Major Concepts for 4th 6 weeks
• Mendel Genetics – Slides 2-25• Pedigrees – Slides 26-36• DNA and RNA (protein synthesis) – Slides 37-
73• Genetic Disorders – Slides 74-78• Mutations – Slides 79-101• Genetic Engineering – Slides 102 -117
Mendel Genetics
• Objectives:• Predict the outcome of a cross between parents
of know genotype.• Determine the probability of a particular trait in
an offspring based upon the genotype of parents and the particular mode of inheritance.
• Incomplete dominance, co-dominance, multiple alleles, polygenic, complete dominance, and sex-linked
Word Wall
Homozygous
Heterozygous
Genotype
Phenotype
GeneAllele
Gamete
Hybrid
True-breeding
Sex Cells – Egg and Sperm
TT or tt
Physical TraitTall
Tt
Form of gene (T or t)2 Alleles (one from each parent that code for trait)
The actual genetic make-upTT:Tt:tt
Big Eyes are dominant = BB or BbSmall eyes = bb
Punnett square example
Alleles for Female
Alleles for male
Both parents are heterozygousYy x Yy
PossibleGenotypes of Offspring1 YY:2 Yy: 1 yyPhenotype –3:1
Genotype = Phenotype = Probability =
R R
r
r4 Rr (heterozygous)4 round100% round
RR or Rr= roundrr = wrinkled
Rr Rr
Rr Rr
Cross a homozygous Round with wrinkled
Parents are RR which is same (homozygous) alleles for dominant and rr which are same for recessive trait
In a Punnett square, theAlleles always move to squares as shown.
The actual alleles
Physical description of trait
Genotype = Phenotype = Probability =
R r
R
r1 RR:2Rr:1rr3 Round, 1 wrinkled75% round, 25% wrinkled
RR or Rr= roundrr = wrinkled
RR Rr
Rr rr
Cross a hybrid with a hybrid
Parents are Rr which is heterozygousCLASSIC – Mendel Hybrid CrossDominant – 75%Recessive – 25%
In a Punnett square, theAlleles always move to squares as shown.
The actual alleles
Physical description of trait
*Determine recessive trait by small number showing the trait
Independent Assortment
• Alleles separate independently during the formation of gametes.
The dihybrid crossEeTt x EeTt
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cross: TtYy x TtYy
TY
TY
Ty
Ty
tY
tY
ty
ty
Tall, yellow Tall, yellow
9 tallplants with
yellow seeds
3 tallplants withgreen seeds
3 dwarfplants with
yellow seeds
1 dwarfplant with
green seeds
Tall, yellow Tall, yellow
Tall, yellow Tall, green Tall, yellow Tall, green
Tall, yellow Tall, yellow Dwarf, yellow Dwarf, yellow
Tall, yellow Tall, green Dwarf, yellow Dwarf, green
TTYY TTYy TtYY TtYy
TTYy TTyy TtYy Ttyy
TtYY TtYy ttYY ttYy
TtYy Ttyy ttYy ttyy
Genotypes:
Phenotypes:
1 TTYY : 2 TTYy : 4 TyYy : 2 TtYY : 1 TTyy : 2 Ttyy : 1 ttYY : 2 : 1 ttyyttYy
Mendel’s Peas Dihybrid Cross
Notice Phenotype Ratio9:3:3:1
Incomplete DominanceJapanese four-o-clock flowers
• Red flower plant genotype = RR• White flower plant genotype = WW• Pink flower plant genotype = RWAppear blended. Incomplete, not Full
Strength.
Genotype = Phenotype = Probability =
R R
W
W4 RW4 Pink100% Pink
RR = RedWW = whiteRW = Pink
RW RW
RW RW
Cross a Red flower with a White Flower
Parents are RR for red and WW for white. Both are homozygous or true breeding.
In a Punnett square, theAlleles always move to squares as shown.
The actual alleles
Physical description of trait
Co Dominance
Roan Cow
FULL Strength
RR x WW = RW orRR X R’R’ = RR’
NOTE: Alleles can be represented different ways. RR for Red, WW for White,RW for Roan or RR for Red, R’R’ for white, and RR’ for Roan. Let’s look at a Punnett Square with both examples.
Genotype = Phenotype = Probability =
R W
W
W2 RW, 2 WW2 Roan, 2 White50% Roan, 50% White
RR = Red cowWW = white cowRW = Roan Cow
RW WW
RW WW
Cross a Roan cow with white cow. Co-Dominance
Parents are RW for Roan which is heterozygous WW which is homozygous for White
In a Punnett square, theAlleles always move to squares as shown.
