Week 2 Biological Macromolecules Quiz
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Questions and Answers

What type of structure do phospholipids form in biological membranes?

  • Bilayers (correct)
  • Vesicles
  • Micelles
  • Monolayers

    • Which of the following compounds are classified as eicosanoids?

  • Testosterone
  • Prostaglandins (correct)
  • Arachidonic acid
  • Cholesterol

    • What is the parent steroid from which other steroids are synthesized?

  • Estrogen
  • Cholesterol (correct)
  • Aldosterone
  • Cortisol

    • Which statement is true regarding the nature of phospholipids?

    <p>Phospholipids are amphipathic with both hydrophilic and hydrophobic properties.</p> Signup and view all the answers

    What role do eicosanoids typically play in physiological processes?

    <p>Act on cells close to their site of production.</p> Signup and view all the answers

    Which of the following describes essential fatty acids?

    <p>They must be obtained from the diet.</p> Signup and view all the answers

    What is the main structural difference between saturated and unsaturated fats?

    <p>Unsaturated fats have double bonds in their chains.</p> Signup and view all the answers

    What is a potential health risk of a diet high in saturated fats?

    <p>Increased risk of cardiovascular disease.</p> Signup and view all the answers

    Which type of fat is typically solid at room temperature?

    <p>Saturated fat.</p> Signup and view all the answers

    What is produced during the hydrogenation process of unsaturated fats?

    <p>Both saturated and trans unsaturated fats.</p> Signup and view all the answers

    Which of the following statements about triglycerides is correct?

    <p>They consist of three fatty acids and one glycerol molecule.</p> Signup and view all the answers

    In which configuration do double bonds usually exist in unsaturated fats?

    <p>Cis configuration.</p> Signup and view all the answers

    What is a common characteristic of fats derived from plants?

    <p>They are usually unsaturated fats.</p> Signup and view all the answers

    What distinguishes proteins from other macromolecules?

    <p>They are polymers of amino acids.</p> Signup and view all the answers

    What is the primary component that all amino acids share?

    <p>A carboxyl group (−COOH).</p> Signup and view all the answers

    Which combination correctly identifies the four major classes of biological macromolecules?

    <p>Carbohydrates, lipids, proteins, nucleic acids.</p> Signup and view all the answers

    What type of bond links amino acids together to form proteins?

    <p>Peptide bonds.</p> Signup and view all the answers

    Which characteristic is NOT true for carbohydrates?

    <p>They provide genetic information.</p> Signup and view all the answers

    What is the general formula for carbohydrates?

    <p>(CH2O)n</p> Signup and view all the answers

    Which of the following is an example of a structural polysaccharide?

    <p>Cellulose.</p> Signup and view all the answers

    Which type of lipid is primarily used for energy storage in the body?

    <p>Triglycerides.</p> Signup and view all the answers

    What best describes the primary structure of proteins?

    <p>The sequence of amino acids in a chain.</p> Signup and view all the answers

    How are amino acids categorized based on their R groups?

    <p>By their charge and polarity.</p> Signup and view all the answers

    Which of the following statements about lipids is correct?

    <p>They can function as both energy storage and heat insulation.</p> Signup and view all the answers

    What role do disulfide bridges play in protein structure?

    <p>They maintain the tertiary structure.</p> Signup and view all the answers

    Which of the following is a characteristic of nucleic acids?

    <p>They store and transmit genetic information.</p> Signup and view all the answers

    In which level of protein structure do α-helices and β-sheets occur?

    <p>Secondary structure.</p> Signup and view all the answers

    Which lipoprotein is commonly referred to as 'bad cholesterol' due to its association with cardiovascular disease?

    <p>Low-density lipoprotein (LDL)</p> Signup and view all the answers

    What is the primary source of cholesterol in the human body?

    <p>Internal synthesis by the liver</p> Signup and view all the answers

    Which of the following nitrogenous bases is present in RNA but not in DNA?

    <p>Uracil (U)</p> Signup and view all the answers

    Which of the following accurately describes the structure of DNA?

    <p>Double-stranded helix</p> Signup and view all the answers

    What type of bond links nucleotides together in a polynucleotide chain?

