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Biology Final Review Guide
Name: _______________________ Spring Semester 2016 Exam: Monday, May 23, 2016 8:15am­ 9:45am Topics Covered on Final DNA Structure and Replication
Protein Synthesis Ecology Multicellular Organismal Development
Genetics
Evolution DNA STRUCTURE AND REPLICATION Vocabulary terms:​
chromatin, sister chromatids, chromosomes, DNA, double helix, nitrogenous bases, purine, pyrimidine, Adenine, Thymine, Guanine, Cytosine, base pair, sugar: deoxyribose, phosphate, nucleotide, complementary base pairing, hydrogen bonds, covalent bonds, genes, DNA polymerase, replication fork, helicase, Hershey­Chase ​
Experiment​
, ​
Rosalind Franklin, Watson and Crick, Semi­conservative model, Erwin Chargaff, ​
Maurice Wilkins, Fredrick Griffith Essential Questions ❏ What is genetic material? What does it do? Deoxyribonucleic acid (DNA) is the genetic material and all living organisms have it. It contains all of the codes for living organisms to maintain homeostasis and thus accomplish all 7 characteristics of life. The “codes” are for genes that likewise code for proteins. ❏ What is DNA? Deoxyribonucleic acid­ genetic material that is necessary for all life. ❏ How is DNA copied? A double stranded DNA molecule is broken by helicase, which separates the two strands by breaking the weak hydrogen bonds that links the nitrogenous bases together. Next, DNA polymerase adds complementary nucleotides to each strand of DNA. The end product is two identical copies of double stranded DNA molecules that are semi­conserved, meaning each double stranded DNA molecule contains one original copy and one new copy. ❏ How is the structure of DNA related to the genetic code? The ordering of nucleotides, or the sequence of the nitrogenous bases, is what makes living organisms different from each other. The sugar­phosphate backbone is identical in all living organisms (bacteria, plants, humans, etc) and even the nitrogenous bases used (adenosine, cytosine, guanine and thymine). Thus, only difference is ordering of A,T,G and C. Objectives 1. Analyze data that enabled scientists to determine that DNA was the hereditary component and why this debate occurred in the scientific community. Chargaff looked at the ratios of the nitrogenous bases and figures out that the ratio of A:T was 1:1 and the ratio of G:C was also 1:1. No other ratios (A:G, A:C, G:T, C:T) were 1:1. This indicated that A bonds with T and G bonds with C. 1 2. Identify and explain the three structural components of DNA. DNA consists of many monomers strung together, called nucleotides. Nucleotide has three parts­ sugar (deoxyribose), phosphate and a nitrogenous base (adenosine, cytosine, thymine and guanine). Thus, a DNA molecule is a polymer. 3. Explain what is implied by the “double helix” structure of DNA. Double helix is the structure that two strands of DNA take when bonded together via hydrogen bonds. A:T contains two hydrogen bonds while G:C contains three hydrogen bonds. The double helix nature is a product of the DNA molecule staying parallel with regards to the two strands. This shape keeps the DNA equal and protected. 4. Explain the importance of hydrogen and covalent bonds with regards to the structure of DNA. Hydrogen bonds are weak bonds and hold the two strands of DNA together via the hydrogen bonds between nitrogen bases on opposite strands. Covalent bonds are strong bonds in which atoms share electrons. The sugar­phosphate and nitrogen bases themselves all contain covalent bonds. This explains why a DNA molecule is “broken” down the middle, keeping two separate strands in tact, as the hydrogen bonds are broken. 2 5. Explain Erwin Chargaff’s discovery and how it aided to the determination of DNA structure. Purines (A,G) bind with pyrimidines (C,T) and A:T hydrogen bond together while C:G do also. 6. Understand the contributions that Erwin Chargaff, Rosalind Franklin, Maurice Wilkins, James Watson, and Francis Crick’s roles in the discovery of DNA structure. Not assessed directly. Watson and Crick figured out the structure of DNA via making a model while Franklin and Wilkins figured out double helix structure of DNA. 7. Students should be able to explain DNA Replication, specifically the enzymes involved, the sequence of events, and why proofread mechanisms exist in DNA replication. Helicase unwinds DNA and breaks hydrogen bonds to open up the double stranded DNA molecule. DNA polymerase adds on complementary DNA nucleotides to both strands. End up with two double stranded DNA molecules. 8. Compare and contrast the three different replication models (​
