Biology Chapter: Carbohydrates

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Questions and Answers

What type of glycosidic linkage is found in maltose?

α-1,6-glycosidic linkage

β-1,6-glycosidic linkage

β-1,4-glycosidic linkage

α-1,4-glycosidic linkage (correct)

What is one of the primary functions of carbohydrates in organisms?

To facilitate DNA replication

To serve as a substrate for synthesizing complex molecules (correct)

To regulate blood sugar levels

To supply vitamins essential for metabolism

Which disaccharide contains a β-1,4-glycosidic linkage?

Starch

Glycogen

Maltose

Lactose (correct)

Which carbohydrate is known for providing structural support to plants?

Cellulose Signup and view all the answers

What is the primary structural difference between amylose and amylopectin?

Amylose consists of α-1,4 linkages while amylopectin is branched with α-1,6 linkages. Signup and view all the answers

What happens to adults who stop producing lactase?

They develop lactose intolerance and may experience discomfort after consuming dairy. Signup and view all the answers

Why are cellulose fibers resistant to degradation?

They have strong β-1,4-glycosidic linkages. Signup and view all the answers

Which of the following carbohydrates is indigestible by most organisms and important for digestive health?

Cellulose Signup and view all the answers

How frequently do branches occur in glycogen compared to amylopectin?

1 out of every 10 glucose subunits in glycogen. Signup and view all the answers

What role do some polysaccharides play in cell identity?

They indicate specific cell types through structural diversity. Signup and view all the answers

What type of sugar polymer is starch made up of?

α-glucose Signup and view all the answers

How do cellulose molecules contribute to the structural integrity of plant cell walls?

They form a fibrous network through hydrogen bonding. Signup and view all the answers

What structural feature differentiates starch from glycogen?

Glycogen has more frequent branching than starch. Signup and view all the answers

Which of the following statements is true about the digestibility of carbohydrates?

Only a few organisms can digest cellulose and chitin. Signup and view all the answers

In which cells is glycogen primarily stored in humans?

Liver and muscle tissues Signup and view all the answers

What is the effect of dietary fiber like cellulose on digestive health?

It adds moisture and bulk to fecal material. Signup and view all the answers

What term describes sugars that consist of a single unit?

Monosaccharides Signup and view all the answers

What role do glycoproteins play in the reproductive process?

They allow sperm to recognize and bind to eggs of the same species. Signup and view all the answers

What is the primary function of carbohydrates in living organisms?

To store energy and act as building blocks Signup and view all the answers

Which characteristic distinguishes aldose from ketose monosaccharides?

The position of the carbonyl group Signup and view all the answers

How does the structure of glucose differ from that of galactose?

They are isomers with varying spatial arrangements Signup and view all the answers

What type of sugar has five carbon atoms and is essential for nucleotide formation?

Ribose Signup and view all the answers

Which statement correctly represents the molecular formula for carbohydrates?

They typically include multiple carbon-hydrogen, hydroxyl, and carbonyl groups Signup and view all the answers

Why are carbohydrates considered polar molecules?

They contain multiple reactive hydroxyl groups Signup and view all the answers

Which type of carbohydrate is formed by a few sugar units linked together?

Oligosaccharides Signup and view all the answers

What type of bond in carbohydrates allows for higher potential energy due to equal sharing of electrons?

C-C bonds Signup and view all the answers

What happens to sperm in the presence of purified egg-surface glycoproteins according to the research?

Sperm lose their ability to attach to eggs. Signup and view all the answers

Which of the following statements about glycolipids is true?

They are lipids that are covalently bonded to one or more carbohydrates. Signup and view all the answers

What is the main function of carbohydrates attached to the plasma membrane?

They act as identification badges for cell recognition. Signup and view all the answers

During photosynthesis, energy from sunlight is primarily converted into what form?

Chemical energy stored in carbohydrates. Signup and view all the answers

Why are the electrons in C=O bonds of CO2 and C-O bonds of carbohydrates held tightly?

Because of the high electronegativity of oxygen. Signup and view all the answers

What is competitive inhibition in the context of sperm and egg recognition?

Glycoproteins block binding sites for sperm. Signup and view all the answers

How are blood types determined?