    <p>Phosphodiester bond</p> Signup and view all the answers

    Which type of RNA is responsible for carrying the genetic information from DNA to the ribosomes for protein synthesis?

    <p>Messenger RNA (mRNA)</p> Signup and view all the answers

    Which family of nitrogenous bases includes adenine and guanine?

    <p>Purines</p> Signup and view all the answers

    What components make up a nucleotide?

    <p>Nitrogenous base, pentose sugar, and phosphate group</p> Signup and view all the answers

    Which of the following types of RNA matches the correct function?

    <p>rRNA - forms the core of ribosomes</p> Signup and view all the answers

    In terms of energy storage, which macromolecule stores the most energy in the human body?

    <p>Fats</p> Signup and view all the answers

    Which process occurs when two monosaccharides bond together through the loss of a water molecule?

    <p>Dehydration synthesis</p> Signup and view all the answers

    Which of the following statements about RNA is incorrect?

    <p>RNA includes thymine as a nitrogenous base</p> Signup and view all the answers

    Which of the following describes the 'pairing rule' in nucleic acids?

    <p>A pairs with T, C pairs with G</p> Signup and view all the answers

    What are the main differences between LDL and HDL in relation to cardiovascular health?

    <p>LDL, or low-density lipoprotein, is considered 'bad' cholesterol as it contributes to cardiovascular disease, whereas HDL, or high-density lipoprotein, is viewed as 'good' cholesterol as it helps to prevent such diseases.</p> Signup and view all the answers

    Describe the structure and function of DNA in cells.

    <p>DNA is a double-helical structure composed of nucleotides that serves as the genetic repository for organisms and directs the synthesis of messenger RNA for protein synthesis.</p> Signup and view all the answers

    What role do nitrogenous bases play in the structure of nucleic acids?

    <p>Nitrogenous bases pair up according to specific rules (A with T and C with G in DNA, A with U in RNA), enabling the formation of the genetic code that determines an organism's traits.</p> Signup and view all the answers

    Explain the process of dehydration synthesis in the context of macromolecule formation.

    <p>Dehydration synthesis occurs when two monomers bond together through the removal of a water molecule, forming polymers such as carbohydrates, proteins, and nucleic acids.</p> Signup and view all the answers

    What are the three main types of RNA, and what is the primary function of each?

    <p>The three types of RNA are messenger RNA (mRNA), which carries genetic information from DNA; ribosomal RNA (rRNA), which forms the core of ribosomes; and transfer RNA (tRNA), which brings amino acids to the ribosome for protein synthesis.</p> Signup and view all the answers

    What is the main process by which unsaturated fats are converted to saturated fats?

    <p>Hydrogenation.</p> Signup and view all the answers

    What is required in the diet because the human body cannot synthesize it?

    <p>Essential fatty acids.</p> Signup and view all the answers

    What are triglycerides composed of?

    <p>Glycerol and three fatty acids.</p> Signup and view all the answers

    What type of fats are primarily liquid at room temperature?

    <p>Unsaturated fats.</p> Signup and view all the answers

    Which type of fatty acids are most animal fats classified as?

    <p>Saturated fatty acids.</p> Signup and view all the answers

    What configuration do double bonds in unsaturated fats usually have?

    <p>Cis configuration.</p> Signup and view all the answers

    What health risk is associated with a diet high in saturated fats?

    <p>Cardiovascular disease.</p> Signup and view all the answers

    What distinguishes saturated fats from unsaturated fats?

    <p>Saturated fats have no double bonds; unsaturated fats have one or more double bonds.</p> Signup and view all the answers

    How many carbon atoms typically make up fatty acids?

    <p>Usually 4 to 24 carbon atoms.</p> Signup and view all the answers

    What byproduct can result from the hydrogenation process?

    <p>Trans unsaturated fats.</p> Signup and view all the answers

    What are the four major classes of biological macromolecules?

    <p>Carbohydrates, lipids, proteins, and nucleic acids.</p> Signup and view all the answers

    How are amino acids linked together to form proteins?

    <p>Amino acids are linked by peptide bonds, formed between the carboxyl group of one amino acid and the amino group of another.</p> Signup and view all the answers

    What characterizes the primary structure of a protein?

