hello everyone in this video we're going to be going over all of the content topics covered in ap biology you may be watching this video at the start of the year to get an idea of what's going to be going on in your ap biology course or you could be watching this video as a review tool to prepare for the ap biology exam in may whatever the reason make sure to give this video a like and subscribe for more life science resources and life lessons you can find on this channel welcome to our ap biology full topic overview if you're using this video as a quick ap biology exam review you can use a few different strategies while you're watching first in this video any key terms or vocab will be highlighted in pink so you can use those words to create flash cards or to jot down these terms as things you'll definitely want to know before the ap exam second if you hear a topic that you're not quite sure about you feel like you don't know well you're not comfortable with write those ideas down and make it part of your study plan lastly in the description below i'll put a bunch of resources that can help with your study plan for the ap biology exam so be sure to check those out as we're going over all of the topics let's get started the ap biology course and exam description is made of eight main units and we'll be going over what's included in all of those today starting with unit one the chemistry of life in this unit we're starting with properties of water now you may have studied this in your regular biology class but make sure you know all of the characteristics that make water special because water and its properties make life possible all living organisms or living systems depend on these properties of water that result from its polarity and its hydrogen bonding so make sure you know what cohesion adhesion capillary action the high specific heat of water surface tension and how it's the universal solvent can all affect life on earth in this unit you also need to be familiar with the properties and structure of biological molecules the four main classes that you study in ap biology are proteins carbohydrates nucleic acids and lipids make sure you also know how these molecules are formed through hydrolysis and dehydration synthesis these are two processes used to cleave and form covalent bonds between different monomers to make up polymers or break down polymers to make monomers when we get to unit two a lot of these concepts might be familiar to you from another biology class that you've taken you'll be going over cell structure different organelles differences between different types of cells like plant and animal cells and prokaryotic and eukaryotic cells but make sure you're very comfortable with these organelles and how they are structured and how they function the ribosomes the smooth endoplasmic reticulum and the rough endoplasmic reticulum the golgi complex or the golgi bodies mitochondria lysosomes vacuoles chloroplasts including the thylakoids that are in the grana and the stroma section of course and then the mitochondria mitochondria made of its matrix and of course the inner mitochondrial membrane now we'll get more into chloroplasts and mitochondria when we get to the cell energy unit but it is important to review what these organelles do and how they're important to the overall function of the cell in this unit as well unit 3 also includes a discussion of surface area to volume ratio and how this limits cell size and particular shapes and how complex structures have evolved to increase the exchange of materials or waste removal in living organisms think of folds along the inner mitochondrial membrane the gyra and sulci of the brain oral the microvilli and the intestines all are there to increase surface area membranes are also featured in this unit make sure you're familiar with the structure of the phospholipid bilayer and how it forms a fluid mosaic model or the barrier between the cell's internal environment and its external environment remember this is a semi-permeable membrane so make sure you review which types of molecules can pass through the membrane easily without support of different proteins and then of course review which types of cells have cell walls and the features and structures of those this unit also includes a discussion of transport including passive transport active transport of course which requires atp and the ideas of endocytosis and exocytosis for the removal or intake of larger molecules both of these processes include vesicles that either fuse with the plasma membrane or that are formed from the plasma membrane in order to take in or excrete large molecules outside of the cell facilitated diffusion is another topic we get into pretty deeply in ap biology make sure you know what aquaporins are for the passage of water certain ion channels and specifically the sodium potassium atpase which helps with membrane potential within the cell you're not familiar with concentration gradients and how those are going to affect transport of molecules make sure you review those as well we also get into donicity and osmoregulation we talk about how water moves from areas of high concentration or high water potential to low water potential across membranes concentration gradients are also important here you should also be familiar with the water potential equations that pop up in this unit these don't pop up very frequently on the actual ap biology exam but they could show up so make sure you review how to use these and how to interpret water potential problems as you're reviewing remember all of this relates back to homeostasis and how the movement of different molecules across membranes helps maintain it another key theme here or key topic here is compartmentalization