Download Biology Chapters 8 and 9 Test Review

Chris Khan 2006
DNA and Viruses
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Humans
o Benign tumors can be removed surgically.
o As humans, our diploid, number of chromosomes we have, is 46.
o Cancer spreads rapidly and is an example of uncontrolled cell division. The cancers compete with tissues and
destroy them.
Cell Division
o Interphase
 G1—the phase in which the cell multiplies its contents, enlarges them and makes new proteins.
 Restriction Point—where the cell commits itself to the entire cycle or chooses to stay in G0 phase, where is
stops dividing
 Synthesis Phase—the phase in which the cell replicates its DNA.
 G2—the phase in which the cell prepares to divide.
 Mitosis Phase—the phase with prophase, metaphase, anaphase and telophase. [See below]
o Mitosis
 Prophase—where the cell’s nuclear membrane breaks down and nuclear material condenses together as the
Centrosome [in plants] or Centriole [in animals] divides.
 Metaphase—where the chromosomes gather in the middle of the cell, the metaphase plate due to effects
of spindle fibers. The astral rays lead to the inside of the cell.
 Anaphase—where spindle fibers condense and centromeres duplicate. Material in the cell moves apart to
opposite sides of the cell due to the contracting of microtubules.
 Telophase—where the entire amount DNA in the cell goes to the sides of the cell and a new nucleus is
formed. In plant cells, the cell plate, formed by cellulose, breaks the cell in half physically. In animal
cells, the cleavage furrow pinches the cell into two cells.
 Cytokinesis—divides the entire cell into two pieces after telophase.
o CDK, or cyclin dependent kinase, adds ATP to other substances.
o MPF, the M-Phase promoting factor, is a protein that triggers the start of the M-Phase.
o CDK levels go up to trigger the cell division, then go back down again.
o Contact Inhibition is when cells touch and stop growing any further.
o DNA when wrapped with histones [protein] makes a nucleosome. These nucleosomes make chromosomes.
o Chromosomes are ONLY visible during mitosis.
o Two chromatids that make up one chromosome are held together by the centromere.
o In a plant, the meristem is where DNA is copied and reproduced.
o If cell division occurs without cytokinesis, there will be two nuclei in one single cell. This multi-nucleated cell is
not good…
Frederick Griffith
o In the 1920s, Griffith worked with Streptococcus pneumonia.
o He tried two types of bacteria and their effects on mice.
o Capsule bacteria, when injected into the mouse, KILLED the mouse [pathogenic].  Non-capsule bacteria, when
injected into the mouse, made it HAPPY [non-pathogenic]. 
o When a capsule bacterium is heated and injected into the mouse it makes the mouse happy  instead of killing  it
like normal. The heat-killed bacteria when combined with non-capsule bacteria kills  the mouse instead of making
it happy  like normal.
o The bacterium acquires capsules. This is called transformates.
o Bacteriophage is a virus that is made of protein and one nucleic acid. This virus injects the nucleic acids into the
cell and then the cell makes more viruses during cell division. The virus spreads and because nucleic acids entered
the cell, they caused the virus to take over the cell.
o Radioactive isotopes “tag” the protein and nucleic acids of a virus to see what exactly enters the cell by using S 35
and P32. (an exp’t done by Hershey & Chase)
o H bonds hold A & T and C & G together.
DNA Replication—makes an identical copy of the cell’s DNA
o Process is DNA  DNA
 1) Unzip the DNA by breaking the H bonds.
 2) From the nucleotide pool, get ‘spare parts’ to complement the DNA.
 3) Attach sugar and phosphates to the nitrogen base.
 4) Check for errors with proofreader enzymes.
o ATP has ribose, while dATP, dTTP, dGTP, and dCTP have deoxyribose.
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This process is semi conservative because it keeps half old material and gets half new material.
The pentose sugars are antiparallel and face opposite directions though they are parallel.
The phosphates connect to the 3rd carbon in the sugars.
Readers read 3’  5’ and Writers write 5’  3’
The replication bubble is the only place where you can copy DNA and other cell material. The replication fork is
the only place where you can start to do this stuff.
o DNA Polymerase copies the DNA.
o Complex Process
 1) Origin of Replication
 Bubbles or Replication Fork
 Helicase unwinds the double helix
 Topoisomerase un-swivels the double helix
 Single strand binding protein holds it open
 Elongation
 Anti-Parallel
 Primase attaches to the DNA and synthesizes RNA primer
 RNA Primer is replaced with the DNA at the end.
o Okazake Fragments are pieces of DNA that have been copied from the lagging strand and NOT the leading
strand. The leading strand is continuous while the lagging strand is done it bits. These Okazake Fragments are the
bits and pieces at the lagging strand
o DNA Primers and RNA Promoters do the same thing: tells the polymerase where to begin copying the DNA or
RNA.
o Process of Replication
 1) Helicase eats apart the helix and the single stranded binding protein holds the strands in place.