    <p>The primary structure is a linear sequence of amino acids linked by covalent bonds.</p> Signup and view all the answers

    What is the main function of carbohydrates in living organisms?

    <p>Carbohydrates serve as a source of energy and play roles in structural integrity and cellular communication.</p> Signup and view all the answers

    What is the role of R groups in amino acids?

    <p>R groups determine the properties and classification of amino acids, influencing protein structure and function.</p> Signup and view all the answers

    Describe the quaternary structure of proteins.

    <p>The quaternary structure refers to the spatial arrangement of multiple polypeptide chains forming a multi-subunit complex.</p> Signup and view all the answers

    How do lipids differ from carbohydrates in terms of energy storage?

    <p>Lipids provide more calories per gram than carbohydrates and are less oxidized, making them more efficient energy storage molecules.</p> Signup and view all the answers

    What distinguishes monosaccharides from polysaccharides?

    <p>Monosaccharides are simple sugars that cannot be broken down further, whereas polysaccharides are long chains of monosaccharides.</p> Signup and view all the answers

    What structural feature distinguishes phospholipids from other lipids?

    <p>Phospholipids have a hydrophilic head and two hydrophobic fatty acid tails, making them amphipathic.</p> Signup and view all the answers

    Describe the origin and significance of eicosanoids in the body.

    <p>Eicosanoids are derived from C20 polyunsaturated fatty acids like arachidonic acid and are important for local cell signaling.</p> Signup and view all the answers

    What is the general backbone structure of steroids?

    <p>Steroids possess a structure with 17 carbon atoms arranged in four fused rings.</p> Signup and view all the answers

    How do phospholipids contribute to the function of biological membranes?

    <p>Phospholipids form bilayers that create a barrier and enable the fluidity of cell membranes.</p> Signup and view all the answers

    What physiological roles do prostaglandins, a type of eicosanoid, play in the body?

    <p>Prostaglandins are involved in processes like inflammation, pain signaling, and regulation of blood flow.</p> Signup and view all the answers

    Identify one crucial function of cholesterol in the body.

    <p>Cholesterol is vital for maintaining the integrity and fluidity of cell membranes.</p> Signup and view all the answers

    What distinguishes eicosanoids from other lipid molecules in terms of their action?

    <p>Eicosanoids act on cells close to their production site and are rapidly degraded.</p> Signup and view all the answers

    Discuss the relationship between steroids and hormones.

    <p>Many steroid molecules function as hormones, regulating diverse physiological processes in the body.</p> Signup and view all the answers

    Explain the significance of amphipathic properties in phospholipids.

    <p>The amphipathic nature allows phospholipids to form bilayers, crucial for creating functional cell membranes.</p> Signup and view all the answers

    What type of fatty acid is eicosanoids primarily derived from?

    <p>Eicosanoids are primarily derived from C20 polyunsaturated fatty acids.</p> Signup and view all the answers

    Study Notes

    Biological Macromolecules

    • All living organisms are made up of cells, which contain atoms and biomolecules.
    • The most prevalent atoms in the human body are oxygen, carbon, hydrogen, and nitrogen.
    • Biomolecules with large molecular weights are called macromolecules.
    • There are four main classes of macromolecules: carbohydrates, lipids, proteins, and nucleic acids.

    Building Blocks of Macromolecules

    • Macromolecules are polymers formed from smaller building blocks called monomers.
    • Carbohydrates are made from monosaccharides (simple sugars).
    • Lipids are assembled from fatty acids and glycerol.
    • Proteins are constructed from amino acids.
    • Nucleic acids are polymers of nucleotides.

    Big 4 Macromolecules - (1) Proteins

    • Proteins are polymers of amino acids linked together by peptide bonds.
    • Amino acids are the building blocks of proteins.
    • Each amino acid has a primary amine group (-NH2), a carboxyl group (-COOH), a hydrogen atom (-H), and a variable R group (or side chain) attached to a central carbon atom (alpha carbon).

    Amino Acids

    • The R group differentiates amino acids based on its characteristics: non-polar, polar, acidic, and basic.
    • Amino acids can be further categorized as essential or non-essential based on whether the human body can synthesize them.