and how different membranes and membrane-bound organelles help compartmentalize specific processes and reactions within the cell these are usually occurring in eukaryotic cells but this is going to minimize competing reactions within the cell provide a favorable environment for specific reactions and help protect the cell from potentially hazardous products that might be result of certain reactions the origins of this we think came from prokaryotic cells forming symbiotic relationships with larger cells which is the theory of endosymbiosis once we get into unit 3 we're talking about cell energy this unit starts with enzymes remember enzymes are proteins so be sure you're able to identify that enzymes are made of amino acids and how there's a specific active site within an enzyme that interacts with a substrate molecule during an enzymatic reaction make sure you know what changes are occurring during enzymatic reactions usually enzymes remain unchanged after the reaction or are able to revert to their original state whereas the substrate is changed or converted into particular products after the reaction occurs you'll be familiar with the effects of different environmental effects on the rate of enzyme reactions whether or not the enzyme will be denatured for example if there's a very hot temperature the amino acid chain could unfold and the enzyme loses its shape and of course different molecules that could inhibit reactions either blocking the active site for competitive inhibition or another site or an allosteric site on the enzyme which also causes a conformational change that prevents the enzyme from reacting in the way it should some of these environmental effects could be temperatures ph or again inhibitors remember enzymes lower the activation energy required for a reaction to occur and they're very useful in many reactions including our cellular respiration reactions which we start talking about once we get to cell energy all living systems require energy and in biological systems we have sequential pathways that allow us to control the transfer of energy effectively but if there is a loss of energy or not high enough input of energy usually that results in disease or death for a particular organism all life on earth ultimately comes from energy from the sun which is captured through photosynthesis in order to produce sugars which are then the inputs for our cellular respiration reactions so photosynthesis harnesses energy from the sun we think it originated in prokaryotic organisms and there's two main parts to it the light reactions which occur within the thylakoids and across the inner membranes of those stacks in the light reactions the chlorophyll pigments are going to absorb energy from light and then there's different protein complexes including photosystems two photosystems one that are going to transfer energy through an electron transport chain which will also come up in cellular respiration but these photosystems are embedded in those internal membranes and are going to help transfer high energy electrons so that we can establish an electrochemical gradient to form atp via adp and inorganic phosphate this is called photophosphorylation which you'll probably remember is similar to oxidative phosphorylation in cellular respiration remember that in this electron transport chain our final electron acceptor is nadp plus and cellular respiration it's going to be oxygen after the light reactions capture energy it'll be transferred into atp and nadph which will then go on to power the light independent reactions also known as the dark reactions which occur in the stroma of the chloroplast this makes up what we also call the calvin cycle where the production of carbohydrates is going to be powered by atp and nadph and we take the ingredients from carbon dioxide and those reactions to form our organic molecules then we get into similar processes within cellular respiration but remember here is where we're taking biological macromolecules including glucose and converting it to energy remember plants also perform cellular respiration not just photosynthesis but not all organisms perform aerobic cellular respiration some of them perform fermentation in this process the electron transport chain reactions are across mitochondrial membranes in eukaryotic organisms nadh and fadh2 are going to be the coenzymes that deliver electrons and oxygen in this case is the final electron acceptor at the end of the electron transport chain in cellular respiration we also get the formation of a proton gradient which is going to drive a flow of protons through our protein atp synthase which helps with oxidative phosphorylation where we can generate atp by decoupling oxidative phosphorylation from the electron transport chain there is heat generated and it can be used by organisms for body temperature regulation going back to the start glycolysis is the first step in aerobic cellular respiration which occurs in the cytosol of the cell so not inside the mitochondria this is the part where glucose is taken to produce atp nadh and pyruvate pyruvate then goes into the mitochondria where more oxidation occurs so that we can get our ingredients for the krebs cycle which occurs within the mitochondrial matrix in the kreb cycle also known as the citric acid cycle carbon dioxide is generated a little bit of atp is also synthesized and nadh and fadh2 are going to continue to carry electrons to the electron transport chain fermentation is another energy producing process and this is when glycolysis is going to keep going without oxygen now this process is a lot less efficient generates much less atp and generally produces alcohol or lactic acids as waste or by-products as we get to the end of unit 3 we're going to