16 Questions
What are the elemental compositions of carbohydrates?
Carbon, hydrogen and oxygen
Why are carbohydrates a major source of energy for cells?
They are easily broken down to produce ATP
What is the main role of carbohydrates in cells?
Structural support and energy source
What is the term for carbohydrates that contain a single sugar molecule?
Monosaccharide
How are sugar molecules bonded together in carbohydrates?
Glycosidic linkages
What type of carbohydrate is maltose?
Disaccharide
What is the classification of monosaccharides containing the aldehyde group?
Aldoses
What is the term for carbohydrates that consist of chains of monosaccharide or disaccharide units?
Polysaccharide
What is the primary function of glucose in human cells?
To serve as a carbohydrate fuel
What is the main difference between aldoses and ketoses?
Aldoses are reducing sugars, while ketoses are non-reducing sugars
What is the product of the reaction between two glucose molecules?
Maltose
Why are disaccharides not able to pass through the cell membrane by diffusion?
Because they are too large
What is the main difference between ribose and deoxyribose?
Ribose is found in RNA, while deoxyribose is found in DNA
What is the purpose of Benedict's reagent in relation to sugars?
To distinguish between aldoses and ketoses
What is the reason why galactose cannot play the same part in respiration as glucose?
Because galactose has a different arrangement of atoms in its molecule
What is the main difference between glucose and fructose?
Glucose is an aldose, while fructose is a ketose
Study Notes
Carbohydrates
- Carbohydrates are molecules composed of carbon, hydrogen, and oxygen atoms.
- They serve as a major source of energy and provide structural support for cells and facilitate cell-cell recognition.
Classification of Carbohydrates
- Carbohydrates can be categorized into three types based on the number of sugar units they contain:
- Monosaccharides: single sugar molecules (e.g., glucose, fructose)
- Disaccharides: two monosaccharides covalently linked (e.g., maltose)
- Polysaccharides: polymers consisting of chains of monosaccharides or disaccharides (e.g., starch, cellulose)
Monosaccharides
- Monosaccharides can be further classified based on the number of carbon atoms they contain:
- Triose (3 carbon atoms)
- Tetrose (4 carbon atoms)
- Pentose (5 carbon atoms)
- Hexose (6 carbon atoms)
- Monosaccharides can also be classified as aldoses (containing an aldehyde group) or ketoses (containing a ketone group)
Examples of Monosaccharides
- Glucose: an aldose, the most important carbohydrate fuel in human cells
- Galactose: an aldose, similar in structure to glucose
- Fructose: a ketose, differs from glucose and galactose in structure and properties
- Ribose and deoxyribose: pentoses, components of nucleotides in RNA and DNA, respectively
Disaccharides
- Formed when two monosaccharides react
- Soluble in water, but too large to pass through the cell membrane by diffusion
- Broken down in the small intestine during digestion to give smaller monosaccharides
Test your knowledge on carbohydrates, including their elemental composition, importance as an energy source, and additional roles in cells.
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