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 Gamete True-breeding TT or tt Homozygous Phenotype Physical Trait Tall Heterozygous Gamete Tt Sex Cells – Egg and Sperm Hybrid Genotype The actual genetic make-up TT:Tt:tt Gene Allele 2 Alleles (one from each parent that code for trait) Form of gene (T or t)

Big Eyes are dominant = BB or Bb Small eyes = bb

Punnett square example Alleles for male Both parents are heterozygous Yy x Yy Alleles for Female Possible Genotypes of Offspring 1 YY:2 Yy: 1 yy Phenotype – 3:1

R R r r Rr Rr Rr Rr Cross a homozygous Round with wrinkled RR or Rr= round rr = wrinkled R R Parents are RR which is same (homozygous) alleles for dominant and rr which are same for recessive trait r In a Punnett square, the Alleles always move to squares as shown. Rr Rr r Rr Rr The actual alleles Genotype = Phenotype = Probability = 4 Rr (heterozygous) 4 round 100% round Physical description of trait

R r R r RR Rr Rr rr Cross a hybrid with a hybrid RR or Rr= round rr = wrinkled R r Parents are Rr which is heterozygous CLASSIC – Mendel Hybrid Cross Dominant – 75% Recessive – 25% R In a Punnett square, the Alleles always move to squares as shown. RR Rr r Rr rr *Determine recessive trait by small number showing the trait The actual alleles Genotype = Phenotype = Probability = 1 RR:2Rr:1rr 3 Round, 1 wrinkled 75% round, 25% wrinkled Physical description of trait

Independent Assortment Alleles separate independently during the formation of gametes.

The dihybrid cross EeTt x EeTt

Mendel’s Peas Dihybrid Cross Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cross: TtYy x TtYy TY Ty tY ty Mendel’s Peas Dihybrid Cross Notice Phenotype Ratio 9:3:3:1 TTYY TTYy TtYY TtYy TY Tall, yellow Tall, yellow Tall, yellow Tall, yellow TTYy TTyy TtYy Ttyy Ty Tall, yellow Tall, green Tall, yellow Tall, green TtYY TtYy ttYY ttYy tY Tall, yellow Tall, yellow Dwarf, yellow Dwarf, yellow TtYy Ttyy ttYy ttyy ty Tall, yellow Tall, green Dwarf, yellow Dwarf, green Genotypes: 1 TTYY : 2 TTYy : 4 TyYy : 2 TtYY : 1 TTyy : 2 Ttyy : 1 ttYY : 2 ttYy : 1 ttyy Phenotypes: 9 tall plants with yellow seeds 3 tall plants with green seeds 3 dwarf plants with yellow seeds 1 dwarf plant with green seeds

Incomplete Dominance Japanese four-o-clock flowers Red flower plant genotype = RR White flower plant genotype = WW Pink flower plant genotype = RW Appear blended. Incomplete, not Full Strength.

R R W W RW RW RW RW Cross a Red flower with a White Flower RR = Red WW = white RW = Pink R R Parents are RR for red and WW for white. Both are homozygous or true breeding. W In a Punnett square, the Alleles always move to squares as shown. RW RW W RW RW The actual alleles Genotype = Phenotype = Probability = 4 RW 4 Pink 100% Pink Physical description of trait

Co Dominance RR x WW = RW or RR X R’R’ = RR’ Roan Cow 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. Co Dominance FULL Strength RR x WW = RW or RR X R’R’ = RR’ Roan Cow

R W W W RW WW RW WW Cross a Roan cow with white cow. Co-Dominance RR = Red cow WW = white cow RW = Roan Cow R W Parents are RW for Roan which is heterozygous WW which is homozygous for White W In a Punnett square, the Alleles always move to squares as shown. RW WW W RW WW The actual alleles Genotype = Phenotype = Probability = 2 RW, 2 WW 2 Roan, 2 White 50% Roan, 50% White Physical description of trait

R R’ R’ R’ RR’ R’R’ RR’ R’R’ Cross a Roan cow with white cow. Co-Dominance RR = Red cow R’R’ = white cow RR’ = Roan Cow R R’ Parents are RW for Roan which is heterozygous WW which is homozygous for White R’ In a Punnett square, the Alleles always move to squares as shown. RR’ R’R’ R’ RR’ R’R’ The actual alleles Genotype = Phenotype = Probability = 2 RR’, 2 R’R’ 2 Roan, 2 White 50% Roan, 50% White 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 A - 2 possible genotypes Type AB Type B – 2 possible genotypes Type O

IA i IB IB IAIB IBi IAIB IBi Cross a heterozygous type A with homozygous type B A = IAIA, IAi B= IBIB, IBi AB =IAIB O = ii IA i IB Punnett square the Alleles always move to squares as shown. IAIB IBi IB IAIB IBi The actual alleles Genotype = Phenotype = Probability = IAIB, IBi 2 AB, 2 B 50% AB, 50% B 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.