The actual alleles
Physical description of trait
Genotype = Phenotype = Probability =
R R’
R’
R’2 RR’, 2 R’R’2 Roan, 2 White50% Roan, 50% White
RR = Red cowR’R’ = white cowRR’ = Roan Cow
RR’ R’R’
RR’ R’R’
Cross a Roan cow with white cow. Co-Dominance
Parents are RW for Roan which is heterozygous WW which is homozygous for White
In a Punnett square, theAlleles always move to squares as shown.
The actual alleles
Physical description of trait
Multiple Alleles
• When more than two alleles (form of gene) contribute to the phenotype.
• Human blood types are an example• There are three possible alleles: A,B, and O• Both A and B are dominant over O.• O is recessive • AB is an example of Co-Dominance
6 different genotypes, 3 different Alleles
• IAIA
• IAi• IAIB
• IBIB
• Ibi• i i Type O
Type AB
Type A - 2 possible genotypes
Type B – 2 possible genotypes
Genotype = Phenotype = Probability =
IA i
IB
IB
IAIB, IBi2 AB, 2 B50% AB, 50% B
A = IAIA, IAiB= IBIB, IBiAB =IAIB O = ii
IAIB IBi
IAIB IBi
Cross a heterozygous type A with homozygous type B
Punnett square theAlleles always move to squares as shown.
The actual alleles
Physical description of trait
Polygenic traits• Traits controlled by two or more
genes.• Lots of variation in trait.• Examples:
–Human height,eye and skin color
Figure 11.17
Skin Color
Autosomal and Sex-Linked Traits
• Autosomal - Traits controlled by genes on chromosomes 1 -22.
• Sex-Linked – Traits controlled by the X chromosome or the Y chromosome.
• Most often sex-linked traits are on the X chromosome.
• Let’s look at some of examples and work together.
Genotype = Phenotype =
Probability =
Xn Y
XN
XnXNXn,XnXn,XNY,XnY2 Females, 1 Normal, 1 Color-blind2 Males, 1 Normal, 1 Color-blind50% Colorblind
Female = XXMale = XYNormal = N, color-blind = n
XNXn XNY
XnXn XnY
Cross a heterozygous female with a colorblind male
The actual alleles
Physical description of trait
Work like any other Punnett Square. Remember no letter on the Y.The trait is connected to the X!
Test Your Knowledge of Punnett Square
• http://www.biology.clc.uc.edu/courses/bio105/geneprob.htm
Sex Cells (Gametes) from Meiosis1N
EGG
Pedigrees
• Apply pedigree data to interpret various modes of genetic inheritance.
A pedigree is a chart of the genetic history of family over several generations.
Scientists or a genetic counselor would find out about your family history and make this chart to analyze.
Symbols in a Pedigree Chart
• Normal Female• Affected female Female carrier Not all
pedigrees show carriers
Normal Male Affected Male
Male carrier – Not possible in Sex-linked traits (if you see carrier male, it is autosomal)
Female is represented by a circle
Male is represented as a square
What does a pedigree chart look like?
1st generation
2nd generation
3rd generation
• Does this pedigree show a sex-linked trait?• Yes, males are affected more than females, and females are carriers.• How many children were born in generation 2 to couple with affected male?• 3, 2 boys and a girl.• What is the genotype of the female in generation 3?• XNXN
• What are genotypes for generation 1?
XNYXNXn
XNXNXnY
1st generation
2nd generation
3rd generation
XNYXNXN or XNXn
XnY
This is the same pedigree without female carriers being shown. The large affect it has on males, tells us it is sex-linked and since it is not showing up in females, it is recessive. NOT all pedigrees will show carriers, so be careful with analyzing!
If carriers are not shown, genotype could be homozygous or heterozygous even though trait is not shown.
XNXN or XNXn
Interpreting a Pedigree Chart
1. Determine if the pedigree chart shows an autosomal or X-linked disease.
– If most of the males in the pedigree are affected the disorder is most likely X-linked
– If it is a 50/50 ratio between men and women the disorder is most likely autosomal
• When interpreting a pedigree chart of a family with a disease like muscular dystrophy, it is important to consider two steps. The first is to determine if the disorder is autosomal or X-linked.
