Enzymes Past Paper PDF

Enzymes 1.7.25 1. Draw a molecule that would most likely be able to interact with this enzyme. 2. Describe one specific role of enzymes in the human body. 3. A person has a high fever of 105°F. State one effect that this high fever would likely have on enzyme activity. 4. Sketch the graph of...

Enzymes 1.7.25 1. Draw a molecule that would most likely be able to interact with this enzyme. 2. Describe one specific role of enzymes in the human body. 3. A person has a high fever of 105°F. State one effect that this high fever would likely have on enzyme activity. 4. Sketch the graph of an enzyme whose optimum pH is 7. Be sure to label both axes and include a scale on the x-axis. Next to the graph describe what happens to the enzyme when the pH increases or decreases. 5. Explain what happens to enzyme activity when the temperature falls below the optimum temperature for that enzyme. 6. Base your answer to the following question on the information below and on your knowledge of biology. Harmless Skin Virus Fights Acne...Acne is caused when hair follicles become blocked with an oily substance called sebum, which the body makes to stop the hair and skin from drying out. Normally harmless bacteria, such as Propionibacterium acnes, that live on the skin can then contaminate and infect the plugged follicles. Phages [a type of virus] appear to help counteract this. When the scientists sequenced the DNA coding of the phages, they discovered that, as well as sharing most of their genetic material, the viruses all had some key features in common. All carry a gene that makes a protein called endolysin – an enzyme thought to destroy bacteria by breaking down their cell walls. And unlike antibiotics, which kill many types of bacteria, including "good" ones that live in our gut, phages are programmed to target only specific bacteria... Source: BBC News September 25, 2012 The protein endolysin belongs to which group of chemical substances? A) hormones B) receptors C) biological catalysts D) molecular bases  The Evolution of Sick Humans Enzymes (1.6-7.25) Describe the structure of proteins Proteins are chains of amino acids. There are 20 different amino acids that can bond together to form long chains. These chains fold up into complex structures. These structures determine the functions of proteins. Define enzyme. Enzymes are globular (somewhat round) proteins that act as biological catalysts. Catalysts speed up chemical reactions by lowering the amount of energy needed for the reaction to occur. Define active site. The active site is the location on an enzyme where a substrate (the molecule acted upon by the enzyme) binds. Explain enzyme–substrate specificity. The active site of each enzyme has a shape that matches a specific substrate(s). Only substrates whose shapes are a match to an enzyme’s active site will bind to the enzyme. Define denaturation Denaturation is a structural change in a protein that results in a loss (usually permanent) of its biological properties. Denaturation is usually caused by an increase in temperature or a change in pH. Explain the effects of temperature, pH and substrate concentration on enzyme activity. Temperature Each enzyme has an optimum temperature, a temperature at which it operates most effectively. As temperature increases above the optimum, the enzyme molecules begin to denature. At lower temperatures, collisions between enzyme and substrate molecules are infrequent. pH Each enzyme has an optimal pH range at which it best operates. Deviations from the optimal pH in either direction will cause enzyme denaturation. Substrate concentration Substrate concentration: Initially, increases in substrate concentration increases the enzyme activity. However, once saturation of the substrate is reached, there is no more increase (or decrease) in enzyme activity.  