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Biology Notes

Biology Notes. Topic: Protein Synthesis Objective: Alabama Course of Study #8 Glencoe High School Meredith Barkley. List of Note-Cards (AL COS #8). #8-1 What is relationship between chromosomes, DNA, & genes? #8-2 Notable Scientists #8-3 Simplified Structure of DNA #8-4 DNA Replication

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Biology Notes

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  1. Biology Notes Topic: Protein Synthesis Objective: Alabama Course of Study #8 Glencoe High School Meredith Barkley

  2. List of Note-Cards (AL COS #8) • #8-1 What is relationship between chromosomes, DNA, & genes? • #8-2 Notable Scientists • #8-3 Simplified Structure of DNA • #8-4 DNA Replication • #8-5 DNA versus RNA • #8-6 Protein Synthesis • #8-7 Protein Synthesis Practice Problems • #8-8 Genetic Variation • #8-9 Examples of Biotechnology • #8-10 Types of Mutations • #8-11 Genetic Disorders

  3. #8-1 What is the relationship between chromosomes, DNA, and genes? • Chromosomes unravel into strand of DNA… • Segments or sub-units of DNA are called genes. • The human genome contains ~ 20,000 genes that codes for proteins, such as enzymes (biological catalysts) within your body!

  4. What kind of genes do you have??? • Remember that genes are basically coded information cells use in order to produce proteins, like enzymes, that are responsible for important jobs within your body. For example, the BRCA 1 and BRCA 2 genes are found on human chromosomes 13 and 17. These genes act as tumor suppressors, preventing uncontrolled cell growth that could lead to malignant tumors.

  5. #8-2 Notable Scientists (1952) Hershey & Chase (1928) Griffith (1949) Chargaff 1900 1915 1930 1945 1960 1975 1990 2005 2020 (1944) Avery (1952) Wilkins & Franklin (1953) Watson & Crick

  6. #8-2 Notable Scientists (1952) Hershey & Chase (1928) Griffith (1949) Chargaff 1900 1915 1930 1945 1960 1975 1990 2005 2020 (1944) Avery (1952) Wilkins & Franklin (1953) Watson & Crick

  7. #8-2 Notable Scientists

  8. #8-2 Notable Scientists

  9. Griffith’s Experiment Illustrated

  10. Griffith’s Experiments Summarized • Made accidental discovery while preparing vaccines against the bacteria Streptococcus pneumoniae • Griffith worked with 2 strains of pneumoniae: • S. pneumoniae (enclosed in capsule & forms smooth colonies) • R. pneumoniae (no capsule & forms rough-edged colonies) • Bacterial colonies with capsules were protected against the bodies immune system and were considered virulent, or able to cause disease. • Through a series of 4 experiments he discovered the process of transformation (change in genotype caused when body takes up foreign genetic DNA)

  11. Hershey and Chase’s Experiment Illustrated

  12. Hershey and Chase’s Experiments Summarized • Question: What is the genetic material within cell? • Answer: DNA • Experiments were used to prove this concept involved “T2 bacteriophages” • bacteriophage : virus that infects bacteria • T2 bacteriophages have phosphorus in their DNA. • T2 bacteriophages have sulfur in their protein coat. • They labeled both phosphorus and sulfur with radioactive isotopes in order to track their location. • After the phages infected E. coli bacteria, the radioactive phosphorus moved into the cell, while the sulfur remained within the phage.

  13. #8-2 Notable Scientists • Match each scientists name with the illustrations provided: • Griffith • Avery • Chargaff • Hershey & Chase • Wilkins & Rosalind Franklin • Watson & Crick

  14. #8-3 Simplified Structure of DNA

  15. #8-3 Simplified Structure of DNA

  16. #8-3 Simplified Structure of DNA

  17. #8-3 Simplified Structure of DNA Draw sketches as needed to accompany your notes! Nucleotide

  18. Practice Problems • Record the complementary strand of DNA that corresponds to the sequence given. • AGG TCA • GTT ACC • GCA TAC TCC AGT would be the complementary DNA strand. CAA TGG would be the complementary DNA strand. CGT ATG would be the complementary DNA strand.