conservative, dispersive and​
semi­conservative) and know which model DNA follows. Semi­Conservative: half old and half new strand. This is the model all life follows and it should be obvious from the replicative process. 9. Explain why proofread mechanisms are necessary in DNA replication and understand the effects when proofreading does not occur. Proofread mechanisms, from RNA polymerase, allow DNA to be identical. When it does not occur, mutations occur. It can be a substitution of a base (point mutation) or an frameshift mutation (insertion or deletion). MULTICELLULAR ORGANISMAL DEVELOPMENT Vocabulary Terms​
­ multicellular organism, chromosome, autosome, sex chromosome, sister chromatids, homologous chromosomes, duplicated chromosomes, unduplicated chromosomes, sexual reproduction, asexual reproduction, mitosis, meiosis, recombination, crossing over, diploid, haploid, somatic cells, gametes, sex cells, egg cell, sperm cell, fertilization, zygote, cells, 3 tissue, organ, organ system, individual, genes, traits, negative feedback loop, set point, homeostasis, cell differentiation/specialization Essential Questions ❏ How do multicellular organisms maintain homeostasis differently compared to single­celled organisms? Multicelullar organisms grow through the process of mitosis, identical cells produced, and must specialize their cells that have certain jobs or functions in order to survive. ❏ How do multicellular organisms develop from a single cell? MC organisms develop from a zygote, a single cell that is diploid­ has two copies of each gene. It must then go through mitosis in order to grow in size and # of cells. Once there are enough cells, the cells can thing begin to specialize, or have certain genes expressed, so that the tissues, organs, then organ systems and organism work together to maintain homeostasis. ❏ How are cells organized in multi­celled organisms? Individual cells organize into same cell types called tissues, groups of tissues are organized into organs, then organ systems and the whole organism. The tissues, organs and organ systems all have specific functions they do to maintain homeostasis. The functions they have are determined by which genes are expressed = which proteins are made. ❏ How do organ systems work together to maintain homeostasis? Organ systems work together using signal molecules, proteins and communication between cells and tissues in order to maintain all aspects of the body at a set point. Negative feedback loops are often used to keep body at the setpoint, the specific range of acceptable control for body to maintain homeostasis. Objectives: 1. Know the role that chromosomes play in multicellular organisms. Chromosomes = coiled pieces of DNA. proper chromosomal number and intactness is essential for an organism to have the correct genes to live. 4 2. Know how multicellular organisms use different cellular division processes for different functions. ○ Know the process that multi­celled organisms use to ​
reproduce​
. ​
Meiosis ○ Know the process that multi­celled organisms use to ​
maintain homeostasis​
. Mitosis 3. Know the process of ​
meiosis​
. Have a double copy of set of DNA = DNA replication has already occurred. So you have two sets of homologous chromosomes. Meiosis I­ crossing over occurs between homologous chromosomes. Then, the homologous chromosomes are split in the two cells. Meiosis II­ sister chromatids are split into two different cells, making four total cells for gametes. Gametes are all unique since the alignment of homologous chromosomes is random (independent assortment). The gametes are haploid, meaning each cell has only one copy of each gene. Start as diploid and end as haploid cells. 4. Know the process of ​
mitosis​
