Science Exam Review Notes PDF

Exam 3 🤩 (ctrl F to find something on the doc/ cmd F for macbook) Unit 1: Central Dogma Notes Key Concepts: 1.1 DNA is the blueprint of all life/Molecule of life DNA stores genetic information that determines traits ○ Main purpose of DNA is to store genetic information...

Exam 3 🤩 (ctrl F to find something on the doc/ cmd F for macbook) Unit 1: Central Dogma Notes Key Concepts: 1.1 DNA is the blueprint of all life/Molecule of life DNA stores genetic information that determines traits ○ Main purpose of DNA is to store genetic information DNA is the shape of a double helix, made with sugar, phosphate, and nitrogenous bases (basically just codons) Nitrogenous base pairing rules ○ A with T ○ G with C 1.2 RNA is essential for making protein ○ Plays a huge role during the central dogma RNA is smaller, and is a single stranded helix ○ Uses uracil (U) instead of thymine (T) ○ (so A pairs with U instead of T) There are 3 different types of RNA ○ TmRNA (messenger RNA, carries instructions, otherwise known as mRNA) ○ rRNA (Ribosomal RNA, forms ribosomes) ○ tRNA (Transfer RNA, carries amino acids) 1.3 Transcription: First step of central dogma, DNA is copied into mRNA mRNA carries the message: It travels to the ribosome Ribosomes build the protein, they follow the instructions within the mRNA Gene expression: Some genes are “turned on” to make proteins, while others are turned off 1.4 Translation: The second step of central dogma, mRNA is turned into protein Translation occur at a cytoplasm During translation, a protein is synthesized using the codons in mRNA as a guide ○ tRNA carrying the anticodons and amino acids to the mRNA comes and builds protein ○ Ribosomes bind the items from tRNA to the mRNA codons whilst the protein is getting created Content: DNA: DNA is the material that makes up your chromosomes and stores genetic information. It also acts as a blueprint for building traits and genes  DNA stands for deoxyribonucleic acid DNA is the blueprint for all living things Sugar and phosphate is the backbone of DNA RNA: RNA is different from DNA Single stranded helix Contains uracil instead of thymine Contains the sugar ribose instead of deoxyribose Its primary goal is to carry genetic information from DNA to ribosomes However, there are 3 different types of RNA: mRNA - messenger RNA, carries genetic instructions tRNA - transfer RNA, carries amino acids to the ribosome ○ Each tRNA molecule contains an anticodon for the amino acid it carries rRNA - ribosomal RNA, forms ribosomes RNA is essential during the process of both transcription and translation Nucleotides: Nucleotide are the building blocks of DNA Nucleotides are composed of three main parts A phosphate group A 5-carbon sugar (deoxyribose in DNA) A nitrogen-containing base There are 4 times of nucleotides, adenine (A), thymine (T), guanine (G), and cytosine (C) Uracil (U) replaces thymine (T) in the RNA The nucleotides have specific pairing rules Adenine (A) always pairs with thymine (T) Guanine (G) always pairs with cytosine © ○ Adenine pairs with uracil (U) in RNA) Transcription: First step in the process of Central Dogma, turns DNA into mRNA the DNA double helix unwinds, and RNA polymerase, an enzyme, builds the mRNA using one strand of the DNA as a template (the RNA strand is basically the opposite pair to the nucleotides of the DNA strand) ○ Of course, T is instead replaced with U ○ Happens in the cytoplasm, ribosomes are used to make proteins Genes: Genes are a part of the DNA that are responsible for traits. Genes code for a specific protein or RNA molecule. Traits are things such as eye color, skin color, or ear size Translation: Translation is the process in central dogma where the mRNA is turned into protein After the mRNA leaves the nucleus, it moves to a ribosome The ribosome reads over the mRNA Molecules of tRNA bring amino acids to the ribosome in the correct anticodon sequence  tRNA temporarily binds to the codons on the mRNA Whilst bound to the mRNA, the tRNA gives up its amino acids Bonds form between them when amino acids are brought one by one to the ribosome ○ This forms a polypeptide chain, continuing until a stop codon is reached My notes: Ribosomes are used to make proteins during translation Translation occurs in the cytoplasm mRNA is NOT made of the same stuff that tRNA is made of mRNA forms inside the nucleus mRNA carries genetic information base = nucleotide codon = 3 nucleotide gene = codon chain DNA