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Biology B Final Exam Review Explain the purpose of DNA replication and the steps involved. Where in the cell does it occur? Purpose: Ensure that the resulting replicated cells each have a complete and exact copy of the original cells genome (genes) So that the daughter cells function like the parent cells Where it occurs: Nucleus Steps for DNA Replication 1. Double helix unwinds 2. Strands separate 3. Free floating DNA nucleotides are bonded to the parent strands by DNA Polymerase (enzyme) Describe the functions of the 3 types of RNA. Be able to identify them in a diagram. Where in the cell are they located and where are they synthesized? mRNA (messenger): rRNA (ribosomal) Copies information from DNA in the nucleus Makes up the ribosome Made in the nucleolus tRNA (transfer): Transfers amino acids in the cytoplasm to the ribosome Compare/contrast DNA vs. RNA (where in the cell each type is found; the subunits and molecules that make up each subunit). DNA Location Number of strands Nucleotide Nucleus RNA mRNA: Nucleus and Cytoplasm rRNA: Ribosome tRNA: Cytoplasm 2 1 Phosphate group Deoxyribose sugar A, T, G, C Phosphate group Ribose sugar A, U, G, C Which nitrogen bases are found in DNA? In RNA? RNA: Adenine Uracil Guanine Cytosine DNA: Adenine Thymine Guanine Cytosine Which nitrogen bases form complimentary pairs in DNA? In RNA? DNA A=T G=C RNA A=U G=C What is the purpose of transcription? Describe the steps involved and where in the cell it takes place. Be able to label a diagram of the process. Purpose: Copy information from DNA in the form of mRNA so that it can be brought to the ribosome to build the protein Steps: 1. Specific sequence of DNA unwinds and separates 2. RNA polymerase (enzyme) adds complementary RNA nucleotides to one strand of DNA 3. When complete, mRNA breaks away from the DNA and leaves the nucleus 4. The DNA winds back up What is the purpose of translation? Describe the steps involved and where in the cell it takes place. Be able to label a diagram of the process. Purpose: Translate the mRNA sequence at the ribosome to build the protein Steps: 1. mRNA leaves the nucleus for the ribosome. 2. Once there, the ribosome exposes the codon on mRNA 3. tRNA with the amino acid that is coded for by the codon, transfers the amino acid to the ribosome a. Codon matches with the anticodon 4. tRNA continues adding amino acids until ribosome reaches stop codon – Makes a polypeptide (Protein) GCU = Ala Tyrosine = UAU, UAC Know how to use a mRNA codon chart. What does GCU on mRNA code for? What is the codon for tyrosine? What is a gene? Sequence of DNA that codes for a specific protein What makes proteins different from one another? What determines which specific protein is to be produced? Differences in proteins: Sequence of amino acids Determines differences: Sequence of nitrogen bases in DNA What are mutations? What kinds of effect can mutations have on an organism? Mutation: Changes in one or more nitrogen bases on DNA or RNA Effect: Change the sequence of amino acids coded for by the DNA/mRNA Create a defective protein Result in an adaptation No effect What are mutagens? Give 3 examples. Mutagen: Something that can cause a mutation (change in the DNA or RNA sequence) Examples: X-ray UV light Chemicals Radioactive substances What causes one cell to have a different function than another cell? All cells in a single organism have the same DNA/genes Differentiation of cells results from activation of different genes Some genes are “turned off” GENETIC TECHNOLOGY (13.2) What is recombinant DNA? DNA from two different sources that has been combined Example: Plasmid DNA What can be produced agriculturally from recombinant DNA? 1. 2. 3. 4. Glowing tobacco plants Plants resistant to insects Bigger produce, animals Drought resistant plants How is genetic engineering (biotechnology) used to produce biomedical products such as insulin? 1. Gene of interest is cut out of the DNA of an organism – Ex. insulin 2. Gene from one organism can be inserted into a plasmid (vector) – Recombinant DNA 3. Plasmid is then inserted into a bacteria 4. Bacteria will use the foreign gene to make insulin EVOLUTION (14.1, 15.1, 15.2) What does the geological time scale show? Be able to analyze and determine the chronological order of organisms. Geological time scale shows the major events in Earth’s history in chronological order What explains the disappearance of fossils from one era/period/rock layer to the next? Extinction – if the fossil no longer appears in rock layers following where it was found, then there is a good chance that it became extinct How do fossils form? How can you determine the age of a fossil? (2 ways) How Formed? Sediment 1. 2. 3. 4. Organism dies Buried under layers of sediments Soft tissue decomposes, bones/hard parts are left behind Pressure fossilizes the bone Ice Amber Trace Mold Cast Age of a Fossil: Relative Dating Where in the rock layers the fossils reside Absolute (radiometric dating) Measuring the amount of radio active isotopes is still present What observations did Charles Darwin make in regards to various species found on the Galapagos Islands? Each species had adaptations specific for the island that they live What are the principles of Darwin’s theory of evolution? Organisms overproduce Variation exist among populations Organisms compete for resources Variations are inherited Those with the better adaptations survive and pass on genes Natural Selection Define natural selection according to Darwin. How do genetics, variation, and environment play a role in natural selection? Natural selection acts on the genes – organisms that survive pass on their genes to offspring What does his theory of evolution suggest? How does natural selection relate to evolution? Organisms with the more favorable variations (differences) have an increased chance of survival and reproduction Organisms best