Download How is protein related to DNA?

Figure 12–2 Griffith’s Experiment
Section 12-1
Heat-killed,
disease-causing
bacteria (smooth
colonies)
Disease-causing
bacteria (smooth
colonies)
Harmless bacteria Heat-killed, disease(rough colonies) causing bacteria
(smooth colonies)
Dies of pneumonia
Go to
Section:
Lives
Lives
Control
(no growth)
Harmless bacteria
(rough colonies)
Dies of pneumonia
Live, disease-causing
bacteria (smooth colonies)
Figure 12–2 Griffith’s Experiment
Section 12-1
Heat-killed,
disease-causing
bacteria (smooth
colonies)
Disease-causing
bacteria (smooth
colonies)
Harmless bacteria Heat-killed, disease(rough colonies) causing bacteria
(smooth colonies)
Dies of pneumonia
Go to
Section:
Lives
Lives
Control
(no growth)
Harmless bacteria
(rough colonies)
Dies of pneumonia
Live, disease-causing
bacteria (smooth colonies)
Avery and Colleagues
• 1944
• Let’s repeat Griffith’s work!
• But which molecule is involved in the
transformation?
• Was the “gene” a carbohydrate, lipid, protein,
RNA or DNA?
Figure 12–4 Hershey-Chase
Experiment
Section 12-1
Go to
Section:
Bacteriophage with
phosphorus-32 in
DNA
Phage infects
bacterium
Radioactivity inside
bacterium
Bacteriophage with
sulfur-35 in protein
coat
Phage infects
bacterium
No radioactivity inside
bacterium
Figure 12–4 Hershey-Chase
Experiment
Section 12-1
Go to
Section:
Bacteriophage with
phosphorus-32 in
DNA
Phage infects
bacterium
Radioactivity inside
bacterium
Bacteriophage with
sulfur-35 in protein
coat
Phage infects
bacterium
No radioactivity inside
bacterium
Figure 12–4 Hershey-Chase
Experiment
Section 12-1
Go to
Section:
Bacteriophage with
phosphorus-32 in
DNA
Phage infects
bacterium
Radioactivity inside
bacterium
Bacteriophage with
sulfur-35 in protein
coat
Phage infects
bacterium
No radioactivity inside
bacterium
James Watson and Francis Crick
Two young scientists responsible for determining the actual
structure of DNA in 1953
Main Characters
•
•
•
•
James Watson
American
23
Has Ph.D. in Biology at
very young age
• Very ambitious
• Wants to be famous
•
•
•
•
•
•
Francis Crick
British
35
No Ph.D.
Trained as a Physicist
Cavendish Lab
Rosalind Franklin
• British chemist who
used x-ray diffraction
technique to determine
the structure of the
DNA molecule
• 1950’s
Chromosomes and DNA
The Nucleus of a cell contains
chromosomes.
• Chromosomes are
composed of coiled DNA
• DNA is composed of
segments called genes
•
Genes determine an
organisms traits
Figure 12-10 Chromosome
Structure of Eukaryotes
Section 12-2
Chromosome
Nucleosome
DNA
double
helix
Coils
Supercoils
Histones
Go to
Section:
DNA Extraction
• Step 1 collect your cells (chewing your cheek)
• Step 2 Lyse the cells (the lysis buffer contains
detergent which will break up the cell
membranes)
• Step 3 Remove the proteins from the DNA
(the protease enzyme and the 50°C water)
• Step 4 Condense the DNA (use salt and
alcohol to take all the individual strands and
collect them together)
Figure 12–7 Structure of DNA
Polymer:
Nucleic Acid
Section 12-1
Monomer:
Nucleotide
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Go to
Section:
Figure 12–5 DNA Nucleotides
Section 12-1
Purines
Adenine
Guanine
Phosphate
group
Go to
Section:
Pyrimidines
Cytosine
Thymine
Deoxyribose
DNA Extraction Matching
• Harvest the cells
• Dissolve cell membranes
• Precipitate the DNA (so it is
visible)
• Break down the proteins
• Make DNA less soluble in
water (allowing it to come
together)
A. Gently chew the inside of
your mouth and rinse with
water
B. Add protease (enzyme),
incubate @ 50⁰C
C. Mix in a detergent solution
D. Add salt
E. Layer cold alcohol over cell
extract
Section 12-1
Percentage of Bases in
Four Organisms
Source of DNA
A
T
G
C
Streptococcus
29.8
31.6
20.5
18.0
Yeast
31.3
32.9
18.7
17.1
Herring
27.8
27.5
22.2
22.6
Human
30.9
29.4
19.9
19.8
Chargaff’s Rules
Go to
Section:
February 28th 1953
The Eagle Pub
in Cambridge,
England
Countdown- 3 days!
