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NUCLEIC ACIDS AND PROTEIN SYNTHESIS
DNA IS THE GENETIC CODE:
 The genetic code is: ________________________________________________
_____________________________________________________________________
EVIDENCE OF DNA AS THE GENETIC CODE:
EXPERIMENTS:
1. (1928) Griffith: _____________________________________
2. (1952) Hershey & Chase: __________________________________
SUMMARY OF GRIFFITH’S EXPERIMENT:
Isolated
2 different strains of pneumonia bacteria (disease causing strain and a harmless
strain) from mice and injected into mice
Griffith
cultured disease causing cells, heated the cells to kill them, and injected
mice…mice lived
He
mixed heat-killed disease causing cells with harmless bacteria, and injected
mice…mice developed pneumonia and died
Heat-killed bacteria passed their disease-causing ability to harmless strain - called this
transformation (one strain had been transformed into another)

Griffith’s Hypothesis: a factor was transferred from the heat-killed bacteria to harmless
bacteria, and since the ability to cause disease was inherited by the transformed bacteria’s
offspring, that factor might be a gene

SUMMARY OF HERSHEY & CHASE EXPERIMENT:
BACTERIOPHAGE: _____________________________________________________
________________________________________________________________________
o Hershey/Chase wanted to determined which part of the bacteriophage (the protein
coat or nucleic acid core) entered the infected cell
o They thought this would allow them to learn whether genes are made of protein or DNA
o They grew viruses in cultures containing 32P and 35S
o If 35S was found in the bacteria, then protein coat was injected into the bacteria
o If 32P was found in bacteria, then DNA had been injected
o Results: all radioactivity in bacteria was from 32P
o
Conclusion: the genetic material of bacteriophage was DNA, not protein
DNA STRUCTURE & FUNCTION
THE BUILDING BLOCKS OF DNA ( _____________________________________)
1. DNA is a polymer made up of _______________________________________.
a) A nucleotide monomer has 3 parts:
1. A 5-C sugar called ________________________________
oDeoxyribose is __________________, b/c it has 5 carbons
2. A ________________________ group
3. 1 of 4 _______________________________
2. Four different nitrogenous bases can be found in DNA. These bases can be of two
forms, either ____________________ or _________________________.
a) Purines (bigger bases - 2 rings): ____________________ & ________________
b) Pyrimidines (smaller bases - 1 ring): ________________ & ________________
HINT: GA is a bigger state than CT - bigger state=bigger bases!
3. Nucleotides join together when _____________________________form between the
sugars and phosphates of the nucleotides. This forms the sugar-phosphate “backbone” of
the DNA molecule.
4. The bases are bonded to the __________________________in the nucleotides.
5. Bases of nucleotides are held to each other by weak _____________________ bonds.
Evidence of DNA’s Structure:
Evidence #1. (1950) Franklin & Wilkins:
 X-Ray Crystallography (Helical Shape)
Evidece #2. (1953) Watson & Crick:
 Double Helix Model & Complementary Base Pairing
DNA STRUCTURE & FUNCTION (cont.)
DNA Structure:
1. DNA is a _______________________________________. There are ______ strands
of DNA in each double helix.

Each strand has a backbone of alternating______________________________.

Backbones of sugar and phosphate are connected to each other at the bases by
_______________________________________________.
2. Complementary base pairing is the specific attraction between certain bases. ______________
(G and A) bond to _____________________________ (C and T).

Adenine (A) always bonds to _____________________

Cytosine (C) always bonds to _____________________
CHARGAFF’S RULE: the # of _____________________ = # of thymine
the # of _____________________= # of guanine
3. Therefore, the bases of _____________________________determine the
_______________________________________.
Hmmm……
If you have a DNA molecule with 120 bases, and 20 of those bases are adenine, how
many thymine, guanine and cytosine are there?
 __________ thymine
___________ cytosine
___________ guanine
What is the matching strand? AATGCGATA
_________________________________
CHROMOSOMES AND DNA REPLICATION
DNA and Chromosomes:

Prokaryotic cells
o DNA molecules are located in the _______________________________
o most have a _________________________________molecule that
contains nearly all of the cell’s genetic info

