Molecular Genetics1

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Molecular Genetics

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Griffiths Experiment
Heat-killed, disease-causing bacteria (smooth
colonies)
Harmless bacteria (rough colonies)
Control(no growth)
Harmless bacteria (rough colonies)
Heat-killed, disease-causing bacteria (smooth
colonies)
Disease-causing bacteria (smooth colonies)
Dies of pneumonia
Dies of pneumonia
Lives
Lives
Live, disease-causingbacteria (smooth colonies)
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Griffiths Experiment
Heat-killed, disease-causing bacteria (smooth
colonies)
Harmless bacteria (rough colonies)
Control(no growth)
Harmless bacteria (rough colonies)
Heat-killed, disease-causing bacteria (smooth
colonies)
Disease-causing bacteria (smooth colonies)
Dies of pneumonia
Dies of pneumonia
Lives
Lives
Live, disease-causingbacteria (smooth colonies)
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Hershey-Chase Experiment
Bacteriophage with phosphorus-32 in DNA
Phage infectsbacterium
Radioactivity inside bacterium
Bacteriophage with sulfur-35 in protein coat
Phage infectsbacterium
No radioactivity inside bacterium
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Hershey-Chase Experiment
Bacteriophage with phosphorus-32 in DNA
Phage infectsbacterium
Radioactivity inside bacterium
Bacteriophage with sulfur-35 in protein coat
Phage infectsbacterium
No radioactivity inside bacterium
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Hershey-Chase Experiment
Bacteriophage with phosphorus-32 in DNA
Phage infectsbacterium
Radioactivity inside bacterium
Bacteriophage with sulfur-35 in protein coat
Phage infectsbacterium
No radioactivity inside bacterium
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Notes

• genetic genes that are inherited

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The Cell

• Nucleus stores genetic information

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Chromosomes DNA
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Notes

• Chromosomes coiled DNA

Nucleosome
Chromosome
DNA double helix
Coils
Supercoils
Histones
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Notes

• DNA (deoxyribonucleic acid) stores and transmits
  information from one generation to the next

Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key Adenine (A) Thymine (T) Cytosine (C) Guanine
(G)
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Notes

• DNA is one type of nucleic acid (one of the
  macromolecules)
• DNA shape is a double helix (twisted ladder)
• Double-stranded

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Notes

• Nucleotide
• nucleic acid molecule
• Is a monomer of DNA
• Made of 3 parts
• 5 carbon sugar (deoxyribose)
• phosphate group
• nitrogen base

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Notes

• there are 4 types of nitrogen bases
• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)

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Notes

• Complementary base pairing
• A only with T
• G only with C
• ATTCGGCCAATT
• TAAGCCGGTTAA

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Why is base pairing important?
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Notes

• DNA replication when DNA makes an exact copy of
  itself also called semi-conservative replication
• DNA unwinds and unzips

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Notes

• 2. New nucleotides are added to the separated
  DNA strands

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Notes

• 3. Two identical molecules of DNA are made, each
  containing half of the original strand and half
  is new

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Notes

• Gene part of DNA that codes for a trait

Exact location on chromosomes
Chromosome 2
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Mapping of Earths Features
Mapping of Cells, Chromosomes, and Genes
Cell
Earth
Chromosome
Country
Chromosome fragment
State
Gene
City
People
Nucleotide base pairs
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How Does the Information from DNA get out of the
Nucleus?
Adenine (DNA and RNA) Cystosine (DNA and
RNA) Guanine(DNA and RNA) Thymine (DNA
only) Uracil (RNA only)
RNApolymerase
DNA
RNA
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Notes

• RNA (ribonucleic acid) type of nucleic acid
  where the information from DNA is transferred
• Single-stranded
• 3 parts to its nucleotide
• 5 carbon sugar (ribose)
• phosphate group
• nitrogen base there are 4 types
• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Uracil (U)

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Notes

• 3 types of RNA
• Messenger RNA (mRNA) carries instructions from
  DNA to ribosome
• Ribosomal RNA (rRNA) part of the ribosome which
  helps make proteins
• Transfer RNA (tRNA) brings amino acids to
  ribosome

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Notes

• Complementary base pairing for RNA
• A only with U
• G only with C
• DNA ATTCGGCCAA
• RNA

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Notes

• Complementary base pairing for RNA
• A only with U
• G only with C
• DNA ATTCGGCCAA
• RNA UAAGCCGGUU

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Notes

• DNA uses thymine RNA uses uracil

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Notes

• Ribosomes
• Link amino acids to form proteins.