The Evolution of Sick Humans Notes 3 (1.10-14.25) Outline the range of functions of proteins including specific examples Proteins function as —enzymes, biological catalysts Example: lactase is an enzyme that breaks down lactose into galactose and glucose — hormones, chemical messengers in an organism Example: insulin signals the uptake of sugar from blood to the interior of liver cells —cell receptors receive signals such as hormones Example: Insulin receptors in liver cells —components of the vertebrate (= animals with backbones) immune system Example: antibodies recognize pathogens —structural components of tissue Example: collagen, the main component of ligaments that connect bones together Outline the organization of human DNA Coding DNA i) the bases of coding DNA contain the information need to form proteins from amino acids (~1%) Non-coding DNA ii) regulatory regions of DNA control the transcription of genes (~20%) iii) 'junk' DNA has no known function (~79%) Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and plants, and homologous structures. Fossil Record: A fossil is the ancient preserved remains of an organism. The fossil record reveals forms of life that are now extinct, but that are clearly ancient members of groups alive today. In addition, sequences of fossils illustrate specific evolutionary changes. In addition to vertebrate bones, fossils include impressions in rock, organisms trapped in amber, and ancient pollen grains. Comparative Anatomy: One example of comparative anatomy is the tetrapod forelimb. Although they have the same function, the bones present in these limbs are the same, suggesting that these species are descendants of earlier species that had the same bone structure. Adaptive radiation occurs when descendants of an ancestor are adapted to a wide variety of habitats. Physical features shared due to evolutionary history (a common ancestor) are said to be 'homologous'. Comparative Embryology Comparative embryology is the study of embryos (unborn developing babies) to understand evolutionary relationships. The more closely related two species are, the more similar are the stages of the embryos’ development. DNA Sequence Comparisons Shared sequences of and nucleotides (DNA) as well as the number of differences among sequences allow determination of relationships among organisms. In order to compare these data, alignments of sequences must be performed. For example: Sp1:AAAATTTTCCCCGGGG Sp2:AAAACTTACCCGGGGG Sp3:AAAACTTACCCGCGGG Sp4:AACATCTTCCACGCTG  Evolution of Sick Humans Quiz 1 Review 1. Sketch and label a nucleotide 2. On the picture below label one covalent bond, one set of hydrogen bonds, place a box around one nucleotide and label it, box and label one base pair. 3. Write a brief description of DNA replication being sure to use the words template, enzyme, and nucleotides. 4. State which bases in DNA are complementary. 5. Explain the word ‘gene’. Include the terms ‘segment’ and ‘protein’ in your brief explanation. 6. State the location in a cell where the following occur: DNA replication, transcription, translation. 7. Transcribe the following DNA to form an RNA sequence: AATTCCGGGCTA ________________ 8. Use your genetic code chart to translate the following codons: ACA GGU CCC UAG  CODED MESSAGES USING THE GENETIC CODE Message 1 CUU-GAA-ACG-UCC UGG-AUC-AAU ACC-CAC-AUC-AGU __________________ _____________ ____________________ GAA-GUG-GAG-AAC-ACG _______________________ Message 2 UAU-GCA-AAC-AAG-GAA-GAG-UCU GCG-AGA-GAG _________________________________ ______________ GGG-CGA-GAA- GCA-ACG _________________________ Message 3 GAA-GCC-ACG GCG-CCU-CCG-CUU-GAG CCC-AUC-GAA _____________ ________________________ _____________ Message 4 UGG-GCU-ACC-UGU-CAC UCA-ACG-GCA-CGG ACG-AGA-GAA-AAA _______________________ ___________________ ____________________ Message 5 UUG-GAG-ACA AUU-ACC CGA-GCA-AUC-AAC ______________ _________ ___________________ Message 6 UGG-GCC-ACA-UGU-CAC ACG-CAU-GAA ACG-CGA-GCG-AUU-AAC _______________________ ______________ _______________________ GAU-AUU-UCG-GCC-CCA-CCG-GAA-GCA-AGG ___________________________________________  The Evolution of Sick Humans Molecular Genetics III (12.18-20.24) Describe the genetic code The genetic code is a system that allows cells to translate information in nucleic acids (RNA & DNA) into proteins. Groups of three RNA nucleotides form ‘codons’, three bases that code for one amino acid. Therefore, a series of codons in an mRNA (m = messenger) molecule carries information for the assembly of one protein. Outline the process of translation leading to protein formation mRNA, carrying information stored in DNA, leaves the nucleus and moves through the cytoplasm to a ribosome. The mRNA binds to the ribosome. The first codon is called the START codon and is always AUG Molecules called transfer RNA (tRNA) are responsible for bringing amino acids to the ribosome/mRNA complex. Each tRNA carries an amino acid at one end and at the other end has a base sequence called an anticodon. Each anticodon is complementary to one codon. The tRNA anticodon binds to the mRNA codon. A second tRNA binds to the second codon. Protein synthesis begins as the 2 amino acids carried by the tRNAs bond together by an enzyme. The process continues until the protein has formed and the STOP codon is reached. Define mutation A gene mutation is any change in the DNA base sequence of the gene.  