functions of carbohydrates in the
human body.

a. They provide energy during their oxidation and a short-term energy reserve.
b. They form part of the framework for nucleic acids and supply

carbon atoms for synthesis of other biomolecules.
c. When linked to proteins, they are involved in the cell–cell and cell–molecule recognition process, and they function asstructural components of cell membranes when linked to lipids.

d. All the above.

d. All of the above

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Biochemistry, the study of the chemical
substances of living organisms, includes the study
of:

a. carbohydrates, lipids, proteins, and salts.
b. carbohydrates, lipids, proteins, and organic salts.
c. carbohydrates, lipids, proteins, and nucleic acids.
d. carbohydrates, lipids, and proteins.

C. carbohydrates, lipids, proteins, and nucleic acids.

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Process in which plants produce carbohydrates

using carbon dioxide, water, and solar energy

Photosynthesis

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It is estimated that more than __ of all organic
carbon atoms are found in the carbohydrate
materials of plants.

A. 50%
B. 25%
C. 100%
D.75%

A. 50%

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What are some uses for for carbohydrates outside of food?

Carbohydrates in the form of cotton and linen are
used as clothing

Carbohydrates in the form of wood are used for
shelter and heating and in making paper

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Most of the matter in plants, except water, is?

Carbohydrate Material.

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what accounts for 75% of dry plant

material and are produced by photosynthesis?

Carbohydrates

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What are 6 Functions of Carbohydrates in the Human Body?

Carbohydrate oxidation provides energy.

• Carbohydrate storage, in the form of glycogen,
provides a short-term energy reserve

• Carbohydrates supply carbon atoms for the
synthesis of other biochemical substances
(proteins, lipids, and nucleic acids)

• Carbohydrates form part of the structural
framework of DNA and RNA molecules

Carbohydrates linked to lipids are structural
components of cell membranes

• Carbohydrates linked to proteins function in a
variety of cell–cell and cell–molecule recognition
processes

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Empirical formula of simple carbohydrates -

CnH2nOn (n is the number of atoms)

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Polyhydroxy aldehyde, ketone,
or a compound that produces such substances
upon hydrolysis

Carbohydrate

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What contains single polyhydroxy aldehyde or ketone

unit

Monosaccharides

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What cannot be broken down into simpler substances

by hydrolysis reactions

Monosaccharides

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What contains 2 monosaccharide units covalently

bonded to each other

Disaccharides

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Contains 3–7 C atoms

Monosaccharides

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Upon hydrolysis, they produce 2

monosaccharide units

Disaccharides

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5 and 6 carbon species are more common

Monosaccharides

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What are Pure Monosaccharides

Water soluble white,

crystalline solids

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Common Disaccharides

Table sugar (sucrose)
and milk sugar (lactose)

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Upon hydrolysis, they produce 2

monosaccharide units

Disaccharides

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Contain three to ten monosaccharide units

covalently bonded to each other

Oligosaccharides

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Free _____ are seldom encountered

in biochemical systems

Oligosaccharides

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Usually found associated with proteins and lipids

in complex molecules

Oligosaccharides

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Contain many monosaccharide units covalently
bonded
• Number of monosaccharide units varies from a
few 100 units to 50,000 units

Polysaccharides

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Name 3 Examples of Polysaccharides

Cellulose - Paper, cotton, wood
– Starch - Bread, pasta, potatoes, rice, corn, beans,
and peas

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Carbohydrates are classified as: a. monosaccharides, disaccharides, oligosaccharides, and polysaccharides. b. polyhydroxy aldehydes or ketones. c. monosaccharides and disaccharides. d. monosaccharides, oligosaccharides, polysaccharides, and polyhydroxy aldehydes or ketones.

