Lecture ILecture IIntro toIntro to

Genetics & DNA Genetics & DNA ReplicationReplication

with a review inwith a review inDNA, RNA, & Protein DNA, RNA, & Protein

SynthesisSynthesis

Standards Covered Standards Covered

4a~ students know the general pathway 4a~ students know the general pathway by which ribosomes synthesize proteins, by which ribosomes synthesize proteins, using using tRNA’stRNA’s to to translatetranslate genetic genetic information in information in mRNAmRNA

4b~ students know how to apply the 4b~ students know how to apply the genetic coding rules to predict the genetic coding rules to predict the sequence of amino acids from a sequence sequence of amino acids from a sequence of of codonscodons in RNA in RNA

4e~ students know proteins can differ 4e~ students know proteins can differ from one another in the number and from one another in the number and sequence of sequence of amino acidsamino acids

Standards Covered Standards Covered

5a~ students know the general structures 5a~ students know the general structures and functions of and functions of DNADNA, , RNARNA, and , and proteinsproteins

5b~ students know how to apply base-5b~ students know how to apply base-pairing rules to explain precise copying of pairing rules to explain precise copying of DNA during DNA during semi-conservative semi-conservative replicationreplication and the and the transcriptiontranscription of of information from DNA into RNAinformation from DNA into RNA

Important Important VocabularyVocabulary

HeredityHeredity – – the passing on of the passing on of characteristics characteristics from parents to from parents to offspringoffspring

TraitsTraits – characteristics that are – characteristics that are inheritedinherited (for example your eye color)(for example your eye color)

GenesGenes – a piece of DNA that provides – a piece of DNA that provides a a codecode or or instructionsinstructions to make a to make a certain proteincertain protein A gene’s specific A gene’s specific locationlocation within your within your

DNA code is called its DNA code is called its locuslocus This is like a “home address”This is like a “home address”

Important Important VocabularyVocabulary

GenotypeGenotype – the – the genetic makeupgenetic makeup of an of an individual or referring to a specific gene or individual or referring to a specific gene or traittrait

PhenotypePhenotype – the – the physical expressionphysical expression of a of a gene or trait as “coded for” by the gene or trait as “coded for” by the GenotypeGenotype

AlleleAllele – – any any alternative form of a genealternative form of a gene that that can be possible for a specific gene at a can be possible for a specific gene at a specific locusspecific locus

DominantDominant – the allele that – the allele that isis expressed expressed when two different alleles are presentwhen two different alleles are present

RecessiveRecessive – the allele that is expressed – the allele that is expressed onlyonly when two copies of that allele are when two copies of that allele are presentpresent

Genotype vs. Genotype vs. PhenotypePhenotype

Your Your DNADNA is the is the genetic blueprintgenetic blueprint for for allall of your physical of your physical characteristics we characteristics we call “traits”call “traits”

The DNA code for a The DNA code for a trait is called the trait is called the genotypegenotype and the and the traittrait that is expressed that is expressed is the is the phenotypephenotype

DNA PolymeraseDNA Polymerase – a special – a special enzymeenzyme responsible for a process called DNA responsible for a process called DNA ReplicationReplication

Semi-conservative replicationSemi-conservative replication – the – the process of making a copy of a DNA strand process of making a copy of a DNA strand by using each complimentary half as a by using each complimentary half as a “template” for two new strands“template” for two new strands

Important Important VocabularyVocabulary

The Cell CycleThe Cell Cycle Cells go Cells go

through the through the cell cycle cell cycle during their during their lifetimelifetime

MOST of the MOST of the life of a cell is life of a cell is in Interphasein Interphase

DNA is DNA is packed into packed into chromosomes chromosomes during late during late G1G1

DNA Arranged in a DNA Arranged in a ChromosomeChromosome

A cell makes copies of its DNA during A cell makes copies of its DNA during the the S-PhaseS-Phase of the cell cycle where the of the cell cycle where the chromosomes “duplicate” and the cell chromosomes “duplicate” and the cell prepares for cell divisionprepares for cell division

S Phase & DNA S Phase & DNA ReplicationReplication

The Structure of DNAThe Structure of DNA

DNA is a long molecule made up of nucleotides

Each nucleotide is made up of three parts: 5-carbon sugar 5-carbon sugar

called deoxyribosecalled deoxyribose Phosphate groupPhosphate group Nitrogen BaseNitrogen Base

Adenine Guanine

Phosphate group

Cytosine Thymine

(Deoxyribose)

5-Carbon Sugar

The NucleotidesThe NucleotidesNitrogen Bases A- adenine

G- guanine

C- cytosine

T- thymine

Chargaff’s RulesChargaff’s Rules

According to Erwin Chargaff:Adenine always pairs with Thymine

Cytosine always pairs with Guanine

Central Dogma Central Dogma ReviewReview

The term The term central dogmacentral dogma is used in is used in science to describe the “making of science to describe the “making of proteins” from instructions coded in the proteins” from instructions coded in the DNADNA

An equation to remember for Central An equation to remember for Central Dogma would be:Dogma would be:

DNA mRNA Amino Acid DNA mRNA Amino Acid ChainChainTranscriptionTranscription TranslationTranslation

Transcription inside the Nucleus

Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

RNA DNA

RNApolymerase

Central DogmaCentral Dogma

Proteins are assembled into Proteins are assembled into polypeptidespolypeptides These are long chains of These are long chains of amino acidsamino acids

There are There are 20 different types20 different types of of amino amino acidsacids

The properties of proteins are The properties of proteins are determined by which order these determined by which order these amino acids are joinedamino acids are joined

Transcription & Transcription & TranslationTranslation Each of these amino acids that mRNA Each of these amino acids that mRNA

“codes” for recognizes the “codes” for recognizes the three base three base pair sequencepair sequence

A A codoncodon consists of “three nucleotides in consists of “three nucleotides in a row” that code for a single amino acida row” that code for a single amino acid AUG AUG codes for the amino acid codes for the amino acid MethionineMethionine

The (20) Amino AcidsThe (20) Amino Acids

Methionine is the universal “start codon” for all

proteins