    Peptides

    • Short chains of amino acids are called peptides.
    • Dipeptide: 2 amino acids
    • Tripeptide: 3 amino acids
    • Oligopeptide: a few amino acids
    • Polypeptide: many amino acids
    • Protein: > 40 amino acids

    Protein Structure

    • Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
    • Primary structure: the linear sequence of amino acids.
    • Secondary structure: the arrangement of adjacent amino acids in a coiled manner, forming alpha-helixes and beta-sheets.
    • Tertiary structure: the three-dimensional arrangement of all amino acids in a folded single polypeptide chain.
    • Quaternary structure: the spatial relationship among different polypeptide chains within a protein with multiple subunits.

    Protein Conformation

    • Proteins fold into specific three-dimensional shapes called conformations.
    • Functional, folded proteins are called "native" conformations.
    • Conformation is determined by the amino acid sequence.

    Intermolecular Forces in Proteins

    • Various forces stabilize protein structures:
      • Hydrogen bonds
      • Hydrophobic interactions
      • Ionic or electrostatic bonds
      • Disulfide bridges

    Biological Functions of Proteins

    • Proteins perform numerous biological functions:
      • Enzymatic catalysis
      • Transport and storage
      • Mechanical functions
      • Movement
      • Protection
      • Information processing

    Big 4 Macromolecules - (2) Carbohydrates

    • Carbohydrates are composed of carbon, hydrogen, and oxygen atoms in a ratio of 1:2:1, or with the general formula (CH2O)n.
    • They are a source of energy and can be quickly mobilized.
    • Carbohydrates are synthesized by photosynthesis in plants.

    Classification of Carbohydrates

    • Carbohydrates are classified based on their structure:
      • Monosaccharides: simple sugars that cannot be broken down further (e.g., glucose, galactose, fructose).
      • Disaccharides: two monosaccharides linked by glycosidic bonds (e.g., maltose, lactose, sucrose).
      • Oligosaccharides: 3 to 10 monosaccharides linked by glycosidic bonds.
      • Polysaccharides: polymers of monosaccharides (e.g., starch, cellulose, glycogen).

    Monosaccharides

    • Glucose is a key monosaccharide:
      • Building block for di- and poly-saccharides.
      • Known as blood sugar in the human body.
      • Normal blood glucose level: 70-99 mg per 100 mL blood (mg/dL).

    Polysaccharides

    • Three important polysaccharides for humans:
      • Glycogen: energy-storage polysaccharide produced by the liver, muscles, brain, uterus, and vagina.
      • Starch: energy-storage polysaccharide found in plants.
      • Cellulose: structural polysaccharide providing strength to plant cell walls, not digestible by humans.

    Biological Functions of Carbohydrates

    • Carbohydrates have multiple roles:
      • Energy stores
      • Fuels
      • Metabolic intermediates
      • Structural elements of DNA, RNA, and cells

    Big 4 Macromolecules - (3) Lipids

    • Lipids are mainly composed of carbon, hydrogen, and oxygen with hydrocarbon chains.
    • They are insoluble in water due to their hydrophobic nature.
    • Lipids are essential for energy storage, heat insulation, and other functions.

    Classification of Lipids

    • Five main types of lipids in humans:
      • Fatty acids: chains of carbon atoms with a carboxyl group at one end and a methyl group at the other. Can be saturated or unsaturated.
      • Triglycerides: commonly known as "fats," composed of glycerol and three fatty acids (can be saturated or unsaturated).
      • Phospholipids: contain two fatty acids and a phosphate group attached to glycerol. Form the basis of cell membranes.
      • Eicosanoids: derived from C20 polyunsaturated fatty acids (e.g., arachidonic acid). Function as physiologically and pharmacologically active compounds.
      • Steroids: lipids with a characteristic 4-ring structure. Cholesterol is a key steroid involved in cell membranes and nervous system function. Other steroids include hormones and bile acids.

