T2: Genes & Health

• What is the process by which gas exchange occurs in organisms?

  Diffusion
• What factors increase the rate of gas exchange by diffusion?

  • Increased surface area
  • Decreased diffusion distance
  • Steeper diffusion gradient
• What does Fick's Law state about the rate of diffusion?

  The larger the surface area, difference in concentration, and shorter the diffusion distance, the quicker the rate.
• How are mammalian lungs adapted for rapid gas exchange?

  • Large surface area due to many alveoli
  • Good blood supply to maintain concentration gradient
  • Short diffusion distance as alveoli are one cell thick
• What is the composition of the cell membrane?

  A partially permeable membrane composed of phospholipids with protein molecules between them.
• What are the main functions of the cell membrane?

  Controlling the movement of substances in and out of the cell and containing receptors for other molecules.
• What is the fluid mosaic model?

  It describes the structure of the cell membrane as a fluid arrangement of phospholipids and proteins.
• What are the types of movement through the cell membrane?

  • Diffusion
  • Facilitated diffusion
  • Osmosis
  • Active transport
  • Endocytosis/Exocytosis
• What is diffusion?

  The passive movement of small, non-polar, lipid-soluble molecules from high to low concentration.
• What factors increase the rate of gas exchange by diffusion?

  Increased surface area, decreased diffusion distance, and a steeper diffusion gradient.
• What is facilitated diffusion?

  A process that requires a channel protein to transport polar, charged, and water-soluble molecules across the membrane.
• What is osmosis?

  The movement of water molecules from low solute concentration to high solute concentration through a partially permeable membrane.
• What is active transport?

  A process that can transport all types of molecules through carrier proteins, requiring energy in the form of ATP.
• What is the role of ATP in active transport?

  ATP provides energy for the transport of molecules against their concentration gradient.
• What are endocytosis and exocytosis?

  • Endocytosis: Transport of large particles into the cell via vesicles.
  • Exocytosis: Transport of large particles out of the cell via vesicles.
• What are the components of a mononucleotide?

  • Bases: Purine (adenine, guanine) and Pyrimidine (cytosine, thymine)
  • Sugar: Deoxyribose
  • Bonding: Phosphodiester bonds and hydrogen bonds
• What is the structure of DNA?

  Double-stranded, alpha double helix with a sugar-phosphate backbone on each strand.
• What are the bases in mRNA?

  • Purine: Adenine, Guanine
  • Pyrimidine: Cytosine, Uracil
• What is the structure of mRNA?

  Single-stranded, not usually folded, carries codons which attach to tRNA via hydrogen bonds.
• What is the structure of tRNA?

  • Single-stranded
  • Folded into a specific pattern held by hydrogen bonds
  • Carries anticodons complementary to mRNA codons
• What are the stages of protein synthesis?

  1. Transcription (in the nucleus)
  2. Translation (at the ribosomes)
• What occurs during transcription?

  A molecule of mRNA is made from a DNA template in the nucleus.
• What is the role of RNA polymerase in transcription?

  RNA polymerase catalyzes the formation of mRNA by joining adjacent nucleotides.
• What happens to mRNA after transcription?

  mRNA moves out of the nucleus through a pore and attaches to a ribosome in the cytoplasm.
• What occurs during translation?

  • mRNA attaches to a ribosome
  • tRNA binds to specific amino acids
  • Amino acids join to form a polypeptide chain until a stop codon is reached

  
• What is a gene?

  A series of bases on a DNA molecule that codes for a series of amino acids in a polypeptide chain.
• What is the genetic code?

  The order of bases on DNA, consisting of triplets that code for particular amino acids.
• What is the significance of triplets in the genetic code?

  Each triplet of bases codes for a particular amino acid in a polypeptide chain.
• What is the relationship between genes and polypeptide chains?


  • A gene codes for a sequence of amino acids.
  • Amino acids are joined by peptide bonds to form a polypeptide chain.
• What is meant by non-coding sections of DNA?

  Parts of the genome that do not code for proteins.
• What happens to tRNA molecules after they detach from amino acids?

  They detach from the amino acids.
• What leads to the formation of a polypeptide chain?

  The process of tRNA molecules detaching from amino acids is repeated until a stop codon is reached on mRNA.
• What is a gene?

  A gene is a series of bases on a DNA molecule that codes for a series of amino acids in a polypeptide chain.
• What does the genetic code consist of?

  The genetic code consists of triplets of bases.
• What does each triplet of bases code for?

  Each triplet of bases codes for a particular amino acid.
• What are the two types of DNA regions mentioned?

  The two types are introns (non-coding) and exons (coding regions).
• What are the features of the genetic code?

  • Non-overlapping: Each triplet is read once and does not share bases.
  • Degenerate: More than one triplet can code for the same amino acid.
  • Triplet code: Each three bases code for one amino acid.
  • Contains start and stop codons for protein synthesis.

  
• What are amino acids considered in the context of proteins?

  Amino acids are the monomers from which proteins are made.
• What groups do amino acids contain?

  Amino acids contain an amino group, a carboxyl group, and a variable R group.
• How many different amino acids are there?

  There are 20 different amino acids.