Basics of DNABasics of DNATodd RightmireTodd Rightmire

Mt. Baker High SchoolMt. Baker High School

Cellular compositionCellular composition

DNA is contained in DNA is contained in nucleus of cellnucleus of cell

Phospho-lipids and Phospho-lipids and proteins combined to proteins combined to form cell membraneform cell membrane

Lipids are fatsLipids are fats

DNA (DeoxyriboNucleic Acid) is a DNA (DeoxyriboNucleic Acid) is a double helixdouble helix

Backbone is made of Backbone is made of sugar-phosphatesugar-phosphate

Base pairs bind the Base pairs bind the backbone togetherbackbone together

Adenine always pairs Adenine always pairs with Thyminewith Thymine

Guanine binds with Guanine binds with CytosineCytosine

Base pairsBase pairs

AA==T – T – double hydrogen bonddouble hydrogen bond

GG C – C – triple hydrogen bondtriple hydrogen bond

Nucleotide (3 chemical Nucleotide (3 chemical groups)groups) Sugar – deoxyriboseSugar – deoxyribose

contains 5 Carbon atomscontains 5 Carbon atoms

Phosphate groupPhosphate group A base (A, T, G, C)A base (A, T, G, C)

Extracting DNA from an onionExtracting DNA from an onion

Papain (enzyme) is found in meat Papain (enzyme) is found in meat tenderizertenderizer destroys cell membranedestroys cell membrane

Detergent – breaks down lipids in cell Detergent – breaks down lipids in cell membranemembrane

Ethanol and heat shock?Ethanol and heat shock?

DNA replication/synthesisDNA replication/synthesis

DNA has a lagging strand DNA has a lagging strand 3’-5’ and a leading strand 3’-5’ and a leading strand 5’-3’5’-3’

The 5’ end matches with The 5’ end matches with a 3’ end in a double helixa 3’ end in a double helix

DNA replication occurs DNA replication occurs every 20 minutes in E. every 20 minutes in E. coli (widely used to coli (widely used to reproduce DNA)reproduce DNA)

Copying DNA moleculeCopying DNA molecule Each DNA strand (double Each DNA strand (double

helix) unzips itselfhelix) unzips itself Happens before cell Happens before cell

division (mitosis and division (mitosis and meiosis)meiosis)

Done in PCR Done in PCR (polymerase chain (polymerase chain reaction) to make a lot of reaction) to make a lot of the same DNA (mass the same DNA (mass replication) for analysis replication) for analysis through fingerprinting.through fingerprinting.

DNA replicationDNA replication

MutationsMutations Caused by chance, genes, Caused by chance, genes,

and environmentand environment ultraviolet lightultraviolet light tobacco/alcoholtobacco/alcohol change in genetic coding of change in genetic coding of

amino acidsamino acids TypesTypes

insertioninsertion deletiondeletion substitutionsubstitution inversion (flipping)inversion (flipping)

Cystic fibrosisCystic fibrosis Some are beneficial – postitive Some are beneficial – postitive

traittrait Drought resistance, etc.Drought resistance, etc.

Sickle cell anemia

Use the Amino Acid Chart to Use the Amino Acid Chart to identify the mutationidentify the mutation

ATT CCG CTA CAA CGA TGC TAGATT CCG CTA CAA CGA TGC TAG

Insertion mutation (inserting a letter in Insertion mutation (inserting a letter in sequence)sequence)

ATT ATT AACC GCT ACA ACG ATG CTA ……CC GCT ACA ACG ATG CTA ……

http://learn.genetics.utah.edu/archive/mutations/http://learn.genetics.utah.edu/archive/mutations/

CancersCancers

Caused by Caused by abnormalities abnormalities (mutations) in genetic (mutations) in genetic material of the material of the transformed cellstransformed cells

Carcinogens – cancer Carcinogens – cancer causing (tobacco, causing (tobacco, smoke, chemicals, smoke, chemicals, radiation, alcohol, etc)radiation, alcohol, etc)