talk a little bit about fitness and how the variation in number or types of molecules and cells can give them a better ability to survive in different environment if an organism is more likely to survive and reproduce in a particular environment we say it has higher evolutionary fitness because it can pass on its genes to its offspring moving on to unit 4 cell cycle and communication this unit starts with cell communication with various types of cell communication including sending signals from cell to cell talking about short and long distance communication including autocrine paracrine endocrine signals and of course this unit includes signal transduction pathways part of signal transaction pathways a lot of times protein modifications or phosphorylation events occur but signal transduction pathways are made of three main steps the signal which is a chemical messenger usually a ligand that's going to bind to another protein specific receptors are going to receive that ligand for example g protein linked receptors and sometimes second messengers can relay that signal within the cell then there's the transduction which is going to be the amplification within the cell for that cellular response which sometimes can trigger thousands of different molecules and amplify the signal within various pathways the response is going to be different depending on the pathway but it could include any of the cellular actions like growth the secretion of specific molecules gene expression or program cell death including apoptosis of course if there's any mutations in the genetic code for specific proteins in these signal transduction pathways that could interfere with these pathways and affect any of the responses that occurred downstream within the pathways other chemicals can also interfere with different components of the cell signaling pathway that could inhibit the final response feedback is another important topic within cell cycle and communication there's positive feedback loops which very simply are amplified responses negative feedback loops which have as a goal to return a system back to its set point and help maintain homeostasis remember homeostasis occurs within dynamic equilibrium because cells and body systems are constantly adjusting to changes within the environment the cell cycle is another important topic within this unit this includes not only cell division but all of the other phases that happen leading up to cell division so interphase which includes g1 s and g2 and even g0 where a cell is not going to divide anymore but could re-enter the cell cycle if it has certain signals and then of course mitosis when the cell is ready to divide which includes prophase metaphase anaphase and telophase and then of course the actual splitting of the cell through cytokinesis the goal of mitosis is to transfer all of the genome to genetically identical daughter cells and the cell cycle is regulated through various checkpoints including cyclins and cyclin-dependent kinases disruptions to the cell cycle can lead to things like cancer where we have cells growing out of control when they should not or programmed early cell death apoptosis when cells should not be dying moving in teen at five let's talk about meiosis this processes goal is to produce haploid gamete or sex cells with half the genetic information from the parent cells this process occurs in two rounds so that we can get half of the genetic information and genetically different cells and make sure you're familiar with some of the differences between mitosis and meiosis there are several parts of meiosis that can increase genetic diversity including crossing over we have an exchange of genetic information between homologous chromosomes and then of course sexual reproduction includes not only crossing over but the random assortment of chromosomes as they align in meiosis and random fertilization of one sex cell from one parent and another sex cell from another parent as we start to talk about the passage of traits between organisms remember that dna and rna carry genetic information all forms of life contain ribosomes which are the locations of protein production and most living organisms share the same central dogma where we go from dna to rna to protein and we also have different metabolic pathways that are conserved across all domains of life gregor mandel described different patterns of inheritance and created laws of segregation and independent assortment even though he didn't know what chromosomes were can be applied to her knowledge of how genes are located on different chromosomes now remember that after meiosis we have fertilization where we fuse two haploid sex cells together and restores a cell to its diploid form and now we have new combinations of alleles or types of genes that can increase variation within populations you should be familiar with how to analyze different traits and how they're inherited through laws of probability and be able to predict patterns of inheritance from different genotypic and phenotypic patterns as we get into non-mendelian genetics this topic also discusses linked genes where we have genes that are close to one another and don't follow the same probability rules but we can use linked genes and our crossover frequencies to calculate map distances and create chromosomal maps sex-linked traits also will not have the same patterns of inheritance as will multiple genes or non-nuclear genes including dna that is located within organelles like mitochondria the environment can also influence the phenotypes and as we get into unit 6 we'll talk more about gene expression but there is phenotypic plasticity that can occur with many genes meaning organisms with the same genotype may exhibit different phenotypes