Lecture 7

    Cards (31)

    • What are the four different types of carbohydrates and how are they classed ?
      Monosaccharides - single sugar unit
      Oligosaccharides - short chain of 2-20 monosaccharides
      Polysaccharides - Long chain of >20 monosaccharides
      Glycoconjugates - carbohydrates linked to proteins or lipids
    • what are the two types of monosaccharides ?
      Aldoses (contain an aldehyde) and ketoses (contains a ketone)
    • What are the smallest monosaccharides ?
      Trioses (3C sugars)
    • What determines the D or L configuration of a molecule ?
      Based on the chiral carbon further away from the aldehyde/ketone
    • Which isomer classification of monosaccharides are most common in nature ?
      D - isomers, L - isomers are less common but do exist in some biological systems
    • What is the classification of monosaccharide isomers based on and what does it mean ?
      Fischer projection of glyceraldehyde
      D - form has hydroxyl group on the right
      L - form has hydroxyl group on the left
    • Why do hexoses and pentoses form cyclic rings ?
      Intermolecular relation of the carbonyl with a hydroxyl group. They form Hemiacetals (from aldoses) or Hemiketals (from ketoses).Two possible anomers are alpha(OH below the ring) and beta (OH above the ring)
    • What bond links together monosaccharides ?
      Glycosidic bonds
    • How does a glycosidic bond form ?
      The anomeric carbon reacts with an -OH group of another sugar
    • What is the source of starch and what is it a mixture of ?
      • Plants
      • Mixture of amylose(a1–> 4) and amylopectin (a1–>4,a1–>6) branches every 24-30 residues
    • What is the source of glycogen and what is its structure ?
      • Animals
      • Similar to amylopectin but more branched (a1-->6 every 8-12 residues). Highly compact and rapidly metabolised.
    • What is the function of cellulose and what is its structure ?
      • Plant cell walls
      • B1-4 linkages, linear unbraced chain's
      • hydrogen bonds between chains, microfibrils
    • What is the function of chitin and what is its structure ?
      • Exoskeleton of insects, fungi walls
      • similar to cellulose but has N-acteylcglucosamine residues instead of glucose
    • What are glycoproteins ?
      proteins with attached carbohydrates
    • What are the main amino acids involved in glycosylation ?
      1. Serine and threonine - O linked glycosylation
      2. Asparagine - N linked glycosylation
    • What are the two types of glycosylation ?
      1. N linked - Sugar molecules attached to the amino group of asparagine
      2. O linked - Sugar molecules attached to the hydroxyl group of either serine or threonine
    • Whta is an example of a glycoprotein and its function and type of glycosylation ?
      • O linked glycosylation attached to either serine or threonine
      • Glycoprotein with carbohydrates stabilising it in blood
      • Breaks down elastin, protein found In connective tissue
    • What is the composition of a nucleotide ?
      1. 5 carbon sugar (ribose/deoxyribose)
      2. Nitrogenous base : Purine (A&G) Pyrimidines (C,T&U)
      3. Phosphate group
    • What is the 4 function of lipids ?
      1. Structural components of membranes
      2. Energy storage
      3. Hormones and vitamins
      4. Bile acids
    • What are the 4 major lipid families and what are their key features ?
      1. Triacylglycerols- glycerol backbone
      2. Glycerolphospholipids- glycerol backbone, phosphate moietites, can include glycol-conjugates
      3. Sphingolipids- Built on sphingosine backbone unit, often Glycoconjugates
      4. Isoprenoids - steroids, lipid vitamins and hormone
    • What are fatty acids ?
      Long hydrocarbon chains
    • What are 3 reasons as to why fatty acid chains vary ?
      1. Chain length - typically between 12-20 carbon atoms in their hydrocarbon tail
      2. Degree of unsaturation - cis fatty acids have double bonds therefore lower boiling point and trans are vice versa
      3. Position of double bonds
    • What are triacylglycerols, their function and structure ?
      -Major form of fat storage
      -3 fatty acids esterified to a glycerol molecule
      -hydrophobic, stored in cells as fat droplets
      -efficient for long term storage, as they pack tightly
    • What are Glycerophospholipids, their function, structure and features ?
      -glycerol backbone,two fatty acids esterified to it, third carbon of the glycerol is linked to a phosphate group
      -Most abundant lipid, make duo cell membrane
      -amphipathic, allows it to form bilayers
    • What is a sphingolipids, their structure function and features ?
      -large family of lipids, import component of biological membranes (plasma membrane )
      -do not have a glycerol backbone, have a sphingosine backbone (3 carbon molecule)
      -amphipathic, hydrophobic tail and hydrophilic head
      -various groups attached to their pilar heads : ceramide, sphingomyelin, Glycosphingolipids
    • What are the various heads that can be attached to the polar head of Sphingolipids and their structure ?
      1. Ceramide - head group is just a hydrogen
      2. Sphingomyelin - head group is phosphocholine (a choline group linked to phosphate)
      3. Glycosphingolipids - where the head group contains sugars or oligosaccharides.
    • Where are sphingolipids abundant in and what is their function ?
      • membranes of eukaryotic cells
      • Involved in : cellular processes, cell signalling, recognition and communication
    • What are steroids and what are they classed as ?
      -lipids classified as isoprenoids (Derived from 5 carbon unit isoprene)
      –four rings structure distinct from other lipid classes
    • What is the structure of a lipid ?
      -fused ring system - four fused carbon rings ( 3 6-membered rings, one 5 membered ring,D)
      -rigid structure, less flexible compared to fatty acid chain
    • What are 3 examples of steroids and their function ?
      1. Cholesterol - structural components of cell membranes, modulates membrane fluidity by inserting itself between phospholipid molecules, makes membrane more stable and less permeable
      2. Steroid hormone - estrogen,testosterone,cortisol and other hormones are steroids derived from cholesterol, import for regulation of various physiological processes
      3. Bile acids - derived from cholesterol, essential for digestion and adoption of dietary fats, emulsify fats in the digestive tract
    • Are steroids amphipathic ?
      Yes
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