THE GENETIC CODE The following chart is used to translate messages in mRNA into amino acid sequences. Each three RNA bases (a codon) are decoded as one amino acid. The left column is the first RNA base, the top row the second RNA base and the right column the third RNA base. Letters in the interior of the chart (those not in bold) are single letter abbreviations of amino acids. U C A G F S Y C U U F L L L S S S P Y STOP STOP H W C STOP R C A G U C L L L I P P P T Q Q H N R R R S C A G U A I I M V T T T A N K K D G S R R C A G U G V V V A A A D E E G G G C A G Practice AAA ________ GCC ________ UGC ________  Genetics Notes I: DNA and Genes 12.9.24 1. List the parts of a nucleotide. 2. Draw a rectangle around one strand of DNA in the figure in the second note. 3. Order the following (here ordered alphabetically) by size from smallest to largest and write a brief description of each: chromosome, gene, nucleotide. 4. Explain the role of genes in heredity. 5. State the bases in DNA that always pair-up with each other.  The Evolution of Sick Human Molecular Genetics II (12.10-11.24) Explain DNA replication Cells of both unicellular and multicellular organisms divide to form new cells. All new cells must have a complete set of chromosomes. Therefore, before cell division, DNA must be copied, or replicated. In order for DNA to replicate, an enzyme must unwind and separate the strands of a DNA molecule. Once this occurs, molecules of another enzyme contact the separated strands and use them as templates. Whenever the enzyme contacts an ‘A’ in a template, it incorporates a ‘T’ into the new, growing strand and vice versa. Whenever the enzyme contacts a ‘G’ it incorporates a ‘C’ into the new, growing strand and vice versa. Explain the significance of complementary base pairing in the conservation of the base sequence of DNA. The significance of the mechanism outlined above is that the DNA molecule is copied precisely from one cell generation to the next. Genes (base sequences) are faithfully passed from one generation to the next. Rarely, mistakes in base pairing occur during DNA replication. These are called “mutations”. Outline DNA Transcription DNA transcription is a process found in all cells. During transcription: —one of the 2 strands of a DNA molecule is used as a template to form a single-stranded RNA molecule. —RNA nucleotides are bonded together by an enzyme —RNA nucleotides are similar to DNA nucleotides; however, they utilize the base U instead of T. —During transcription messenger RNA (mRNA) is formed. This molecule delivers the genetic information stored in DNA to the ribosome.  Genetics and Biotechnology DNA and Genes (12.9-10.24) Define DNA (deoxyribonucleic acid) DNA is the molecule that stores genetic information necessary for heredity; it is comprised of subunits known as nucleotides. Explain how a DNA double helix is formed A DNA double helix is formed when two single strands of DNA come together and form hydrogen bonds between bases. The bases A and T form bonds together and the bases G and C form bonds together. The double- stranded molecule then twists into a double helix. Define chromosome A chromosome is a structure made of DNA and protein found in the nucleus of eukaryotic organisms. Define gene A gene is a segment of DNA that contains the genetic information needed for the cell to produce a particular protein. The genetic information takes the form of a series of bases (abbreviated A, C, T, and G). Note: Actual genes include many more base pairs than are shown here Define trait A trait is a characteristic of an organism determined completely or partially by one or more genes. Define heredity Heredity is the passing of genetic information from one generation to the next through reproduction. Reliable inheritance of genetic information ensures that offspring resemble their parents.