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Prokaryotic Cell
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Animal Cell
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Plant Cell
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Notes

• Functions of Protein
• Structural
• muscle, hair, etc.
• Chemical
• antibodies, hormones, enzymes, etc.
• Its monomer is the amino acid

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Notes

• Ribosomes organelles that translate information
  from RNA in order to build protein
• Amino acid a monomer of a protein
• Polypeptide a chain of amino acids
• Protein one of the basic building materials for
  the cell a chain of polypeptides
• Trait physical characteristics of an organism
  numerous proteins formed together to make a
  trait, such as hair color

Trait
Protein
Protein
Polypeptide chain
Polypeptide chain
Polypeptide chain
Amino Acid
Amino Acid
Amino Acid
Amino Acid
Amino Acid
Amino Acid
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Notes

• Codon 3 nucleotides of DNA or RNA that codes
  for amino acids (the basic building block of
  protein)
• For example, AGC Serine
• codon amino acid

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GENETIC CODE IN mRNA FORMAT
2nd base in codon
U C A G
U Phe Phe Leu Leu Ser Ser Ser Ser Tyr Tyr STOP STOP Cys Cys STOP Trp U C A G
C Leu Leu Leu Leu Pro Pro Pro Pro His His Gln Gln Arg Arg Arg Arg U C A G
A Ile Ile Ile Met Thr Thr Thr Thr Asn Asn Lys Lys Ser Ser Arg Arg U C A G
G Val Val Val Val Ala Ala Ala Ala Asp Asp Glu Glu Gly Gly Gly Gly U C A G
3rd base in codon
1st base in codon
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Notes

• Central Dogma describes the process how cells
  build materials to maintain, grow, and repair
  themselves
• DNA gt RNA gt ribosome gt protein gt trait

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Notes

• Protein synthesis process of making protein.
  There are 2 phases

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Notes

• Phase 1 - Transcription process where info from
  DNA is transferred to messenger RNA (mRNA)
• RNA polymerase (enzyme) unzips DNA
• RNA polymerase adds nucleotides to make mRNA
• Stop codon
• mRNA leaves nucleus

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Notes

• Phase 2 - Translation process where mRNA is
  read to make protein
• ribosome reads mRNA codon
• transfer RNA (tRNA) with an anti-codon (region on
  tRNA with 3 nucleotides complementary to mRNA
  codon) brings amino acids according to codon
• Amino acids connect to form a polypeptide chain
  until stop codon is reached. This will
  eventually form into protein.

Anti-codon
Codon
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• Steps to Replication
• Find the complementary DNA on the original strand
• ATCCTG
• TAGGAC
• Steps to Protein Synthesis
• Find the complementary mRNA from the DNA
  (transcription)
• ATCCTG
• UAGGAC
• Find the matching anti-codon on tRNA
  (translation)
• UAGGAC
• AUCCUG
• Find the amino acids on the chart that
  corresponds to the mRNA
• UAG / GAC
• Trp / Asp

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• DNA ATGGCTATGAGC
• Complementary DNA TACCGATACTCG
• mRNA UACCGAUACUCG
• tRNA anti-codons AUGGCUAUGAGC
• Polypeptide chain (amino acids)
  Tyrosine-Arginine-Tyrosine-Serine

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Try This

1. What are the tRNA anticodons to the DNA strand
   ATCGGTCAA?
2. What are the DNA codons to the mRNA strand
   UCGAACGGU?
3. If the polypeptide chain is Met-Trp, what is the
   DNA strand?
4. In your own words, describe the process of how
   you get a trait from DNA.

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X-men and Mutations
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Notes

• Mutations are changes in DNA.

Deletion
Substitution
Insertion
Frameshift Mutation causes the most changes
Point Mutation
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Notes

• Point mutation a change in one nucleotide in a
  strand of DNA
• Substitution when one nucleotide is substituted
  for another
• Old AGTTCG
• New AGCTCG

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Notes

• Frameshift mutations
• Deletion deletion of one or more nucleotides
• Old AGTTCG
• New AGTCG
• Insertion addition of one or more nucleotides
• Old AGTTCG
• New ACGTTCG
• Most harmful because it affects most of the DNA
  strand
• Old THE CAT ATE THE RAT
• New THC ATA TET HER AT

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Types of Chromosome Mutations
Deletion
Duplication
Inversion
Translocation
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Notes

• Mutations can be beneficial, harmful, or has no
  effect at all depending on the environment.
• For example, there is a mutation that gives a cat
  no fur versus a cat with fur. Which will survive
  better in a hot environment? Which will survive
  better in a cold environment?

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Genetic Diseases
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Tay-Sachs
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Cystic Fibrosis
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Cystic Fibrosis
Chromosome 7
CFTR gene
The most common allele that causes cystic
fibrosis is missing 3 DNA bases. As a result,
the amino acid phenylalanine is missing from the
CFTR protein.
Normal CFTR is a chloride ion channel in cell
membranes. Abnormal CFTR cannot be transported
to the cell membrane.
The cells in the persons airways are unable to
transport chloride ions. As a result, the airways
become clogged with a thick mucus.
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Polydactylism
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Brachydactylism
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Hairy Face
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Hypertrichosis
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Try It