Mutagens – mutation Mutagens – mutation forming substanceforming substance

http://http://www.johnkyrk.com/www.johnkyrk.com/

meiosis.htmlmeiosis.html Aneupliody – change in number of Aneupliody – change in number of

chromosomes leads to chromosomal disorderschromosomes leads to chromosomal disorders Downs syndrome – extra 21Downs syndrome – extra 21stst chromosome chromosome Edwards syndrome – three chromosome 18 Edwards syndrome – three chromosome 18

50% die in uteuro50% die in uteuro 25% die by 2 months25% die by 2 months 5-10% survive 1 year.5-10% survive 1 year.

Patau Syndrome – trisomy (3) of chromosome 13Patau Syndrome – trisomy (3) of chromosome 13 All other chromosomal abnormalities are fatal in All other chromosomal abnormalities are fatal in

uteurouteuro

TranscriptionTranscription

DNA is copied to RNADNA is copied to RNA T is changed to a UT is changed to a U So then A bonds with a U So then A bonds with a U

(Uracil)(Uracil) Proceeds in the 5’-3’ Proceeds in the 5’-3’

positionposition mRNA – leaves nucleus mRNA – leaves nucleus

as a copy and codes for as a copy and codes for an amino acid an amino acid (translation)(translation)

TranslationTranslation

occurs within the occurs within the cytoplasm of cellcytoplasm of cell

tRNA – transfer RNAtRNA – transfer RNA decodes information decodes information

from mRNA to from mRNA to produce amino acidsproduce amino acids

3 codons translate to 3 codons translate to an amino acidan amino acid

Translation animationTranslation animation

Amino AcidAmino Acid

A chain of nucleotides A chain of nucleotides makes a codon (3 makes a codon (3 letter word such as letter word such as ATT, GCAATT, GCA

Each codon makes Each codon makes an amino acid (20 an amino acid (20 essential Amino essential Amino Acids)Acids)

““Stop” codons means Stop” codons means translation stops and translation stops and a gene is completea gene is complete

GenesGenes

A string of codons codes A string of codons codes for several amino acids to for several amino acids to form a geneform a gene

A gene can be as short A gene can be as short as 50 nucleotides and as as 50 nucleotides and as long as 250 million.long as 250 million.

Humans have over 3 Humans have over 3 billion nucleotides or 1 billion nucleotides or 1 billion codonsbillion codons

Each gene codes for a Each gene codes for a certain trait.certain trait.

Chromosome

Gene pairingGene pairing

Every gene is paired by the gene of the Every gene is paired by the gene of the opposite sexopposite sex

Dominant or recessive (R) or (r)Dominant or recessive (R) or (r) Heterozygous - carrier (different) - RrHeterozygous - carrier (different) - Rr Homozygous (same) – rr or RRHomozygous (same) – rr or RR Dominant gene is expressed as phenotypeDominant gene is expressed as phenotype Punnett SquarePunnett Square

Punnett SquarePunnett Square

ChromosomesChromosomes

Macromolecule of DNAMacromolecule of DNA Contains many genesContains many genes Usually contained in the Usually contained in the

nucleus. nucleus. Eukaryotic cells Eukaryotic cells

mitochondria and mitochondria and chloroplasts contain chloroplasts contain chromosomeschromosomes

Human cell – 23 pairs of Human cell – 23 pairs of chromosomes (23 from chromosomes (23 from dad, 23 from mom)dad, 23 from mom)

Males have XY Males have XY chromosomechromosome

Females have XX Females have XX chromosomechromosome

XYY has been attributed XYY has been attributed is a trait of several serial is a trait of several serial killerskillers

Sperm contains X or YSperm contains X or Y An X is always donated An X is always donated

by a female and an X or a by a female and an X or a Y is donated by the maleY is donated by the male