• Protein Structure- wrap up/ discuss
• HW Check: Read and Notes p. 47, 48
and 51-53
• Enzyme Discussion and Video
• Reminder: DNA History and Structure
Test Friday
How is protein related to DNA?
Gene Expression
DNA
RNA
Protein
Traits
Review
ORGANIC POLYMER
Monomer
Function in living
things
Carbohydrate
Monosaccharide
Energy transfer.
Used in
photosynthesis and
cellular respiration
Lipid
Glycerol and Fatty
Acids
Major Component of
cell membranes
Nucleic Acid
Nucleotide
DNA and RNA. Used
to carry genetic
code.
?
?
?
PROTEINS
Macromolecules that contain:
•Carbon
•Hydrogen
•Oxygen
•Nitrogen
Monomer: Amino Acids (20 different kinds in nature)
•Amino group
•Carboxyl group
•R-Group
Polymers: Protein; many different shapes
due to the nature of the R-group
Figure 2-16 Amino Acids
Section 2-3
General structure
Amino group
Carboxyl
group
Alanine
Go to
Section:
Serine
Uses:
•control rate of reactions (act as enzymes)
•Structural molecule: formation of bones and muscles
•help with transport of substances across the cell membrane
•help fight disease (many immune system molecules are proteins)
Examples:
Hemoglobin
Keratin
Oxytocin
Proteins are the “construction
workers” that build you, repair you,
and make you work!
Food Sources:
Section 2-3
•Dairy products (yogurt, milk, cheese)
•Lean meats (chicken, pork, beef)
Figure 2-17 A Protein
Amino
acids
Go to
Section:
What Are Enzymes?
• Proteins that act
as Catalyst to
accelerate a
chemical reaction
• Not permanently
changed in the
process
27
Enzymes
• Are specific for
what they will
catalyze
• Are Reusable
• End in –ase
-Sucrase
-Lactase
-Maltase
28
Enzymes work by weakening bonds - they HELP the
reaction happen – they DO NOT ADD ENERGY!
Without Enzyme
With Enzyme
Free
Energy
Free energy of activation
Reactants
Products
Progress of the reaction
29
Enzyme-Substrate Complex
• The reactant an
enzyme acts on
is called the
substrate
Substrate
Fun Fact:
Substrate is another
word for “reactant”
Joins
Enzyme
30
• The Active Site is a specific
region of an enzyme molecule which
binds to the substrate.
Substrate
Enzyme
Active
Site
31
Examples of enzymes at work in my body:
Sucrase breaks down sucrose
Lactase breaks down lactose
Peptidase breaks down small proteins into amino acids
DNA Helicase unwinds DNA before the process of gene copying
DNA polymerase brings together nucleotides to produce new DNA
32
Answers to DNA Modeling Lab
• Question 3
• Question 4
• Each original strand
serves as a template to
make the new strand
(semi-conservative)
• Complementary base
pairing is used to create
the new strands
• DNA polymerase
proofreads
• To make copies of our
genes
• For the processes of
mitosis (growth and
repair) and meiosis
(sexual reproduction)
Chromosomes and DNA
The Nucleus of a cell contains
chromosomes.
• Chromosomes are
composed of coiled DNA
• DNA is composed of
segments called genes
•
Genes determine an
organisms traits
Prokaryotic Chromosome Structure
Chromosome
E. coli bacterium
Bases on the chromosome
Go to
Section:
Figure 12-10 Chromosome
Structure of Eukaryotes
Section 12-2
Chromosome
Nucleosome
DNA
double
helix
Coils
Supercoils
Histones
Go to
Section:
Figure 12–11 DNA Replication
New strand
Original
strand
DNA
polymerase
Growth
DNA
polymerase
Growth
Replication
fork
Replication
fork
New strand
Go to
Section:
Original
strand
Nitrogenous
bases
Summary of DNA Replication
1. DNA Helicase (enzyme) “unzips” the DNA
molecule.
2. Each strand serves as a template for the
attachment of complementary bases
3. DNA Polymerase (enzyme) assembles a new
complementary strand for each original
strand of the DNA molecule
4. DNA Polymerase also proofreads the newly
assembled strands
DNA vs. RNA
How does the code in
DNA get carried out by
the cell?