Eukaryotic Cells
o DNA is in the _____________________in the form of
_________________________
o Eukaryotic chromosomes contain _________ and ___________________,
packed together to form _____________________________
 Chromatin consists of DNA tightly coiled around proteins called
_______________________________
 DNA and histones together form ___________________________
 Nucleosomes can fold huge lengths of DNA into the
nucleus (the nucleus contains more than 1 meter of DNA!)
DNA Replication:

Structure of DNA relates to its function
o Each strand of DNA double helix has info needed to create the other half
because of __________________________________________
o Model of replication is __________________________________because
____________________________________________________________
____________________________________________________________

Eukaryotes
o DNA replication occurs at _______________________________and
proceeds in _______________________________directions until each
chromosome is replicated
o Replication forks: _____________________________________________
_______________________________________________________________

Prokaryotes
o Replication begins at a _____________________________and proceeds in
________________________directions until entire chromosomes is replicated
Steps of DNA Replication:
1. Enzyme __________________________“unzips” the strands of the double helix by
breaking the hydrogen bonds that hold the bases together.
2. The separated strands of DNA serve as ________________________from which new
copies can be made.
3. The now exposed bases are free to match up with their complementary bases to form
another strand of DNA.
4. _______________________________________adds new complementary DNA
nucleotides to the template strand.
 DNA strands have a 3’ end and a 5’ end
 Primed numbers refer to the carbon atoms at the end - 3’ end C is bonded to an
OH and 5’ end carbon is bonded to a phosphate group
 DNA polymerase adds nucleotides to the _____________________ end ONLY
5. _________________________________________links new pieces together
RNA

RNA stands for ____________________________________________________
o Monomers: RNA nucleotides.
o Structural Differences between DNA and RNA:
 Sugar: __________________________
 Bases:
 Pyrimidines: __________________and cytosine (C)
 Purines: adenine (A), and guanine (G)
o Shape: _____________________________________________
DNA vs RNA
DNA
SUGAR
SHAPE
RNA
BASES
Types of RNA:
1. Messenger RNA (mRNA): _______________________________________________
________________________________________________________________________
2. Transfer RNA (tRNA): _________________________________________________
________________________________________________________________________
3. Ribosomal RNA (rRNA a.k.a. ribosome): __________________________________
________________________________________________________________________
TRANSCRIPTION
Definition: Transcription is ________________________________________________
________________________________________________________________________
________________________________________________________________________
Location: in cell ___________________________
Purpose: _______________________________________________________________
_______________________________________________________________________
This is done so that mRNA can leave the nucleus and take these instructions to the
_______________________ where it will be used to make ________________________
Summary:

The bases of DNA are grouped into 3 letter “words”. These words are called
________________________________

____________________________________ (enzyme) attaches to DNA and
separates the DNA strands. The RNA polymerase then uses one strand of DNA
as a template from which nucleotides are assembled into a strand of mRNA.
o RNA polymerase only binds to DNA in an area called the
______________________ region, which has a specific base sequence.
The promoters _______________________________________________
___________________________________________________________

mRNA bases are floating around in the nucleus and now can match up with their
complementary DNA base (A-U and C-G) with the help of RNA Polymerase.

A strand of mRNA is made which _____________________________________
_______________________________________carrying DNA’s “instructions”.
TRANSCRIPTION: RNA Editing
 RNA is produced by copying ______________________________

DNA contains sequences of nucleotides called ____________________ that are
not involved in coding for proteins

____________________________ are DNA sequences that code for proteins

When RNA is formed, both __________________________________ are copied
from DNA, but the introns are _________________________________while it is
still in the nucleus

The remaining _____________________ are then joined back together to form
________________________________________
PROTEIN SYNTHESIS
Definiton: Protein Synthesis a.k.a. ______________________________is the decoding
of a strand of _______________________into a strand of _______________________
(protein)
Location: on the ____________________________________ in the cytoplasm of cells.
Purpose: to use the info (DNA’s instructions) found in __________________________
to link together ___________________________ to make ________________________
Summary:
 The bases of mRNA are grouped into 3 letter “words” too. These words are called
_____________________________