  19. #8-4 DNA Replication • Refer to this diagram as you go through your notes, remembering there is more detail here than you will be responsible for… Don’t get overwhelmed!!!

  20. #8-4 DNA Replication Prokaryotes Picture Before we talk about the copying / replication of DNA, it’s helpful to remember that DNA within prokaryotes will be found within the cell’s cytoplasm in a single loop. Prokaryotic cells may also contain plastids with additional DNA.

  21. #8-4 DNA Replication Picture Eukaryotes Before we talk about the copying / replication of DNA, it’s helpful to remember that DNA within eukaryotes will be found within the cell’s nucleus. Extra-nuclear DNA can also be found within the mitochondria and chloroplasts of eukaryotic cells. (connection to Endosymbiotic Theory)

  22. #8-4 DNA Replication • Prior to all forms of cell division, DNA is replicated/copied. • DNA Replication occurs during the S Phase (synthesis) of Interphase within the cell cycle for eukaryotic cells. Remember, this is why a typical cell spends 90% of its life in interphase…takes time to copy DNA and other cellular components. • DNA replication involves a series of complex processess that we can simply summarize into the following steps. • DNA is unwound/unzipped. • New nucleotide sequences are added. • The end result of DNA replication is that two DNA molecules have been formed, each composed of a new strand and an original strand. (semi-conservative model)

  23. #8-4 DNA Replication: Initiation • DNA replication will take place at certain points called origins. • This process is aided by special proteins. • Remember all enzymes are classified as proteins. These enzymes speed up biological processes. • This picture represents the semi-conservative model of DNA replication, meaning each DNA molecule will be made of one new and one original stand.)

  24. #8-4 DNA Replication: Elongation • The enzyme DNA helicaseopens up / unzips the double helix of DNA by breaking the hydrogen bonds that linked the complimentary nitrogen bases between the strands. • The areas where the DNA separates are called replication forks because of their y-shape.

  25. Prokaryotic and Eukaryotic DNA have a different number of replication forks… Prokaryotes Eukaryotes Remember, DNA within prokaryotes is found within a nucleoid (nucleus like region) in a single loop. The replication of a human chromosome with only one pair of replication forks from a single origin would take 33 days!!! Therefore, a human chromosome is replicated in ~100 sections, reducing the time to replicate the DNA to about 8 hours.

  26. #8-4 DNA Replication: Elongation • As DNA helicase unwinds/unzips DNA… a replication bubble is formed. This bubble is where DNA will be copied. • Single stranded binding proteins help hold and temporarily separate each original strand of DNA.

  27. #8-4 DNA Replication: Elongation • As the double helix is pulled apart, the enzyme DNA polymerase adds new nucleotides to the exposed nitrogen bases, according to base-pairing rules. DNA polymerase also functions in proofreading in an attempt to correct any incorrect sequences.

  28. #8-4 DNA Replication: Elongation • One strand will work ahead of the other, because of the structure of the strand. The one that works at a quicker pace is known as the leading strand. The lagging strand works like a sewing machine back-stitching…

  29. #8-4 DNA Replication • This process produces two DNA molecules, each made up of a new strand and an original strand. • This is referred to as the semi-conservative model of DNA replication. • Simple, right?? 

  30. #8-5 RNA versus DNA

  31. #8-5 RNA versus DNA

  32. #8-5 RNA versus DNA Why is RNA important? RNA plays an essential role in protein synthesis within your body.

  33. #8-6 Protein Synthesis

  34. #8-6 Protein Synthesis Transcription The instructions for making a protein are transferred from a gene in DNA to a RNA molecule called mRNA (messenger RNA). The RNA instructions are written as a series of three-nucleotide sequences on the mRNA called codons. This messenger RNA will carry the instructions for making the protein from a gene and deliver it to a site of translation.

