MCAT · Biology 1 · Chapter 1 · Section 1.4

Chapter 1: Biological Molecules and Enzymes

Section 1.4: Carbohydrates

STUDY

Question 1:
Name 2 primary biological importances of carbohydrates.
→ Energy storage
     Provision of easily accessible energy to the body

Question 2:
Similar to _____, carbohydrates are able to store a large amount of energy due to high concentration of _____ bonds in themselves.
→ Lipids
     C-H

Question 3:
Carbohydrates store _____ (more or less) energy per gram than lipids because carbohydrates have _____ (higher or lower) concentration of _____ bonds. _____ are also present along the carbon chain.
→ Less
     Lower
     C-H
     Alcohols

Question 4:
The consistent structure of carbohydrates allows them to be easily stacked together in the cell, which contributes to their usefulness for _____.
→ Energy storage

Question 5:
_____ reaction allows carbohydrates to join together and form long chains of _____ for energy storage, whereas _____ reaction allows the release of single sugar molecules called _____ that tissues can use for energy.
→ Dehydration
     Polysaccharides
     Reverse hydrolysis
     Monosaccharides

Question 6:
Carbohydrates can be thought of as Carbon and _____ in a fixed 1:1 ratio. For each Carbon atom, there exists 1 _____ atom and 2 _____ atoms. The formula for any carbohydrates is: _____.
→ Water
     Oxygen
     Hydrogens

     C_n(H₂O)_n

Question 7:

Name 2 examples for 6-carbon carbohydrates, one of which should be the most commonly occurring 6-carbohydrate. The terminology for a 6-carbon carbohydrate is _____.

→ Fructose

     Glucose (the most commonly occurring 6-carbon carbohydrate) 

     Hexose

Question 8:

Almost all digested carbohydrates reaching body cells have been converted to _____ by the liver or intestinal cells.

→ Glucose

Question 9:

The cell can _____ (oxidize or reduce) glucose to convert its _____ energy to a more readily usable form, _____. If the cell already has a sufficient amount of this readily usable form, glucose is _____ (polymerized or depolymerized) to the polysaccharide form, _____, or converted to fat.
→ Oxidize
     Chemical
     ATP (= Adenosine TriPhosphate)
     Polymerized
     Glycogen

Question 10:
Glycogen is a _____ (branched or unbranched) glucose _____ (polymer or monomer) with _____ (alpha or beta) linkages. Glycogen is found in all animal cells, but especially abundant in _____ and _____ cells.
→ Branched
     Polymer
     Alpha
     Muscle
     Liver

Question 11:
_____ (organ) regulates the blood glucose level, so its cells are 1 of the few cell types capable of reforming glucose from glycogen and releasing it back into the bloodstream when needed. Only certain epithelial cells in the digestive track and the proximal tubule of the _____ (organ) are capable of absorbing glucose against a concentration gradient. This is done via a secondary active transport mechanism down the concentration gradient of _____. All other cells absorb glucose via _____.
→ Liver
     Kidney
     Sodium
     Facilitated diffusion (a process of spontaneous passive transport of molecules or ions across
     membrane via specific transmembrane proteins)

Question 12:
_____, when present, increases the rate of facilitated diffusion for glucose and other monosaccharides. When absent, only _____ and _____ cells are capable of absorbing sufficient amounts of glucose via facilitated transport system.
→ Insulin
     Neural
     Hepatic

Question 13:
Just like animals, plants join glucose molecules to form polysaccharides. However, while animals use _____ for long-term storage, plants use _____ instead.
→ Glycogen
     Starch

Question 14:
Name 2 forms of starch and briefly describe their components.
→ Amylose: branched or unbranched, has the same alpha linkages as glycogen
     Amylopectin: resemble glycogen but has a different branching structure

(Source: http://image.slidesharecdn.com/lecture14carbohydratescompletetobetaught-140904231611-phpapp01/95/lecture-14-carbohydrates-complete-to-be-taught-17-638.jpg?cb=1409872606)

Question 15:

Glycogen and starch are composed of _____ linkages, whereas cellulose is composed of _____ linkages. Glycogen and starch serve as _____ in animals and plants, respectively; whereas cellulose serves as _____ in plants.

(Source: https://biochemistry3rst.files.wordpress.com/2014/02/219_three_important_polysaccharides-01.jpg)

→ Alpha
     Beta
     Energy storage
     Structural material

Question 16:
Humans _____ (do or do not) have enzymes to digest the alpha linkages of starch. Humans _____ (do or do not) have enzymes to digest the alpha linkages of glycogen. Humans _____ (do or do not) have enzymes to digest the beta linkages of cellulose. If do not, give an example of how such linkages can be digested and which animals have this mechanism.
→ Do
     Do
     Do not: cows and certain insects have bacteria in their digestive system that release enzyme to
     digest beta linkages in cellulose

Question 17:
For glucose polymers, animals eat alpha linkage, but only _____ break beta linkages. The stability of beta linkages of cellulose makes it a tough, stable molecule that can be used to build plant's _____.
→ Bacteria
     Cell walls

PRACTICE

Question 1:
Name 2 primary biological importances of carbohydrates.

