Biology Polysaccharides Overview

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Questions and Answers

What is the primary role of receptor tyrosine kinases (RTKs) in cell signaling?

To attach phosphates to tyrosines and trigger multiple pathways (correct)

To allow ions to pass through a hydrophobic membrane

To directly breakdown glycogen into glucose

To facilitate cyclic AMP synthesis

How does the activated hormone-receptor complex function in the cell?

By forming dimer structures with other receptors

By acting as a transcription factor to turn on specific genes (correct)

By generating cyclic AMP and calcium ions

By facilitating the breakdown of glycogen

What effect does the cholera toxin have on intestinal cells?

It allows the entry of calcium ions through ion channels

It triggers excessive secretion of salt from the cells (correct)

It keeps a G protein in its inactive form

It enhances glycogen breakdown

Which of the following describes second messengers in cell signaling?

They are small, nonprotein molecules or ions that diffuse within the cell Signup and view all the answers

What initial action occurs when a ligand activates a ligand-gated ion channel receptor?

The receptor changes shape to act as a gate for ions Signup and view all the answers

What process allows cells to recycle their own organelles and macromolecules?

Autophagy Signup and view all the answers

Which vacuole type is primarily involved in pumping excess water out of cells in freshwater protists?

Contractile vacuoles Signup and view all the answers

Which organelle is responsible for the generation of ATP through cellular respiration?

Mitochondria Signup and view all the answers

What theory explains the evolutionary origin of mitochondria and chloroplasts?

Endosymbiotic Theory Signup and view all the answers

Which of the following is a feature shared by mitochondria and chloroplasts that supports their prokaryotic origins?

Containment of free ribosomes Signup and view all the answers

What is the primary function of glycogen in animals?

Providing energy during demand Signup and view all the answers

Which of the following correctly describes cellulose?

It is a major component of plant cell walls. Signup and view all the answers

What distinguishes storage polysaccharides from structural polysaccharides?

Storage polysaccharides provide energy when needed. Signup and view all the answers

What is true regarding glycosidic linkages?

They involve dehydration reactions between monosaccharides. Signup and view all the answers

Which statement is true about chitin?

It provides structural support in fungal cell walls. Signup and view all the answers

What characterizes lipids compared to other biological molecules?

They are unable to form polymers. Signup and view all the answers

What is the role of cellulose in human nutrition?

It acts as insoluble fiber in the digestive tract. Signup and view all the answers

Fats are primarily constructed from which components?

Glycerol and fatty acids. Signup and view all the answers

What is the first stage of cell signaling as discovered by Earl Sutherland?

Reception Signup and view all the answers

Which type of receptor is known as the largest family of cell-surface receptors?

G Protein-coupled receptors Signup and view all the answers

What occurs when GDP is bound to a G protein?

The protein is inactive Signup and view all the answers

Epinephrine, as a medication, is classified under which category of agents?

Alpha- and beta-adrenergic agonists Signup and view all the answers

What is the role of a G protein in cell signaling?

To act as an on/off switch Signup and view all the answers

Which stage in cell signaling directly triggers a specific response in the target cell?

Response Signup and view all the answers

What is a characteristic of the interaction between a signaling molecule and its receptor?

It is highly specific and often involves conformational change Signup and view all the answers

Which of the following statements about G protein-coupled receptors (GPCRs) is true?

They are transmembrane proteins that interact with G proteins. Signup and view all the answers

What distinguishes saturated fatty acids from unsaturated fatty acids?

Saturated fatty acids contain no double bonds. Signup and view all the answers

Which of the following is a major function of fat in the body?

Energy storage. Signup and view all the answers

What is true about phospholipids in relation to cell membranes?

Phospholipids spontaneously form a lipid bilayer. Signup and view all the answers

Which statement about cholesterol is correct?

Cholesterol's structure consists of four fused rings. Signup and view all the answers

What defines proteins as polymers?

They are made up of multiple amino acid monomers. Signup and view all the answers

Which type of bond connects amino acids in proteins?

Peptide bond. Signup and view all the answers

What characterizes essential fatty acids?

They must be obtained through the diet. Signup and view all the answers

How do electric charges of amino acids influence their behavior in water?

Charged amino acids can form ionic interactions with water. Signup and view all the answers

What is the primary role of digestive enzymes?

To catalyze the hydrolysis of food molecules. Signup and view all the answers

Which of the following statements about nonpolar amino acids is accurate?

They tend to aggregate in aqueous environments. Signup and view all the answers

Study Notes

Polysaccharides

Serve as energy storage or structural components.
Function and architecture are influenced by sugar monomers and glycosidic linkage positions.

Storage Polysaccharides

Glycogen: Main storage polysaccharide in animals, primarily located in liver and muscle cells; hydrolyzed to release glucose for energy.
Starch: Plant storage polysaccharide made entirely of glucose monomers.

Structural Polysaccharides

Cellulose: Major component of plant cell walls; polymer of glucose with different glycosidic linkages than starch.
Passes through human digestive system as insoluble fiber; digested by some microbial enzymes.
Chitin: Found in arthropod exoskeletons and fungal cell walls.

Lipids

Diverse group that does not form polymers; characterized by hydrophobic nature.
Key types: fats, phospholipids, and steroids.

Fats

Comprise glycerol head and fatty acid tails connected by ester bonds.
Saturated fatty acids lack double bonds and are solid at room temperature; derived mainly from animals.
Unsaturated fatty acids contain one or more double bonds; liquid at room temperature; common in plants and fish.
Primary function is energy storage, cushioning organs, and insulating the body.

Phospholipids

Form cell membranes; consist of two fatty acids and a phosphate group; have hydrophilic heads and hydrophobic tails, leading to the formation of lipid bilayers.

Steroids

Composed of a carbon skeleton with four fused rings; cholesterol serves as a key component in animal cell membranes, but high levels can contribute to cardiovascular disease.

Proteins

Account for over half of dry cell mass and perform numerous functions, including enzymatic activities, structural support, and defense against pathogens.

Enzymes

Proteins that catalyze chemical reactions; typically end in -ase (e.g., lipases, proteases).

Amino Acids

Building blocks of proteins; consist of carboxyl and amino groups; differ in their R groups (side chains) which dictate their properties.

Mitochondria and Chloroplasts

Organelles that convert energy forms; mitochondria focus on cellular respiration while chloroplasts are involved in photosynthesis.
Both derived from prokaryotic ancestors, supporting the Endosymbiotic Theory.

Cell Signaling

Involves chemical signaling through hormones; occurs in three stages: reception, transduction, and response.

Reception

The process where signaling molecules bind to specific receptors on target cells, initiating a conformational change.

Types of Cell-Surface Receptors

G Protein-Coupled Receptors (GPCRs): Largest family of receptors, linked with diseases; act with G proteins as switches.
Receptor Tyrosine Kinases (RTKs): Attach phosphates to tyrosines; trigger multiple signaling pathways; mutations linked to various cancers.
Ion Channels: Ligand-gated channels that open with signal binding, allowing ion flow (e.g., Na+, Ca2+).

Second Messengers

Small, nonprotein molecules or ions that facilitate signaling inside cells, such as cyclic AMP (cAMP) and calcium ions, commonly activated by GPCRs and RTKs.
Cholera toxin modifies G proteins to remain active, resulting in excess salt secretion from intestinal cells.

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Description

Explore the fascinating world of polysaccharides, focusing on their storage and structural roles in organisms. This quiz covers important concepts such as glycogen's function in animals and the relationship between sugar monomers and glycosidic linkages. Test your knowledge and understanding of these essential biological molecules.