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Unit Overview – pages 250-251

1. What are the 3 components of this DNA nucleotide? 2. What is the function of DNA in the cell?. Unit Overview – pages 250-251. Genetics. DNA and Genes. DNA: The Molecule of Heredity. Section 11.1 Summary – pages 281 - 287. What is DNA?.

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Unit Overview – pages 250-251

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  1. 1. What are the 3 components of this DNA nucleotide?2. What is the function of DNA in the cell?

  2. Unit Overview – pages 250-251 Genetics DNA and Genes DNA: The Molecule of Heredity

  3. Section 11.1 Summary – pages 281 - 287 What is DNA? • The environment influences how an organism develops. • DNA ultimately determines an organism’s traits. • DNA molecules do this through the genetic information they hold. • Within the structure of DNA is the information for life—the complete instructions for manufacturing all the proteins for an organism.

  4. Section 11.1 Summary – pages 281 - 287 What is DNA? • DNA achieves its control by determining the structure of proteins. • Your body is made up of proteins. • Your body’s functions depend on proteins called enzymes.

  5. Section 11.1 Summary – pages 281 - 287 DNA as the genetic material • In 1952 Alfred Hershey and Martha Chase performed an experiment using radioactively labeled viruses that infect bacteria. • These viruses were made of only protein and DNA.

  6. Section 11.1 Summary – pages 281 - 287 The structure of nucleotides • DNA is a polymer made of repeating subunits called nucleotides. Nitrogenous base Phosphate group Sugar (deoxyribose)

  7. Section 11.1 Summary – pages 281 - 287 The structure of nucleotides • Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base. • Deoxyribose is the simple sugar in DNA • The phosphate group is composed of one atom of phosphorus surrounded by four oxygen atoms.

  8. Section 11.1 Summary – pages 281 - 287 The structure of nucleotides • A nitrogenous base is a carbon ring structure that contains one or more atoms of nitrogen. • In DNA, there are four possible nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Cytosine (C) Guanine (G) Thymine (T) Adenine (A)

  9. Section 11.1 Summary – pages 281 - 287 The structure of nucleotides • Thus, in DNA there are four possible nucleotides, each containing one of these four bases.

  10. Section 11.1 Summary – pages 281 - 287 The structure of nucleotides • Nucleotides join together to form long chains. • The phosphate groups and deoxyribose molecules form the backbone of the chain. • The nitrogenous bases stick out like the teeth of a zipper.

  11. Section 11.1 Summary – pages 281 - 287 The structure of nucleotides • In DNA, adenine always pairs with thymine, and guanine always pairs with cytosine.

  12. Section 11.1 Summary – pages 281 - 287 The structure of DNA • In 1953, Watson and Crick proposed that DNA is made of two chains of nucleotides held together by nitrogenous bases. • Watson and Crick also proposed that DNA is shaped like a long zipper that is twisted into a coil like a spring.

  13. Section 11.1 Summary – pages 281 - 287 The structure of DNA • Because DNA is composed of two strands twisted together, its shape is called double helix.

  14. Section 11.1 Summary – pages 281 - 287 The importance of nucleotide sequences The sequence of nucleotides forms the unique genetic information of an organism. The closer the relationship is between two organisms, the more similar their DNA nucleotide sequences will be. Chromosome

  15. Section 11.1 Summary – pages 281 - 287 Replication of DNA • Before a cell can divide by mitosis or meiosis, it must first make a copy of its chromosomes. • The DNA in the chromosomes is copied in a process called DNA replication. • Without DNA replication, new cells would have only half the DNA of their parents.

  16. Section 11.1 Summary – pages 281 - 287 DNA Replication of DNA Replication Replication

  17. Section 11.1 Summary – pages 281 - 287 Copying DNA • DNA is copied during interphase prior to mitosis and meiosis. • It is important that the new copies are exactly like the original molecules.