. Sister chromatids (identical copies) from split and each new cell contains two copies of each gene. The new cells are completely identical to each other. Start and end as diploid cells. 5. Determine the tiers of organization for multicellular organisms and understand how organ systems work together to maintain homeostasis. Cells → tissues → organs → organ systems → organism 6. Understand how to analyze negative feedback loops. Body adjusts (acclimates) to maintain homeostasis. If body is too hot, you may sweat to lower BT back to setpoint. If body is 5 too cold, you may shiver to produce heat to increase BT back to setpoint. 7. Know how cells specialize or differentiate to form organized structures that have a particular function and why specialization/differentiation is necessary for multicellular organisms. Cells specialize by certain genes being expressed in certain cells. Skin cells produce melanin to protect you from the sun’s harmful rays while stomach cells produce enzymes that digest food. Specialization enables cells to divide the workload into a more manageable amount, much like students working together to get a single assignment done by dividing up questions to accomplish task quicker. PROTEIN SYNTHESIS Vocabulary: genetic code, central dogma, protein synthesis, gene expression, transcription, nucleus, gene, messenger RNA(mRNA), RNA (ribonucleic acid), RNA polymerase, nucleotides, adenine, uracil, guanine, cytosine, start signal, stop signal, translation, protein, transfer RNA (tRNA), ribosomal RNA (rRNA), codon, anticodon, ribosome, amino acids, polypeptide, protein, E​
xit site, ​
P​
eptide site, ​
A​
ctive site, mutation types­ point (substitution), frameshift (insertion, deletion) Essential Questions ● How can a change in DNA’s code affect the protein to be synthesised? Mutations can change a single amino acid in an entire protein that affects the way a protein folds. If it does not fold properly, it is detrimental to its functioning. Proteins do so much for your body and without them, life would not exist. The order of nucleotides in DNA affects the order of nucleotides in RNA, which affects the ordering of amino acids and thus the protein. ● How is DNA’s code expressed? DNA (transcription) → mRNA occurs in the nucleus. Involves RNA polymerase and nucleotides with A,C,G and U mRNA (translation) → protein occurs outside the nucleus on ribosomes. It involves the mRNA sequence, ribosomes, tRNA, amino acids, sites, etc. ● How do proteins enable organisms to maintain homeostasis? Essential for living. Virtually every cell part contains proteins. In plasma membranes, cytoskeleton, hormones, red blood cells, etc. Objectives 1. Know the central dogma of protein synthesis.​
DNA → RNA → Protein 2. List the three main parts of every nucleotide and describe three ways in which DNA polymers differ from RNA polymers. 6 Phosphate, ribose sugar, and nitrogenous bases A,C,G and ​
Uracil. RNA polymers are single stranded, contain ribose instead of deoxyribose, and contain the nitrogen base uracil instead of thymine. 3. Be able to explain the major steps of transcription and the overall process. DNA → RNA Inside the nucleus DNA (a gene) is copied into mRNA. Double stranded DNA moelcule is opened by hydrogen bonds broken via RNA polymerase. RNA polymerase then adds complentary RNA nucleotides to template strand (gene) that are complementary. Once the gene is copied, the mRNA exits the nucleus. 4. Be able to explain the major steps of translation and the overall process/be able to describe how ribosomes use mRNA, tRNA and amino acids to manufacture a protein. mRNA → Protein ● the mRNA Start Codon, AUG, gets into the P Site of the ribosome. ● a tRNA​
binds its anticodon to the mRNA codon at the P site inside the ribosome. Met​
7 ●
●
●
●
a different tRNA that has an anticodon matching the next codon enters the ribosome at the A site. Now, both the P and A sites have tRNA holding specific amino acids. The amino acids will undergo dehydration synthesis to form a peptide bond. the ribosome moves down the mRNA to the next codon, and another amino acid is released from the tRNA to form a peptide bond. Process continues until the entire protein is made. 5. Given a sequence of bases on a single DNA strand, be able to illustrate and explain the processes of transcription and translation. Be able to identify parts of translation if given a diagram. Use image above. 6. Given a sequence of DNA or mRNA bases and an amino acid decoding table, be able to determine the order of amino acids coded for by the mRNA. DNA Sequence: CCT,GCT,AAT mRNA sequence: GGACGAUUA
