Anatomy & Physiology I Unit Four

Anatomy & Anatomy & Physiology IPhysiology I

Unit FourUnit Four

The monomers are The monomers are nucleotidesnucleotidesFunctionsFunctions::HeredityHeredityProtein Protein synthesissynthesis

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Nitrogen baseNitrogen base

Pentose sugarPentose sugar

Phosphate groupPhosphate group

DNA & RNA StructureDNA & RNA Structure

ExampleExamples:s:•DNADNA•RNARNA

Single Single stranded stranded with three with three forms – forms – tRNA, tRNA, rRNA, and rRNA, and mRNAmRNA

Double Double stranded, stranded, double double helix helix moleculemolecule

DNA & RNA StructureDNA & RNA Structure

DNA & DNA & RNA RNA

StructurStructuree

DNA & RNA FunctionsDNA & RNA Functions

DNA & RNA Base DNA & RNA Base PairingPairing

DNA & RNA Base PairingDNA & RNA Base Pairing

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A T G C A T T G A A G C T G G T A GA T G C A T T G A A G C T G G T A G

DNA replicationDNA replication

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A U G C A U U G A A G C U G G U A GA U G C A U U G A A G C U G G U A G

RNA transcriptionRNA transcription

DNA ReplicationDNA Replication

Protein SynthesisProtein Synthesis

Protein synthesis goes on all Protein synthesis goes on all the time in most cellsthe time in most cellsThis very important process This very important process is directed by the genetic is directed by the genetic code on DNAcode on DNA

Protein SynthesisProtein Synthesis

Protein synthesis occurs in Protein synthesis occurs in two processes:two processes: ~ transcription (production ~ transcription (production of RNA of RNA from DNA)from DNA) ~ translation (production of ~ translation (production of proteins from RNA)proteins from RNA)Both processes are fueled by Both processes are fueled by ATP ATP

Protein Synthesis: TranscriptionProtein Synthesis: Transcription

RNA polymerase attaches to RNA polymerase attaches to specific areas of the DNA specific areas of the DNA (genes) and “unzips” the (genes) and “unzips” the hydrogen bonds hydrogen bonds The RNA polymerase also The RNA polymerase also begins the building of the begins the building of the RNA by adding RNA RNA by adding RNA nucleotides in accordance nucleotides in accordance with the DNA base sequence with the DNA base sequence

Protein Synthesis: Protein Synthesis: TranscriptionTranscription

Protein Protein Synthesis: Synthesis: TranscriptTranscript

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Protein Synthesis: TranscriptionProtein Synthesis: Transcription

Once transcribed, mRNA and Once transcribed, mRNA and tRNA are sent out of the tRNA are sent out of the nucleus and to the ribosomes nucleus and to the ribosomes in the cytoplasm in the cytoplasm rRNA is transferred to the rRNA is transferred to the nucleolus to become a part of nucleolus to become a part of newly formed ribosomes newly formed ribosomes

Protein Synthesis: Protein Synthesis: TranscriptionTranscription

mRNA carries a series of mRNA carries a series of codons that code for specific codons that code for specific amino acids amino acids A codon is a sequence of A codon is a sequence of three nucleotide bases on three nucleotide bases on mRNAmRNASince there are only four RNA Since there are only four RNA bases and there are three in bases and there are three in each codon, there are 64 each codon, there are 64 condon possibilities condon possibilities

Protein Synthesis: Protein Synthesis: TranslationTranslation

The genetic code is the use of The genetic code is the use of these 64 codons coding for 20 these 64 codons coding for 20 amino acids amino acids Remember - the synthesis of Remember - the synthesis of a specific protein requires a a specific protein requires a specific sequence of amino specific sequence of amino acidsacids


Therefore the sequence of Therefore the sequence of codons on mRNA must be codons on mRNA must be sequentially specific sequentially specific


The genetic code is The genetic code is commaless and non-commaless and non-overlapping, meaning it is overlapping, meaning it is read in frames of three read in frames of three without gaps or overlapswithout gaps or overlaps

There is one initiation codon - There is one initiation codon - AUGAUG


There are three stop codons - There are three stop codons - UAA, UAG & UGAUAA, UAG & UGA

Translation is the process by Translation is the process by which RNA produces proteins which RNA produces proteins in ribosomesin ribosomes - mRNA carries the code from - mRNA carries the code from DNADNA - tRNA carries amino acids to - tRNA carries amino acids to the the ribosomeribosome - rRNA is a component of the - rRNA is a component of the ribosomeribosome

Protein Synthesis - Protein Synthesis - TranslationTranslation

By way of the genetic code, By way of the genetic code, RNA “translates” from the RNA “translates” from the language of nucleic acids to language of nucleic acids to that of proteinsthat of proteins


