Nucleic acids, Replication, and Protein Synthesis
1.
2.
3.
4.
5.
Can we see DNA with the naked eye? **
What evidence supports the presence of DNA? **
Would every cell in a particular org. have the same DNA? **
Why are sex cells an exception? **
Why must replication of DNA be accurate? **
I. Nucleic Acids
A. Scientific discoveries
1. Griffith 1928
(basically found that DNA is genetic material)
a. studied (**) in mice
b. S type - smooth- had a coat,
virulent b/c it killed mice
R type - rough- no coat,
avirulent b/c mice live
c. heat killed S cells were injected,
mice (**)
d. heat killed S + living R were injected
mice (**)
e. cultured smooth cells from dead mice
f. Griffith called this (**)
b/c something got into R to make S
What caused this? **
2. Hershey and Chase 1952
(basically found that DNA is genetic material)
a. studied (**)- virus that infects bacteria
b. they knew viruses attached to bacteria cells
and bacteria were changed
c. they didn’t know if it was the protein capsule or DNA
d. labeled capsid (protein coat) with S35 and DNA with P32
e. found (**) in bacteria cells, not (**)
f. therefore, nucleic acids (DNA) is the genetic material
g. (**) - incorporation of viral DNA
into host cell's DNA
B. DNA (deoxyribonucleic acid)
1. carries the genetic blueprints for life (heredity)
2. in the nucleus of eukaryotic cells as chromatin
3. structure is a (**) (like twisted ladder, supercoiled to make chromosomes)
a. Watson & Crick uncovered the structure 1962, built model (wood, plastic, wire)
b. used x-ray diffraction information from Rosalind Franklin (died 1958) & Wilkins
4. backbone of the ladder is made of
a. sugar called (**)
b. phosphate
5. rungs of the ladder made of bases
a. purines (double ring) (**) and (**)
b. pyrimidines (single ring) (**) and (**)
6. antiparallel structure- bases only pair in a certain way (Chargaff’s Rule)
a. ADENINE = THYMINE double hydrogen bond (make up a base pair)
Franklin’s x-ray
diffraction of DNA
b. CYTOSINE = GUANINE triple hydrogen bond (make up a base pair)
7. monomers of DNA are (**) (sugar, phosphate, base)
DNA diagrams:
T A
C
= phosphate group
=5 carbon sugar
(deoxyribose)
G
A
G
C
T
C
A
T
G
C. RNA (ribonucleic acid)
1. uses information that DNA stores to synthesize proteins
2. single stranded, made of nucleotides where the sugar is (**)
3. uracil is used instead of thymine
4. 3 types
a. mRNA-(**), has codons, is a pattern for a.a. assembly in
ribosome
protein synth. because it copies DNA
b. tRNA-(**), has anticodon region and carries an amino acid
to the ribosome, cloverleaf or folded shape, 1 for each a.a.
c. rRNA- (**), forms ribosomes by combining with proteins
(large subunit and small subunit)
D. DNA vs. RNA
1. two similarities between RNA and DNA
a. (**)
b. (**)
2. five differences between RNA and DNA
a. (**)
b. (**)
c. (**)
d. 3 types of RNA, only 1 type of DNA
e. locations: RNA in the nucleolus, ER, and cytoplasm; DNA only in nucleus
= nitrogenous bases
A~ adenine
T~ thymine
C~ cytosine
G~ guanine
Discussion Questions ***************************************************
1. What happens during interphase? **
2. Does this happen before or after a cell divides? **
3. Why does it happen this way? **
4. What is replication or what does it mean? **
5. What is the shape of DNA? **
6. How can we get a molecule shaped like this to copy itself? **
II. Replication (~>^<~ honors) http://www.johnkyrk.com/DNAreplic.swf
A. DNA has the ability to duplicate or make copies of itself.
1. to replicate, strands must be untwisted and unzipped. (hydrogen bonds broken)
2. replicating DNA is called a "replicating fork," each strand is a template (pattern)
3. DNA polymerase allows free nucleotides to bond to open strands (AtoT & CtoG)
~>^<~ 4. DNA polymerase only works 5' to 3', adding to 3'
~>^<~ 5. 5' to 3' strand is the leading strand replicated constantly, 3' to 5' is lagging strand
~>^<~ 6. lagging strand has to be constructed away from fork in Okazaki fragments (1968)
~>^<~ 7. DNA ligase joins the fragments
8. end with 2 strands of DNA, each with 1 old and 1 new strand (semi-conservative)
B. Replication is during interphase so each new daughter cell has the same information before mitosis.
1. What is a code? ** (ex. *)
2. How is DNA a code? **
**WMZ RH GSV TVM`VGRX YOFVKIRMG ULI MVD ORUV**
BIOLOGY= YRLOLTB (A=Z,B=Y,C=X,D=W,E=V,F=U,G=T,H=S,I=R,J=Q,K=P,L=O,M=N)
adv HW- make coded message, give 1 clue word w/ message, bring key and solution on separate page
III. Genetic code
A. is a system that contains information needed by cells to function and make proteins
B. proteins made from assortments of 20 different (**)
C. genetic code is determined by 4 nucleotide bases (A,T,C,G)
1. only 4 nucleotides/letters in the language and 20 a.a. to code for
2. 4 letters are not enough to code for 20 a.a.'s, DNA uses ‘words’ with 3 letters.
