End Show 2–3 Carbon Compounds Slide 1 of 37 Copyright Pearson Prentice Hall Nucleic Acids Nucleic acids are polymers assembled from individual monomers known as nucleotides.

End Show 2–3 Carbon Compounds Slide 2 of 37 Copyright Pearson Prentice Hall Nucleic Acids Nucleic acids store and transmit hereditary, or genetic, information. ribonucleic acid (RNA) deoxyribonucleic acid (DNA)

End Show 2–3 Carbon Compounds Slide 3 of 37 Structure of DNA Structure of DNA Deoxyribonucleic acid Polymer of the monomer – Nucleotides Single nucleotide 5 carbon sugar – deoxyribose A phosphate group A nitrogen base S P N-base Nucleotide * Sugar & phosphate alternate to make up the sides of the strand **Found only in nucleus

End Show 2–3 Carbon Compounds Slide 4 of 37 Copyright Pearson Prentice Hall Nucleic Acids Nucleotides consist of three parts: a 5-carbon sugar a phosphate group a nitrogenous base Five types of bases: Adenine (A) with T Thymine (T) with A Cytosine (C) with G Guanine (G) with C

End Show 2–3 Carbon Compounds Slide 5 of 37 Ribonucleic acid RNA Ribonucleic acid The other Nucleic Acid Acts as a messenger between DNA and the ribosomes and carries out protein synthesis DNA is too large to get out of the nucleus; it is also protected in the nucleus from DNases. The cell uses RNA to bring its message to the rest of the cell for protein synthesis

End Show 2–3 Carbon Compounds Slide 6 of 37 How DNA & RNA Differ: * RNA is a single stranded molecule *RNA has ribose sugar instead of deoxyribose *RNA contains Uracil in place of Thymine so Adenine bonds with Uracil *RNA can be found in the nucleus, cytoplasm or at the ribosomes

End Show 2–3 Carbon Compounds Slide 7 of 37 Let’s Review!!! Ribosomes are small organelles that are involved with making proteins They are made up of proteins and rRNA They consist of two subunits – large and small Ribosomes are found both in the cytoplasm and on the endoplasmic reticulum

End Show 2–3 Carbon Compounds Slide 8 of 37 There are three different kinds of RNA Messenger RNA (mRNA) Formed in the nucleus and goes to the ribosomes; carries genetic code from DNA through the cytoplasm to the ribosomes Transfer RNA (tRNA) Shaped like T; carries amino acids to the mRNA on the ribosomes Ribosomal RNA (rRNA) Most abundant; found in globular form (like a big glob) and makes up the ribosomes

End Show 2–3 Carbon Compounds Slide 9 of 37 The Process of Protein Synthesis * Process by which DNA codes for the production of proteins (polypeptide chains) and protein assembly - Polypeptide chains are polymers of the 20 different amino acids. - Uses a genetic code – chemical letters in RNA that make up words which code for particular amino acids - Check your understanding: what happens if the letters change?

End Show 2–3 Carbon Compounds Slide 10 of 37 Part I. Transcription of DNA into mRNA (the message) FYI – any of the three types of RNA are made this way DNA flattens and is unzipped exposing its bases (template) – sound familiar? –RNA polymerase binds free RNA nucleotides to exposed DNA bases starting at a promoter – a specific DNA nucleotide pattern –Complementary base pairing occurs, EXCEPT THERE IS NO THYMINE IN RNA. Instead, Adenine bonds with Uracil just as Thymine from DNA would bond with Adenine. –Transcription continues until a termination signal is given (punctuation) to stop the transcription process –If DNA reads: ATC GTC GAT TGG C AA –mRNA leaves the nucleus through a pore to go out into the cytosol to locate a ribosome mRNA: UAG CAG CUA ACC GUU

End Show 2–3 Carbon Compounds Slide 11 of 37 The Genetic Code: Where a group of 3 nucleotide bases translates into a particular amino acid This 3 “letter word” is called a codon Codons are groups of 3 adjacent bases on mRNA (AAA, CCC GGG) Each codon will specify a specific amino acid. When the codon is recognized by the anticodon, this is called Translation There are 64 different codons with punctuation as well for start and stop

End Show 2–3 Carbon Compounds Slide 12 of 37 Start codon Stop Codons

End Show 2–3 Carbon Compounds Slide 13 of 37 About the genetic code … Codons are code words found in mRNA Codons code for particular amino acids Three of the 64 codons are stop, one is start – AUG = methionine The code is degenerate – more than one codon can code for an amino acid – why is this important? The code is UNIVERSAL!!!