Question 2:
Similar to _____, carbohydrates are able to store a large amount of energy due to high concentration of _____ bonds in themselves.

Question 3:
Carbohydrates store _____ (more or less) energy per gram than lipids because carbohydrates have _____ (higher or lower) concentration of _____ bonds. _____ are also present along the carbon chain.

Question 4:
The consistent structure of carbohydrates allows them to be easily stacked together in the cell, which contributes to their usefulness for _____.

Question 5:
_____ reaction allows carbohydrates to join together and form long chains of _____ for energy storage, whereas _____ reaction allows the release of single sugar molecules called _____ that tissues can use for energy.

Question 6:
Carbohydrates can be thought of as Carbon and _____ in a fixed 1:1 ratio. For each Carbon atom, there exists 1 _____ atom and 2 _____ atoms. The formula for any carbohydrates is: _____.

Question 7:

Name 2 examples for 6-carbon carbohydrates, one of which should be the most commonly occurring 6-carbohydrate. The terminology for a 6-carbon carbohydrate is _____.

Question 8:

Almost all digested carbohydrates reaching body cells have been converted to _____ by the liver or intestinal cells.

Question 9:

The cell can _____ (oxidize or reduce) glucose to convert its _____ energy to a more readily usable form, _____. If the cell already has a sufficient amount of this readily usable form, glucose is _____ (polymerized or depolymerized) to the polysaccharide form, _____, or converted to fat.

Question 10:
Glycogen is a _____ (branched or unbranched) glucose _____ (polymer or monomer) with _____ (alpha or beta) linkages. Glycogen is found in all animal cells, but especially abundant in _____ and _____ cells.

Question 11:
_____ (organ) regulates the blood glucose level, so its cells are 1 of the few cell types capable of reforming glucose from glycogen and releasing it back into the bloodstream when needed. Only certain epithelial cells in the digestive track and the proximal tubule of the _____ (organ) are capable of absorbing glucose against a concentration gradient. This is done via a secondary active transport mechanism down the concentration gradient of _____. All other cells absorb glucose via _____.

Question 12:
_____, when present, increases the rate of facilitated diffusion for glucose and other monosaccharides. When absent, only _____ and _____ cells are capable of absorbing sufficient amounts of glucose via facilitated transport system.

Question 13:
Just like animals, plants join glucose molecules to form polysaccharides. However, while animals use _____ for long-term storage, plants use _____ instead.

Question 14:
Name 2 forms of starch and briefly describe their components.

Question 15:
Glycogen and starch are composed of _____ linkages, whereas cellulose is composed of _____ linkages. Glycogen and starch serve as _____ in animals and plants, respectively; whereas cellulose serves as _____ in plants.

(Source: https://biochemistry3rst.files.wordpress.com/2014/02/219_three_important_polysaccharides-01.jpg)

Question 16:
Humans _____ (do or do not) have enzymes to digest the alpha linkages of starch. Humans _____ (do or do not) have enzymes to digest the alpha linkages of glycogen. Humans _____ (do or do not) have enzymes to digest the beta linkages of cellulose. If do not, give an example of how such linkages can be digested and which animals have this mechanism.

Question 17:
For glucose polymers, animals eat alpha linkage, but only _____ break beta linkages. The stability of beta linkages of cellulose makes it a tough, stable molecule that can be used to build plant's _____.

ANSWER KEY

Question 1:
→ Energy storage
     Provision of easily accessible energy to the body

Question 2:
→ Lipids
     C-H

Question 3:
→ Less
     Lower
     C-H
     Alcohols

Question 4:
→ Energy storage

Question 5:
→ Dehydration
     Polysaccharides
     Reverse hydrolysis
     Monosaccharides

Question 6:
→ Water
     Oxygen
     Hydrogens

     C_n(H₂O)_n

Question 7:

→ Fructose

     Glucose (the most commonly occurring 6-carbon carbohydrate) 

     Hexose

Question 8:

→ Glucose

Question 9:

→ Oxidize
     Chemical
     ATP (= Adenosine TriPhosphate)
     Polymerized
     Glycogen

Question 10:
→ Branched
     Polymer
     Alpha
     Muscle
     Liver

Question 11:
→ Liver
     Kidney
     Sodium
     Facilitated diffusion (a process of spontaneous passive transport of molecules or ions across
     membrane via specific transmembrane proteins)

Question 12:
→ Insulin
     Neural
     Hepatic

Question 13:
→ Glycogen
     Starch

Question 14:
→ Amylose: branched or unbranched, has the same alpha linkages as glycogen
     Amylopectin: resemble glycogen but has a different branching structure

(Source: http://image.slidesharecdn.com/lecture14carbohydratescompletetobetaught-140904231611-phpapp01/95/lecture-14-carbohydrates-complete-to-be-taught-17-638.jpg?cb=1409872606)

Question 15:
→ Alpha
     Beta
     Energy storage
     Structural material

Question 16:
→ Do
     Do
     Do not: cows and certain insects have bacteria in their digestive system that release enzyme to
     digest beta linkages in cellulose

Question 17:
→ Bacteria
     Cell walls