  35. #8-6 Protein Synthesis • Notice that during transcription, DNA within the nucleus is used as a template to make mRNA. DNA temporarily elongates and unwinds. After the mRNA has been made, the double helix reforms, and mRNA leaves the nucleus with its copy of the instructions to make a protein written in RNA code.

  36. #8-6 Protein Synthesis Ribosomes Function in Synthesizing Proteins Translation The information to make proteins is transferred from the language of RNA (nucleotides) to the language of proteins (amino acids). This takes place in cytoplasm where ribosomes are located. There are 64 possible codon sequences that can be translated into 20 different amino acids.

  37. #8-6 Protein Synthesis • Translation of codons into amino acids

  38. Interpreting the Genetic Code of Codons into Amino Acids, the Building blocks of Proteins (pg 211) Notice the Codon sequences that will START or STOP the process of protein synthesis!

  39. #8-7 Protein Synthesis Practice *Remember, you will need a table (like the one found on page 211 of your Holt Biology textbook) in order to complete “translation” which involves recording the name of the amino acid that corresponds to the mRNA codon you recorded/transcribed.

  40. #8-7 Protein Synthesis Practice *Remember, you will need a table (like the one found on page 211 of your Holt Biology textbook) in order to complete “translation” which involves recording the name of the amino acid that corresponds to the mRNA codon you recorded/transcribed.

  41. #8-7 Protein Synthesis Practice *Remember, you will need a table (like the one found on page 211 of your Holt Biology textbook) in order to complete “translation” which involves recording the name of the amino acid that corresponds to the mRNA codon you recorded/transcribed.

  42. #8-7 Protein Synthesis Practice

  43. Gene Regulation and Structure • This section will be added later for Pre-AP Bio Students 

  44. #8-8 Genetic Variation • Genetic variation describes naturally occurring genetic differences among individuals of the same species • This variation permits flexibility and survival of a population in the face of changing environmental circumstances. • Consequently, genetic variation is often considered an advantage, as it is a form of preparation for the unexpected. Genetic variation may increase through the following processes  • Independent Assortment • Crossing Over • Random Fertilization • Genetic Engineering / Biotechnology • Mutation

  45. #8-9 Examples of Biotechnology Biotechnology (AKA genetic engineering): process of manipulating genes for practical purposes This may involve building recombinant DNA: DNA made from 2 or more different organisms Human Genome Project Genetically engineered drugs and vaccines DNA fingerprinting Agriculture Animal Farming

  46. #8-10 Mutations within DNA What is a mutation and who can it affect??? Major Types of Mutation Mutation: change in DNA Mutation to somatic cells (body cells) affect only the individual in which they occur. Mutations to gametes (sex cells) can be passed on to the offspring of an affected individual. Point Mutation: changes a single nucleotide within a DNA sequence. This may or may not affect function of the gene in regards to protein synthesis. (Ex: inversion) Reading Frame Shift Mutation: alters entire reading frame of DNA sequence, affecting function in protein synthesis. (Example: addition, deletion) pg.220

  47. Case Study: Knowing Your Genome • Actress Angelina Jolie announced in a New York Times op-ed article on Tuesday that she underwent a preventive double mastectomy after learning that she carries a mutation of the BRCA1 gene, which sharply increases her risk of developing breast cancer and ovarian cancer. • (2013 CNN) "My doctors estimated that I had an 87 percent risk of breast cancer and a 50 percent risk of ovarian cancer, although the risk is different in the case of each woman…Once I knew that this was my reality, I decided to be proactive and to minimize the risk as much I could. I made a decision to have a preventive double mastectomy.“ – Angelina Jolie

  48. Case Study: Knowing Your Genome Additional Information BRCA 1 and 2 Genes: Mutation to These Genes Associated With Increased Risk of Breast Cancer… Read this Reader’s Digest article 5 Surprising Facts You Didn’t Know About the Breast Cancer Gene, to find out more about Angelina Jolie’s decision. KEY QUESTION: What are potential benefits AND drawbacks of having your genome screened for potential disease???

  49. #8-11 Genetic Disorders

  50. #8-11 Genetic Disorders

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