    Cholesterol

    • Lipoproteins are droplets in the blood that are a complex of cholesterol, fat, phospholipids and protein
    • Bad cholesterol is low-density lipoprotein (LDL), which has a high ratio of lipid to protein and contributes to cardiovascular disease
    • Good cholesterol is high-density lipoprotein (HDL), which has a lower ratio of lipid to protein and may help to prevent cardiovascular disease
    • Only ~15% of cholesterol comes from the diet, the other 85% is internally synthesized, primarily by the liver

    Nucleic Acids

    • Nucleic acids are polymers of nucleotides, i.e., polynucleotides
    • Each nucleotide consists of a nitrogenous base, a pentose sugar (i.e., a monosaccharide) and a phosphate group
    • The portion of a nucleotide without the phosphate group is called a nucleoside

    The Two Common Nucleic Acids

    • deoxyribonucleic acid (DNA) contains a 2'-deoxyribose
    • ribonucleic acid (RNA) contains a ribose
    • DNA is the repository of our genes
    • DNA directs the synthesis of messenger RNA (mRNA), which controls protein synthesis

    Nitrogenous Bases

    • Two families of nitrogenous bases: Purines (adenine and guanine) have double rings and pyrimidines (cytosine, thymine and uracil) have single rings.
    • In DNA, we have A T C G
    • In RNA, we have A U C G
    • Pairing rule: A pairs with T ; C pairs with G

    Polynucleotides

    • Nucleic acids are polynucleotides
    • Linear polymers of nucleotides formed as 5'-nucleoside monophosphates are successively added to the 3'-OH group of the preceding nucleotide
    • The sequence of bases along a nucleotide polymer is unique for each gene
    • Polynucleotides are made up of nucleotides linked by the –OH group on the 3´carbon of one nucleotide and the phosphate on the 5´carbon on the next, which is known as a phosphodiester bond
    • Two polynucleotides that spiral around an imaginary axis and form a double helix
    • DNA serve as a storage materials for genetic information in all living cells, i.e., genes

    RNA

    • Smaller cousins of DNA
    • Consist of one nucleotide chain instead of double helix which means it is a single strand
    • Interpret the code in DNA and use those instructions to synthesize proteins
    • Three types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA)
    • RNA contains uracil (U)

    Further Info of the Big 4 Macromolecules

    • Fats store the most energy - ~80% of the energy in the human body and ~146 ATP from a triglyceride
    • Proteins are less likely to be broken down to make ATP

    Macromolecules

    • Polymers of monosaccharides  carbohydrates
    • Polymers of amino acids  proteins
    • Polymers of nucleotides  nucleic acids
    • Dehydration synthesis occurs when 2 monomers bond together through the loss of a water molecule
    • A hydrolysis reaction occurs when a polymer dissembles into monomers, and it is the reverse of the dehydration synthesis

    Biological Macromolecules

    • Living organisms, including humans, are composed of cells.
    • Cells consist of atoms and biomolecules in varying proportions.
    • The most abundant atoms in the human body are oxygen, carbon, hydrogen, and nitrogen.
    • Molecules are formed when atoms combine.
    • Macromolecules are large biomolecules with substantial molecular weight.
    • The four major classes of macromolecules are carbohydrates, lipids, proteins, and nucleic acids.

    Building Blocks of Macromolecules

    • Macromolecules are polymers composed of smaller building blocks called monomers.
    • Monomers for each macromolecule class are:
      • Carbohydrates: Monosaccharides
      • Lipids: Fatty acids and glycerol
      • Proteins: Amino acids
      • Nucleic acids: Nucleotides

    Big 4 Macromolecules - (1) Proteins

    • Proteins are polymers of amino acids.
    • Amino acids are the building blocks of proteins and contain:
      • A primary amine group (-NH2)
      • A carboxyl group (-COOH)
      • A hydrogen atom (-H)
      • A variable R group (side chain)
    • All components of an amino acid are linked covalently to a central carbon atom called the alpha carbon (Cα).

    Amino Acids (cont’d)

    • The R group of amino acids can be hydrocarbons or other functional groups like -OH, -COOH, and -NH2.
    • Additional carbons in the R side chain are designated as β, γ, δ, and ε.
    • Amino acids are categorized into four groups based on R group characteristics:
      • Non-polar
      • Polar
      • Acidic (negatively charged)
      • Basic (positively charged)

    Peptides

    • Peptides and proteins are formed when amino acids are joined by amide bonds (peptide bonds).
    • The carboxyl group of one amino acid links to the amino group of another.
    • A chain of linked amino acids forms a polypeptide chain.
    • Peptides are short polymers of amino acids, classified by length:
      • Dipeptide (2 amino acids)
      • Tripeptide (3 amino acids)
      • Oligopeptide (a few amino acids)
      • Polypeptides (many amino acids)
      • Proteins (> 40 amino acids)