Meiosis (haploid)Meiosis (haploid)

formation of a new individual by combining two formation of a new individual by combining two haploid sex cells (gametes – sperm/egg)haploid sex cells (gametes – sperm/egg)

Fertilization – genetic info from two separate cells Fertilization – genetic info from two separate cells (1/2 of original genetic info)(1/2 of original genetic info)

both gametes are haploid – 1 set of both gametes are haploid – 1 set of chromosomeschromosomes

combine as a zygote with 2 sets of chromosomescombine as a zygote with 2 sets of chromosomes meiosis is a process to convert a diploid to a meiosis is a process to convert a diploid to a

haploid gamete causing a change in genetic haploid gamete causing a change in genetic information to increase the diversity of offspringinformation to increase the diversity of offspring

Meiosis Meiosis

Meiosis (haploid)Meiosis (haploid)

Meiosis I and IIMeiosis I and II

Mitosis AnimationMitosis Animation

MitosisMitosis

Natural Cloning Natural Cloning (replicates parent cell)(replicates parent cell)

Cell divisionCell division

Law of SegregationLaw of Segregation

alleles are alleles are responsible for traits responsible for traits from each parent are from each parent are separated and are separated and are randomly combined randomly combined with the other parent with the other parent at fertilization.at fertilization.

Parent provides one Parent provides one of the two genes for of the two genes for each traiteach trait

Law of SegregationLaw of Segregation

1.1. Alternative forms for Alternative forms for genesgenes

2.2. Each trait inherits one Each trait inherits one alternative forms from alternative forms from each parent. Called each parent. Called alleles.alleles.

3.3. Gametes- allele pairs Gametes- allele pairs separate or separate or segregate segregate leaving only 1 allele for leaving only 1 allele for each trait.each trait.

4.4. When 2 alleles of a pair When 2 alleles of a pair are different, one is are different, one is dominant, one is dominant, one is recessive.recessive.

Law of Independent AssortmentLaw of Independent Assortment

allele pairs separate allele pairs separate independently during independently during formation of gametes. formation of gametes.

Traits are transmitted to Traits are transmitted to offspring independent of offspring independent of each other. each other.

Reason why there is Reason why there is diversity among siblings diversity among siblings and organismsand organisms

G – green pod, g – yellowG – green pod, g – yellow Y – Yellow seeds, g - Y – Yellow seeds, g -

greengreen

9:3:3:1 ratio when breeding 2 heterozygous traits (Dihybrid cross)

Genotype and PhenotypeGenotype and Phenotype

Genotype – genetic make up Genotype – genetic make up Phenotype – physical traitsPhenotype – physical traits Phenotype is expressed always by Phenotype is expressed always by

dominant allele. dominant allele. Phenotype = Genotype + EnvironmentPhenotype = Genotype + Environment

means that what something looks like means that what something looks like depends on genetics AND environment!!!depends on genetics AND environment!!!

Gel ElectrophoresisGel Electrophoresis

What is it?What is it? Electrophoresis separates DNA and Electrophoresis separates DNA and

Proteins using electricity through a porous Proteins using electricity through a porous

material.material.

Movement of the DNA and Protein is a Movement of the DNA and Protein is a

function of size.function of size.

• DNA speed is based on size. DNA speed is based on size.

• Smaller is Faster and Bigger is slower.Smaller is Faster and Bigger is slower.

It’s like McDonalds on a busy weekend. It’s like McDonalds on a busy weekend.

Porous Material UsedPorous Material Used Agarose (Natural Polysaccharide)Agarose (Natural Polysaccharide)

Most commonly used material in research.Most commonly used material in research. Polyacrylamide (Synthetic Material)Polyacrylamide (Synthetic Material)

Ideal when accuracy and precision are important. Ideal when accuracy and precision are important.

DNA VisualizationDNA VisualizationAutoradiographyAutoradiography

RadioisotopesRadioisotopes Intercalating Dyes

Ethidum Bromide