TOPIC 2

• alveoli increases surface area to volume ratio so more oxygen can be absorbed
• in ficks law of diffusion as object size increases surface area : volume deacreases
• how is the mammalian lung adapted for rapid gaseous exchange

  they have alveoli with large surface area and with good blood supply to transport oxygen and through inhalation and exhalation
• what is the structure of a phospholipid

  phospholipid is a glycerol with a phosphate head and two fatty acid tails joined by ester bonds
• how is bilayer formed

  when phospholipds are facing each other with they fatty acid taila infront so hydrophilic ends are outwards
• what is the difference between fluid mosaic model and sandwich model

  in fluid mosaic model the proteins are randomly embedded in bilayer and has glycolipids and cholesterol while in sandwich model there are no such components and proteins are present on outside of membrane
• what is the similarity between sandiwtxh and fluid models

  they both consist of bilayer and protein
• what is diffusion

  movement of substances from region of power concentration to higher concentration
• what is osmosis

  movement of water molecules through partially permeable membrane down the water potential gradient
• what is facilitated diffusion

  transport of molecules with help of transport proteins
• what is Active transport

  movement of molecules and ions through cell membrane from region of lower concentration to region of higher concentration with ATP and requires carrier proteins
• how does a channel protein work?

  it extends through bilayer to transport molecules through it
• how does carrier protein work

  they change shape
• what is the stricture of amina acid

  carbon attached to a amino group and COOH with an R group aswell
• how are polypeptides formed

  by linking amino acids with peptide bonds by condensation
• define primary structure of protein

  sequence of amino acids in a polypeptide chain joined by peptide bonds
• what is secondary structure of protein

  primary structure folds and forms hydrogen bonds between C=O of one amino acid residue and N-H group of another

  can be helix or beta pleated sheets
• what is tertiary structure of protein

  when secondary folds happen due to R groups and forms hydrogen bonds or ionic bonds or disulfide bonds
• how is quaternary structure formed

  formed by production of combination of peptides in which the shape is provided
• what is shape of fibrous protein?

  long and narrow
• what is shape of globular protein

  spherical
• what is structure of fibrous protein

  secondary
• what is structure of globular protein

  tertiary
• what is role of fibrous protein

  it plays a structural role
• is fibrous or globular protein soluble?

  globular
• give and example of fibrous protein

  collagen

  fibrin

  keratin
• give example of globular protein

  haemoglobin

  firbrinogen

  insulin
• what is an enzyme

  biological catalyst that reduces activation energy and speeds up rate of chemical reaction by weakening bonds

  these are globular/tertiary
• what does an intercellular enzyme do

  catalyze reaction inside cells
• what is the induced fit theory

  the active site changes shape for specific substrate
• state what purines are and how they differ from pyramidines

  purines like base pair C U G have double rings while the pyramidines like A G dont
• what is the base pair of adenine?

  Thymine
• what is the base pair of guanine

  cytosine
• what type of bond is present between two nucleotides

  phosphodiester bond
• what is the type of bond present between base pakrs?

  Hydrogen bond
• in DNA replication the helicase unwinds the DNA by breaking hydrogen bonds between them and each strand acts as a new template for free nucleotides

  the exposed bands attract nucleotides and hydrogen bonds made again

  DNA polymerase catalyses condensation reaction making phosphodiester bonds

  ligase joins fragments formed in lagging strand
• in semi conservative what happens in the second round

  light strand is formed
• what are the natures of genetic code

  triplet code

  non overlapping

  degenerative
• what’s is the gene

  sequence of bases on DNA that codes for sequence of amino acids in polypeptide chains
• what are the events that occur in transciption

  • RNA polymerase attach to promoter region Of DNA & UnwInd and break hydrogen bonds.
  • antisense strand act as template for free nucleorides to pair with using base pairing.
  • RNA polymerase bind nucleotides forming phosphodlester bonds ccondensation)

  • continued till stop sequence reached & mRNA pell away from DNA and rewinds