depending on different environmental cues sources of genetic variation within different organisms include segregation independent assortment and fertilization and as we have an understanding of chromosomal inheritance we know how genes are transmitted from parents to offspring sometimes human genetic disorders can be caused by entire chromosomal abnormalities or abnormalities within a single nucleotide of a single gene continuing on with unit 6 we get to gene expression and regulation make sure by now you're familiar with dna and rna structure how nucleotides are shaped and how it's the heritable information and the genetic code for all life on earth in prokaryotic organisms we have circular chromosomes and eukaryotic organisms we have linear chromosomes prokaryotic organisms also include plasmids which are extra chromosomal pieces of dna dna contains different bases different nucleotide bases including our purines g and a pyrimidines c t and u and be sure you know your base pairing rules how a pairs with t and u and g pairs with c of course remember u only appears in rna not in dna this topic also includes dna replication where new nucleotides are added in the five to three prime direction dna replication is semi-conservative meaning a new strand is built off an old template strand to produce two new dna molecules and there's different enzymes involved in the process including dna helicase topoisomerase dna polymerase and dna ligase and be sure you recognize what each of their roles are within the process of dna replication in protein synthesis the first step is transcription where mrna is going to carry information transcribed from a dna template where then different trna molecules that have anticodons will be able to recruit amino acids in the correct order to form the protein from the dna instructions this will form our primary peptide sequence or primary sequence of amino acids so that the protein can continue its folding for the rest of its structure our rna is going to form the ribosome and remember that first step transcription is where we go from our dna template to our rna molecule via rna polymerase the strand that is red to build the rna molecule is called the template strand the non-coding strand or the minus or antisense strand but this also occurs in the five to three prime direction where new nucleotides are added from five to three prime then there can be modifications of this mrna transcript after it's created including the addition of a poly a tail a gtp cap for stabilization the excision of introns so that we can have the exons be included so introns are cut out we can also get alternative splicing where we have different parts different exons that are included in the final mrna transcript translation then occurs at the ribosomes so in prokaryotic organisms this is simultaneously occurring because it's not separated by the nucleus and the cytoplasm but in eukaryotic organisms the mrna will leave the nucleus in order for this to happen at the ribosomes it happens in three main steps initiation elongation and termination it starts with the start codon the codons are going to code for a specific amino acid that trna is going to bring or recruit over the amino acid and then the stop codon is where that sequence terminates we can also go from rna to dna in specific retroviruses with the help of reverse transcriptase and translation and genes are regulated by different regulatory sequences different epigenetic factors and cells can differentiate meaning certain parts of the genetic code are read during developmental processes so we have the same genetic code in all cells within one organism but different parts of the genome are expressed in different cells transcription factors can also regulate different genes and in prokaryotes some of this genetic regulation is caused by operons where we have inducible operons like our lac operon repressible operons like our trip operon but eukaryotes do not have operons they have transcription factors promoters and inhibitors that could turn on or off particular genes remember if a gene is mutated even if it's just a single nucleotide this could lead to phenotypic changes changes in the actual trait these can be positive negative or neutral but it depends on the environment and the particular organism's needs whether or not these changes are going to affect the organism in a big way or a small way usually errors in dna replication or dna repair are going to lead to these random mutations and errors in mitosis and meiosis are going to lead to errors in chromosome number again this is all subject to natural selection and whether or not the environment and whether or not these changes are going to be positive or negative in that environment lastly in unit 6 there's biotechnology and make sure you're familiar with the genetic engineering techniques including electrophoresis polymerase chain reaction bacterial transformation and dna sequencing we come to our second and last unit it starts with natural selection make sure you know the causes and how natural selection can affect populations fitness again is measured by an individual's ability to survive and reproduce and pass on its genes and different phenotypes are going to determine how successful an organism is in a particular environment again phenotypes are determined by genotypes so genetic variation plays a huge role in the success of a particular population remember populations evolve not individuals in artificial selection humans have an effect on the variation in different species and there's a relationship between changes in the environment and evolutionary changes in populations we can see this through convergent evolution when selective pressures yield very similar phenotypes or