Chapter 13: RNA & Protein Synthesis. Section: 13 1 RNA

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1 Chapter 13: RNA & Protein Synthesis 12-3 RNA and Protein Synthesis Section: 13 1 RNA 1 of 39

2 12 3 RNA and Protein Synthesis 12 3 RNA and Protein Synthesis Genes contain coded DNA instructions that tell cells how to build of proteins. Genetic instructions can be decoded by copying part of the nucleotide sequence from DNA into RNA. RNA then uses the genetic instructions or coded information for making proteins. 2 of 39

3 12 3 RNA and Protein Synthesis The Structure of RNA The Structure of RNA There are three main differences between RNA and DNA: The sugar in RNA is ribose instead of deoxyribose. RNA is generally single-stranded. RNA contains uracil in place of thymine. When RNA identifies adenine it substitutes uracil in place of thymine 3 of 39

4 12 3 RNA and Protein Synthesis Types of RNA Types of RNA There are three main types of RNA: messenger RNA (mrna) ribosomal RNA (rrna) transfer RNA (trna) 4 of 39

5 12 3 RNA and Protein Synthesis Types of RNA Messenger RNA (mrna) carries copies of instructions for assembling amino acids into proteins. 5 of 39

6 12 3 RNA and Protein Synthesis Types of RNA Ribosome Ribosomal RNA Ribosomes are made up of proteins and ribosomal RNA (rrna). Proteins are assembled on ribosomes. 6 of 39

7 12 3 RNA and Protein Synthesis Types of RNA Amino acid Transfer RNA During protein construction, transfer RNA (trna) transfers each amino acid to the ribosome. 7 of 39

8 12 3 RNA and Protein Synthesis Transcription RNA RNA polymerase DNA 8 of 39

9 12 3 RNA and Protein Synthesis Transcription Transcription DNA is copied in the form of RNA This first process is called transcription. The process begins at a section of DNA called a promoter. Promoters show RNA polymerase exactly where to begin making RNA. 9 of 39

10 12 3 RNA and Protein Synthesis Protein Synthesis DNA molecule DNA strand (template) 3 5 TRANSCRIPTION mrna 5 3 Codon TRANSLATION Protein 10 of 39 Amino acid

11 12 3 RNA and Protein Synthesis RNA Editing RNA Editing Some DNA within a gene is not needed to produce a protein. These areas are called introns. The DNA sequences that code for proteins are called exons. 11 of 39

12 12 3 RNA and Protein Synthesis RNA Editing The introns are cut out of RNA molecules. The exons are then spliced together to form mrna. Then a cap and tail are added to to form the final mrna molecule. Exon Intron Cap DNA Pre-mRNA mrna Tail 12 of 39

13 Chapter 13: RNA and Protein Synthesis 12-3 RNA and Protein Synthesis Section: 13 2 Ribosomes and Protein Synthesis 13 of 39

14 12 3 RNA and Protein Synthesis The Genetic Code The Genetic Code The genetic code is the language of mrna instructions. The code is written using four letters (the bases: A, U, C, and G). 14 of 39

15 12 3 RNA and Protein Synthesis The Genetic Code Genetic codes are read 3 bases at a time. A codon consists of three consecutive nucleotides on mrna that specify a particular amino acid. There are about 20 different amino acids. 15 of 39

16 12 3 RNA and Protein Synthesis The Genetic Code There are 64 possible 3-base codes. Start codon 16 of 39

17 12 3 RNA and Protein Synthesis Translation Translation Translation is the decoding of an mrna message into a a series of amino acids which form the polypeptide chain (protein). Translation takes place on ribosomes in the cytoplasm. During translation, the cell uses information from messenger RNA to produce proteins. Nucleus mrna 17 of 39

18 12 3 RNA and Protein Synthesis Translation The ribosome binds new trna molecules and amino acids as it moves along the mrna. Methionine Phenylalanine trna Lysine trna Anti-codon Ribosome mrna Start codon 18 of 39

19 12 3 RNA and Protein Synthesis Translation Protein Synthesis Lysine trna mrna Ribosome Translation direction 19 of 39

20 12 3 RNA and Protein Synthesis Translation The process continues until the ribosome reaches a stop codon. Polypeptide trna Ribosome mrna 20 of 39

21 12 3 RNA and Protein Synthesis Genes and Proteins Codon Codon Codon DNA Single strand of DNA mrna Codon Codon Codon mrna Protein Alanine Arginine Leucine Amino acids within a polypeptide 21 of 39

22 12 3 Continue to: - or - Click to Launch: 22 of 39

23 12 3 The role of a master plan in a building is similar to the role of which molecule? a. messenger RNA b. DNA c. transfer RNA d. ribosomal RNA 23 of 39