Xn Y XN Xn XNXn XNY XnXn XnY Cross a heterozygous female with a colorblind male Female = XX Male = XY Normal = N, color-blind = n Xn Y XN XNXn XNY Work like any other Punnett Square. Remember no letter on the Y. The trait is connected to the X! Xn XnXn XnY The actual alleles Genotype = Phenotype = Probability = XNXn,XnXn,XNY,XnY 2 Females, 1 Normal, 1 Color-blind 2 Males, 1 Normal, 1 Color-blind 50% Colorblind Physical description of trait

Test Your Knowledge of Punnett Square http://www.biology.clc.uc.edu/courses/bio105/geneprob.htm

Sex Cells (Gametes) from Meiosis 1N 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 Female is represented by a circle Male is represented as a square Male carrier – Not possible in Sex-linked traits (if you see carrier male, it is autosomal)

What does a pedigree chart look like? XNXn XNXN XNY XnY 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?

XNXN or XNXn XNXN or XNXn XNY XnY If carriers are not shown, genotype could be homozygous or heterozygous even though trait is not shown. XNXN or XNXn XNXN or XNXn XNY XnY 1st generation 2nd generation 3rd generation 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!

Interpreting a Pedigree Chart 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 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 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 disorder has 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 disorder Skips a generation, then the disorder is recessive. If a carrier is shown, it is recessive also.

Central Dogma of Molecular Biology! Scientists call this the: DNA DNA Central Dogma of Molecular Biology! RNA RNA Protein Protein

DNA Nucleotide Deoxyribose Nucleic Acid O=P-O Phosphate Group N Nitrogenous base (A, G, C, or T) CH2 O C1 C4 C3 C2 5 Sugar (deoxyribose)

Watson and Crick constructed a Model of DNA showing the double helix. James Watson and Francis Crick worked out the three-dimensional structure of DNA, based on work by Rosalind Franklin Figure 10.3A, B

DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C) “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. T A G C

DNA Double Helix P P G C T A DNA Nucleotides joined together O 1 2 3 4 5 P O 1 2 3 4 5 Notice base pairing A + T G + C G C T A

The Code of Life… A T C G T A T G C G G… 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 A-T, G-C 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 DNA molecule contains one original and one new complementary strand Each strand of the original DNA serves as a template for the new strand

Complementary base pairs form new strands. DNA Replication Complementary base pairs form new strands.

(which code for a specific AMINO ACID …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.

DNA Trait Protein 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 always STAYS in Nucleus DNA and RNA Comparison Double Strand Single Strand A+T G+C A+U G+C Both have Phosphate Deoxyribose Ribose DNA always STAYS in Nucleus RNA is in nucleus during transcription, moves in cytoplasm, and on ribosome during translation.

Table 14.2 Types of RNA Type of RNA Functions in Function Messenger RNA (mRNA) Nucleus, migrates to ribosomes in cytoplasm Carries DNA sequence information to ribosomes Transfer RNA (tRNA) Cytoplasm Provides linkage between mRNA and amino acids; transfers amino acids to ribosomes Figure: Table 14.2 Title: Types of RNA. Caption: 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 information constituting an organism’s genotype is carried in its sequence of bases The DNA is transcribed into RNA, which is translated into the polypeptide DNA TRANSCRIPTION RNA TRANSLATION Protein Figure 10.6A

Transcription produces genetic messages in the form of mRNA RNA nucleotide RNA polymerase Direction of transcription Template strand of DNA Newly made RNA Figure 10.9A

In transcription, DNA helix unzips RNA polymerase In transcription, DNA helix unzips DNA of gene Promoter DNA Terminator DNA Initiation RNA nucleotides line up along one strand of DNA, following the base-pairing rules single-stranded messenger RNA peels away and DNA strands rejoin Elongation Area shown in Figure 10.9A Termination Growing RNA Completed RNA RNA polymerase Figure 10.9B

Eukaryotic RNA is processed before leaving the nucleus Noncoding segments, introns, are spliced out A cap and a tail are added to the ends Exon Intron Exon Intron Exon DNA Transcription Addition of cap and tail Cap RNA transcript with cap and tail Introns removed Tail Exons spliced together mRNA Coding sequence NUCLEUS CYTOPLASM Figure 10.10

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 Amino Acids tRNA Anti-codon codon Proteins – Express Traits rRNA and tRNA translate The message to make proteins

Translation of nucleic acids into amino acids 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.