a. monosaccharides, disaccharides, oligosaccharides, and polysaccharides

C atom attached to 4 different | groups

Chiral center

Bromochloroiodomethane is a ___ organic molecule

Chiral

``` A carbohydrate molecule whose mirror image is not superimposable is said to be a _____ molecule. a. achiral b. chiral c. nonidentical d. nonsuperimposable ```

b. chiral

Two Types of Stereoisomers

Enantiomers: Stereoisomers whose molecules are non-superimposable mirror images of each other • Molecules with chiral center – Diastereomers: Stereoisomers whose molecules are not mirror images of each other • Example: Cis-trans isomers

What feature does a carbohydrate possess that generates stereoisomerism? a. Presence of a chiral center b. Presence of structural rigidity c. Presence of three or more carbon atoms d. Presence of an achiral center

a. Presence of a chiral center

Two-dimensional structural notation for showing the spatial arrangement of groups about chiral centers in molecules • According to this formula, a chiral center is represented as the intersection of vertical and horizontal lines • Functional groups of high priority will be written at the top

Fischer Project Formula (see slides 31-33)

• The four groups attached to the atom at the chiral center assume a tetrahedral geometry governed by the following conventions:

Tetrahedral Arrangements (See slide 30)

What formula is used to show the two-dimensional structure of groups around chiral centers in a molecule?

Fischer projection

- Vibrational Characteristics of Ordinary | Light and Plane-Polarized Light

See Slide 38

Name the properties of Ordinary light waves and Plane polarized light waves

Ordinary: Vibrate in all directions Plane Polarized Light Waves: One direction

Dextrorotatory compound: Chiral compound that rotates light towards ___ • Levorotatory compound: Chiral compound that rotates light towards ___

Dextrorotatory: Right (Clockwise) Levorotatory: Left (Counterclockwise)

Interactions Between Chiral Compounds

Check Slides 40 and 41

What is meant when it is said that carbohydrates are optically active compounds? a. A solution of carbohydrate when placed in a light beam reflects the light back to the observer. b. A solution of carbohydrate will rotate the plane of polarized light. c. A solution of carbohydrate will not rotate the plane of polarized light. d. Being optically active, they do not possess handedness.

b.A solution of carbohydrate will rotate the plane of | polarized light.

Triose

3 carbon atoms

Tetrose

4 carbon atoms

Pentoses

5 carbon atoms

Hexoses

6 carbon atoms

Aldoses:

Monosaccharides with one aldehyde | group

Ketoses:

Monosaccharides with one ketone group

Aldohexose

Monosaccharide with aldehyde group | and 6 C atom

Ketopentose

Monosaccharide with ketone group and | 5 C atoms

What structural feature distinguishes an aldose and a ketose? a. An aldose possesses an aldehyde group, and a ketose possesses a ketone group. b. An aldose contains 5 carbon atoms, and a ketose contains 6 carbon atoms. c. An aldose possesses only –OH groups, and a ketose possesses a carbonyl group. d. An aldose possesses a ketone group, and a ketose possesses an aldehyde group.

a. An aldose possesses an aldehyde group, and a ketose | possesses a ketone group.

4 Groups of Monosaccharides

Ketoses, Aldohexose, Ketopentose, Aldoses

Most abundant in nature | Most important source of human nutrition

D-Glucose

Other names for Glucose

– Dextrose | – Blood sugar

Glucose is a Six-membered cyclic form

see slide 50

``` Milk sugar • Synthesized in human beings • Also called brain sugar – Part of brain and nerve tissue • Used to differentiate between blood types ```

D-Galactose

D-Galactose is a Six-membered cyclic form

See Slide 51

``` Ketohexose • Sweetest tasting of all sugars – Found in many fruits and in honey • Good dietary sugar due to higher sweetness ```

D-Fructose

D-Fructose is a Five-membered cyclic form

See Slide 52

``` Part of a variety of complex molecules which include: – RNA – ATP – DNA ```

D-Ribose

D-Ribose is a Five-membered cyclic form

see slide 53

Which monosaccharide is the most important from | a human nutritional standpoint?

Glucose

Cyclic Hemiacetal Forms of D-Glucose

• Dominant forms of monosaccharides with 5 or | more C atoms

Cyclic structures are formed by

the reaction of carbonyl group (C=O) with hydroxyl (–OH) group on carbon 5

Cyclic monosaccharides that differ only in the position of the substituents on the anomeric carbon atom

Anomers (see slide 57, 58)

Cyclic monosaccharide containing a | five-atom ring

Furanose

Cyclic monosaccharide containing a | six-atom ring

Pyranose

Monosaccharides in nature have cyclic forms because they can form: a. internal acetals that are stable. b. internal hemiacetals that are stable. c. internal acetals that are rapidly converted to stable hemiacetals. d. internal hemiacetals that are rapidly converted to stable acetals.

b. internal hemiacetals that are stable.

Two-dimensional structural notation that specifies the threedimensional structure of a cyclic form of a monosaccharide

Haworth projection formula

α and β Configuration

Slide 64

–OH Group Position

Slide 65

Haworth projection formula for a monosaccharide is a formula showing: a. a line structure of a stable internal acetal. b. a two-dimensional notation that specifies the three dimensional structure of a cyclic monosaccharide. c. a line structure of a stable internal hemiacetal. d. a two-dimensional notation that specifies the three dimensional structure of a stable cyclic acetal.

b. a two-dimensional notation that specifies the three dimensional structure of a cyclic monosaccharide.