  18. Section 11.1 Summary – pages 281 - 287 Copying DNA New DNA molecule Original DNA Strand Free Nucleotides New DNA molecule New DNA Strand Original DNA Strand Original DNA

  19. Section 11.1 Summary – pages 281 - 287 Copying DNA New DNA molecule Original DNA Strand Free Nucleotides New DNA molecule New DNA Strand Original DNA Strand Original DNA

  20. Section 11.1 Summary – pages 281 - 287 Copying DNA New DNA molecule Original DNA Strand Free Nucleotides New DNA molecule New DNA Strand Original DNA Strand Original DNA

  21. DNAi • How DNA is packaged • DNA unzip • Replicating the helix • Mechanism of replication Book of Life • DNA Basics

  22. Section 1 Check Question 1 What importance did the experiment performed by Alfred Hershey and Martha Chase have in determining what genetic material was? Answer Many scientists believed protein was the genetic material. However, an experiment using radioactively labeled viruses allowed Hershey and Chase to provide convincing evidence that DNA is the genetic material.

  23. Section 1 Check Question 2 Which of the following is NOT a component of DNA? A. simple sugars B. phosphate groups C. nitrogenous bases D. proteins The answer is D.

  24. Section 1 Check Question 3 Which of the following correctly comprises a complimentary base pair? A. adenine – thymine B. thymine – guanine C. guanine – adenine D. cytosine – thymine The answer is A.

  25. bELLRINGER page 288 • What parts does RNA have that DNA does not have?

  26. Section 11.2 Summary – pages 288 - 295 Genes and Proteins • The sequence of nucleotides in DNA contain information. • This information is put to work through the production of proteins. • Proteins fold into complex, three- dimensional shapes to become key cell structures and regulators of cell functions.

  27. Section 11.2 Summary – page 2888- 295 Genes and Proteins • You learned earlier that proteins are polymers of amino acids. • The sequence of nucleotides in each gene contains information for assembling the string of amino acids that make up a single protein.

  28. Section 11.2 Summary – pages 288 - 295 RNA • RNA like DNA, is a nucleic acid. RNA structure differs from DNA structure in three ways. • First, RNA is single stranded—it looks like one-half of a zipper —whereas DNA is double stranded.

  29. Section 11.2 Summary – pages 288 - 295 RNA Ribose • The sugar in RNA is ribose; DNA’s sugar is deoxyribose.

  30. Section 11.2 Summary – pages 288 - 295 RNA • Both DNA and RNA contain four nitrogenous bases. • Rather than thymine, RNA contains a similar base called uracil (U). • Uracil forms a base pair with adenine in RNA, just as thymine does in DNA. Uracil Hydrogen bonds Adenine

  31. Section 11.2 Summary – pages 288 - 295 RNA • DNA provides workers with the instructions for making the proteins, and workers build the proteins. • The workers for protein synthesis are RNA molecules.

  32. Section 11.2 Summary – pages 288 - 295 RNA • There are three types of RNA that help build proteins. • Messenger RNA (mRNA) brings instructions from DNA in the nucleus to the cell’s factory floor, the cytoplasm. • On the factory floor, mRNA moves to the assembly line, a ribosome.

  33. Section 11.2 Summary – pages 288 - 295 RNA • Ribosomal RNA (rRNA) binds to the mRNA and uses the instructions to assemble the amino acids in the correct order. • The ribosome is made of ribosomal RNA.

  34. Section 11.2 Summary – pages 288 - 295 RNA • Transfer RNA (tRNA) delivers amino acids to the ribosome to be assembled into a protein.

  35. Section 11.2 Summary – pages 288 - 295 Transcription • Transcription is a process in which enzymes make an RNA copy of a portion of a DNA strand in the cell’s nucleus. • Transcription results in the formation of one single-stranded RNA molecule.

  36. Section 11.2 Summary – pages 288 - 295 RNA Processing • Not all the nucleotides in the DNA of eukaryotic cells carry instructions—orcode—for making proteins. • Genes usually contain many long noncoding nucleotide sequences, called introns, that are scattered among the coding sequences.

  37. Section 11.2 Summary – pages 288 - 295 RNA Processing • Regions that contain information are called exons because they are expressed. • When mRNA is transcribed from DNA, both introns and exons are copied. • The introns must be removed from the mRNA before it can function to make a protein.