End Show 2–3 Carbon Compounds Slide 14 of 37 What is an anticodon and how does the amino acid get selected?

End Show 2–3 Carbon Compounds Slide 15 of 37 Part II. Translation of mRNA into protein * At the ribosome, the process of translation occurs. Several ribosomes may undergo this process at one time mRNA will temporarily bind with the two ribosomal subunits tRNA is waiting in the cytoplasm with its corresponding amino acid Starting with the start codon (AUG), in groups of 3, mRNA will determine which amino acid tRNA must bring to the ribosome. Animation – Virtual CellVirtual Cell

End Show 2–3 Carbon Compounds Slide 16 of 37 Transcription Translation Polypeptide forming

End Show 2–3 Carbon Compounds Slide 17 of 37 Once tRNA brings the correct amino acid to mRNA at the ribosome, it releases and goes back to the cytoplasm to pick up it corresponding amino acid Adjacent amino acids bond together, making a peptide bond to form a polypeptide. Chain could be up to 10,000 amino acids long This continues until the entire message is translated. The chain of amino acids is formed called a polypeptide (protein). The translation ends when a STOP codon is reached (UAA, UAG, UGA).

End Show 2–3 Carbon Compounds Slide 18 of 37 When things go wrong: Does this process ever make a mistake? Have you ever had to copy a large amount of information? What is the likelihood of you making a mistake or more? What could cause these changes?

End Show 2–3 Carbon Compounds Slide 19 of 37 Changes in genetic materialGene Mutations: alters one or more genes Chromosomal Mutations: alter the entire chromosome or a portion of it.

End Show 2–3 Carbon Compounds Slide 20 of 37 Gene Mutations Point Mutations Point Mutations – affect only one amino acid Frameshift mutations Frameshift mutations – May affect an entire amino acid sequence.

End Show 2–3 Carbon Compounds Slide 21 of 37 Point mutation involves a change in one or a few nucleotides. Influences a single amino acid in the polypeptide change; caused by a substitution of a nitrogen base. Sickle cell anemia is an example of this – GUG instead of GAG Valine instead of glutamic acid

End Show 2–3 Carbon Compounds Slide 22 of 37 THE FAT CAT ATE THE RAT Take out “C” in Cat & substitute a “B” THE FAT BAT ATE THE RAT In this case, it does not really change the meaning to the sentence or the protein formed

End Show 2–3 Carbon Compounds Slide 23 of 37 If DNA reads: A T G G T C G A T T G G CAA mRNA: U A C C A G C U A AC C GUU Amino Acid: Tyrosine - Glutamine – Leucine -Threonine – Valine But if mRNA: U A C C A G C A A AC C GUU The AA: Tyrosine – Glutamine – Glutamine – Threonine – Valine

End Show 2–3 Carbon Compounds Slide 24 of 37 Frameshift mutation involves a change in the entire protein formed or a large portion of it. Caused by insertions (additions) or deletions of nitrogen bases. Tay-Sachs is a disease caused by a frameshift mutation

End Show 2–3 Carbon Compounds Slide 25 of 37 THE FAT CAT ATE THE RAT Take out “E” in THE & group into 3’s THF ATC ATA TET HER AT_ This makes no sense at all!!

End Show 2–3 Carbon Compounds Slide 26 of 37 If DNA reads: A T G G T C G A T T G G CAA mRNA: U A C C A G C U A AC C GUU AA: Tyrosine - Glutamine – Leucine -Threonine – Valine BUT if mRNA: U A C C A G U A A C C G U U _ THEN Amino Acid: Tyrosine - Glutamine – STOP!!!! The entire sentence makes no sense. The protein formed would be totally different

End Show 2–3 Carbon Compounds Slide 27 of 37 So which form of a mutation would be more severe? Frameshift mutation …Frameshift mutation … since an entirely new protein would be formed

End Show 2–3 Carbon Compounds Slide 28 of 37 CHROMOSOMAL MUTATIONS involve changes in number and structure of the chromosomes. Could change location of genes on the chromosomes or the number of copies of some of the genes.

End Show 2–3 Carbon Compounds Slide 29 of 37 Deletions – part of a chromosome is missing Duplications – Extra copies of genes are inserted Inversions – Reverse direction of parts of the chromosome Chromosomal Mutations animation

End Show 2–3 Carbon Compounds Slide 30 of 37 Parts of one non-homologous chromosome breaks off and attached onto another non-homologous chromosome Translocations

End Show 2–3 Carbon Compounds Slide 31 of 37