Which of the monosaccharides glucose, fructose, galactose, and ribose has each of the following structural characteristics? (There may be more than one correct answer for a given characteristic) a. It is a pentose. b. It is a ketose. c. Its cyclic form has a 6-membered ring. d. Its cyclic form has two carbon atoms outside the ring.

a. It is a pentose: Ribose b. It is a ketose: Fructose c. Its cyclic form has a 6-membered ring: Glucose, and galactose d. Its cyclic form has two carbon atoms outside the ring: Fructose

Five important reactions of monosaccharides:

``` Oxidation to acidic sugars – Reduction to sugar alcohols – Glycoside formation – Phosphate ester formation – Amino sugar formation ```

- Formed when weak oxidizing agents such as Tollens and Benedict’s solutions oxidize the aldehyde end

Aldonic acid

Carbohydrate that gives a positive | test with Tollens and Benedict’s solutions

Reducing Sugar

Sorbitol

Used as a moisturizing agent in foods and cosmetics and as a sweetening agent in chewing gum

Acetal formed from a cyclic monosaccharide by replacement of the hemiacetal carbon –OH group with an –OR group

Glycoside

Glycoside produced from glucose

Glucoside

Glycoside produced from galactose

Galactoside

Hydroxyl groups of a monosaccharide can react with inorganic oxyacids to form inorganic esters • Phosphate esters of various monosaccharides are stable in aqueous solution and play important roles in the metabolism of carbohydrates

Phosphate Ester Formation

- Formed when one of the hydroxyl groups of a monosaccharide is replaced with an amino group

Amino sugar

``` Which of the following sugars can be oxidized by Tollens and Benedict’s reagents in basic conditions? a. D-glucose, an aldohexose b. D-fructose, a ketohexose c. D-mannose, an aldohexose d. All the above ```

d. All the above

Maltose (Malt Sugar)

See Slide 80

Cellobiose

See Slide 81

Lactose

See Slide 82

a condition in which people lack the enzyme lactase needed to hydrolyze lactose to galactose and glucose

Lactose intolerance | see slide 84 for more information on what happens

The most abundant of all disaccharides and found in plants • Produced commercially from the juice of sugar cane and sugar beets

Sucrose (Table Sugar)

What is the linkage that is formed when two monosaccharides react to form a disaccharide called? a. Alcohol group linkage b. Glycosidic linkage c. Hemiacetal linkage d. Acetal linkage

b. Glycosidic linkage

``` Which disaccharide is a nonreducing sugar? a. Maltose b. Lactose c. Cellobiose d .Sucrose ```

d. Sucrose

Which of these disaccharides, i.e., maltose, cellobiose, lactose, and sucrose, have the following structural or reaction characteristics? (There may be more than one correct answer for a given characteristic) a. Two different monosaccharide units are present. b. Hydrolysis produces only monosaccharides. c. Its glycosidic linkage is a “head-to-head” linkage. d. It is not a reducing sugar

a. Two different monosaccharide units are present. Lactose, sucrose b. Hydrolysis produces only monosaccharides. Maltose, cellobiose, lactose, sucrose c. Its glycosidic linkage is a “head-to-head” linkage. Sucrose d.It is not a reducing sugar. Sucrose

Carbohydrates that contain 3–10 monosaccharide units bonded to each other via glycosidic linkages

Oligosaccharides

Blood Types and Oligosaccharides

See Slide 93 and 94

``` Which of the following is a toxin produced by potato plants? a. Raffinose b. Stachyose c. Solanine d. None of the above ```

c. Solanine

Polymers of many monosaccharide units bonded with glycosidic linkages

Polysaccharides

Two types of Polysaccharides

– Homopolysaccharide | – Heteropolysaccharide

Not sweet and do not show positive tests with Tollen’s and Benedict’s solutions, whereas monosaccharides are sweet and show positive tests • Limited water solubility

• Polysaccharides

A _____ is a polysaccharide in which only one type of monosaccharide monomer is present. a. heteropolysaccharide b. homopolysaccharide c. heteromonosaccharide d. homomonosaccharide

b. homopolysaccharide

Polysaccharide that is a storage form for monosaccharides and used as an energy source in cells