By the type of oligosaccharides present on the surface of blood cells. Signup and view all the answers

Why do carbohydrates store more chemical energy than carbon dioxide?

They have a higher number of C-H bonds. Signup and view all the answers

Which enzyme is primarily responsible for breaking down glycogen?

Phosphorylase Signup and view all the answers

Which type of glycosidic linkage in starch allows efficient hydrolysis for energy release?

α-glycosidic linkages Signup and view all the answers

How many molecules of ATP can approximately be produced from a single candy worth 15 Calories of energy?

3 × 10²³ Signup and view all the answers

What is the main role of amylases in digestion?

To hydrolyze starch Signup and view all the answers

What substance is synthesized from glucose during energy production?

ATP Signup and view all the answers

Which type of polysaccharides are more resistant to enzymatic degradation?

Structural polysaccharides Signup and view all the answers

Study Notes

Characteristics of Life and Carbohydrates

Proteins and nucleic acids exhibit information, replication, and evolution—three fundamental characteristics of life.
Carbohydrates contribute to energy, the fourth characteristic of life.

Structure of Carbohydrates

Carbohydrates include monosaccharides ("one sugar"), oligosaccharides ("few sugars"), and polysaccharides ("many sugars").
Molecular formula of carbohydrates is (CH2O)n, indicating carbon-hydrate groups.
Composed of carbonyl groups (C=O) and hydroxyl groups (-OH), with multiple carbon-hydrogen bonds (C-H).
Sugars are vital for chemical energy and synthesis of larger compounds.

Monosaccharides

Monosaccharides are simple sugars, with carbonyl groups distinguishing them: aldehyde sugars (aldoses) or ketone sugars (ketoses).
They are polar and soluble in water due to reactive hydroxyl groups.
Types include trioses (3 carbons), pentoses (5 carbons, like ribose), and hexoses (6 carbons, like glucose).
Structural differences, such as the position of hydroxyl groups, can significantly affect function.

Disaccharides

Maltose is a disaccharide formed from two glucose molecules with an α-1,4-glycosidic linkage.
Lactose consists of glucose and galactose, linked by a β-1,4-glycosidic linkage.
The structural differences between maltose and lactose lead to specific enzymatic hydrolysis, with lactase required for lactose digestion.

Storage Polysaccharides

Starch is a storage polysaccharide in plants, composed of α-glucose linked mostly by α-1,4 linkages, forming a helical structure.
Two forms: amylose (unbranched) and amylopectin (branched with α-1,6 linkages).
Glycogen serves a similar storage role in animals, stored in liver and muscle tissues, with more frequent branching compared to starch.

Functions of Carbohydrates

Serve as substrates for synthesizing complex molecules (e.g., RNA and DNA).
Provide fibrous structural materials like cellulose and chitin, crucial for strength and elasticity in cells.
Indicate cell identity via glycoproteins and glycolipids, essential for cell-cell recognition and signaling.

Carbohydrates and Digestive Health

Cellulose is indigestible but vital for digestive health, aiding in the movement of fecal material through the intestinal tract.

Carbohydrate Energy Storage

Carbohydrates transform energy; plants convert sunlight into chemical energy stored in carbohydrates through photosynthesis.
Carbohydrates contain more potential energy than carbon dioxide due to favorable bond arrangements (C-C and C-H bonds).

Energy Release and ATP Production

Carbohydrates and fats serve as fuel; fats store twice as much energy per gram compared to carbohydrates.
Hydrolysis of α-glycosidic linkages in starch and glycogen releases glucose for energy.
Phosphorylase is key for hydrolyzing glycogen, while amylases digest starch.
Energy released during glucose breakdown is captured in ATP synthesis, using ADP and inorganic phosphate.

ATP Production and Energy Utilization

A small amount of sugar can yield a substantial number of ATP molecules; approximately 15 Calories can produce about 3 × 10^23 ATP molecules.
An average person uses this amount of ATP within two minutes, underlining the high energy demands of cellular processes.

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Description

This quiz explores the role of carbohydrates in living organisms, focusing on their structure and function. You'll learn about different types of carbohydrates, including monosaccharides, oligosaccharides, and polysaccharides, and their significance in energy production. Test your understanding of this fundamental aspect of biology!