use codon table to match codon with amino acid Amino Acids: glycine­proline­leucine 7. Be familiar with the possible effects of point and frameshift mutations. Point mutation­ single nucleotide is modified, may change amino acid, may not. Frameshift mutation­ changes amino acid sequence and almost always detrimental. 8 GENETICS Vocabulary: Heredity, genetics, pea plants, monohybrid cross, true­breeding/purebreeding, P generation, F1 generation, F2 generation, alleles, dominant, recessive, homozygous, heterozygous, genotype, phenotype, law of segregation, law of independent assortment, punnett square, dihybrid cross, pedigree, sex­linked (x­linked/y inheritance), polygenic inheritance, incomplete dominance, codominance, multiple alleles, autosomal inheritance, sex­linked inheritance, ​
sickle cell anemia, cystic fibrosis, hemophilia, huntington’s disease Essential Questions ❏ How is heritable information passed from one generation to the next? Through the process of ​
meiosis​
and then two haploid gametes coming together to produce diploid offspring. ❏ What are different patterns by which heritable information passed from one generation to the next? Complete dominance­ the dominant allele masks the expression of the recessive allele. TT and Tt appear exactly the same (phenotype). For two alleles, there are two phenotypes. Incomplete dominance­ neither allele is dominant over the other and heterozygotes (Tt) contain a blend of both alleles. For two alleles, there are three phenotypes. Codominance­ both alleles are dominant, so if present, they will be expressed. Thus, Tt will contain both phenotypes, not a blend or mixture. Sex­linked­ a trait located on either the X or Y chromosome Autosomal­ a trait located on any chromosome excluding the sex chromosomes. ❏ How does this unit provide evidence of the relatedness of living things in the world? Alleles, or different forms of a gene, are extremely similar, enough to provide the same function in most cases, yet differ genetically (ordering of nitrogen bases). Objectives 1. Discuss the genotypes and phenotypes of Mendel's P, F1 and F2 generations and be able to carry out these crosses. Genotype: specific copies of alleles an individual has/ combination of alleles Phenotype: physical appearance of alleles an individual has. P generation: crossed two different purebreed individuals, tall and short. F1 generation: all individuals were tall. F2 generation: 3 tall individuals and 1 short individual ratios. 9 Determined that tall was dominant to short and that mixing heterozygotes produced a 3:1 tall:short ratio. 2. Know Mendel's Law of Segregation and Law of Independent Assortment and illustrate these laws in an appropriate cross. Law of Segregation­ two alleles align into different gametes irrespective of the alleles present during meiosis so that each gamete gets one copy of the gene. (allele) monohybrid crosses demonstrate this Law. Independent Assortment­ different traits have an equal chance of ending up in the same cell or in different cells. Dihybrid crosses demonstrate this Law. Boxes represent cells, letters represent alleles. Tt separates into different boxes. 3. Be able to carry out crosses concerning complete dominance, incomplete dominance, codominance, sex­linked inheritance, multiple alleles, and dihybrid crosses using Punnett Squares. Construct practice problems by going through old notes or using online practice problems provided for you on the website underneath Unit 9: Inheritance Patterns tab. http://www.clayton.k12.mo.us/Page/17022 4. Understand the difference between polygenic and polyallelic. Polygenic = multiple genes codes for a single trait. Ex. height is based on genes x, y and z. Polyallelic = three or more alleles codes for a single trait. Ex. Blood Type A, B, O 5. Be able to interpret pedigrees. A pedigree gives information about related individuals with a particular trait. Autosomal Dominant­ every generation is affected and no noticeable trends for males to females affected. 10 6. Be able to identify and distinguish between the following genetic diseases: sickle cell anemia, cystic fibrosis, hemophilia, huntington’s disease ECOLOGY Vocabulary:​