• If the disorder is X-linked most of the males will have the disorder because the Y-chromosome cannot mask the affects of an affected X-chromosome. A female can have the disorder, but it would be a very low percentage. For a female to be affected, she would have had to receive an affected gene from both the mother and the father. This means that the father would have the disorder and the mother was a carrier.
• In an autosomal disorder, the disorder is not found on the X or Y chromosome. It is found on the other 22 chromosomes in the human body. This means that men and women have an equal chance of having the disorder.
Is it Autosomal or X-linked?
Autosomal because it affects males and females equally
Interpreting a Pedigree Chart
2. Determine whether the disorder is dominant or recessive.
– If the disorder is dominant, one of the parents must have the disorder.
– If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.
It is important to find out if a disorder is dominant or recessive. For example, Huntington’s disease is a dominant disorder. If you have only one dominant gene you will have Huntington’s disease, which is a lethal disorder. The disorder does not show up until a person is in their middle ages such as 45. It will quickly decrease their motor skills and the brain will begin to deteriorate.
• If a disorder is dominant, one parent must have the disorder (either homozygous dominant (TT) or heterozygous recessive (Tt). Both parents do not have to have the disorder. One parent might not have the disorder or be a carrier. If a disease is dominant, it does not skip a generation unless one parent is heterozygous dominant (Tt) and the other parent is homozygous recessive (tt). In this case the child has a chance of not receiving the dominant gene.
• If the disorder is recessive, a parent does not have to have the disorder, but could still pass it to their offspring. This would happen when a parent is heterozygous recessive (Tt) and passes on the recessive (t) gene. This means this disorder can skip generations. An example of a recessive disorder would be sickle cell anemia.
Dominant or Recessive?
It is dominant because a parent in every generation has the disorder. Remember if a parent in every generation has the disorder, the disorderhas not skipped a generation. If the disorder has not skipped a generation,the disorder is dominant.
Practice Analyzing Pedigrees
• http://www.zerobio.com/drag_gr11/pedigree/pedigree_overview.htm
Dominant or Recessive?
It is recessive, because a parent in every generation does not have the disorder. If a disorderSkips a generation, then the disorder is recessive. If a carrier is shown, it is recessive also.
DNADNA
RNARNA
ProteinProtein
Scientists call this the:
Central
Dogma of
Molecular
Biology!
DNA NucleotideDeoxyribose Nucleic Acid
OO=P-O O
Phosphate Group
NNitrogenous base (A, G, C, or T)
CH2
O
C1C4
C3 C2
5
Sugar(deoxyribose)
• James Watson and Francis Crick worked out the three-dimensional structure of DNA, based on work by Rosalind Franklin
Watson and Crick constructed a Model of DNA showing the double helix.
Figure 10.3A, B
DNA Double Helix
NitrogenousBase (A,T,G or C)
“Rungs of ladder”
“Legs of ladder”
Phosphate &Sugar Backbone
Chargaff’s Rule
• Adenine must pair with Thymine
• Guanine must pair with Cytosine
• Their amounts in a given DNA molecule will be about the same.
G CT A
DNA Double Helix
P
P
P
O
O
O
1
23
4
5
5
3
3
5
P
P
PO
O
O
1
2 3
4
5
5
3
5
3
G C
T A
DNA Nucleotides joined together Notice base pairing
A + T G + C
The Code of Life…
• The “code” of the chromosome is the SPECIFIC ORDER that bases occur. Proteins are built from the code.
A T C G T A T G C G G…
DNA Replication• DNA must be copied so new cells will
have complete instructions for making the RIGHT proteins.
• The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing:
A-T, G-C
• Each strand of the original DNA serves as a template for the new strand
Each DNA molecule contains one original and one new complementary strand
DNA Replication• Complementary base pairs form new strands.
• …DNA control cell functions by serving as a template for PROTEIN structure.
• RNA uses base pairing, but the T is replaced with U for Uracil. A + U, G + C
• 3 Nucleotides = a triplet or CODON(which code for a specific AMINO ACID
• AMINO ACIDS are the building blocks of proteins.
• Proteins regulate cell activity and express traits controlled by genes.
Protein
DNA
Trait
DNA – Blueprint for Life
RNA – Ribosome – Amino Acid
Expresses Trait
Protein Synthesis – Building Proteins
DNA contains the instructions for the proteins that are needed for life. If the DNA does not replicate correctly, the wrong protein could be made.