Types of RNA mRNA contains codons which code for amino acids. What amino acid will the code CAU make? 3 Letter Code for amino acids His

Virtually all organisms share the same genetic code “unity of life” Second Base U C A G UUU UCU UAU UGU U phe tyr cys UUC UCC UAC UGC C U ser UUA UCA UAA stop UGA stop A leu UUG UCG UAG stop UGG trp G CUU CCU CAU CGU U his CUC CCC CAC CGC C C leu pro arg CUA CCA CAA CGA A gln CUG CCG CAG CGG G First Base Third Base AUU ACU AAU AGU U asn ser AUC ile ACC AAC AGC C A thr AUA ACA AAA AGA A lys arg Figure: 14-07 Title: The genetic code dictionary. Caption: If we know what a given mRNA codon is, how can we find out what amino acid it codes for? This dictionary of the genetic code offers a way. In Figure 14.5, you saw that the codon CGU coded for the amino acid arginine (arg). Looking that up here, C is the first base (go to the C row along the “first base” line), G is the second base (go to the G column under the “second base” line) and U is the third (go to the codon parallel with the U in the “third base” line). AUG met (start) ACG AAG AGG G GUU GCU GAU GGU U asp GUC GCC GAC GGC C G val ala gly GUA GCA GAA GGA A glu GUG GCG GAG GGG G 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 AUG = methionine Start of genetic message End Figure 10.13A

An exercise in translating the genetic code Transcribed strand DNA Transcription RNA Start codon Stop codon Translation Polypeptide Figure 10.8B

Proteins are built from chains of amino acids Gene 1 Gene 3 DNA molecule Gene 2 Proteins are built from chains of amino acids DNA strand TRANSCRIPTION RNA Codon TRANSLATION Polypeptide Amino acid

Ribosomes build polypeptides (chain of amino acids) Next amino acid to be added to polypeptide Growing polypeptide tRNA molecules P site A site Growing polypeptide Large subunit tRNA P A mRNA mRNA binding site Codons mRNA Small subunit Figure 10.12A-C

mRNA, a specific tRNA, and the ribosome subunits assemble during initiation Large ribosomal subunit Initiator tRNA P site A site Start codon Small ribosomal subunit mRNA 1 2 Figure 10.13B

Amino acid Polypeptide A site P site Anticodon mRNA 1 Codon recognition mRNA movement Stop codon New peptide bond 2 Peptide bond formation 3 Translocation Figure 10.14

Overview of Protein Synthesis

Let’s look at it ONE more time! TRANSCRIPTION DNA Stage mRNA is transcribed from a DNA template. 1 mRNA RNA polymerase Amino acid TRANSLATION Stage Each amino acid attaches to its proper tRNA with the help of a specific enzyme and ATP. 2 Enzyme tRNA Initiator tRNA Anticodon Stage Initiation of polypeptide synthesis 3 Large ribosomal subunit The mRNA, the first tRNA, and the ribosomal subunits come together. Start Codon Small ribosomal subunit mRNA Figure 10.15

New peptide bond forming Growing polypeptide Stage Elongation 4 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. Codons mRNA Polypeptide Stage Termination 5 The ribosome recognizes a stop codon. The poly-peptide is terminated and released. Stop Codon Figure 10.15 (continued)

DNA Trait Protein 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. Using the chart on page 303, identify the amino acids coded for by these codons: UGG CAG UGC tryptophan-glutamine-cysteine

Genetic Disorders

Genetic Disorders Autosomal Recessive Normal = N nn = cystic fibrosis Both parents Must be Carriers Nn X Nn

Sickle Cell Anemia Autosomal recessive Both parents must be carriers To pass to children. Nn X Nn Or one is carrier and other has condition. Nn x nn Would not show in parents if Carriers

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.

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 Gene Protein Trait Many mutations do not change the amino acid, so NO mutation will occur. Expresses Trait Mutation – wrong protein

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

Sickle-cell hemoglobin Normal hemoglobin DNA Mutant hemoglobin DNA mRNA mRNA Normal hemoglobin Sickle-cell hemoglobin Glu Val Example of Sickle Cell mutation

Illustration of mutations NORMAL GENE mRNA Protein Met Lys Phe Gly Ala BASE SUBSTITUTION Met Lys Phe Ser Ala BASE DELETION Missing Met Lys Leu Ala His Figure 10.16B

Chromosomal changes can be large or small Deletion Homologous chromosomes Duplication Inversion Reciprocal translocation Nonhomologous chromosomes Figure 8.23A, B

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 2n = 46

Normal Female Karotype

Male, Trisomy 21 (Down’s) 2n = 47 Can you spot the problem?

Female Down’s Syndrome

Klinefelter’s Syndrome

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 Bacteria Remove bacterial DNA (plasmid). Cut the Bacterial DNA with “restriction enzymes”. Cut the DNA from another organism with “restriction enzymes”. Combine the cut pieces of DNA together with another enzyme and insert them into bacteria. Reproduce the recombinant bacteria. The foreign genes will be expressed in the bacteria.

Benefits of Recombinant Bacteria Bacteria can make human insulin or human growth hormone. 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 Mice – used to study human immune system Chickens – more resistant to infections Cows – increase milk supply and leaner meat 4. Goats, sheep and pigs – produce human proteins in their milk

Transgenic Goat Carries a foreign gene that has been inserted into its genome. . 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. Human DNA in a Goat Cell

How to Create a Transgenic Animal Desired DNA is added to an egg cell.

The DNA of plants and animals can also be altered. 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 Reaction PCR PCR allows scientists to make many copies of a piece of DNA. 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”.