Each codon has a specific meaning, which is understood by the ribosome. Each codon
represents an_______________________________. (Codons code for amino acids)

As each codon of the mRNA moves through the ribosome, the ribosome decodes
the codon’s “meaning” and determines the amino acids that it represents. These
amino acids are then brought to the ribosome by _________________________

tRNA matches up to the codons using an ____________________________
Anticodons are 3 bases on _____________________ – anticodons match with
________________________

These amino acids connect to one another through _____________________
bonds, forming a long chain called a _________________________ or a protein.
o Stop codons: codons on the MRNA that ___________________________
_______________________________________________________________
TYING IT ALL TOGETHER:
___________________codes for the _________________________ that make up a
________________________________that determines a ______________________!
MUTATIONS
A
_____________________________is any change (error) in the nucleotide sequence.
It
may involve a part of the chromosome, or only a single base pair.
Mutations
are caused by ___________________________, physical or chemical agents
that cause mutations.
There
are two types of mutations:
 ____________________________ Mutations
 ____________________________ Mutations
CHROMOSOMAL MUTATIONS

Chromosomal mutations: ________________________________________________
________________________________________________________________________

There are four types of chromosomal mutations:
1. Deletions: _____________________________________________________
_________________________________________________________________
2. Duplications: __________________________________________________
_________________________________________________________________
3. Inversions: ____________________________________________________
_________________________________________________________________
4. Translocations: _________________________________________________
__________________________________________________________________
GENE MUTATIONS
Gene
mutations: ________________________________________________________
_______________________________________________________________________
There
are two types of gene mutations:
1. Base Substitutions
Point Mutations
Silent Mutations
2. Base Insertions & Deletions
Frameshift Mutations
BASE SUBSTITUTIONS

Point Mutations-one base is replaced with another base that changes the
_________________in a way that ____________________________ the amino acid.
EX: DNA: AAT CGA
mRNA: UUA GCU
Amino Acids: Leucine Alanine
Mutated DNA: AAT TGA
mRNA: UUA ACU
Amino Acids: Leucine Threonine
DISEASES: CYSTIC FIBROSIS, HUNTINGTONS

Silent Mutations-one base is replaced with another base that changes the mRNA codon
________________________________________________________________________
EX: DNA: AAT CGA
mRNA: UUA GCU
Amino Acids: Leucine Alanine
Mutated DNA: AAC CGA
mRNA: UUG GCU
Amino Acids: Leucine Alanine
BASE INSERTIONS AND DELETIONS:
Frameshift
Mutations-the inserting or deleting of one or more bases that ___________
________________________________________________________________________
EX: DNA: AAT CGA
mRNA: UUA GCU
Amino Acids: Leucine Alanine
Mutated DNA: AAT TCG A
mRNA: UUA AGC U
Amino Acids: Leucine Serine
DISEASES: SICKLE CELL ANEMIA
GENE REGULATION

A fraction of genes in a cell are expressed at any given time
An Example of Gene Regulation in Prokaryotes

In E. Coli, there is a cluster of 3 genes that are turned on/off together

Operon: _______________________________________________________________

These genes must be on for the bacterium to use the sugar lactose as food
Called
the ______________ operon

Lac operon genes code for proteins that ______________________________________
of bacterium and break the lactose into _________________________and
______________________________

Operator: ______________________________________________________________
________________________________________________________________________

Repressor: molecule that _________________________ genes by preventing
_____________________________from binding, therefore not allowing
______________________________ to occur
o
So, if _________________________is present, repressor binds to operator
and blocks transcription by preventing RNA polymerase from binding.
o
When lactose is present, it binds to the repressor, removes it, and then
transcription can occur!
Eukaryotic Gene Regulation

Eukaryotic gene regulation is more complex than prokaryotic

“TATA” box
o
o
Short region of DNA containing the sequence TATATA or TATAAA that
appears next to many promoter regions in eukaryotic genes
Believed to help position RNA polymerase by marking point just before
where transcription begins

Hox genes
o
Controls the differentiation of cells and tissues in the embryo