    Protein Structure

    • Proteins have complex structures, often visualized using ribbon and space-filling models.
    • The polypeptide chain folds into a specific shape known as conformation.
    • Functional, folded proteins are called "native" conformations.
    • Conformation is determined by the amino acid sequence.
    • Proteins have four levels of structure:
      • Primary
      • Secondary
      • Tertiary
      • Quaternary

    The FOUR Levels of Protein Structure

    • Primary structure is a linear sequence of amino acids linked by covalent bonds (amide bonds).
    • Secondary structure involves the arrangement of adjacent amino acids in a coiled manner, such as α-helix and β-sheets, primarily stabilized by hydrogen bonds.
    • Tertiary structure is the three-dimensional arrangement of all amino acids in a folded single polypeptide chain, stabilized by hydrogen bonds, hydrophobic interactions, ionic bonds, and disulfide bridges.
    • Quaternary structure describes the spatial relationship among different polypeptide chains, forming assembled subunits.

    Intermolecular Forces in Proteins

    • Proteins are stabilized by various intermolecular forces:
      • Hydrogen bonds
      • Hydrophobic interactions
      • Ionic (electrostatic) bonds
      • Disulfide bridges

    Biological Functions of Proteins

    • Proteins perform a wide range of biological functions:
      • Enzymatic catalysis
      • Transport and storage
      • Mechanical functions
      • Movement
      • Protection
      • Information processing

    Big 4 Macromolecules - (2) Carbohydrates

    • Carbohydrates are compounds composed of carbon (C), hydrogen (H), and oxygen (O) with a general formula of (CH2O)n, where n is the number of carbon atoms.
    • For example, glucose has the formula C6H12O6.
    • Carbohydrates do not contain genetic information.
    • A source of readily accessible energy.
    • Also known as sugars due to their sweet taste.
    • Synthesized by plants through photosynthesis.

    Classification of Carbohydrates

    • Carbohydrates are classified based on their structure:
      • Monosaccharides (simple sugars) – cannot be broken down further, e.g., Glucose, Galactose, Fructose
      • Disaccharides – two monosaccharides linked by glycosidic bonds, e.g., Maltose, Lactose, Sucrose
      • Oligosaccharides – 3 to 10 monosaccharides linked by glycosidic bonds
      • Polysaccharides – polymers of monosaccharides, e.g., Starch, Cellulose, Glycogen

    Monosaccharides

    • Glucose is a prominent monosaccharide:
      • Building block for di- and poly-saccharides
      • Known as blood sugar
      • Main simple carbohydrate in human metabolism

    Polysaccharides

    • The three significant polysaccharides for humans are glycogen, starch, and cellulose:
      • Glycogen is the energy storage polysaccharide in animals, produced by cells in the liver, muscles, brain, uterus, and vagina.
      • Starch is the energy storage polysaccharide in plants, a digestible polysaccharide in the human diet.
      • Cellulose is a structural polysaccharide that provides strength to plant cell walls, but humans lack the enzymes to digest it.

    Biological Functions of Carbohydrates

    • Carbohydrates serve as:
      • Energy stores
      • Fuels
      • Metabolic intermediates
      • Structural elements in DNA, RNA, and cells

    Big 4 Macromolecules - (3) Lipids

    • Mostly composed of carbon, hydrogen, and oxygen atoms, mainly of hydrocarbon chains.
    • Insoluble in water due to nonpolar covalent bonds (hydrophobic molecules).
    • Do not contain genetic information.
    • Used for energy storage and heat insulation.
    • Have more calories per gram than carbohydrates due to less oxidation.
    • Five main types of lipids in humans:
      • Fatty acids
      • Triglycerides
      • Phospholipids
      • Eicosanoids
      • Steroids

    i. Fatty Acids

    • Fatty acids are chains of carbon atoms (usually 4 to 24), with a carboxyl group at one end and a methyl group at the other.
    • Can be saturated or unsaturated.
    • Most fatty acids can be synthesized by the human body, but some (essential fatty acids) must be obtained from the diet. 