24 12 3 A base that is present in RNA but NOT in DNA is a. thymine. b. uracil. c. cytosine. d. adenine. 24 of 39

25 12 3 The nucleic acid responsible for bringing individual amino acids to the ribosome is a. transfer RNA. b. DNA. c. messenger RNA. d. ribosomal RNA. 25 of 39

26 12 3 A region of a DNA molecule that indicates to an enzyme where to bind to make RNA is the a. intron. b. exon. c. promoter. d. codon. 26 of 39

27 12 3 A codon typically carries sufficient information to specify a(an) a. single base pair in RNA. b. single amino acid. c. entire protein. d. single base pair in DNA. 27 of 39

28 END OF SECTION

29 Chapter 13: RNA & Protein Synthesis 12-4 Mutations Section: 13 3 Mutations 29 of 24

30 12 4 Mutations 12-4 Mutations Mutations are changes in the genetic material. 30 of 24

31 12 4 Mutations Kinds of Mutations Kinds of Mutations Mutations that produce changes in a gene are known as gene mutations. Mutations that produce changes in whole chromosomes are known as chromosomal mutations. 31 of 24

32 12 4 Mutations Kinds of Mutations Gene Mutations Gene mutations involving a change in one or a few nucleotides are known as point mutations because they occur at a single point in the DNA sequence. Point mutations include: substitutions, insertions, and deletions. Point mutations usually occur during replication. Sickle-cell disease is the result of a point mutation. 32 of 24

33 12 4 Mutations Kinds of Mutations Substitutions usually affect no more than a single amino acid. One base is changed to another base (e.g., T and A are substituted for C and G) 33 of 24

34 12 4 Mutations Kinds of Mutations The effects of insertions or deletions (types of point mutations) are more dramatic. The addition or deletion of a nucleotide causes a shift in the grouping of codons that are read. Changes like these are called frameshift mutations. 34 of 24

35 12 4 Mutations Kinds of Mutations In an insertion, an extra base is inserted into a base sequence. Note the changes in amino acids before the insertion (top) and after the insertion (bottom). This protein produced will not be able to perform its normal function. 35 of 24

36 12 4 Mutations Kinds of Mutations In a deletion, the loss of a single base is deleted and the reading frame is shifted. 36 of 24

37 12 4 Mutations Kinds of Mutations Chromosomal Mutations Chromosomal mutations involve changes in the number or structure of chromosomes. There are 4 types of chromosomal mutations include: - deletions, - duplications, - inversions, and - translocations. 37 of 24

38 12 4 Mutations Kinds of Mutations Deletions involve the loss of all or part of a chromosome. 38 of 24

39 12 4 Mutations Kinds of Mutations Duplications produce extra copies of parts of a chromosome. 39 of 24

40 12 4 Mutations Kinds of Mutations Inversions reverse the direction of parts of chromosomes. 40 of 24

41 12 4 Mutations Kinds of Mutations Translocations occurs when part of one chromosome breaks off and attaches to another. 41 of 24

42 12 4 Mutations Significance of Mutations Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations can be beneficial (e.g., oil eating bacteria). It is estimated that there is 1 incorrect base insertion for every 10,000,000 bases. 42 of 24

43 12 4 Mutations Significance of Mutations Significance of Mutations Some mutations are the cause of environmental conditions. Mutagens can cause genetic disorders. Chemical mutagens: pesticides, tobacco smoke are some. Physical mutagens: x-rays, UV light are some examples 43 of 24

44 12 4 Mutations Significance of Mutations Significance of Mutations Mutations in some African mosquitoes have caused them to be resistant to pesticides. Polyploidy (triploids 3n and tetraploids 4n), is the condition in which an organism has extra sets of chromosomes. Examples: apples, limes, (most citrus), strawberries, mums, dahlias, pansies, some wheat, bananas, oats, kiwi, sugar cane, watermelon, tulips, lilies, cotton, tobacco, peanuts 44 of 24

45 12 4 Continue to: - or - Click to Launch: 45 of 24

46 12 4 A mutation in which all or part of a chromosome is lost is called a(an) a. duplication. b. deletion. c. inversion. d. point mutation. 46 of 24

47 12 4 A mutation that affects every amino acid following an insertion or deletion is called a(an) a. frameshift mutation. b. point mutation. c. chromosomal mutation. d. inversion. 47 of 24

48 END OF SECTION

DNA, RNA, Protein synthesis, and Mutations. Chapters 12-13.3

DNA, RNA, Protein synthesis, and Mutations Chapters 12-13.3 1A)Identify the components of DNA and explain its role in heredity. DNA s Role in heredity: Contains the genetic information of a cell that can