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RNARNA

Ribonucleic AcidRibonucleic Acid

Structure of RNAStructure of RNA

Single strandedSingle stranded Ribose SugarRibose Sugar 5 carbon sugar5 carbon sugar Phosphate groupPhosphate group Adenine, Uracil, Cytosine, GuanineAdenine, Uracil, Cytosine, Guanine

Types of RNATypes of RNA

Three main typesThree main types Messenger RNAMessenger RNA (mRNA) – transfers (mRNA) – transfers

DNA code to ribosomes for translation.DNA code to ribosomes for translation. Transfer RNATransfer RNA (tRNA) – brings amino (tRNA) – brings amino

acids to ribosomes for protein synthesis.acids to ribosomes for protein synthesis. Ribosomal RNARibosomal RNA (rRNA) – Ribosomes are (rRNA) – Ribosomes are

made of rRNA and protein.made of rRNA and protein.

TranscriptionTranscription

RNA molecules are produced by copying part RNA molecules are produced by copying part of the nucleotide sequence of DNA into of the nucleotide sequence of DNA into complementary sequence in RNA, a process complementary sequence in RNA, a process called called transcriptiontranscription..

During transcription, RNA polymerase binds to During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a polymerase then uses one strand of DNA as a template from which nucleotides are template from which nucleotides are assembled into a strand of mRNA.assembled into a strand of mRNA.

How Does it Work?How Does it Work?

RNA Polymerase looks for a region on RNA Polymerase looks for a region on the DNA known as a promoter, where it the DNA known as a promoter, where it binds and begins transcription.binds and begins transcription.

RNA strands are then edited. Some RNA strands are then edited. Some parts are removed (parts are removed (intronsintrons) - which are ) - which are not expressed – and other that are left not expressed – and other that are left are called exons or expressed genes.are called exons or expressed genes.

The Genetic CodeThe Genetic Code

This is the language of mRNA.This is the language of mRNA. Based on the 4 bases of mRNA.Based on the 4 bases of mRNA. ““Words” are 3 RNA sequences called Words” are 3 RNA sequences called

codonscodons.. The strand aaacguucgccc would be The strand aaacguucgccc would be

separated as aaa-cgu-ucg-ccc the amino separated as aaa-cgu-ucg-ccc the amino acids would then be Lysine – Arginine – acids would then be Lysine – Arginine – Serine - ProlineSerine - Proline

Genetic CodesGenetic Codes

TranslationTranslation

During translation, the cell uses information During translation, the cell uses information from messenger RNA to produce proteins.from messenger RNA to produce proteins.

A – Transcription occurs in nucleus.A – Transcription occurs in nucleus. B – mRNA moves to the cytoplasm then to the B – mRNA moves to the cytoplasm then to the

ribosomes. tRNA “read” the mRNA and obtain ribosomes. tRNA “read” the mRNA and obtain the amino acid coded for.the amino acid coded for.

C – Ribosomes attach amino acids together C – Ribosomes attach amino acids together forming a polypeptide chain.forming a polypeptide chain.

D – Polypeptide chain keeps growing until a D – Polypeptide chain keeps growing until a stop codon is reached.stop codon is reached.

MUTATIONSMUTATIONS

Changes in Changes in DNADNA that affect genetic that affect genetic informationinformation

MutationsMutations

Gene mutations result from changes in a Gene mutations result from changes in a single gene. Chromosomal mutations single gene. Chromosomal mutations involve changes whole chromosomes.involve changes whole chromosomes.

Gene MutationsGene Mutations

Point Mutations – changes Point Mutations – changes in in one or a fewone or a few nucleotides nucleotides SubstitutionSubstitution

THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT HAT ATE THE RATTHE FAT HAT ATE THE RAT

InsertionInsertion THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT CAT XLW ATE THE RATTHE FAT CAT XLW ATE THE RAT

DeletionDeletion THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT ATE THE RATTHE FAT ATE THE RAT

Gene MutationsGene Mutations Frameshift Mutations – shifts Frameshift Mutations – shifts

the the reading framereading frame of the genetic of the genetic message so that the message so that the protein protein may not be able to perform its may not be able to perform its function.function. InsertionInsertion

THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT HCA TAT ETH ERA TTHE FAT HCA TAT ETH ERA T

DeletionDeletion THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT TEF ATC ATA TET GER ATTEF ATC ATA TET GER AT

H

H

Chromosome MutationsChromosome Mutations Changes in number and structure of entire Changes in number and structure of entire

chromosomes chromosomes Original Chromosome Original Chromosome ABC * DEFABC * DEF DeletionDeletion AC * DEFAC * DEF DuplicationDuplication ABBC * DEFABBC * DEF InversionInversion AED * CBFAED * CBF TranslocationTranslocation ABC * JKLABC * JKL

GHI * DEFGHI * DEF

Significance of MutationsSignificance of Mutations• Most are neutralMost are neutral

• Eye colorEye color• Birth marksBirth marks

• Some are harmfulSome are harmful• Sickle Cell AnemiaSickle Cell Anemia• Down SyndromeDown Syndrome

• Some are beneficialSome are beneficial• Sickle Cell Anemia to MalariaSickle Cell Anemia to Malaria• Immunity to HIVImmunity to HIV

What Causes Mutations?What Causes Mutations? There are two ways in which DNA can There are two ways in which DNA can

become mutated:become mutated: Mutations can be inherited. Mutations can be inherited.

Parent to childParent to child

Mutations can be acquired.Mutations can be acquired. Environmental damageEnvironmental damage Mistakes when DNA is copied Mistakes when DNA is copied

Chromosome MutationsChromosome Mutations

Down SyndromeDown Syndrome Chromosome 21 does Chromosome 21 does

not separate correctly.not separate correctly. They have 47 They have 47

chromosomes in stead chromosomes in stead of 46.of 46.

Children with Down Children with Down Syndrome develop Syndrome develop slower, may have heart slower, may have heart and stomach illnesses and stomach illnesses and vary greatly in their and vary greatly in their degree of inteligence.degree of inteligence.

Chromosome MutationsChromosome Mutations

Cri-du-chatCri-du-chat Deletion of material on 5Deletion of material on 5thth

chromosomechromosome Characterized by the cat-like Characterized by the cat-like

cry made by cri-du-chat cry made by cri-du-chat babiesbabies

Varied levels of metal Varied levels of metal handicapshandicaps

Sex Chromosome Sex Chromosome AbnormalitiesAbnormalities Klinefelter’s Klinefelter’s

SyndromeSyndrome XXY, XXYY, XXXYXXY, XXYY, XXXY MaleMale SterilitySterility Small testiclesSmall testicles Breast enlargementBreast enlargement

Sex Chromosome Sex Chromosome AbnormalitiesAbnormalities

XYY SyndromeXYY Syndrome Normal male traitsNormal male traits Often tall and thinOften tall and thin Associated with antisocial and behavioral Associated with antisocial and behavioral

problemsproblems

Sex Chromosome Sex Chromosome MutationsMutations

Turner’s SyndromeTurner’s Syndrome XX FemaleFemale sex organs don't sex organs don't

mature at mature at adolescenceadolescence

sterilitysterility short stature short stature

Sex Chromosome Sex Chromosome MutationsMutations

XXXXXX Trisomy XTrisomy X FemaleFemale Little or no visible differencesLittle or no visible differences tall staturetall stature learning disabilitieslearning disabilities limited fertility limited fertility

Some mutations even Some mutations even make it on SNL!make it on SNL!