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Next Toppers - 11th ScienceWhole chapter · Hinglish
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Must-know facts
24 facts
- 01Living and non-living matter contain the same elements; living matter has relatively far more carbon and hydrogen.
- 02Tissue ground in trichloroacetic acid and filtered gives the acid-soluble pool (filtrate) and the acid-insoluble fraction (retentate).
- 03Wet weight, then dry weight after removing water, then ash after burning; ash holds inorganic elements such as calcium and magnesium.
- 04Alpha-amino acids: H, COOH, NH2 and an R group on the alpha carbon; 20 types in proteins; glycine (R = H), alanine (methyl), serine (hydroxy methyl).
- 05Acidic glutamic acid, basic lysine, neutral valine; aromatic tyrosine, phenylalanine, tryptophan; zwitterion depends on pH.
- 06Palmitic acid 16 C, arachidonic acid 20 C; glycerol is trihydroxy propane; lecithin is a membrane phospholipid.
- 07Nucleoside = base + sugar; nucleotide = base + sugar + phosphate.
- 08Adenine and guanine are purines; cytosine, thymine and uracil are pyrimidines.
- 09Acid-soluble pool: 18 to about 800 Da. Macromolecules except lipids: 10,000 Da and above. Micromolecules: under 1000 Da.
- 10Lipids come down in the insoluble fraction as membrane vesicles; they are not strictly macromolecules.
- 11Water is the most abundant chemical in cells (70–90% of cell mass); proteins 10–15%.
- 12Proteins are heteropolymers joined by peptide bonds; cellulose is a homopolymer of glucose; inulin is a polymer of fructose.
- 13Collagen is the most abundant protein in animals; RuBisCO is the most abundant in the biosphere.
- 14Starch helices hold iodine (blue); cellulose cannot. Glycogen is branched, reducing end on the right.
- 15Chitin of arthropod exoskeletons is a complex polysaccharide of amino-sugars.
- 16Four levels of protein structure; only right-handed helices; adult haemoglobin = 2 alpha + 2 beta subunits.
- 17Ribozymes are nucleic acids that act as enzymes.
- 18Most enzymes are damaged above about 40°C; thermophile enzymes stay active up to 80–90°C.
- 19Carbonic anhydrase: about 200 molecules of H2CO3 an hour without it, about 600,000 a second with it (about 10 million times faster).
- 20Enzymes lower activation energy; E + S ⇌ ES → EP → E + P.
- 21Velocity rises with substrate and plateaus at Vmax when all enzyme is occupied.
- 22Malonate competitively inhibits succinic dehydrogenase by resembling succinate.
- 23Six enzyme classes: oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases.
- 24Co-factors: prosthetic group (haem in peroxidase and catalase), co-enzyme (NAD, NADP contain niacin), metal ion (zinc in carboxypeptidase).
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Key terms
23 terms
- Acid-soluble pool
- The filtrate left when tissue ground in trichloroacetic acid is strained; it holds the small molecules.
- Acid-insoluble fraction
- The retentate from the same filtration; it holds proteins, nucleic acids, polysaccharides and membrane lipids.
- Ash
- What remains after dried tissue is fully burnt; it contains inorganic elements such as calcium and magnesium.
- Alpha-amino acid
- An amino acid whose amino and carboxyl groups are on the same carbon, the alpha carbon.
- Zwitterion
- The form of an amino acid that carries both a positive and a negative charge at a particular pH.
- Triglyceride
- Glycerol with three fatty acids esterified to it; a fat or an oil.
- Phospholipid
- A lipid containing phosphorus and a phosphorylated organic compound, found in cell membranes; lecithin is one.
- Nucleoside
- A nitrogen base attached to a sugar.
- Nucleotide
- A nucleoside with a phosphate esterified to its sugar; the building block of nucleic acids.
- Secondary metabolite
- A compound of plants, fungi or microbes, such as an alkaloid or pigment, whose role in its host is often not fully known.
- Heteropolymer
- A polymer built from more than one type of monomer, such as a protein.
- Homopolymer
- A polymer of one type of monomer repeated many times, such as cellulose.
- Primary structure
- The sequence of amino acids in a protein, from the N-terminal to the C-terminal.
- Tertiary structure
- The folding of a whole protein chain on itself into a three-dimensional shape.
- Quaternary structure
- The arrangement of two or more folded polypeptide subunits relative to one another.
- Ribozyme
- A nucleic acid that acts as an enzyme.
- Active site
- The crevice or pocket in an enzyme into which the substrate fits.
- Activation energy
- The difference in energy between the substrate and the transition state; enzymes lower it.
- Vmax
- The maximum velocity of an enzyme reaction, reached when all enzyme molecules are occupied by substrate.
- Competitive inhibitor
- A substance resembling the substrate that competes for the active site, like malonate for succinic dehydrogenase.
- Apoenzyme
- The protein part of an enzyme that needs a co-factor to be active.
- Prosthetic group
- An organic co-factor tightly bound to the apoenzyme, such as haem in catalase.
- Co-enzyme
- An organic co-factor that binds only briefly during catalysis and serves many enzymes, such as NAD.