 2) Primase attaches polymerase.
 3) Polymerase adds DNA nucleotides to the DNA strands like a stapler.
DNA Transcription—implements the code
o Process is DNA  RNA
o DNA cannot exit the nucleus but the RNA must exit its nucleolus
o Initiation
 RNA Polymerase binds to the promoter region using transcription factors, proteins that tell it where to
begin.
 DNA is unzipped and unraveled, breaking H bonds between the nitrogen bases.
o Elongation
 From RNA nucleotide pool, RNA nucleotides bind to complementary bases on open DNA strands.
 The two Phosphates are removed.& the sugar and phosphate join
o DNA Code is found in the sequence of nitrogen bases.
o In DNA transcription, the RNA complements DNA.
o Termination
 Release RNA from DNA at termination region to form the primary RNA transcript (preRNA)
o Edit/Process
 Remove introns [garbage] and splice together exons [usable stuff].
 Add ‘mG cap’ and the ‘poly a tail.’
 These are chemical signals that say the editing process is done.
o 3 RNA Types
 mRNA—messenger RNA takes information from nucleus to give to the ribosomes.
 rRNA—ribosomal RNA is part of the ribosome structure
 tRNA—picks up amino acids and brings them to mRNA.
o Genetic Code
 20 codes are needed.
 41 = 4 (single) too few
 42 = 16 (double) too few
 43 = 64 (triple) more than enough
o The promoter molecules tell transcription when to start.
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RNA Polymerase moves along DNA and forms RNA that is complementary to the DNA
RNA Processing removes introns, portions that do NOT code for proteins. SNRNPS are small nuclear
ribonucleoproteins that remove introns.
The codes tell you what to do with the proteins.
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o 20 codes are needed because there are 20 amino acids.
DNA Translation—processes RNA and makes peptide bonds to hold amino acids together
o DNA  RNA  Protein
o You need a starting codon to tell the reading where to begin.
o Experiments were conducted to find out what which triplets of nitrogen bases created. (i.e. In UAAUAAUAA, you
always get 2 A’s and 1 U, but you can find out three different things.)
o Once you find out what a human body’s genetic code sequence is, you can get cells to make things for you that can
cure diseases.
o Stem Cells are used for research and have no specialized function at the time.
o AUG is a ‘start code’ that also stands for methionine.
o UUU—phenylalanine.
o UAA, UAG, and UGA are all stop codes.
o The missing enzymes from PKU convert phenyalanine to tyrosine.
o DNA often reads the first two letters but not the last letter in a code.
o Primary Structure of DNA comes from mRNA.
o Anti-codons are complements on transfer RNA.
o tRNA’s are like adaptors, like when you have a 3-pronged appliance and only a 2-pronged outlet. They let two
amino acids connect to the mRNA.
o Codons pair with anti-codons by action of ribosomes. They enter in the “A” site; get processed in the “P” site and
exit in the “E” site.
o Codons are the triplets that match with anti-codons.
o Dehydration Synthesis and polypeptide bonds bond amino acids together.
o Termination Proteins stop codons from pairing; they terminate the process.
o Translocation is movement from one site to another; to the next triplet.
o Mutations
 Point Mutation—affects only 1-2 bases.
 Frame Shift—starts reading in the wrong place.
o If you skip a codon, you are missing that aa which it codes for
o If you miss a base, everything after the missing base gets shifted over.
o Enzyme Deficiency Diseases are diseases caused because enzymes are lacked.
o Initiation
 tRNA charging—tRNA picks up amino acids.
 mRNA + initiator RNA + ribosomal subunit + initiation factors come together.
o Elongation
 Codon Recognition
 mRNA codon + RNA-amino acids (anti-codon) enter at the A-site; AUG is the initiation code.
 Codons move over to the P site.
 Peptide Bond Formation
 Adjacent amino acids on the P and A sites form a peptide bond because of dehydration synthesis.
o Translocation
 tRNA in the P site moves to the E site and exits
 tRNA + growing protein chain in the A site moves to the P site
 Next tRNA-amino acid comes into the A site
 Repeat process
o Termination
 At the termination code (UAA, UAG, UGA), the releasing factor causes tRNA to release and ribosomes to
separate into subunits.
Viruses
o 1) Base Pair Viruses
 Missense
 Doesn’t make sense… alters amino acid code so the aa is changed base
 Nonsense
 Changes an amino acid code into a stop code, so only ½ protein is created. This makes unfinished
proteins.
o 2) Base Pair Insertion or Deletion
 May lead to a frame shift mutation
 Improper groups
o All stuff after that is incorrect