Biology Unit Test T2 P3 Flashcards
(30 cards)
How many covalent bonds does a carbon atom form?
Carbon atoms have four valence electrons, which means they can form up to four covalent bonds with other atoms. This unique bonding ability allows carbon to create a wide variety of stable and complex structures. As a result, carbon is essential for building the backbone of organic molecules. It plays a key role in forming important biological compounds like carbohydrates and lipids.
Which functional group is characteristic of alcohol?
The hydroxyl group (-OH) is a defining feature of alcohols and is commonly found in carbohydrates. These groups increase the polarity of carbohydrate molecules, making them highly soluble in water. Their presence also enables carbohydrates to form hydrogen bonds with water molecules and other compounds. This property is crucial for many of the biological functions carbohydrates perform in living organisms.
What is an example of a polysaccharide?
Starch is a polysaccharide made up of numerous glucose units linked together. It serves as a primary energy storage molecule in plants. Starch is composed of two types of glucose polymers: amylose, which is mostly linear, and amylopectin, which is highly branched. These structures allow starch to be compact and efficient for storing energy.
What does the formation of macromolecules from monomers involve?
Condensation reactions link monomers together to form larger polymers, with the release of a water molecule each time a bond is formed. This process is essential for building complex biological macromolecules. Carbohydrates, proteins, and nucleic acids are all synthesized through condensation reactions. These reactions enable cells to construct large, functional molecules from simpler building blocks.
What does ATP provide energy for?
ATP (adenosine triphosphate) supplies energy for numerous cellular activities, including the synthesis of macromolecules. During condensation reactions, ATP hydrolysis releases energy that drives these energy-requiring (endergonic) processes. This energy helps form bonds between monomers to build larger molecules like proteins, nucleic acids, and polysaccharides. Without ATP, cells would not be able to efficiently carry out these essential reactions.
What is the main structure difference between amylose and amylopectin?
Amylopectin and amylose are two components of starch, differing in their structure. Amylose is mostly linear, forming long, unbranched chains of glucose units. In contrast, amylopectin is highly branched, with many side chains extending from the main chain. This branching allows enzymes to access multiple points at once, enabling quicker breakdown and faster energy release compared to amylose.
What does the hydrolysis of a polysaccharide result in?
Hydrolysis is the process of breaking down polysaccharides into smaller carbohydrate units by adding water. It begins by splitting large polysaccharides into disaccharides and eventually into monosaccharides like glucose. This reaction is essential for digestion, as it allows the body to absorb and use carbohydrates for energy. Enzymes in the digestive system help speed up this process, ensuring efficient nutrient breakdown.
What is a description of beta-glucose in cellulose?
Beta-glucose molecules in cellulose are linked by glycosidic bonds that alternate in orientation, resulting in straight, unbranched chains. These chains align closely and form strong hydrogen bonds with each other, creating rigid, fibrous structures. This arrangement gives cellulose its high tensile strength, making it ideal for structural support in plant cell walls. Additionally, the tightly packed chains make cellulose insoluble in water.
What does the strength of cellulose microfibrils in plant cell walls provide?
Cellulose microfibrils are bundles of tightly packed cellulose chains that reinforce plant cell walls. They provide structural support, giving the cell wall rigidity and strength. This rigidity helps plant cells maintain their shape and resist the inward pressure caused by water entering the cell, known as osmotic pressure. As a result, cellulose is essential for maintaining the integrity and proper function of plant cells.
What do glycoproteins play an important role in?
Glycoproteins are important for cell-to-cell recognition and communication. The carbohydrate parts of glycoproteins, found on the surface of cells, serve as specific recognition sites. These sites allow cells to identify and interact with other cells, antibodies, and signaling molecules. This function is essential for processes like immune response and tissue development.
What is adipose tissue mainly involved in?
Glycoproteins on the surface of red blood cells play a key role in determining a person’s blood type. The specific sugar molecules attached to these glycoproteins act as markers that distinguish blood types A, B, AB, or O. For example, type A blood has A sugars, type B has B sugars, type AB has both, and type O lacks these sugars. These differences are important for blood transfusions and immune system recognition.
Explain why liquids are hydrophobic?
Lipids are hydrophobic because they contain long, nonpolar hydrocarbon chains. These chains do not have charged or polar regions, so they cannot form hydrogen bonds with water molecules. As a result, lipids do not dissolve in water and are considered insoluble. This property allows lipids to form barriers like cell membranes.
Triglycerides are formed by condensation reactions involve what?
Triglycerides are created when three fatty acid molecules join with one glycerol molecule through condensation reactions. During this process, each fatty acid forms a covalent bond with glycerol, releasing a water molecule for each bond formed. In total, three water molecules are released when a triglyceride is formed. This structure serves as a major form of energy storage in organisms.
What do saturated fatty acids have?
Saturated fatty acids contain only single bonds between the carbon atoms in their hydrocarbon chains. This allows the chains to pack closely together in a tight, orderly arrangement. Because of this tight packing, saturated fats tend to be solid at room temperature. This structural property affects their physical state and how they function in organisms.
What is the difference between cis and trans unsaturated fatty acid?
In cis-unsaturated fatty acids, the hydrogen atoms attached to the carbon atoms of the double bond are on the same side. This causes the molecule to bend or kink, preventing tight packing. In contrast, trans-unsaturated fatty acids have hydrogen atoms on opposite sides of the double bond, resulting in a straighter shape. This straighter structure allows trans fats to pack more closely, similar to saturated fats.
Why do phospholipids form bilayers in water?
Phospholipids arrange themselves into bilayers where their hydrophilic heads face the watery environments both inside and outside the cell. Meanwhile, their hydrophobic tails point inward, away from the water, facing each other in the center of the bilayer. This structure minimizes the contact between water and the hydrophobic tails. As a result, the bilayer forms a stable barrier that is essential for cell membrane function.
What is adipose tissue mainly involved in?
Adipose tissue is primarily made up of triglycerides and serves as a long-term energy storage in the body. Because lipids have a high energy content, they are very efficient at storing large amounts of energy. Besides energy storage, the fat in adipose tissue also acts as an insulator, helping to regulate body temperature. This combination makes adipose tissue vital for both energy balance and thermal protection.
Explain why a steroid hormone can pass directly through a phospholipid bilayer?
Steroid hormones are non-polar molecules, which allows them to easily pass through the hydrophobic interior of the phospholipid bilayer. Because of their non-polar nature, they can diffuse directly across the cell membrane without needing transport proteins. This ability enables steroid hormones to enter cells efficiently. Once inside, they can interact with specific receptors to regulate various cellular processes.
Why is cellulose a structural polysaccharide?
Cellulose is a structural polysaccharide that forms strong, rigid microfibrils in plant cell walls. These microfibrils are made of tightly packed chains of beta-glucose molecules linked together. They provide essential support, giving the cell walls strength and rigidity. This structural role helps plants maintain their shape and resist external pressures.
Which property of triglycerides makes them suitable for long-term energy storage?
Triglycerides are ideal for long-term energy storage because they have a high caloric value per unit mass. They provide more energy per gram than carbohydrates or proteins, making them highly efficient. This dense energy storage allows organisms to store large amounts of fuel in a compact form. As a result, triglycerides serve as an important energy reserve for sustained use.
What term is a polysaccharide made of beta-glucose that forms strong microfibrils?
Cellulose
What term is a molecule that acts in cell recognition?
Glycoprotein
What term is a single unit that can bond to form larger macromolecules?
Monomer
What term is a reaction breaking down polymers using water?
Hydrolysis