phenotypic adaptations in different populations as we get into population genetics we'll be talking about mutations again again mutations are random but they are a huge driver of genetic diversity within populations make sure you know what genetic drift is including the bottleneck effect and the founder effect and how migration and gene flow can also affect the genetic makeup of a population hardy-weinberg comes in here which is a set of equations you'll need to know that can be used as a model for describing allelic frequencies in a population that's not evolving if there is a change in allelic frequencies then it's a type of evidence that there is evolution occurring within a population the next topic is different pieces of evidence for evolution make sure you recognize the data types and different types of evidence including geographical geological physical biochemical mathematical and different types of fossils morphology can also give us information into how organisms have evolved or certain evolutionary pressures mean homologous features or vestigial structures that are shared by ancestors we can look at evidence for common ancestry through things like membrane-bound organelles linear chromosomes and genes that contain introns next topic includes speciation phylogeny and extinction topic you'll learn how to read phylogenetic trees and cladograms not only read them but also build them and which types of data are the best use when constructing a phylogenetic tree for example molecular data is typically the most reliable when constructing a phylogenetic tree shared derived characteristics can also be useful as we get into speciation make sure you know the conditions for which speciation might occur different types of speciation including punctuated equilibrium and gradualism divergent evolution and then how species become extinct and what factors might affect extinction species diversity with an ecosystem can affect the ability of the population to respond to different changes in the environment the more diverse a population is the better it is able to withstand different environmental changes and the more likely it is to survive there are many experiments to determine how the origin of life occurred on earth earth formed about 4.6 billion years ago and there are different models for explaining the origin of the first types of life some of these include the miller and yuri experiments to figure out how organic molecules appeared to be the building blocks for more complex molecules and the idea of the rna world hypothesis to propose that rna was the first genetic material moving into our final unit unit 8 ecology begins with responses to the environment both behavioral and physiological and there's no specific organismal behaviors that you'll need to know at this point but make sure you have lots of examples in mind this also includes communication and exchange of information both internal within an organism and external between different organisms and of course behavioral responses that affect an organism's fitness energy flow within populations is another important topic make sure you're familiar with strategies that different organisms use in order to obtain or maintain energy there are changes in energy availability within ecosystems and you should be familiar with the effects these have on populations and the ecosystems autotrophs remember capture energy from our sun or other physical sources in the environment and heterotrophs capture energy from other organisms or organic compounds produced by other organisms as we go up in energy or trophic levels there is a significant loss of energy but ultimately all energy on earth comes from the sun as we get into population ecology make sure you're familiar with factories that influence the growth of populations population density as well as community structures interactions and what things are dependent on energy availability there are several equations that you might need to be familiar with as far as population growth goes and that includes just general population growth exponential population growth or logistic growth also known as the equation for carrying capacity in order to calculate the diversity of a particular community you might need to use simpson's diversity index which is another equation that pops up within this unit finally communities change over time but it's good to be familiar with different population dynamics including competition predation and other forms of symbiosis parasitism mutualism and conventionalism are all types of symbiosis within different communities there's also cooperative behaviors or coordination between different organisms make sure you're familiar with themes in biodiversity and how the diversity of an ecosystem can lead to more resilience to change a keystone species is an organism that helps hold a system together and disruptions to an ecosystem can include introductions of invasive species or many other human activities geological and meteorological activity can also influence and disrupt ecosystems as well which can result in things like habitat changes or even extinction events that's all for all the topics and content covered on the ap biology exam now i didn't mention many of the scientific skills that you'll need to be successful on the ap biology exam but i hope this video has given you a better idea of what's covered in all of the topics that might pop up as you're preparing to either take this course or take the ap bio exam let me know if this video has been helpful in the comments below be sure to check out some of my other videos for exactly how to prepare to be successful on the ap biology exam thanks so much for watching give this video a like if it's been helpful and i'll see you later