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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
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What are carbohydrates? What is their funtion?
- generally long chains of [polymers] sugars
- storage, structure, & energy
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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
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What are phospholipids?
consist of two fatty acids of varying length bonded to a phosphate group
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What are steroids?
- they are precursors to significant hormones
- components of membranes
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What are proteins?
composed of 20 amino acids and they are the largest of the biological molecules
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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
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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
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Nucleus
contains the DNA of the cell in organized masses called chromosomes
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Ribosomes
read the RNA produced in the nucleus and translate the genetic instructions to produce proteins
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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]
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Golgi Apparatus
- responsible for packaging, processing, and shipping
- transports materials from the ER throughout the cell
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Lysosomes
- where intracellular digestion takes place
- packed with hydrolytic enzymes that allows it to hydrolyze proteins, fats, sugars, and nucleic acids
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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
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Mitochondrion
found in most eukaryotic cells and are the site of respiration
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Cholorplasts
found in plants and are the site of photosynthesis
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Cell Membrane
the most important component of the cell, contributing to protection, communication, and the passage of substances into and out of the cell
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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]
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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
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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
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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.
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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.
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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.
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In which direction does DNA polymerase replicate?
5' to 3'
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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
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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
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What functions as a messenger from the original DNA helix in the nucleus to the cytosol or on the rough ER?
mRNA
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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.
tRNA
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