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Zebra Power Point Notes
Per.
DNA: The Genetic Material
DNA Discovery
 Griffith:
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Avery:
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Hershey & Chase:
DNA Structure
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A Nucleic Acid What is another nucleic acid? ___________________________
Nucleotides – consist of a five-carbon _____________, a _____________ group, and a ________________ base
Chargaff’s rule: ________________=______________ and ______________=___________________
X-ray Diffraction data aided in detecting the structure of DNA by indicating that DNA was a _____________ ____
Watson and Crick – built a model of the double helix that conformed to other scientists research
1. Two outside strands consist of alternating _________________ (sugar) and phosphate
2. Cytosine and guanine bases pair to each other by _______________hydrogen bonds
3. Thymine and adenine bases pair to each other by _____________ hydrogen bonds
DNA often is compared to a _________________ ladder
____________ of the ladder are represented by the alternating deoxyribose and phosphate
The pairs of bases (cytosine-guanine or thymine-adenine) form the __________ of the ladder
Orientation
 On the top rail, the strand is said to be oriented 5’ to 3’, the bottom runs in the __________________ direction
and is oriented 3’ to 5’
Chromosome structure
 DNA coils around ________________ (proteins) to form nucleosomes, which coil to form chromatin fibers
 The chromatin fibers supercoil to form chromosomes that are visible in the _____________ stage of mitosis
Replication of DNA
_____________________Replication
 Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of
parental DNA and one strand of new DNA What is the complementary strand for the DNA segment: ACTGGA ?
Unwinding
 DNA helicase, an enzyme, is responsible for unwinding and ___________________ the double helix.
 RNA __________________ adds a short segment of RNA, called RNA primer, on each DNA strand.
Base Pairing
 DNA polymerase continues adding appropriate ______________________ to the chain by adding to the 3’ end
of the new DNA strand. What else does it do? ____________________________________________________
 One strand is called the leading strand and is elongated as the DNA unwinds
 The other strand of DNA, called the lagging strand, elongates away from the replication fork
 The ____________________ strand is synthesized discontinuously into small segments called Okazaki fragments
Joining
 DNA _______________________ removes the RNA primer and fills in the place with DNA nucleotides
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 DNA ___________________ links the two sections
Comparing DNA Replication in Eukaryotes and Prokaryotes
 Eukaryotic DNA unwinds in ________________________ areas as DNA is replicated
 In prokaryotes, the _________________________ DNA strand is opened at one origin of replication
DNA, RNA, and Protein
Central ___________________ What does this mean? ________________________________________________
 RNA contains the sugar ribose and the base ______________________ instead of thymine
 It is single-stranded
Messenger RNA (mRNA)
 Long strands of RNA nucleotides that are formed ________________________ to one strand of DNA
Ribosomal RNA (rRNA)
 Associates with proteins to form ribosomes in the ______________________
Transfer RNA (tRNA)
 Smaller segments of RNA nucleotides that transport ______________ ____________ to the ribosome
Transcription
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Through transcription, the DNA code is transferred to mRNA in the _____________ What is the mRNA
transcribed from the DNA segment ACAGGA ? _____________ Which two amino acids does this segment code
for? ________________ __________________
 DNA is unzipped in the nucleus and RNA ____________________ binds to a specific section where an mRNA will
be synthesized
RNA Processing
 The code on the DNA is interrupted periodically by sequences that are _______ in the final mRNA that exits
 Intervening sequences are called ___________
 Remaining pieces of DNA that serve as the _________________ sequences are called exons
The mRNA Genetic Code
 Experiments during the 1960’s demonstrated that the DNA code was a ________________-base code
 The three-base code in DNA or mRNA is called a codon. What is the “start” codon? __________
 A codon codes for an amino acid. 64 mRNA codons are in the genetic code with instructions for 20 amino acids,
a start codon and 3 stop codons. Why is the genetic code redundant? __________________________________
Translation
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In translation, tRNA molecules act as the _________________ of the mRNA codon sequence
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 At the middle of the tRNA folded strand, there is a three-base coding sequence called the ________________
 Each anticodon is complementary to a codon on the _________
One Gene – One Enzyme
 The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene
codes for one _________________. A polypeptide is also another name for a _______________________
Summarize the Central Dogma
Replication -------------
Where?
Nucleotides
involved?
Enzymes
involved?
End Result?
