Download CHAPTER 11.1

CHAPTER 11.1
GENES ARE MADE OF DNA
What is in your GENES?

No not that kind!

These kind of genes!
GRIFFITH’S “TRANSFORMING
FACTOR” IS THE GENETIC
MATERIAL

Frederick Griffith proved that a substance
in one strain of bacteria causes a change
in another strain
FIGURE 11.1
AVERY SHOWS DNA IS THE
TRANSFORMING FACTOR
Oswald Avery, Alfred Hershey, and Martha
Chase took Griffith’s experiment one step
further
 Did experiments with viruses
 Concluded that DNA is the genetic
material of the cell

VIRUS EXPERIMENTS PROVIDE
MORE EVIDENCE
A virus consists of a package of nucleic
acid in a protein coat
 Bacteriophage- a virus that infect bacteria

VIRUS
Figure 11-4
DNA’S STRUCTURE

1950 Rosalind Franklin and Maurice Wilkins
produced photographs of DNA using x-ray
crystallography
Erwin Chargaff- 1952
Observed that the number of adenine
equals the number of thymine .
 Observed that the number of guanine
equals the number of cytosine.

DOUBLE HELIX

In 1953 James Watson and Francis Crick
looked at the photographs and with
Chargaff’s discovery gave DNA a shape of a
double helix
DOUBLE HELIX

Double Helix- twisting shape

Hypothesized that the strands were
connected by hydrogen bonds
CLASS WORK

Make a list of at least four of the scientists
we discussed today and discuss their
contribution to the discovery of DNA.
CHAPTER 11.2
NUCLEIC ACIDS STORE
INFORMATION IN THEIR
SEQUENCE OF CHEMICAL UNITS
THE BUILDING BLOCKS OF DNA
 DNA-
deoxyribonucleic acid, heritable
genetic information of an organism
 Polymer built from monomers
 Nucleotides- monomers of DNA, building
blocks, contain three parts
NUCLEOTIDES
 1)
A ring shaped sugar called deoxyribose
 2) A phosphate group
 3) A nitrogenous base
NITROGENOUS BASE
 Divided
into two groups
 Pyrimidines- single ring structures
 Purines- double ring structures
DNA STRANDS

Nucleotides are joined together by covalent
bonds between the sugar and phosphate
COMPLEMENTARY BASE PAIRS
 Adenine
(A) bonds to Thymine (T)
 Guanine (G) bonds to Cytosine (C)
 EXAMPLE:
 AAT GCT ATG
 TTA CGA TAC
PRACTICE
 1)
 2)
 3)
 4)
 5)
AAT GGC TAT
CAT GAT TAC
CCG TTA CCA
GCG ATA GAC
CAG TCA GCA
THE TEMPLATE MECHANISM

When a cell divides a complete new set of
genetic instructions is made
THE TEMPLATE MECHANISM
 DNA
Replication- the process of copying
the DNA molecule
Enzymes Involved in Replication
 DNA
Helicase- unzips DNA, breaks the
Hydrogen bonds between the base pairs in
order to create origin of replication
REPLICATION OF THE DOUBLE
HELIX

DNA Polymerase- makes the covalent bonds
between the nucleotides
Class Work
 1.
Describe how DNA replicates by using a
template.
2. List the steps involved in DNA
replication.
3. Under what circumstances is DNA
replicated?
Class Work
 1.
What are the three parts of a
nucleotide? Which parts make up the
backbone of a DNA strand?
2. List the two base pairs found in DNA.
3. If six bases on one strand of a DNA
double helix are AGTCGG, what are the six
bases on the complementary section of
the other strand of DNA?
THE TEMPLATE MECHANISM

When a cell divides a complete new set of
genetic instructions is made
THE TEMPLATE MECHANISM
 DNA
Replication- the process of copying
the DNA molecule
REPLICATION OF THE
DOUBLE HELIX

DNA Polymerase- makes the covalent bonds
between the nucleotides
Class Work
 1.
Describe how DNA replicates by using a
template.
2. List the steps involved in DNA
replication.
3. Under what circumstances is DNA
replicated?
CHAPTER 11.4 and 11.5
A GENE PROVIDES THE
INFORMATION FOR MAKING A
SPECIFIC PROTEIN