fit for the environment pass on their genes What does natural selection specifically act on? Variations and genes Define speciation. Describe the processes that allow new species to be formed. How do you know when a new species has formed? Speciation: Process: The development/evolution of a new species Geographic isolation Reproductive isolation Mutation How Know: Species can no longer interbreed (cannot produce viable offspring) What is the difference between geographic isolation and reproductive isolation? Geographic isolation: Species are separated by a barrier (Ex: mountain, large river) Do not interbreed Reproductive isolation: Species are different because of reproductive structures or behaviors (mating seasons, calls) Do not interbreed Geographic Isolation Reproductive Isolation How can organisms become “resistant” to things like pesticides, antibiotics, etc? When a pesticide or antibiotics is used, it will generally kill most organisms off A select few will survive Survivors have resistance in their genes The survivors will reproduce and a majority of the population will be “resistant” How can scientists determine whether two different species came from a common/related ancestor? Homologous structures: same structure, different function Embryological similarity: similar structures as an embryo Molecular homology: DNA and gene similarity (biochemistry) Homologous Structures Embryology Define genetic drift. What is a gene pool? Describe what happens to a gene pool (benefits and consequences) when genetic drift occurs. How can lethal alleles be maintained in a gene pool? Genetic Drift – When a random mutation (or alelle) is found within a population that isolated itself from the general population – change in allele frequency Gene Pool – collection of all of the alleles in the population When genetic drift occurs: Specific traits become more prevalent within the population Can be dominant or recessive Ex. Tay Sachs, Polydactyly Lethal Alleles are maintained (kept in the population) because individuals can be carriers for the bad allele (Ex. Tay sachs, cystic fibrosis, sickle cell) What causes evolution to occur more quickly in a population? Population is small Isolated Many Mutations HUMAN BODY SYSTEMS: Nervous (36.1, 36.3), Immune (39.1, 39.2), Endocrine (35.3), Skeletal (34.2), Muscular (34.3), Digestive (35.1), Respiratory (37.1), Circulatory (37.2), Urinary (37.3) What are the major functions of each system? What are the major organs within each system and what are their specific functions? Nervous System: Processes information, controls every process Immune System: Build up resistance to disease Endocrine System: Releases hormones to maintain growth, metabolism, and homeostasis Digestive System: Break down nutrients from food Circulatory System: Distribute blood, oxygen, nutrients throughout the body Respiratory System: Exchange oxygen and carbon dioxide in cells Skeletal and Muscular System: Support and movement of the body Exocrine: Dispose of waste (urine, sweat) What is the relationship between one system and each of the other systems? How does each system work with the other systems? For example, be able to explain what systems would work together in order for you to be able to jump or talk? to maintain homeostasis? to respond to stimuli? breathe? digest food? SEE INTERACTION CHART Describe the function and structure of a neuron. Function: Receive and send chemical/electrical signals from outside environment Nervous System (36.1, 36.3) and Endocrine System (35.3) What are the three types of neurons? 1. Sensory Neuron: a. Receive signals 2. Interneuron: a. Brain and spinal cord b. Process info 3. Motor neuron: a. Do response What is an impulse? Path that signals in the nervous system take Pathway: Senses Sensory neuron interneuron (brain) motor neuron – muscle (movement) How do drugs affect the transmission of an impulse? Drugs can slow down response time They interfere with the passing of signals from one neuron to another Compete with neurotransmitters for receptors on neurons Explain how a feedback loop (negative feedback system) works. Immune System (39.1, 39.2, 34.1, 18.1, 18.2) What is the body’s first line of defense? Second line? First Line of Defense Barriers Inflammation Second Line of Defense Cell Mediated Response: T cells cytotoxic T cells Humoral Response: B cells antibodies How does immunity occur? How does the immune system respond to antigens? 1. Macrophage engulfs a pathogen 2. Activates T helper cell a. T helper cell activates B cell i. B cell makes antibodies ii. Makes memory cells b. T helper cell activates cytotoxic T cell i. Cytotoxic T cell destroys infected cells ii. Makes memory cells What are pathogens, antibodies, antigens? Pathogen: Disease causing substance Antigen: Foreign substance in the body Antibodies: Proteins that the immune system uses to find and attach to pathogens and antigens What is the function of white blood cells? Identify antigens Break down and remove antigens B cells – make antibodies T cells – Destroy infected cells What are the functions antibodies? Antibodies are released by B cells Bind to antigens Signal Macrophages to digest antigen Compare/contrast viruses vs. bacteria (characteristics). How does each one “work” once it infects the body? How do you treat the illnesses that each one produces? What are some effective defenses against each one? Viruses Bacteria How infects Uses a host cell Produces toxins Treatment Run course or antivirals Antibiotics Defenses Vaccines Anti-microbials How does HIV affect the immune system? Attacks and uses Helper T cells to make more HIV viruses Helper T cells activate the immune system What is AIDS? What can result from this disorder? Acquired Immunodeficiency Syndrome When the number of T cells drops below a certain number Individual dies from opportunistic infections Infections that are usually easily defended against with a healthy immune system