1.4 Carbohydrates and Lipids Flashcards
To understand carbohydrates and lipids
What is a carbohydrate
An energy-rich biomolecule consisting of carbon, oxygen, and hydrogen
How are carbohydrates built in photosynthesising organisms?
In photosynthesising organisms, carbon dioxide and H2O molecules are used as “raw materials” to build carbohydrates
How are carbohydrates categorised?
Carbohydrates are categorised into 2 groups: simple and complex
What do organisms use carbohydrates for?
Organisms use carbohydrates as an energy source, building materials, and for cell-to-cell communication
What are the complex carbohydrates?
Oligosaccharides and polysaccharides
What is the difference between simple and complex carbohydrates?
Simple: Quickly digestible sugars
Complex: Larger molecules that take longer to break down
What are the simple carbohydrates?
Monosaccharides and disaccharides
What is a monosaccharide?
A single sugar molecule, the simplest type of carbohydrate
What is a disaccharide?
A disaccharide is made from 2 monosaccharide units by a dehydration synthesis reaction
What is an oligosaccharide?
A short chain of 3-10 sugar units
What is a polysaccharide?
A long chain of 10 or more sugar units
Why are monosaccharides a building block for complex carbohydrates?
Because it cannot be broken down further
What is glucose in terms of monosaccharides?
The most widely used monosaccharide; the primary source of energy
How do plants produce glucose?
During photosynthesis
All monosaccharides can occur in a linear form, but when/how do they form rings?
When formed in H2O (water), monosaccharides with 5 or more carbon atoms fold on themselves to form a ring
What is an isomer, and what is an example?
Molecules with the same chemical formulas but different arrangement of atoms (ex. galactose, fructose, glucose. answers may vary)
What are glucose’s arrangements?
Alpha-glucose and Beta-glucose, which are two different arrangements of the -OH group
Different arrangements of the -OH group on glucose can give chemicals different properties. What are two examples?
Starches, composed of alpha-glucose, are digestible for humans
Cellulose, assembled from beta-glucose, is indigestible for humans
(answers may vary)
What is an example of a disaccharide made from 2 monosaccharides?
2 alpha-glucose molecules form maltose, a disaccharide molecule, through dehydration (removal of an H2O molecule)
How are disaccharide carbohydrates hydrophilic?
They have the same functional groups that make monosaccharides hydrophilic (-OH hydroxyl group). This means they are soluble, easily dissolved in water
What is a monomer?
A small molecule that can chemically bond to other molecules
What is a glycosidic bond?
A bond formed between 2 monosaccharides to form larger carbohydrates (ex. disaccharides, oligosaccharides, polysaccharides) through dehydration synthesis (removal of an H2O molecule)
What is a complex carbohydrate composed of?
Complex carbohydrates (polysaccharides) are molecules composed of hundreds to thousands of monosaccharides linked together
What are complex carbohydrates important for?
Some are used for energy storage, like starch and glycogen
Others are essential for structural support, such as cellulose and chitin
What is a polysaccharide molecule?
Large carbohydrate molecules that contain many linked monosaccharides, typically serving structural or energy storage functions in organisms.
What is polymerisation?
The process in which identical or similar subunits, which are called monomers, link together in a long chain to form a larger molecule, called a polymer.
What are some examples of polymers found in cells?
Polysaccharides (cellulose, glycogen, starch), DNA, RNA, and proteins are examples of polymers found in cells
What are the most common polysaccharides?
The most common polysaccharides are plant starches, glycogen, chitin, and cellulose.
Why do lipids not dissolve in water?
Lipids are generally non-polar because they are made up of hydrocarbon chains or rings, which makes them insoluble in water.
What is cellulose, and why is it important?
Cellulose is the main component of plant cell walls and the most abundant organic molecule on Earth. It provides strength to cell walls through numerous hydrogen bonds.
What gives cellulose fibres their great strength?
The long, straight cellulose molecules have many polar -OH groups, which allow them to form hundreds or thousands of hydrogen bonds side by side, giving the fibres their strength.