ONE GENE, ONE
POLYPEPTIDE- Don’t need to
write
George Beadle and Edward Tatum worked
with the bread mold neurospora crassa

ONE GENE, ONE
POLYPEPTIDE- Don’t need to
write
One Gene-One Enzyme Hypothesis- the
function of an individual gene is to dictate the
production of a specific enzyme
 Now…ONE GENE-ONE POLYPEPTIDE
HYPOTHESIS
INFORMATION FLOW: DNA TO
RNA TO PROTEIN

RNA- ribonucleic acid, has a sugar or
ribose, base uracil, single stranded
INFORMATION FLOW: DNA TO
RNA TO PROTEIN

DNA
 Deoxyribose
 Thymine
 Double-Stranded

RNA
 Ribose
 Uracil
 Single Stranded
INFORMATION FLOW: DNA TO
RNA TO PROTEIN
INFORMATION FLOW: DNA TO
RNA TO PROTEIN


Transcription- when DNA is converted into
single stranded mRNA, in nucleus
mRNA moves to cytoplasm while DNA
stays in the nucleus
INFORMATION FLOW: DNA TO
RNA TO PROTEIN

Translation- the nucleic acid information
(RNA) is converted into amino acids, in
cytoplasm
 Codon- a three-base “word” that codes for one
amino acid
 Several codons form a polypeptide
TRANSLATION: RNA TO
PROTEIN
 Transfer RNA- translates the 3 letter codon of mRNA
into an amino acid
TRANSLATION: RNA TO
PROTEIN
 Anticodon- a triplet of bases that is complementary to
a specific mRNA sequence
THE TRIPLET CODE

Marshall Nirenberg figured out that the
codon UUU makes the amino acid
phenylalanine
CHANGE THE DNA to mRNA

1.
2.
3.
4.
5.

PAGE 12 CLASSWORK/HW




TAT CAT GAT
CCA GGG CTA
TAC TAG TTC
GCA ATA TTC
GCA ATG CCT
CLASS WORK

1. How did Beadle and Tatum's research result
in the "one gene–one polypeptide" hypothesis?
2. Which molecule completes the flow of
information from DNA to protein?
3. Which amino acid is coded for by the RNA
sequence CUA?
4. List two ways RNA is different from DNA.
CHAPTER 11.5
THERE ARE TWO MAIN STEPS
FROM GENE TO PROTEIN
TRANSCRIPTION: DNA TO
RNA

3 types of RNA
– Messenger RNA (mRNA)
– Transfer RNA (tRNA)
– Ribosomal RNA (rRNA)
Messenger RNA- an RNA molecule which is
transcribed (COPIED) from a DNA template
 RNA Polymerase- links the RNA nucleotides
together

EDITING THE RNA MESSAGE
Intron- non-coding regions of DNA
 Exon- parts of a gene that will be

translated or expressed
 RNA Splicing- when the introns are
removed from the RNA before it moves to
the cytoplasm

TRANSLATION: RNA TO
PROTEIN
Transfer RNA- translates the 3 letter codon of
mRNA into an amino acid

TRANSLATION: RNA TO
PROTEIN
Anticodon- a triplet of bases that is
complementary to a specific RNA sequence
 Ribosomal RNA- located in the ribosome
CLASS WORK

1. What kind of nucleic acid is made during
transcription?
2. How do introns and exons relate to RNA
splicing?
3. List the three RNA types involved in
transcription and translation, and describe the
role of each.
4. Briefly describe the steps of protein synthesis.
CHAPTER 11.6
MUTATIONS CAN CHANGE THE
MEANING OF GENES
HOW MUTATIONS AFFECT
GENES

Mutation- any change in the nucleotide
sequence of DNA
 Two types
– Base Substitution
– Base Insertion/Deletion
WHAT CAUSES MUTATIONS?
Errors in DNA replication
 Mutagens- physical or chemical agents
that cause mutations

– X-rays
– UV Light
– Smoking

Mutations can be harmful or beneficial
CLASS WORK
1. Explain why a base substitution is often
less harmful than a base deletion or
insertion.
 2. Describe how a mutation could be
helpful rather than harmful.
 3. Give an example of a mutagen.


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