Cell Phys Exam #1

• Glycosidic bond is the two-bond link between the rings in an oligosaccharide or polysaccharide
• Common disaccharides:

  • Sucrose: Glucose and Fructose linked by α(1→2)β
  • Lactose: Galactose and Glucose linked by β(1→4)
  • Maltose: Glucose and Glucose linked by α(1→4)
• Lactose itself cannot be absorbed by the intestine and must be broken down into absorbable sugars Glucose and Galactose
• Starch contains two types of glucose polymer:

  • Amylose: linear polymer of D-glucose residues in (α 1  4) linkage
  • Amylopectin: has stretches of similarly linked residues between branch points. The linkage at the branch is (α 1  6)
• Glycogen is a polymer of (α 1  4) linked subunits of glucose, with (α 1  6) - linked branches

  • Glycogen is an excellent source of energy and the storage form of Glucose
  • Major storage sites for Glycogen are the Liver and Muscle
• Cellulose is a structural element in plant cell walls and is a homopolysaccharide composed of D-glucose units in β configuration

  • Chitin is a linear homopolysaccharide composed of N-acetylglucosamine residues in β linkage, found in the exoskeletons of arthropods like insects, lobsters, and crabs
• Amino acids are classified into three groups:

  • Essential amino acids: Cannot be made by the body and must come from food
  • Nonessential amino acids: Can be produced by the body
  • Conditional amino acids: Usually not essential, but needed during sickness or stress
• Peptide Bonds:

  • Amino acids react to form peptide (amide) bonds
  • Direction is always N-terminal to C-terminal
  • Different peptide lengths: Dipeptide (2 residues), Tripeptide (3 residues), Oligopeptide (a few residues), Polypeptide (many residues), Protein (many residues with defined 2D and 3D structure)
• Disulfide Bonds:

  • Disulfide bonds between two Cysteine residues play a major role in the crosslinking, folding, and stability of proteins
  • Protein crosslinking increases rigidity, functions, and proteolytic resistance
  • Insulin is an example of a protein with cysteine crosslinking, connected by disulfide bonds
• Protein Structure:

  • Proteins come in various sizes and shapes, with fibrous proteins having a thread-like shape and globular proteins having spherical shapes
  • Proteins with one polypeptide chain have primary, secondary, and tertiary structures
  • Proteins with two or more chains have a quaternary structure
• Levels of structure in proteins:

  • Primary structure: sequence of amino acids linked by peptide bonds
  • Secondary structure: arrangement into units like α helix
  • Tertiary structure: folded polypeptide, part of the quaternary structure of multi-subunit proteins like hemoglobin
• Folding and Denaturing Proteins:

  • Protein folding (tertiary structure) is primarily driven by the hydrophobic effect and electrostatics
  • Denaturation: complete or partial unfolding of a protein, causing loss of biological activity
  • Proteins can be denatured by heat, mechanical agitation, pH changes, detergents, organic solvents, and chaotropic agents
• Detergents, organic solvents (acetone, alcohols), and chaotropic agents (e.g. urea, guanidinium ion) cause hydrophobic disruption
• Sickle cell anemia:

  • Mutation of Glutamic acid to Valine in hemoglobin leads to aggregation and sickle shape
  • Can confer resistance to malaria but cause painful obstruction of capillaries
• Huntington's disease (HD):

  • Caused by abnormal huntingtin protein with more than 36 CAG repeats
  • Mutant protein prone to aggregation, leading to symptoms
• Enzyme Km is a measure of substrate affinity, lower Km means tighter substrate binding
• Enzymes have unique shapes with active sites for specific substrates
• Enzyme "Accessories" Terminology:

  • Enzymes require cofactors for catalysis
  • Apoenzyme is the protein part of the enzyme
  • Holoenzymes consist of apoenzymes and cofactors
  • Cofactors include metal cofactors (e.g. Zn++), coenzymes (e.g. NAD(H)), and prosthetic groups (e.g. Heme)
• Enzyme Regulation:

  • Allosteric regulation alters enzyme structure and activity
  • Competitive, uncompetitive, and mixed/noncompetitive inhibition
  • Reversible inhibition mechanism
• DNA Replication:

  • Begins at Origins of Replication
  • Strands open to form Replication Forks
  • New strands grow at the forks
  • RNA primers made on lagging strand and erased by DNA repair enzyme
• Cell Cycle:

  • Cyclins (G1/S, S, M, G1) regulate cell cycle progression
  • M-Cdk triggers spindle assembly in mitosis
  • Mitotic spindle structure and phases (metaphase, anaphase, telophase, cytokinesis)
• Biochemistry:

  • Hemiacetals formed by reaction between alcohol and aldehydes
  • Glucose monitors use Glucose oxidase to react with metals for electric current
  • Dietary fibers lower cholesterol levels
• Protein Structure:

  • Phenylketonuria caused by lack of phenylalanine hydroxylase
  • Red blood cells can't use fat for ATP production
  • Three amino acids (Serine, Threonine, Tyrosine) can be phosphorylated
• Protein Structure:

  • Peptide backbone with attached side chains
  • Nonpolar amino acid side chains form a hydrophobic core
  • Differences between fibrous and globular proteins
  • Glycine is rare in alpha helix and beta sheet structures due to conformational flexibility
• DNA:

  • Write the complementary sequence of the given DNA template
• 3 main sections of the cells: nucleus, cytoplasm, and outer layer
• what do both prokaryotes and eukaryotes have in common? both have DNA, ribosomes, a plasma membrane, and cytoplasm
• sugars make up polysaccharides
• fatty acids make up fats, lipids, and membranes
• amino acids make up proteins
• nucleotides make up nucleic acids
• a bacterial cell is 30% chemicals and 70% H2O
• glycosidic bonds is 2 bonds sharing an oxygen
• lactose can't be absorbed by intestines
• lactose must be broken down into glucose and galactose
• 2 types of glucose polymer in starch: think (Amy)
• glycogen is stored in the liver and muscles
• examples of INSOLUBLE fiber is: whole-wheat flour, wheat bran, green beans
• fiber: normalizes bowel movements, helps maintain bowel heath, lowers cholesterol, and controls blood sugar
• nucleotide: has a phosphate TAIL