How do paper towels, made of cellulose, absorb water but not dissolve in it?
Paper towels are made of cellulose, a long fibrous polysaccharide, which attracts water but does not dissolve due to its large size.
How does the insolubility of lipids in water benefit cells?
Their insolubility in water helps cells by forming membranes, protecting the cell, separating different areas, and storing energy in the form of triglycerides without dissolving or interfering with cellular processes
Why are polysaccharides very hydrophilic but not soluble in water?
Polysaccharides are very polar and attract water, but because they are such large and complex molecules, they cannot dissolve in water.
What are some other functions of lipids?
Lipids serve as energy sources, hormones that regulate cellular activities, and vitamins.
What are the five main categories of lipids?
The five main categories of lipids are fatty acids, fats, phospholipids, steroids, and waxes.
What is a lipid?
Lipids are a general term for non-polar biological molecules composed mostly of hydrogen, carbon, and lesser amounts of oxygen.
What is the structural backbone of most lipids derived from?
Fatty acids
What is the basic structure of a fatty acid?
A fatty acid consists of a single hydrocarbon chain with a carboxyl functional group (-COOH) at one end.
What gives fatty acids their acidic properties?
The carboxyl group (-COOH) gives fatty acids their acidic properties by releasing a hydrogen ion in solution, making the molecule act as an acid by increasing the concentration of hydrogen ions
How many carbons are typically found in fatty acids?
Fatty acids usually have hydrocarbon chains with 4 or more carbons, and common ones have even numbers of 14 to 22 carbons.
How does chain length affect the water solubility of fatty acids?
As the chain length increases, fatty acids become progressively less water-soluble.
What is an unsaturated fatty acid?
An unsaturated fatty acid has one or more double bonds between carbons, which means it has fewer hydrogen atoms.
What is the difference between monounsaturated and polyunsaturated fatty acids?
Monounsaturated fatty acids have one double bond in the hydrocarbon chain, while polyunsaturated fatty acids have more than one double bond in the hydrocarbon chain
What is a saturated fatty acid?
A saturated fatty acid has only single bond between carbons and holds the most hydrogen atoms possible.
How does the presence of a double bond affect the structure of an unsaturated fatty acid?
The presence of a double bond creates a kink in the molecule, causing it to bend.
What is a fat composed of?
One glycerol molecule and one to three fatty acid chains.
What is a triglyceride?
A triglyceride is a type of fat with three fatty acid chains attached to a glycerol molecule.
What distinguishes saturated fats from unsaturated fats?
Saturated fats have no double bonds between carbon atoms and are usually solid at room temperature, while unsaturated fats have one or more double bonds and are generally liquid at room temperature.
Why are unsaturated fats usually liquid and saturated fats solid?
Unsaturated fats have kinks in their chains due to double bonds, preventing tight packing, so they remain liquid. Saturated fats have straight chains that pack tightly, making them solid.
How do lipids compare to carbohydrates in terms of energy storage?
Lipids provide more than twice as much energy storage compared to carbohydrates, making them an efficient energy source.
Why is it beneficial to consume unsaturated fats?
Unsaturated fats, found in plant oils and fish, are generally healthier than saturated fats and can improve heart health.
Most common oligosaccharides
Raffinose, gentianose, maltotriose
Starch is a polysaccharide that serves as a storage form of energy in plants. What are two types of starch?
Amylose and amylopectin, made entirely up of glucose
The free end of the polysaccharide is called a…
Reducing end
What are phospholipids, and why are they important?
Phospholipids are essential lipids in cell membranes, with a glycerol backbone, two fatty acids, and a phosphate group. They are critical for cell membrane structure.
How are phospholipids structured?
Phospholipids have a glycerol backbone with two fatty acid chains (hydrophobic tails) and a phosphate group (hydrophilic head).
What does “amphipathic” mean in relation to phospholipids?
Amphipathic means that phospholipids have both hydrophobic (non-polar) and hydrophilic (polar) regions.