Storage polysaccharide

Glucose is the monomeric unit | – Storage polysaccharide in plants

Starch

Types of Polysaccharides Isolated From Starch

Amylose, • Amylopectin

``` Glucose storage polysaccharide in humans and animals • Contains only glucose units • Branched chain polymer with α(1->4) glycosidic bonds in straight chains and α(1->6) in branches • Three times more highly branched than amylopectin in starch • Contains up to 1,000,000 glucose units ```

Glycogen

Excess glucose in blood is stored in the form of:

Glycogen

In starch, two different glucose-containing polysaccharides can be isolated. They are _____ and _____ a. glycogen; amylose b. amylose; amylopectin c. amylose; cellulose d. glycogen; cellulose

b. amylose; amylopectin

``` Linear homopolysaccharide with β(14) glycosidic bond • Contains up to 5000 glucose units with molecular mass of 900,000 amu It serves as dietary fiber in food and readily absorbs water resulting in softer stools ```

Cellulose

Similar to cellulose structurally and functionally • Linear polymer with all β(1->4) glycosidic linkages – It has an N-acetyl amino derivative of glucose • Function is to give rigidity to the exoskeletons of crabs, lobsters, shrimp, insects, and other arthropods

Chitin

``` What is the structural component of plant cell walls? a. Starch b. Glycogen c. Chitin d. Cellulose ```

d. Cellulose

The Structure of Chitin

slide 112

Polysaccharides with a repeating disaccharide unit containing an amino sugar and a sugar with a negative charge due to a sulfate or a carboxyl group • They are heteropolysaccharides, i.e., different monosaccharides exist in an altering pattern

Acidic polysaccharides

Examples of Acidic polysaccharides

Hyaluronic acid | Heparin

Alternating residues of N-acetyl- β-Dglucosamine and D-glucuronate • Highly viscous and serve as lubricants in the fluid of joints as well as vitreous humor of the eye

Hyaluronic Acid

Polysaccharide with 15–90 disaccharide residues per chain • Blood anticoagulant

Heparin

Heparin, a well known acidic polysaccharide, is best known for its biochemical function as a(n) _____. a. coagulant b. anticoagulant c. exoskeleton d. dietary fiber

b. anticoagulant

Dietary monosaccharides or disaccharides Sweet to taste and commonly referred to as sugars

Simple carbohydrates

Dietary polysaccharides – Include starch and cellulose, which are normally not sweet to taste

Complex carbohydrates

``` Dietary carbohydrates constitute _____ of the diet of most people. a.10% b.25% c.35% d.50% ```

d. 50%

Lipid molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it

Glycolipid

Protein molecule that has one or more carbohydrate (or carbohydrate derivative) units covalently bonded to it

Glycoprotein

``` A protein molecule that has one or more carbohydrate units covalently bonded to it is known as a(n) _____. a. glycolipid b. glucoprotein c. glycoprotein d. oligosaccharide protein ```

b. glucoprotein

D-glucose consists of six carbon atoms. When drawn using the Fischer projection formula, how do you determine that it is the D isomer? How many chiral carbon centers does it have and how many stereoisomers are possible? a. The –OH on the chiral carbon farthest from the carbonyl group points to the right. There are five chiral centers providing 32 stereoisomers. b. The –OH on the chiral carbon farthest from the carbonyl group points to the right. There are four chiral centers providing 16 stereoisomers. c. The –OH on the chiral carbon farthest from the carbonyl group points to the left. There are five chiral centers providing 32 stereoisomers. d. The –OH on the chiral carbon farthest from the carbonyl group points to the left. There are four chiral centers providing 16 stereoisomers.

b. The –OH on the chiral carbon farthest from the carbonyl group points to the right. There are four chiral centers providing 16 stereoisomers.

Prior to a marathon run, an athlete consumes large amounts of complex carbohydrates to do what is known as “carbohydrate loading.” What happens in the body to the glucose molecules present in these complex carbohydrates and why is carbohydrate loading important? a. The complex carbohydrates are broken down to glucose and any excess glucose, not used for immediate energy, is stored in the form of glycogen, which can be used later as a source of stored energy. b. The complex carbohydrates are broken down to glucose and any excess glucose, not used for immediate energy, is stored in the form of starch, which can be used later as a source of stored energy. c. The complex carbohydrates are broken down to galactose and any excess galactose, not used for immediate energy, is stored in the form of glycogen, which can be used later as a source of stored energy. d. The complex carbohydrates are broken down to glucose and any excess glucose, not used for immediate energy, is stored in the form of glycogen, which can be used later to produce muscle tissue needed to complete the marathon.

a. The complex carbohydrates are broken down to glucose and any excess glucose, not used for immediate energy, is stored in the form of glycogen, which can be used later as a source of stored energy.

Exam 1 Flashcards

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