Protein Synthesis
Protein Synthesis
•2- step process
including
Transcription and
Translation
Figure 12–14 Transcription
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
DNA
RNA
Go to
Section:
Section 12-5
Typical Gene Structure
Regulatory
sites
Promoter
(RNA polymerase
binding site)
Start transcription
Go to
Section:
DNA strand
Stop transcription
mRNA Editing
mRNA Editing
Figure 12–17 The Genetic Code
Go to
Section:
Figure 12–18 Translation
Nucleus
Messenger RNA
Messenger RNA is transcribed in the nucleus.
Phenylalanine
tRNA
The mRNA then enters the cytoplasm and
attaches to a ribosome. Translation begins at
AUG, the start codon. Each transfer RNA has
an anticodon whose bases are complementary
to a codon on the mRNA strand. The ribosome
positions the start codon to attract its
anticodon, which is part of the tRNA that binds
methionine. The ribosome also binds the next
codon and its anticodon.
Ribosome
Go to
Section:
mRNA
Transfer RNA
Methionine
mRNA
Lysine
Start codon
Figure 12–18 Translation (continued)
The Polypeptide “Assembly Line”
The ribosome joins the two amino acids—
methionine and phenylalanine—and breaks
the bond between methionine and its tRNA.
The tRNA floats away, allowing the ribosome
to bind to another tRNA. The ribosome moves
along the mRNA, binding new tRNA molecules
and amino acids.
Lysine
Growing polypeptide chain
Ribosome
tRNA
tRNA
mRNA
Completing the Polypeptide
mRNA
Ribosome
Go to
Section:
Translation direction
The process continues until the ribosome reaches
one of the three stop codons. The result is a
growing polypeptide chain.
Fig. 17-20
Growing
polypeptides
Completed
polypeptide
Incoming
ribosomal
subunits
Start of
mRNA
(5 end)
(a)
End of
mRNA
(3 end)
Ribosomes
mRNA
(b)
0.1 µm
Concept Map
Section 12-3
RNA
can be
Messenger RNA
also called
which functions to
mRNA
Go to
Section:
Ribosomal RNA
Carry instructions
also called
which functions to
rRNA
Combine
with proteins
from
to
to make up
DNA
Ribosome
Ribosomes
Transfer RNA
also called
which functions to
tRNA
Bring
amino acids to
ribosome
Central Dogma of Biology
Gene Expression
DNA
RNA
Protein
Traits
Mutations
Example:
BRAF V600E
Heredity Influenced Mutations
(Germline Mutations)
Environmentally Influenced
Mutations (Somatic Mutations)
• Mistake that is present in
the DNA of virtually all body
cells
• The mistake must occur in
the reproductive cells
(sperm or egg)
• The mistake is copied into
every body cell and can be
passed to the next
generation
• Changes in the DNA that
occur throughout the
person’s life.
• Mutations are only passed
to the descendants of the
mutated cell during cell
division (mitosis)
• Possible causes: Cell division
mistakes, sun damage,
radiations exposure, toxins,
aging
Case Study Mutation: Sickle Cell
Anemia
• Normal Hemoglobin Gene mRNA:
– CCC GAA GAA AAA
• Sickle Cell Hemoglobin Gene mRNA:
– CCC GUU GAA AAA
Mutations
Gene Mutations:
Substitution, Insertion, and Deletion
Deletion
Substitution
Go to
Section:
Insertion
Case Study Mutation: Sickle Cell
Anemia
• Normal Hemoglobin Gene mRNA:
– CCC GAA GAA AAA
– Pro Glu Glu Lys
• Sickle Cell Hemoglobin Gene mRNA:
– CCC GUU GAA AAA
– Pro Val Glu Lys
Types of Gene Mutation
Figure 12–20 Chromosomal
Mutations
Section 12-4
Deletion
Duplication
Inversion
Translocation
Go to
Section:
Examples of Chromosomal Mutations
• Examples of structural
chromosomal abnormalities
include cri du chat
syndrome. Children with
this syndrome have an
abnormally developed
larynx that makes their cry
sound like the mewing of a
cat in distress, as well as
systemic defects. Affected
children usually die in
infancy. Cri du chat is
caused by a deletion of a
segment of DNA in
chromosome 5.
• A structural abnormality in
chromosome 21 occurs in
about 4% of people with
Down syndrome. In this
abnormality, a
translocation, a piece of
chromosome 21 breaks off
during meiosis of the egg or
sperm cell and attaches to
chromosome 13, 14, or 22.
Example Chromosomal Mutations
• Down Syndrome
– 47 XY or 47 XX (extra chromosome 21)
• Turner Syndrome
– 45 X (female missing one X)
• Klinefelter Syndrome
– 47 XXY (male with an extra X)