  38. Section 11.2 Summary – pages 288 - 295 RNA Processing • Enzymes in the nucleus cut out the intron segments and paste the mRNA back together. • The mRNA then leaves the nucleus and travels to the ribosome.

  39. DNAi • Transcription • mRNA splicing

  40. Section 11.2 Summary – pages 288 - 295 • What are the three types of RNA? • How do they work together to build a protein?

  41. Section 11.2 Summary – pages 288 - 295 The Genetic Code • The nucleotide sequence transcribed from DNA to a strand of messenger RNA acts as a genetic message, the complete information for the building of a protein. • A code is needed to convert the language of mRNA into the language of proteins.

  42. Section 11.2 Summary – pages 288 - 295 The Genetic Code • A codon is a group of three nitrogenous bases in mRNA that code for one amino acid. • Sixty-four combinations are possible when a sequence of three bases is used. • There are 64 different mRNA codons in the genetic code.

  43. Section 11.2 Summary – pages 288 - 295 The Genetic Code The Messenger RNA Genetic Code First Letter Third Letter Second Letter U A G C U U Phenylalanine (UUU) Serine (UCU) Tyrosine (UAU) Cysteine (UGU) C Cysteine (UGC) Phenylalanine (UUC) Serine (UCC) Tyrosine (UAC) A Stop (UGA) Serine (UCA) Stop (UAA) Leucine (UUA) G Leucine (UUG) Serine (UCG) Stop (UAG) Tryptophan (UGG) C U Arginine (CGU) Leucine (CUU) Proline (CCU) Histadine (CAU) Arginine (CGC) Proline (CCC) C Leucine (CUC) Histadine (CAC) A Proline (CCA) Arginine (CGA) Leucine (CUA) Glutamine (CAA) Arginine (CGG) G Glutamine (CAG) Proline (CCG) Leucine (CUG) A U Isoleucine (AUU) Threonine (ACU) Asparagine (AAU) Serine (AGU) C Serine (AGC) Asparagine (AAC) Isoleucine (AUC) Threonine (ACC) A Arginine (AGA) Isoleucine (AUA) Threonine (ACA) Lysine (AAA) G Arginine (AGG) Methionine;Start (AUG) Threonine (ACG) Lysine (AAG) G Glycine (GGU) U Valine (GUU) Alanine (GCU) Aspartate (GAU) Valine (GUC) Aspartate (GAC) Glycine (GGC) Glycine (GGC) C Alanine (GCC) A Glycine (GGA) Alanine (GCA) Glutamate (GAA) Valine (GUA) Glutamate (GAG) Glycine (GGG) Alanine (GCG) G Valine (GUG)

  44. Section 11.2 Summary – pages 288 - 295 The Genetic Code • Some codons do not code for amino acids; they provide instructions for making the protein. • More than one codon can code for the same amino acid. • However, for any one codon, there can be only one amino acid.

  45. Section 11.2 Summary – pages 288 - 295 Translation: From mRNA to Protein • Translation is the process of converting the information in a sequence of nitrogenous bases in mRNA into a sequence of amino acids in protein. • Translation takes place at the ribosomes in the cytoplasm.

  46. Section 11.2 Summary – pages 288 - 295 The role of transfer RNA • For proteins to be built, the 20 different amino acids dissolved in the cytoplasm must be brought to the ribosomes. • This is the role of transfer RNA.

  47. Section 11.2 Summary – pages 288 - 295 The role of transfer RNA Amino acid • Each tRNA molecule attaches to only one type of amino acid. • An anticodon is a sequence of three bases found on tRNA. Chain of RNA nucleotides Transfer RNA molecule Anticondon

  48. Section 11.2 Summary – pages 288 - 295 The role of transfer RNA Ribosome mRNA codon

  49. Section 11.2 Summary – pages 288 - 295 The role of transfer RNA • The first codon on mRNA is AUG, which codes for the amino acid methionine. • AUG signals the start of protein synthesis. • Then the ribosome slides along the mRNA to the next codon.

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