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2010-01-24 14:28:05
HESI nursing entrance exam

biology section for the nursing entrance exam
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  1. What is the most significant aspect of water? What does this cause?
    • the polarity of its bonds
    • waters high specific heat; strong cohesive & adhesive properties; when water freezes it forms a lattice resulting in floating; acts as a versatile solvent that can be used to dissolve a number of different substances
  2. What are carbohydrates? What is their funtion?
    • generally long chains of [polymers] sugars
    • storage, structure, & energy
  3. What are lipids? What is important about the two types?
    • fatty acids that are grouped into two categories - saturated & unsaturated
    • saturated: no double bonds in their hydrocarbon tail, solid at room temp, bad for your health
    • unsaturated: one or more double bonds in their hydrocarbon tail, liquid at room temp
  4. What are phospholipids?
    consist of two fatty acids of varying length bonded to a phosphate group
  5. What are steroids?
    • they are precursors to significant hormones
    • components of membranes
  6. What are proteins?
    composed of 20 amino acids and they are the largest of the biological molecules
  7. What are the two types of nucleic acids? What does each do?
    • Deoxyribonucleic acid [DNA]: contains the genetic code that is needed for replication
    • Ribonucleic acid [RNA]: used in transfer as a messenger of the genetic code
  8. What are the enzymes that are needed for replication and what is the function of each?
    • DNA Helicase: Unwinds a portion of the DNA double helix
    • RNA Primase: Attaches RNA primers to the replicating strands.
    • DNA Polymerase delta: Binds to the 5' - 3' strand in order to bring nucleotides and create the daughter leading strand.
    • DNA Polymerase epsilon: Binds to the 3' - 5' strand in order to create discontinuous segments starting from different RNA primers.
    • Exonuclease (DNA Polymerase I): Finds and removes the RNA Primers
    • DNA Ligase: Adds phosphate in the remaining gaps of the phosphate - sugar backbone
    • Nucleases: Remove wrong nucleotides from the daughter strand
  9. Nucleus
    contains the DNA of the cell in organized masses called chromosomes
  10. Ribosomes
    read the RNA produced in the nucleus and translate the genetic instructions to produce proteins
  11. Endoplasmic Reticulum
    • found attached to the nuclear membrane and consists of 2 continuous parts
    • rough ER: the section of the ER covered in ribosomes [responsible for protein synthesis and membrane production]
    • smooth ER: lacks ribosomes [detoxifies and metabolizes many molecules]
  12. Golgi Apparatus
    • responsible for packaging, processing, and shipping
    • transports materials from the ER throughout the cell
  13. Lysosomes
    • where intracellular digestion takes place
    • packed with hydrolytic enzymes that allows it to hydrolyze proteins, fats, sugars, and nucleic acids
  14. Vacuoles
    • membrane-enclosed structures that have various functions depending on cell type
    • cells, through phagocytosis, uptake food through the cell membrane, creating a food vacuole
    • plant cells have a central vacuole that functions in storage, waste disposal, protection, and hydrolysis
  15. Mitochondrion
    found in most eukaryotic cells and are the site of respiration
  16. Cholorplasts
    found in plants and are the site of photosynthesis
  17. Cell Membrane
    the most important component of the cell, contributing to protection, communication, and the passage of substances into and out of the cell
  18. What are the three steps in cellular respiration and what happens at each?
    • glycolysis: conversion of glucose to pyruvate [takes place in the cytosol of the cell and produces 2 ATP, 2 pyruvate, and 2 NADH]
    • krebs cycle: the pyruvate is transported into a mitochondrion and used in the 1st of a series of reactions [for a single consumed glucose molecule, 2 ATP, 6 CO2, & 6 NADH are made]
    • electron transport chain: NADH molecules are oxidized to produce O2 and H2O [for every glucose molecule, 28 -32 ATP can be made]
  19. What are the two steps in photosynthesis and what happens at each?
    • light reactions: the cell accomplishes the production of ATP by absorbing light and using that energy to split a water molecule and transfer the electron, creating NADPH and producing ATP
    • calvin cycle: the sugar is polymerized and stored as a polymer of glucose
  20. interphase: G1
    cells increase in size, produce RNA & synthesize protein. An important cell cycle control mechanism activated during this period [G1 checkpoint] ensures that everything is ready for DNA synthesis
  21. interphase: S
    to produce 2 complete daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs during this S [synthesis] phase.
  22. interphase: G2
    during the gap between DNA synthesis & mitosis, the cell will continue to grow & produce new proteins. At the end of this gap is another control checkpoint to determine if the cell can now proceed to enter M [mitosis] & divide.
  23. interphase: M
    cell growth & protein production stop at this stage. All of the cells energy is focused on the division into two similiar daughter cells. There is a checkpoint in the middle of mitosis.
  24. In which direction does DNA polymerase replicate?
    5' to 3'
  25. Transcription
    • an RNA strand, complementary to the original strand of DNA. is produced
    • this RNA strand is called messenger RNA
    • Uracil is substituted for Thymine
  26. Translation
    • the mRNA slides through the ribosome
    • every group of 3 bases along the stretch of RNA is called a codon, and each of these codes for a specific amino acid
    • each amino acid is bonded together and released by the preceding tRNA molecule, creating an elongated chain of amino acids
  27. What functions as a messenger from the original DNA helix in the nucleus to the cytosol or on the rough ER?
  28. The Anticodon is located on a unit called _____, which carries a specific amino acid – it binds to the ribosome when its codon is sliding through the ribosome.