How do phospholipids arrange themselves in cell membranes?
In cell membranes, phospholipids form a bilayer with hydrophilic heads facing outward toward water and hydrophobic tails facing inward.
What is an example of a phospholipid?
Lipid bilayer is an example of a phospholipid.
What is the basic structure of steroids?
Steroids have a structure based on four fused carbon rings.
What distinguishes different steroids from one another?
Small differences in the side groups attached to the carbon rings distinguish one steroid from another.
What are sterols, and what are their properties?
Sterols are a type of steroid with a single polar –OH (hydroxyl) group at one end and a non-polar hydrocarbon chain at the other. They have dual solubility properties.
How can excessive cholesterol affect health?
High cholesterol levels and a diet rich in saturated fats can lead to atherosclerosis, the buildup of fat and cholesterol on artery walls, which clog arteries and can result in heart attacks.
What are waxes made of?
Waxes are large lipid molecules composed of long fatty acid chains linked to alcohols or carbon rings.
What are anabolic steroids and their effects?
Anabolic steroids mimic testosterone and are used to build muscle mass. They are banned in sports due to harmful effects like high blood pressure, depression, and growth issues in young people.
What are the characteristics of waxes?
Waxes are hydrophobic, non-polar, and soft solids over a wide range of temperatures.
What are some functions of waxes in nature?
Waxes provide waterproof coatings, such as cutin on plants to conserve water and protect against infections, and beeswax used in honeycombs.
Why are steroids important, even though they tend to have a bad reputation?
Because they serve essential functions in the body. Cholesterol is a steroid, which is important for the structure and fluidity of cell membranes. It helps make important compounds like vitamin D, bile acids, and hormones like testosterone and estrogen.
Distinguish between a fatty acid and fat (triglyceride)
A fatty acid is a long hydrocarbon chain with a carboxyl group at one end. A fat (triglyceride) is made up of 3 fatty acids and 1 glycerol with an Ester bond
What is an ester bond?
An ester bond is a chemical link between a carboxyl group (–COOH) and a hydroxyl group (–OH) that forms when a fatty acid and glycerol combine.
List the 7 lipid functions
- Digestion (aids in digestion and absorption of nutrients)
- Insulation (provides thermal insulation to maintain body temperature)
- Food Storage (serves as a long-term energy storage in fat)
- Chemical Signaling (acts as hormones and signaling molecules)
- Structural (contributes to cell membrane structure)
- Fat-Soluble Vitamins (helps in absorption and regulation of vitamins A, D, E, K)
- Protective Coating (creates a waterproof barrier to repel water)
What is cholesterol?
A type of lipid and steroid that is essential for cell membranes. It maintains membrane fluidity in extreme conditions, helps produce vitamins and bile, and is involved in making sex hormones like testosterone and estrogen.
What are anabolic steroids?
Synthetic drugs that mimic male sex hormones to increase/build muscle mass. Used by cancer/AIDS patients but is abused by others.
What are steroids used as?
Used as drugs to reduce inflammation (ex. asthma)
What is the basic structure of steroids?
Lipids with four carbon ring framework.
What are waxes?
Waxes are lipids containing long-chain fatty acids that are linked to alcohols or carbon rings. They are solid and firm at room temperature, providing protective coatings for plants and animals.
What is cutin?
Cutin is a type of wax produced by the epidermal cells of plants. It forms a water-resistant coating on leaves, fruits, and stems, helping plants resist disease and conserve water.
Provide the function of fat, as well as an example
Energy storage and insulation; an example is butter and olive oil
Where are triglycerides (fats) stored?
Triglycerides are carried in the blood and stored in adipose (fat) tissues
What are ketoacids and how are they used for energy?
Ketoacids are compounds created by the liver from fatty acids when blood sugar levels are low. They can be used as an alternative energy source by the body, especially when glucose/blood sugar levels are low.
Difference between saturated and unsaturated fats?
Unsaturated fats have double bonds between carbons
Saturated fats have single bonds between carbons