DNA and RNA Comparison
DNA always STAYS in NucleusRNA is in nucleus during transcription, moves in cytoplasm, and on ribosome during translation.
Deoxyribose Ribose
A+TG+C
A+UG+C
Double Strand
Single Strand
Both have Phosphate
Table 14.2Types of RNA
Type of RNA Functions in Function
Messenger RNA(mRNA)
Nucleus, migratesto ribosomesin cytoplasm
Carries DNA sequenceinformation to ribosomes
Transfer RNA(tRNA)
Cytoplasm Provides linkage between mRNAand amino acids;transfers aminoacids to ribosomes
Ribosomal RNA(rRNA)
Cytoplasm Structural component of ribosomes
DNA makes RNA during Transcription
• DNA can “unzip” itself and RNA nucleotides match up to the DNA strand.
• Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.
– The DNA is transcribed into RNA, which is translated into the polypeptide
Figure 10.6A
DNA
RNA
Protein
TRANSCRIPTION
TRANSLATION
• The information constituting an organism’s genotype is carried in its sequence of bases
Transcription produces genetic messages in the form of mRNA
Figure 10.9A
RNApolymerase
RNA nucleotide
Direction oftranscription
Newly made RNA
Templatestrand of DNA
• In transcription, DNA helix unzips
– RNA nucleotides line up along one strand of DNA, following the base-pairing rules
– single-stranded messenger RNA peels away and DNA strands rejoin
RNA polymerase
DNA of gene
PromoterDNA Terminator
DNAInitiation
Elongation
Termination
Area shownin Figure 10.9A
GrowingRNA
RNApolymerase
Completed RNA
Figure 10.9B
• Noncoding segments, introns, are spliced out
• A cap and a tail are added to the ends
Eukaryotic RNA is processed before leaving the nucleus
Figure 10.10
DNA
RNAtranscriptwith capand tail
mRNA
Exon Intron IntronExon Exon
TranscriptionAddition of cap and tail
Introns removed
Exons spliced together
Coding sequence
NUCLEUS
CYTOPLASM
Tail
Cap
RNA builds Proteins from Amino Acids during Translation
• The cell uses information from “messenger” RNA to produce proteins
mRNA leaves the nucleus to go to ribosome
rRNA and tRNA translateThe message to make proteins
tRNAAmino Acids
codon
Anti-codon
Proteins – Express Traits
• The “words” of the DNA “language” are triplets of bases called codons
• The codons in a gene specify the amino acid sequence of a polypeptide
• RNA Transcription copies the DNA onto mRNA.• Translation takes place in the cytoplasm on the
ribosomes.• tRNA picks up the correct amino acid and builds
a protein on the rRNA from the mRNA.
Translation of nucleic acids into amino acids
Types of RNA
• mRNA contains codons which code for amino acids.
3 LetterCode for amino acids
What amino acid will the code CAU make?
His
U C A G
U
C
A
G
GACU
GACU
GACU
GACU
UUUUUCUUAUUG
CUUCUCCUACUG
AUUAUCAUAAUG
GUUGUCGUAGUG
phe
leu
leu
ile
met (start)
val
UCUUCCUCAUCG
CCUCCCCCACCG
ACUACCACAACG
GCUGCCGCAGCG
ser
pro
thr
ala
UAUUACUAAUAG
CAUCACCAACAG
AAUAAC
AAGAAA
GAUGACGAAGAG
tyr
stopstop
his
gln
asn
lys
asp
glu
UGUUGCUGAUGG
CGUCGCCGACGG
AGUAGCAGAAGG
GGUGGCGGAGGG
cys
stoptrp
arg
ser
arg
gly
First Base T
hird Base
Second Base
Virtually all organisms share the same genetic code “unity of life”
64 possible combinations – 20 specific amino acids
What signals the ribosome to start translating the mRNA Into a new amino acid sequence and signals it to stop?