    ii. Triglycerides

    • Commonly known as "fats". 
    • Composed of glycerol and three fatty acids. 
    • Fats can be solid or liquid at room temperature:
      • Most animal fats are saturated, making them solid at room temperature. 
      • Plant fats and fish fats are typically unsaturated, making them liquid at room temperature. 
    • A diet high in saturated fats can contribute to cardiovascular disease through plaque deposits.
    • Hydrogenation converts unsaturated fats (cis) to saturated fats by adding hydrogen, but can produce trans unsaturated fats. 

    iii. Phospholipids

    • One glycerol molecule is attached to two fatty acids and one phosphate group. 
    • Fatty acid tails are hydrophobic, while the phosphate group and its attachments form a hydrophilic head (amphipathic).
    • Important components of biological membranes, including cell membranes. 

    iv. Eicosanoids

    • Derived from C20 polyunsaturated fatty acids, such as arachidonic acid.
    • Examples include prostaglandins, thromboxane, and leukotrienes.
    • Active compounds with physiological and pharmacological effects.
    • Act locally and are rapidly degraded.

    v. Steroids

    • Lipids with 17 carbon atoms arranged in four rings. 
    • Cholesterol is the precursor for other steroids:
      • Important component of animal cell membranes. 
      • Essential for proper nervous system function.
    • Other steroids include cortisol, aldosterone, progesterone, estrogens, testosterones, and bile acids.

    Cholesterol

    • Cholesterol is a lipid found in cell membranes
    • It's also used to synthesize steroid hormones
    • "Good cholesterol" (HDL) has a lower ratio of lipid to protein and may help prevent cardiovascular disease
    • "Bad cholesterol" (LDL) has a high ratio of lipid to protein and contributes to cardiovascular disease
    • Only 15% of cholesterol comes from the diet, the remaining 85% is synthesized internally, primarily by the liver

    Nucleic Acids

    • Nucleic acids are polymers of nucleotides
    • Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group
    • The portion of a nucleotide without the phosphate group is called a nucleoside

    DNA and RNA

    • Deoxyribonucleic acid (DNA) contains a 2'-deoxyribose
    • Ribonucleic acid (RNA) contains a ribose
    • DNA is the repository of genes
    • DNA directs the synthesis of messenger RNA (mRNA), which controls protein synthesis

    Nitrogenous Bases

    • Two families of nitrogenous bases: purines and pyrimidines
    • Purines (adenine and guanine) have double rings
    • Pyrimidines (cytosine, thymine, and uracil) have single rings
    • DNA contains A, T, C, and G
    • RNA contains A, U, C, and G
    • Pairing rule: A pairs with T; C pairs with G

    Polynucleotides

    • Nucleic acids are polynucleotides, linear polymers of nucleotides
    • The sequence of bases along a nucleotide polymer is unique for each gene
    • Polynucleotides are made up of nucleotides linked by the –OH group on the 3' carbon of one nucleotide and the phosphate on the 5' carbon of the next - this is called a phosphodiester bond
    • Two polynucleotides that spiral around an imaginary axis to form a double helix - DNA serves as a storage material for genetic information in all living cells (genes)

    RNA

    • RNA is smaller than DNA
    • It consists of a single nucleotide chain - not a double helix
    • RNA interprets the code in DNA and uses those instructions to synthesize proteins
    • Three types of RNA: mRNA, rRNA, and tRNA
    • RNA contains uracil (U)

    Macromolecules

    • Fats store the most energy (~80% of the energy in the human body)
    • Proteins are less likely to be broken down to make ATP
    • Polymers of monosaccharides  carbohydrates
    • Polymers of amino acids  proteins
    • Polymers of nucleotides  nucleic acids

    Synthesis and Breakdown of Macromolecules

    • Synthesis (Dehydration): two monomers bond together through the loss of a water molecule
    • Breakdown (Hydrolysis): a polymer breaks down into monomers, the reverse of dehydration synthesis

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    Med1003 Week 2 Lecture PDF

    Description

    Test your knowledge on biological macromolecules, their building blocks, and the four main classes: carbohydrates, lipids, proteins, and nucleic acids. This quiz explores the structure and function of these essential biomolecules in living organisms.

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