Transcription ------------
Translation ---------------
Gene Regulation and Mutation
Eukaryote Gene Regulation
 Controlling transcription: Transcription factors ensure that a gene is used at the ___________ time and that
proteins are made in the right _________________
 The complex structure of __________________________ DNA also regulates transcription
Hox Genes
 Hox genes are responsible for the general ________________ pattern of most animals
Mutations
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Why is the redundancy of the Genetic Code a good thing? ____________________________________________
A _________________________ change that occurs in a cell’s DNA is called a mutation
Types of mutations
Point mutation or frameshift
Substitution, Insertion or Deletion
Duplication or Tandem Repeats
Mutation Type
Analogy Sentence
Example of Associated Disorder
Normal
THE BIG FAT CAT ATE THE WET RAT
Normal
1.
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THE BIZ FAT CAT ATE THE WET RAT
Achondroplasia
2.
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THE BIG RAT CAT ATE THE WET BAT
Muscular Dystrophy
4.
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THB IGF ATC ATA TET HEW ETR AT
Cystic Fibrosis
5.
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THE BIG ZFA TCA TAT ETH EWE TRA
Crohn’s Disease
6.
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THE BIG FAT FAT CAT ATE THE WET RAT
Charcot-Marie-Tooth Disease
7.
?
THE BIG FAT CAT CAT CAT CAT CAT CAT…
Huntington's disease
Protein Folding and Stability
 Substitutions can also lead to genetic __________________ Sequence of amino acids determine shape
 Can change both the folding and ______________________of the protein
Causes of Mutation
 Can occur spontaneously What does this mean? ____________________________________________
 Mutagens -________________________ and radiation also can damage DNA
 High-energy forms of radiation, such as X rays and gamma rays, are ______________ mutagenic
Body-cell v. Sex-cell Mutation
 _________ cell mutations are not passed on to the next generation Why not? ___________________________
 Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in _____________
cell of the offspring. ****This allows for natural selection of adaptations that leads to evolution.
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CHECK YOUR LEARNING! Transcription FIB
KEY CONCEPT: Transcription converts a gene into a single-stranded RNA molecule.
DNA provides the instructions needed by a cell to make ______________. But the instructions
are _________ made directly into proteins. First, a DNA message is ______________ into RNA in a process
called transcription. Then, the RNA message is converted into proteins in a process called
___________________. The relationship between these molecules and processes is summed up in the central
dogma, which states that information flows in one direction, from _______ to _________ to
________________.
Like DNA, RNA is a _________________. It is made of nucleotides that consist of a __________ __group, a
sugar, and a nitrogen-containing base. However, RNA differs in important ways from DNA:
(1) RNA contains the sugar ribose, not ___________________;
(2) RNA is made up of the nucleotides A, C, G, and _____________, which forms base pairs with A;
(3) RNA is usually _____________-stranded. This structure enables RNA to fold back on itself into specific
structures that can catalyze reactions, much like an _________________.
8
C
H
A
P
T
E
R
During transcription, a _________ is transferred into RNA. Specific DNA sequences and a combination of
accessory proteins help RNA _____________ recognize the start of a gene. RNA polymerase is a large enzyme
that bonds ______________ together to make RNA.
P
r
o
t
e
i
n
s
t
o
D
N
A
F
r
o
m
RNA polymerase, in combination with the other proteins, forms a __________ transcription complex that
unwinds a segment of the _______ molecule. Using only one strand of DNA as a template, RNA polymerase
strings together a complementary RNA strand that has ________in place of T. The DNA strand zips back
together as the transcription complex moves ____________ along the gene.
Transcription makes three main types of RNA.
• Messenger RNA (mRNA) is the intermediate message between _______ and proteins.
It is the only type of RNA that will be translated to form a __________________.
• Ribosomal RNA (rRNA) forms a significant part of ________________.
• Transfer RNA (tRNA) carries _____________ from the cytoplasm to the ribosome during translation.
The DNA of a cell therefore has genes that code for proteins, as well as genes that code for rRNA and tRNA.
Word Bank (words may be used more than once) : amino acids, converted, deoxyribose,
DNA, enzyme, forward, gene, large, not, nucleic acid, nucleotides, protein(s), phosphate,
polymerase, ribosomes, single, translation, uracil
1. What is stated in the central dogma?
Need help? Refer to pp. 239-240 in text.
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