Water Flashcards
What kind of bonds does water form between its molecules? What does this do? 3 points about this type of bond?
Water forms hydrogen bonds. These weak attractions stabilize structures, form between molecules, and maintain biological functions.
Why does the attraction in hydrogen bonds occur? Meaning? How is this shown?
Hydrogen bonds occur due to water’s polarity—oxygen is δ–, hydrogen is δ+. These partial charges attract molecules together.
Why is water a liquid between 0 and 100 degrees? How does this work?
Hydrogen bonds cause cohesion, holding water molecules together. Evaporation requires breaking hydrogen bonds (energy-intensive). Below 0°C, molecules form a rigid lattice (ice).
What are the eight properties of water that are important for living things? How do each work?
Thermal stability, freezing (ice floats), evaporation (cools), liquid state (transport), cohesion (surface tension, xylem transport), solvent properties, reactant (photosynthesis, hydrolysis), incompressibility (pressure systems).
What are polymers? Comprising of? What are the three biologically important polymers?
Polymers are long chains of monomers. Three important types: nucleic acids, polysaccharides, and proteins.
What are the monomers of nucleic acids? What are these made up of? How many types are there? Names?
Nucleotides are the monomers of nucleic acids. They consist of a pentose sugar (ribose/deoxyribose), phosphate group, and nucleotide base (A, C, G, T, U).
Two examples of complex carbohydrate polysaccharides? What are the monomers of proteins? How many types are there? What can you do to diversify protein structures?
Polysaccharides: Starch and cellulose. Protein monomers: Amino acids (20 types). Amino acid sequence variations provide protein diversity.
What do carbohydrates consist of? What is their general formula? Which three main groups can carbohydrates be divided into?
Carbohydrates consist of carbon, oxygen, and hydrogen. The general formula for a carbohydrate is (CH2O)x. Carbohydrates can be divided into three main groups: monosaccharides, disaccharides, and polysaccharides.
What are monosaccharides? Two properties they possess? What are pentose sugars? Two examples? What are hexose sugars? An example? What are the two forms of this and how do they differ? Why does their difference matter?
Monosaccharides are single sugar units used as monomers to build other carbohydrates. They are soluble and sweet reducing sugars. Pentose sugars contain five carbons, e.g., ribose and deoxyribose. Hexose sugars contain six carbons, e.g., glucose. Glucose has two forms: alpha (α) glucose and beta (β) glucose, differing in the position of the –H and –OH groups on the first carbon atom. This affects the polysaccharides they form.
What are disaccharides? How is this achieved? Two properties that all disaccharides possess? A property that most possess? Which disaccharide doesn’t? How are they formed? The most common way this can happen? Two examples of this reaction? How can disaccharides be converted back?
Disaccharides are two monosaccharides bonded together by a glycosidic bond. They are soluble and sweet. Most are reducing sugars, except sucrose. They are formed by a condensation reaction, usually forming a 1,4 glycosidic bond. Examples: glucose + fructose = sucrose, glucose + glucose = maltose, glucose + galactose = lactose. They can be broken down by hydrolysis.
What are polysaccharides? An example? What is this made of?
Polysaccharides are large insoluble molecules. Starch consists of amylose and amylopectin.
What does amylose consist of? What trait does this lead to? Why? What is amylose used for? In which organism? Why? Why is each trait important?
Amylose is a long unbranched chain of α-glucose subunits with 1,4 glycosidic bonds. The chain coils up, hiding hydroxyl groups inside, making it less soluble. It is used for glucose and energy storage in plants. It is compact and insoluble, so it doesn’t affect water potential. Glucose subunits can be easily accessed.
How are amylopectin and glycogen similar to amylose? How do the two substances differ from amylose? What are amylopectin and glycogen each used for? How do they differ? Which other properties do they have in common with amylose?
Both are long chains of α-glucose with 1,4 glycosidic bonds, but they also have 1,6 glycosidic bonds, making them branched. Amylopectin (plants) has fewer branches than glycogen (animals). Glycogen is more branched, allowing for rapid glucose release. Both are insoluble and compact.
What does cellulose consist of? How are the units joined? What is the chain like? Why can adjacent cellulose molecules bind? How many are in a microfibril? What do many microfibrils form? Two properties of cellulose? What is it used for? Why?
Cellulose is a long unbranched chain of β-glucose with 1,4 glycosidic bonds, forming straight chains. Hydrogen bonds between chains form microfibrils (60–70 molecules), which group into macrofibrils. Cellulose is strong and insoluble, used in plant cell walls for structural support.
Three examples of lipids? One property of lipids?
Triglycerides, phospholipids, steroids. Lipids are insoluble in water.
What is a triglyceride? How is it held together? What are the bonds called? How can they be broken? What are triglyceride molecules used for? How are they thus used? What is released when this happens? Three other functions/advantages of triglycerides?
A triglyceride has one glycerol and three fatty acids. The ester bonds are formed by condensation and broken by hydrolysis. They store energy, release energy and water in aerobic respiration. Other functions: organ protection, insulation, buoyancy.
What are fatty acids? What is a saturated fatty acid? Where are these found? What effect does being saturated have on fatty acid properties? What are unsaturated fatty acids? Where are they found? How does being unsaturated affect their properties?
Fatty acids are carbon chains with hydrogen atoms. Saturated fatty acids have no double bonds, found in animal fats, solid at room temperature. Unsaturated fatty acids have double bonds, found in plant oils, liquid at room temperature.
How do phospholipids differ from triglycerides? How do phospholipids interact with water? What does this allow for? Why is this significant?
Phospholipids have one fatty acid replaced by a phosphate group. Their hydrophobic tails repel water, and hydrophilic heads attract water. They form bilayers, crucial for cell membranes.
How are amino acids similar? What differs? What do all proteins consist of? What are they held together by? How are these formed?
Amino acids share a basic structure but differ in R groups. Proteins are long chains of amino acids joined by peptide bonds via condensation.
What are globular proteins? How do they differ from other proteins? What are they used for? What does this rely on? What is their shape and activity affected by? Therefore?
Globular proteins are folded into a spherical shape, soluble, active in metabolism, and shape-sensitive to temperature. Example: haemoglobin carries oxygen.
An example of a globular enzyme? What does it do? What is its structure like? What is its substrate? Which cofactor does it use? Where is this located?
Amylase hydrolyses amylose. It has alpha-helices, beta-sheets, and an active site holding a calcium ion as a cofactor.
An example of a globular hormone? What is this used for? What does it consist of? Held together by?
Insulin regulates blood glucose, has two polypeptides linked by disulfide bridges.
What are fibrous proteins like structurally? What is their solubility like? A unique feature? Three examples?
Fibrous proteins have repeated sequences, are insoluble, form structural fibres. Examples: collagen, keratin, elastin.
Keratin
Elastin
What are inorganic ions? List examples and their functions.
Examples: NH4+, Ca2+, Cl-, H+, Fe2+, Na+, K+, PO43-. Functions range from enzyme activation to blood pH regulation.
How do you test for proteins, reducing sugars, non-reducing sugars, starch, fat? What does a positive result look like?
Biuret test (proteins: purple), Benedict’s test (reducing sugars: brick red), Iodine test (starch: blue-black), Sudan III (lipids: red layer).