• DNA TACAAGACCTTATAATTC
• mRNA AUGUUCUGGAAUAUUAAG
• Polypeptide chain (amino acids)
  Methionine-Phenylalanine-Tryptophan-Asparagine-Iso
  leucine-STOP
• Delete the fourth base from the DNA sequence.
• New DNA TACAGACCTTATAATTC
• New mRNA AUGUCUGGAAUAUUAAG
• New polypeptide chain (amino acids)Methionine-Ser
  ine-Glycine-Isoleucine-Leucine

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Notes

• Proteins can differ from one another in the
  number and sequence of amino acids
• Have different shapes
• A mutation can change the protein so that it
  doesnt work properly

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DNA Fingerprinting

• DNA fingerprinting is used in several ways.
• evidence in criminal cases
• paternity tests
• immigration requests
• studying biodiversity
• tracking genetically modified crops

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Gel Electrophoresis
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Gel Electrophoresis
Power source
DNA plus restriction enzyme
Longer fragments
Shorter fragments
Mixture of DNA fragments
Gel
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Southern Blot
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DNA Sequencing
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PCR
DNA polymerase adds complementary strand
DNA heated to separate strands
DNA fragment to be copied
PCRcycles 1 DNAcopies 1
3 4
4 8
5 etc. 16 etc.
2 2
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Transgenic Animals

• used to study diseases and gene functions.
• transgenic mice used to study development and
  disease
• gene knockout mice used to study gene function

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Knockout Genes
Recombinant DNA
Flanking sequences match host
Host Cell DNA
Target gene
Recombinant DNA replaces target gene
Modified Host Cell DNA
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Notes

• Cloning organism produced that is genetically
  identical to parent

The cloned cat CC which stands for carbon copy
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• Cloning occurs in nature.

• bacteria (binary fission)
• some plants (from roots)
• some simple animals (budding, regeneration)

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• Cloning has potential benefits.

• organs for transplant into humans
• save endangered species
• Cloning raises concerns.
• low success rate
• clones imperfect and less healthy than original
  animal
• decreased biodiversity

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Cloning by Nuclear Transfer
A donor cell is taken from a sheeps udder.
Donor Nucleus
These two cells are fused using an electric shock.
Fused Cell
Egg Cell
The nucleus of the egg cell is removed.
An egg cell is taken from an adult female sheep.
The fused cell begins dividing normally.
Embryo
Cloned Lamb
The embryo is placed in the uterus of a foster
mother.
The embryo develops normally into a lambDolly
Foster Mother
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Dolly the Sheep
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Notes

• Genetic engineering process of isolating a gene
  from DNA of one organism and transferring it to
  the DNA of another

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Tobacco plant Firefly gene
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Glow-in-the-Dark Mouse
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Glow-in-the-Dark Kitties
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Glow-in-the-Dark Piglets
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Glowbunny and Glofish
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Featherless Chickens
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M. mycoides

• The first synthetic cell.
• Even though the manmade DNA needed an already
  living cell to start working, eventually it
  reproduced.
• The researchers picked two species of Mycoplasma,
  simple germs that contain a single chromosome and
  lack the cell walls that form barriers in other
  bacteria. First, they chemically synthesized the
  genome of M. mycoides, that goat germ, twice as
  large as the germ genome they'd previously built.
• Then they transplanted it into a living cell from
  a different Mycoplasma species

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Notes

• Restriction enzyme enzymes that cuts DNA at a
  specific sequence of nucleotides
• Sticky ends ends of DNA that was cut with
  restriction enzymes

Recognition sequences
DNA sequence
Restriction enzyme EcoRI cuts the DNA into
fragments.
Sticky end
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Notes

• Plasmid circular DNA found in bacteria

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Notes

• Recombinant DNA DNA made from 2 or more
  different organisms

Gene for human growth hormone
Recombinant DNA
Gene for human growth hormone
DNA recombination
Human Cell
Sticky ends
DNA insertion
Bacterial Cell
Bacterial chromosome
Bacterial cell for containing gene for human
growth hormone
Plasmid
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Practice

• ACGGTCTTCGGTAT
• TGCCAGAAGCCATA
• If the restriction enzyme BamIII cut DNA at this
  site CGGT
• GCCA
• where would it cut on the above DNA strand?

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From Time, May 26, 2003
Many agricultural plants are undergoing genetic
engineering to fight pests
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Genetically Engineered Medicines
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From Time, May 26, 2003
Agricultural plants have been modified to contain
human genes to produce human proteins to fight
human disease
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Notes

• Gene therapy replaces defective or missing genes,
  or adds new genes, to treat a disease.

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Gene Therapy Techniques

• Several different experimental techniques
• genetically engineered viruses used to infect a
  patients cells
• insert gene to stimulate immune system to attack
  cancer cells
• insert suicide genes into cancer cells that
  activate a drug

Bone marrow cell
Nucleus
Normal hemoglobin gene
Chromosomes
Bone marrow
Genetically engineered virus
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Genetic Engineering Concerns

• possible long-term health effects of eating
  genetically modified (GM) foods
• possible effects of GM plants on ecosystems and
  biodiversity

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From Time, November 29, 1999
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This corn contained a protein that provides
resistance to pests and was only approved for
animal foods