Protein Protein Synthesis: Synthesis: TranslationTranslation

Protein Synthesis: Protein Synthesis: ReviewReview

InterphasInterphaseeGG11 – organelles – organelles doubledoubleS – DNA S – DNA replicatesreplicatesGG22 – proteins – proteins producedproduced

MitosisMitosisProphaseProphaseMetaphaseMetaphaseAnaphaseAnaphaseTelophaseTelophase

CytokineCytokinesissis

Significance of Significance of Cell DivisionCell Division

Cell division (mitosis) Cell division (mitosis) is an efficient process is an efficient process that assures the that assures the correct number of correct number of chromosomes will be chromosomes will be found in the new found in the new daughter cellsdaughter cells

Significance of Cell Significance of Cell DivisionDivision

Chromosome number is a Chromosome number is a critical characteristic in critical characteristic in determining a species and the determining a species and the viability of an organismviability of an organismCorrect chromosomes Correct chromosomes numbers are essential for numbers are essential for successful fertilization eventssuccessful fertilization events


In animals, increasing or In animals, increasing or decreasing chromosome decreasing chromosome numbers has deleterious numbers has deleterious effectseffects


The functions of cell division The functions of cell division are:are: ~ growth~ growth ~ repair~ repair ~ replacement~ replacementCellular homeostasis is the Cellular homeostasis is the maintaining of a constant maintaining of a constant number of body cellsnumber of body cells


Cellular homeostasis is Cellular homeostasis is maintained by a number of maintained by a number of factors:factors: + cell size+ cell size + nutrient availability+ nutrient availability + DNA damage+ DNA damage + growth factors+ growth factors + cell population density+ cell population density


Surface to volume ratio Surface to volume ratio determines the maximum size determines the maximum size a cell can obtaina cell can obtainThe amount of nutrients The amount of nutrients available is a factor in the rate available is a factor in the rate of growthof growthGrowth factors such as cyclins, Growth factors such as cyclins, Cdks and hormones influence Cdks and hormones influence the speed and amount of cell the speed and amount of cell growthgrowth


The density of cells also The density of cells also controls cell growth – loss of controls cell growth – loss of cells stimulates cell division, cells stimulates cell division, adequate numbers of cells adequate numbers of cells inhibit the processinhibit the process

CancerCancer

Cell division is orchestrated by Cell division is orchestrated by proteins and hormones so that proteins and hormones so that growth and division is growth and division is controlledcontrolledCancer cells are normal body Cancer cells are normal body cells that are transformed. In cells that are transformed. In this transformed state, they this transformed state, they ignore the controls of cell ignore the controls of cell division and multiply uncheckeddivision and multiply unchecked

CancerCancer

Normally, the immune system Normally, the immune system destroys these cancer cells, but destroys these cancer cells, but some may escape destruction some may escape destruction and then form a tumorand then form a tumorA tumor is a mass of cancer cells A tumor is a mass of cancer cells found within otherwise normal found within otherwise normal tissuetissue

CancerCancerA tumor is said to be benign if A tumor is said to be benign if the cancer cells remain within the cancer cells remain within the tumor. These can usually the tumor. These can usually be removed through surgerybe removed through surgeryA malignant tumor contains A malignant tumor contains cancer cells that are invasive, cancer cells that are invasive, meaning they spread to other meaning they spread to other tissues. A person with a tissues. A person with a malignant tumor is said to have malignant tumor is said to have cancercancer

CancerCancer

Remember - cell division is Remember - cell division is orchestrated by proteins and orchestrated by proteins and hormones so that growth and hormones so that growth and division is controlleddivision is controlledOncogenes are those that initiate Oncogenes are those that initiate cell division, but in an cell division, but in an accelerated and exaggerated accelerated and exaggerated processprocess

CancerCancer

Tumor suppressor genes are Tumor suppressor genes are those that prevent cell division those that prevent cell division and promote normal cell deathand promote normal cell deathIf tumor suppressor genes are If tumor suppressor genes are altered, inactivated or removed altered, inactivated or removed the result can be cancerthe result can be cancer

CancerCancer

Cancer can occur through Cancer can occur through genetic abnormalities, genetic abnormalities, activating oncogenes and/or activating oncogenes and/or inactivating tumor suppressor inactivating tumor suppressor genesgenesEnvironmental influences can Environmental influences can also affect the activity and also affect the activity and inactivity of these genesinactivity of these genes

CancerCancer

Environmental influences include:Environmental influences include: ~ diet~ diet ~ exercise~ exercise ~ sun exposure~ sun exposure ~ smoking~ smoking ~ altering of DNA~ altering of DNA

Anatomy & Physiology I Unit Four

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