An initiation codon marks the start of an mRNA message
Figure 10.13A
End
Start of genetic message
AUG = methionine
• An exercise in translating the genetic code
Figure 10.8B
Startcodon
RNA
Transcribed strand
StopcodonTranslation
Transcription
DNA
Polypeptide
Proteins are built from chains of amino acids
DNA molecule
Gene 1
Gene 2
Gene 3
DNA strand
TRANSCRIPTION
RNA
Polypeptide
TRANSLATIONCodon
Amino acid
Ribosomes build polypeptides (chain of amino acids)
Figure 10.12A-C
Codons
tRNAmolecules
mRNA
Growingpolypeptide
Largesubunit
Smallsubunit
mRNA
mRNAbindingsite
P site A site
P A
Growingpolypeptide
tRNA
Next amino acidto be added topolypeptide
• mRNA, a specific tRNA, and the ribosome subunits assemble during initiation
Figure 10.13B
1
Initiator tRNA
mRNA
Startcodon Small ribosomal
subunit
2
P site
Largeribosomalsubunit
A site
Figure 10.14
1 Codon recognition
Amino acid
Anticodon
AsiteP site
Polypeptide
2 Peptide bond formation
3 Translocation
Newpeptidebond
mRNAmovement
mRNA
Stopcodon
Overview of Protein Synthesis
• Let’s look at it ONE more time!
Figure 10.15
1Stage mRNA istranscribed from aDNA template.
Anticodon
DNA
mRNARNApolymerase
TRANSLATION
Enzyme
Amino acid
tRNA
InitiatortRNA
Largeribosomalsubunit
Smallribosomalsubunit
mRNA
Start Codon
2Stage Each amino acid attaches to its proper tRNA with the help of a specific enzyme and ATP.
3Stage Initiation of polypeptide synthesis
The mRNA, the first tRNA, and the ribosomal subunits come together.
TRANSCRIPTION
Figure 10.15 (continued)
4Stage ElongationGrowingpolypeptide
Codons
5Stage Termination
mRNA
Newpeptidebondforming
Stop Codon
The ribosome recognizes a stop codon. The poly-peptide is terminated and released.
A succession of tRNAs add their amino acids to the polypeptide chain as the mRNA is moved through the ribosome, one codon at a time.
Polypeptide
Protein
DNA
Trait
DNA – Blueprint for Life
RNA – Ribosome – Amino Acid
Expresses Trait
1. Why is transcription necessary?Transcription makes messenger RNA (mRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm.
2. Describe transcription.RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble mRNA.
3. Why is translation necessary?Translation assures that the right amino acids are joined together by peptides to form the correct protein.
4. Describe translation.The cell uses information from mRNA to produce proteins. The tRNA brings the right amino acid to ribosome, rRNA to produce a specific amino acid chain that will later become an active protein.
5. What are the main differences between DNA and RNA.DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil.
6. Using the chart on page 303, identify the amino acids coded for by these codons: UGG CAG UGCtryptophan-glutamine-cysteine
Genetic Disorders
Genetic DisordersAutosomal Recessive
Both parents Must be Carriers Nn X Nn
Normal = Nnn = cystic fibrosis
Sickle Cell Anemia
Autosomal recessiveBoth parents must be carriers To pass to children.Nn X NnOr one is carrier and other has condition. Nn x nn
Would not show in parents ifCarriers
Tay-Sachs
Autosomal Recessive
Huntingdon’s Disease
Autosomal Dominant
What Are Mutations?
• Changes in the nucleotide sequence of DNA
• May occur in somatic cells (body cells,aren’t passed to offspring)
• May occur in gametes (eggs & sperm) and be passed to offspring
• May be chromosomal or gene mutations.
Protein
DNA
Gene
Trait
DNA – If there is a mutation in the DNA strand, then the RNA strand will be changed
If the mRNA brings the wrong instructions, may result in wrong protein – Ribosome – Amino Acid
Expresses TraitMutation – wrong protein
Many mutations do not change the amino acid, so NO mutation will occur.
Protein Translation
• Modified genetic code is “translated” into proteins
• Codon code is specific, but redundant!– 20 amino acids– 64 triplet (codon) combinations
Which is why some mutations don’t matter!
Gene Mutations
• Change in the nucleotide sequence of a gene
• May only involve a single nucleotide
• May be due to copying errors, chemicals, viruses, etc.