D. 3 bases = 1 codon ‘word’ codes for 1 a.a.
E. (**)
F. the genetic code is on DNA and is copied and carried by a messenger, mRNA, b/c
(**)
IV. Protein Synthesis (BIG MAC) a.a.(monomers) linked = polypeptides (polymers)
A. Transcription- process of making a complementary strand of mRNA from DNA
1. (**)
2. mRNA uses one DNA strand
(lagging strand-3' to 5') as a template (pattern)
3. (**)
4. introns (**) are removed and exons (**) are
rejoined
5. mRNA (5' to 3') leaves nucleus and travels to a
(**) in the cytoplasm
B. Translation- synthesis of a polypeptide (or protein)
from the info. on mRNA
1. as mRNA enters the cytoplasm, a (**)
attaches to the mRNA
2. ‘start’ codon on mRNA (5’AUG 3’) is recognized
3. tRNA anticodon binds to mRNA codon, brings
proper a.a. to the ribosomes
4. a.a. are chemically joined (**) by
enzymes to
form a protein
5. protein leaves the mRNA/ribosome/tRNA complex
(**)
(**)
(**)
Translation animation:
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html
For reference, look at the codon chart on the next page.
You DO NOT have to memorize it. You WILL have to know how to use it!
mRNA Codon Chart
To use the codon chart:
Determine the ROW by looking for the first base in the codon along the left side of the chart.
Determine the COLUMN by looking for the second base in the codon along the top of the chart.
Place your finger in the box where the two intersect.
Determine the POSITION by looking for the last base in the codon along the right side.
ex. mRNA codon= CAC...the amino acid coded for is Histidine.
First
Position
(5’ end)
U
C
A
G
Second Position
U
C
A
G
Third
Position
(3’ end)
Phenylalanine
Phenylalanine
Leucine
Leucine
Leucine
Leucine
Leucine
Leucine
Isoleucine
Isoleucine
Isoleucine
Methionine (start)
Valine
Valine
Valine
Valine
Serine
Serine
Serine
Serine
Proline
Proline
Proline
Proline
Threonine
Threonine
Threonine
Threonine
Alanine
Alanine
Alanine
Alanine
Tyrosine
Tyrosine
STOP
STOP
Histidine
Histidine
Glutamine
Glutamine
Asparagine
Asparagine
Lysine
Lysine
Aspartic Acid
Aspartic Acid
Glutamic Acid
Glutamic Acid
Cysteine
Cysteine
STOP
Tryptophan
Arginine
Arginine
Arginine
Arginine
Serine
Serine
Arginine
Arginine
Glycine
Glycine
Glycine
Glycine
U
C
A
G
U
C
A
G
U
C
A
G
U
C
A
G
V. DNA Technology
A. Genetic engineering
1. inserting foreign DNA into host DNA to make recombinant DNA
2. (**)- any DNA with foreign DNA in it
3. human genes that code for specific proteins are inserted into a plasmid
4. (**)- circular piece of bacterial DNA
5. the bacterial cell makes the protein that the human (**) codes for
a. human growth hormone
b. insulin
c. interferon- proteins produced in response to foreign agents (virus, bacteria, parasites, tumors)
6. example: a plasmid with the gene for insulin is injected into a bacteria cell, the bacteria reads the
plasmid and starts to make insulin.
B. Human Genome Project (started **, ended **)
1. was a collaborative effort of international scientists
2. to determine the (**) and (**)of each gene
3. to ultimately (**)
C. Electrophoresis and DNA Profiles
1. Electrophoresis gels are DNA (**)
a. NO 2 people have the same profile b/c every person’s
DNA is different
b. the only exceptions are (**).
2. (**) have many uses including
a. identifying a murderer or a rapist
b. determining who the parent of a child may be.
3. How electrophoresis works:
a. DNA sample is extracted from the (**) of a cells
b. PCR (polymerase chain reaction) is used to (**) DNA
c. DNA is mixed with (**) enzymes that cut up
the DNA at specific spots. For example, a restrictive
enzyme will only cut where the sequence is ATTACG.
TAATGC
d. the cut up DNA is placed into wells (holes or depressions, 4 blue arrows) in the gel and an
electrical current (red arrow) flows through the (**) making the pieces of DNA move.
e. the (**) the piece of DNA, the farther it moves through the gel
(small objects have an easier time moving through a fluid than large pieces).
DNA strand A T C G C G A T T A C G A A A T G C G C A T T A C G A T G G
T A G C G C T A A T G C T T T A C G C G T A A T G C T A C C
person 1
A T C G C G A T T A C G A A C G C A T T A C G A T G GACCC
T A G C G C T A A T G C T T G C G T A A T G C T A C CTGGG
person 2
C G G A T T A C G A T G G A T T A C G G C T A G C G T A T C
G C C T A A T G C T A C C T A A T G C C G A T C G C A T A G
After a gel has been run, the DNA
has migrated through the gel and
bands form on the gel.
The sequence of bands is known as a
person’s DNA profile.
A= baby Jane
B= Mother
C= Dad #1
D= Dad #2
E= Dad #3
Who is the father of Baby Jane? (**)
A
B
C
D
E