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Population, Species, Habitat, Community, Ecosystem, biomes, Decomposer, Trophic levels­ primary producer, primary consumer, secondary consumer, tertiary consumer, Energy Conversion, 10% Rule, Herbivores, Carnivores, Omnivores, Detrivores, Heterotroph, Autotroph, Water cycle (Evaporation, Transpiration, Precipitation, Percolation), Carbon cycle (photosynthesis, cellular respiration, combustion, decay), Nitrogen cycle (atmospheric nitrogen, ground nitrogen, bacteria, plants and animals), Global Warming, Greenhouse Effect, Ozone layer (stratosphere), Fossil Fuels, symbiotic relationships­ commensalism, parasitism, mutualism, fundamental niche, realized niche, logistic growth vs. exponential growth, primary succession, secondary succession, climax community, pioneer species, mass extinction Essential Questions ❏ Why do organisms rely on other organisms and the environment for survival? You can answer this. ❏ How are humans impacting biomes and in which ways? Humans are causing ecosystems to become imbalanced and are changing te environment much more quickly than nature can adjust and fix the problem. This causes competition where there has not previously been competition before. Organisms must have the required genetic material that enables them to either acclimate or adapt to the new environment. How humans live and the massive number of humans being produced exponentially is not feasible, since resources are limited. ❏ Why do ecosystems need to be balanced? You can answer this. Objectives 1. Be able to identify the different levels within a biome­ population, community, ecosystem, biome, biotic and abiotic factors. 2. Be able to construct a food chain demonstrating energy transfer, analyze food chains and understand 10% Rule of trophic levels. Class as a whole rocked this section. 3. Be able to construct, interpret and analyze a series of interconnected food chains (food web) and understand the effects that one population may have on another. Class as a whole rocked this section. 4. Understand the different types of symbiotic relationships between organisms within an ecosystem. 11 Parasitism­​
one organism takes advantage of a different organism and harms 2nd organism in the process. Example tapeworms and dogs­ tapeworm gains nutrients while dog’s intestine is harmed. Mutualism­​
both organisms benefit from interactions with each other. Example leaf cutter ants provide food and shelter for fungi, who provides alternative food source for ants. Commensalism​
­ one organism benefits and one organism is unharmed. 5. Understand how anthropomorphic impacts (disease, agriculture, habitat loss, invasive species, pollution, and climate change) disrupt balanced ecosystems and biomes. 6. U​
nderstand the abiotic cycles that recycle necessary nutrients and molecules­ water, carbon and nitrogen­ throughout the globe. 7. Understand how certain events lead to primary or secondary succession and how pioneer species kickstart the re­building of a climax community. Primary succession is an event in which new land is inhabited by life for the ​
very first time​
. An event that would trigger this is receding glaciers or new land made due to hardening lava into rock. Pioneer species are the first species to arrive in a primary event. They can live in almost inhospitable climates and are low on the energy pyramid­ autotrophic or a decomposer. Secondary succession is an event in which a disturbed area experiences a re­growth. A disturbed area enabling secondary succession to occur includes all natural disasters (floods, hurricanes, fires, storms, tornados, etc.). EVOLUTION Refer to Evolution Study Guide Essential Questions ● How do species change through time? Allele frequencies change due to genetic variations. Genetic variations are caused through sexual reproduction, mutations and gene flow. All of these introduce new alleles into a population. If genetic variation exists, then the mechanisms of evolution can cause the allele frequencies to shift or change (evolution) over generations within a population. Mechanisms of Evolution Natural Selection­ particular phenotypes are beneficial for reproduction and thus those are “selected for”. More individuals with these alleles reproduce and increase the change of the beneficial allele existing in the population. 12 Artificial Selection­ humans pick traits or phenotypes they like. Dog breeds and farming are great examples of this. NON RANDOM MATING Sexual Selection­ males and females within a population determine which traits they like. Males can fight for females, or females can choose specific traits they like. Ex. fighting rams and birds of paradise. NON RANDOM MATING Genetic Drift­ random allele becomes most prevalent allele while the other decreases in frequently or even gets eliminated from the population. In the mutagen valley simulation, yellow allele was eliminated due to chance. Could the blue allele have the same chance of being least prevalent? Yes. RANDOM Bottleneck Effect­ random act of a huge decrease in population