Point Mutation• Change of a single
nucleotide• Includes the deletion,
insertion, or substitution of ONE nucleotide in a gene
• Sickle Cell disease is the result of one nucleotide substitution
• Occurs in the hemoglobin gene
Frameshift Mutation• Inserting or deleting one or more nucleotides
• Changes the “reading frame” like changing a sentence
• Proteins built incorrectly
Example of Sickle Cell mutation
Normal hemoglobin DNA
mRNA
Normal hemoglobin
Glu
Mutant hemoglobin DNA
mRNA
Sickle-cell hemoglobin
Val
• Illustration of mutations
Figure 10.16B
mRNA
NORMAL GENE
BASE SUBSTITUTION
BASE DELETION
Protein Met Lys Phe Gly Ala
Met Lys Phe Ser Ala
Met Lys Leu Ala His
Missing
Figure 8.23A, B
Deletion
Duplication
Inversion
Homologouschromosomes
Reciprocaltranslocatio
n
Nonhomologouschromosomes
• Chromosomal changes can be large or small
Chromosome Mutations• May Involve:
– Changing the structure of a chromosome
– Can cause abnormal development of offspring. of part
Deletion
• Due to breakage• A piece of a chromosome is lost
Inversion
• Chromosome segment breaks off
• Segment flips around backwards
• Segment reattaches
Duplication
• Occurs when a gene sequence is repeated
Translocation
• Involves two chromosomes that aren’t homologous
• Part of one chromosome is transferred to another chromosomes
Nondisjunction• Failure of chromosomes to separate during meiosis
• Causes gamete to have too many or too few chromosomes
• Disorders:– Down Syndrome – three 21st chromosomes– Turner Syndrome – single X chromosome– Klinefelter’s Syndrome – XXY chromosomes
Normal Male Karotype
962n = 46
Normal Female Karotype
972n = 46
Male, Trisomy 21 (Down’s)
982n = 47Can you spot the problem?
Female Down’s Syndrome
992n = 47
Klinefelter’s Syndrome
1002n = 47
Genetic Engineering
• Evaluate the scientific and ethical issues associated with gene technologies.
• Genetic Engineers refers to the alteration of an organism’s genes for practical purposes.
• Recombinant DNA
• Transgenic Organisms
• Cloning
• Stem Cell Research
• Gel Electrophoresis/DNA fingerprinting
Recombinant Bacteria1. Remove bacterial DNA (plasmid).
2. Cut the Bacterial DNA with “restriction enzymes”.
3. Cut the DNA from another organism with “restriction enzymes”.
4. Combine the cut pieces of DNA together with another enzyme and insert them into bacteria.
5. Reproduce the recombinant bacteria.
6. The foreign genes will be expressed in the bacteria.
Benefits of Recombinant Bacteria
1. Bacteria can make human insulin or human growth hormone.
2. Bacteria can be engineered to “eat” oil spills.
Recombinant DNA
• The ability to combine the DNA of one organism with the DNA of another organism.
• Recombinant DNA technology was first used in the 1970’s with bacteria.
Genetically modified organisms are called transgenic organisms.
TRANSGENIC ANIMALS
1. Mice – used to study human immune system
2. Chickens – more resistant to infections
3. Cows – increase milk supply and leaner meat 4. Goats, sheep and pigs – produce human proteins in their milk
Human DNA in a Goat Cell
This goat contains a human gene that codes for a blood clotting agent. The blood clotting agent can be harvested in the goat’s milk.
.
Transgenic GoatCarries a foreign gene that has been inserted into its genome.
Desired DNA is
added to an egg cell.
How to Create a Transgenic Animal
The DNA of plants and animals can also be altered.
PLANTS
1. disease-resistant and insect-resistant crops
2. Hardier fruit
3. 70-75% of food in supermarket is genetically modified.
How to Create a Genetically Modified Plant
1.Create recombinant bacteria with desired gene.
2. Allow the bacteria to “infect" the plant cells.
3. Desired gene is inserted into plant chromosomes.
DNA Cloning
• Transfer of DNA fragment from one organism to a self-replicating genetic element such as bacterial plasmid
Reproductive Cloning
• Generate an animal that has the same nuclear DNA as another existing animal.
Therapeutic Cloning
• Also called “embryo cloning”, is the production of human embryos for use in research.
• Stem Cell Collection:• Are unspecialized cells
capable of renewing themselves through cell division.
• Under certain experimental conditions, they can be induced to become tissue or organ specific cells with special functions.
What do you think about eating genetically modified foods?
Polymerase Chain ReactionPCR
• PCR allows scientists to make many copies of a piece of DNA.
1. Heat the DNA so it “unzips”.
2. Add the complementary nitrogenous bases.
3. Allow DNA to cool so the complementary strands can “zip” together.
Steps Involved in Gel Electrophoresis
1. “Cut” DNA sample with restriction enzymes.
2. Run the DNA fragments through a gel.
3. Bands will form in the gel.
4. Everyone’s DNA bands are unique and can be used to identify a person.
5. DNA bands are like “genetic fingerprints”.