BIO 181 Molecular Basis of Inheritance – Flashcards
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what is this chapter about?
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the structure of DNA
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who discovered the structure of DNA?
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Watson and Crick
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many people used to think that ____ were the genetic material
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proteins
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what is Chargaff's rule?
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A=T and G=C
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What did Rosalind Franklin do?
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worked on x-ray crystallography and created a x-ray diffraction photograph of DNA depicting helix shape
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where did Watson and Crick get there idea of the double helix from?
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from Franklin's photos of DNA
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DNA is a bunch of _____ attached together
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nucleotides
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a bunch of nucleotides attached together is called a _____
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nucleic acid
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DNA and RNA are ______
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nucleic acids
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a nucleotide is composed of...?
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a sugar (deoxyribose), phosphate, and nitrogenous base
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nuleotides are ____ of nucleic acids
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monomers
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how do nucleotides bond?
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through dehydration synthesis (the sugar with "OH" at the 3' end and the phosphate with OH come together, form H20, and release it -> water is removed and the nucleotides are bonded by 1 oxygen)
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DNA is ______ meaning that it's 5 to 3 on one side and is 3 to 5 on the other side
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antiparallel
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DNA is made up of ______ and ______ backbones with ______ in the middle
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sugar and phosphate, nitrogenous bases
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a helix is the most ____ structure
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stable
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purines are bases with __-ring structures
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2
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which bases are purines?
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adenine and guanine
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pyrimidines are bases with __-ring structures
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1
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which bases are pyrimidines?
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thymine, cytosine, and uracil (RNA)
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purine + purine are too ____?
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wide
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pyrimidine + pyrimidine are too ____?
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narrow
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purine + pyrimidine are ____?
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just right
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how many H bonds for A+T?
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2 H bonds
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how many H bonds for G+C?
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3 H bonds
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general idea of DNA replication in the body?
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(a) begins with one parent molecule (b) DNA strands separate (c) DNA molecules (4 total) consisting of one parental strand and one new strand
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DNA molecules (4 total) consisting of one parental strand and one new strand - this type of replication is called?
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semi-conservative
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interphase
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prior to mitosis
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___% is interphase
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90
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replication occurs in the ______ phase
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synthesis
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What is meant by the description "antiparallel" regarding the strands that make up DNA?
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The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
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In E. coli, there is a mutation in a gene called... that alters the topoisomerase that normally acts at the origin. Which of the following would you expect as a result of this mutation?
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The DNA will supercoil, becoming overwound.
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what is topoisomerase?
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an enzyme that alters the supercoiled form of a DNA molecule (prevents DNA from twisting a lot)
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At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' T G C A A T C C 5' An RNA primer is formed from the above template. Which of the following represents the primer sequence?
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5' A C G U U A G G 3'
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What is the function of single stranded binding protein?
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stabilizing single-stranded DNA at the replication fork
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The leading and the lagging strands differ in that...
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the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
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In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
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thymine ... cytosine
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DNA is usually _________, whereas RNA is usually _________.
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double-stranded ... single-stranded
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You can tell if it's a DNA nucleotide and not an RNA nucleotide because you see a _____.
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sugar with two, and not three, oxygen atoms
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In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.
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1' ... 5'
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Nucleic acids are assembled in the _____ direction.
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5' to 3'
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Short segments of newly synthesized DNA are joined into a continuous strand by _____.
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ligase
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The first step in the replication of DNA is catalyzed by _____.
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helicase
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The action of helicase creates _____.
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replication forks and replication bubbles
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Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
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DNA polymerase can assemble DNA only in the 5' to 3' direction
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The synthesis of a new strand begins with the synthesis of a(n) _____.
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RNA primer complementary to a preexisting DNA strand
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_____ catalyzes the formation of an RNA primer.
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Primase
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An old DNA strand is used as a _____ for the assembly of a new DNA strand.
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template
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the _____ of one nucleotide binds to the ____ of the next, and so on.
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sugar ... phosphate
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There are four kinds of DNA nucleotides, abbreviated _______.
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A, T, C, and G
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The sugar and phosphate groups are the same for all DNA nucleotides. The _____ is the one part that changes.
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base
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Research indicates that the best estimate of your age is from ______.
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markers in your cells
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The cells examined from the 2,400 people in this study (New Video: The Effect of Exercise on Cells) were from ______.
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blood
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What damages cells and causes cell aging?
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inflammation
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The researchers used strands of DNA located at the ends of chromosomes (called telomeres) to classify the cells they studied. What assumption did they make about telomeres?
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Longer telomeres indicate younger cells.
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The researchers found that telomeres were ______.
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longer in individuals who exercised regularly
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The research showed that individuals who _______ had younger looking cells based on telomere measurements.
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exercised for an average of 30 minutes per day