size. Those individuals that die were randomly killed = NOT BASED ON PHENOTYPE Founder Effect­ individuals leave from a population and bring the few alleles they have with them. Small population increases (think of inbreeding) Gene Flow­ individuals from a population enter and leave, introducing or taking away alleles. ● How do multiple lines of evidence support the theory of evolution? Convergent Evolution­ analogous structures (very different in structure but same function) Example­ birds, butterflies and bats wings. Divergent Evolution­ homologous structures (very similar in structure but different functions) Example­ all mammals have very same number of bones. DNA/Genetics­ % of similarity between genomes of different species. Fossils­ demonstrate different, extinct species as well as living species that share similar features as living species today. Embryology­ many embryos, regardless of animal type, look extremely similar in the womb. One would expect little developmental pressures inside the womb. Vocabulary​
—Evolution (descent with modification), Genetic variability, natural selection, fitness (reproductive fitness), artificial selection, vestigial structures, homologous structures, analogous structures, embryological development, divergent and convergent evolution, theory, hypothesis, law, mutation, gene flow, migration (immigration, emigration), crossing over, independent assortment, genetic drift, founder effect, genetic bottleneck, speciation, isolation (geographic, reproductive, behavior, temporal) stabilizing selection, disruptive selection, directional selection, sexual selection, allele frequency, adaptation, acclimation Learning Targets/Objectives 13 1​
. Discuss what is meant by a scientific hypothesis, theory and law­­ use examples to correct the misconception that theories can become laws with enough testing. 2. Identify and explain multiple lines of evidence that support the theory of evolution. Include the following evidences in your discussion: direct observation, homologous structures, analogous structures, vestigial structures, fossil record and DNA analysis. Stated above in essential questions Same bone structure yet different functions­ bats fly, humans grasp, cats pounce and claw,, birds fly, whales push through water, horses run. 3. Identify and explain what is meant by genetic variation as well as the sources of variation in populations. Include the following sources: mutation, immigration, crossing over, sexual reproduction, independent assortment. Genetic variation is having multiple alleles or multiple traits/phenotypes for each gene. Humans have many variations of characteristics­ not everyone has black hair, not everyone has brown eyes, etc. Mutation:​
change in DNA sequence Immigration (gene flow)​
: individuals move in and out of the population, bringing in their alleles and taking away their alleles when they enter or exit. Crossing Over​
: process during meiosis that ensures each gamete has a completely unique set of genes. Sexual Reproduction​
: the recombination of genetic material enables offspring to be genetically different from their parents through meiosis (independent assortment, crossing over), and random pairing of gametes) 4. Identify and explain the mechanisms that result in a change in allelic frequencies from generation to generation. Include the following mechanisms: gene flow, genetic drift, natural selection, artificial selection, founder effect, genetic bottleneck. See above 14 5. Identify and explain the role of isolation (geographical, behavioral, temporal) on speciation. Geographical­ a single population has had a barrier to separate it into two populations. This can lead to speciation if they have different selection pressures. Behavorial­ two populations behave in different manners (mating callings, mating rituals, etc). That prevent the individuals from the two populations mating with each other. Temporal­ two populations mate or copulate at different times of the year. Reproductive­ two populations can produce fertile offspring. 6. Identify and explain and the differences between stabilizing, directional and disruptive selection. Directional­ one extreme of the variation spectrum is chosen. Stabilizing­ the intermediate variation of the spectrum is chosen. Disruptive­ both extremes of variation of the spectrum is chosen. “is chosen” = selected for = more mating success = change in allele frequencies = evolution 15