provides instructions A (adenine) always pairs with T (thymine) except when RNA is formed, which is when A pairs with U (uracil) G (guanine) always pairs with C (cytosine) There are many types of proteins, being structural, transport, motor, storage, and enzyme proteins, which are all essential for life Unit 2: Bioengineering Notes Key concepts: 2.1 DNA replication is essential for growth, repair, and reproduction in organisms ○ We would simply stop growing if this process stopped DNA replication is the process of copying a cell’s DNA before it divides ○ Ensures accurate passing down of genetic information Enzymes like helicase and DNA polymerase play a heavy role during the process 2.2 Mutations are changes in the DNA codon sequence ○ Changes in nucleotides, mainly affects the creation of proteins There are 2 types of mutations, point(substitution) and frameshift(insertion/deletion) Mutations can either 1. Be neutral 2. Be harmful or 3. Be beneficial Many genetic disorders are caused by mutations ex. hemophilia 2.3 Humans have 23 pairs of chromosomes, 2 chromosomes in each ○ Each chromosome gives half of your genetic information, one from each parent A karyotype is a picture of all your chromosomes ○ Helps figure out sex and genetic disorders Some genetic disorders are caused by too many or less chromosomes Sex chromosomes determine biological sex  ○ Males have 1 X and 1 Y chromosome ○ Females have 2 X’s 2.4 Cloning is the process of creating a genetically identical replica of the parent organism ○ Nearly the same if not identical to asexual reproduction, different process Cloning involves transferring a nucleus from a donor cell into an egg that got its nucleus removed 2.5 Similarities: ○ Both involve improving the traits of an organism Differences: ○ Genetic engineering is a lot faster and more accurate compared to selective breeding ○ Selective breeding is a lot slower, and relies on natural selection for traits Content: DNA replication: DNA replication is the process of creating an exact copy of a cell’s DNA before the cell divides and a new cell is formed. The process of DNA replication are as follows: 1. An enzyme called DNA helicase unwinds the DNA helix, separating it into 2 strands 2. RNA primers attach to the separate strands, providing a starting point for DNA synthesis (making new DNA) 3. DNA polymerase adds new nucleotides to the strand, following the pairing rules, DNA polymerase also proofreads over the new strand to check if its correct 4. Once both strands have been remade, the DNA strands are connected, forming new DNA This ensures the accurate passing down of the same genetic information Contributes to your growth, repair, and reproduction systems within our body ○ DNA replication is a semi-conservative process Mutations Mutations occur when the DNA instructions are changed. They are caused from changes within codon orders, aka if something happens to a nucleotide. Mutations can either happen from something small as the substitution of a nucleotide, or something huge like insertion or deletion of a nucleotide. There are 4 types of mutations: Substitution/point mutations: Changes a single nucleotide, might alter the protein Silent mutation: Does not change the amino acid sequence at all (mutation has no effect) Missense mutations: Change the amino acid sequence entirely Nonsense mutations: Creates a stop codon prematurely, ends the protein early Frameshift mutations: Shifts the entire codon order, leading to a entirely new protein ○ Insertion: Adds a new nucleotide to the codon sequence ○ Deletion: Removes a nucleotide from the codon sequence Mutations can either:  Have no effect Benefit the organism Or most likely, Harmful to the organism Chromosomes Humans have 23 pairs of chromosomes, with 46 in total. Each chromosome in a pair gives you half of your parents genetic information, one from your mom and one from your dad. Karyotypes are a picture of all your chromosomes. They help figure out any genetic disorders and your biological sex. Some genetic disorders are caused by having too many or too few chromosomes ex. Down syndrome You have a separate pair of chromosomes that determine your sex ○ Males have 1 X and 1 Y chromosome ○ Females have 2 X chromosomes Reproduction When a sperm cell fertilizes an egg cell, it results in a zygote, which inherits a complete set of 23 chromosomes from each parent. Cloning Cloning is the process of creating a genetically-identical copy of the parent. Cloning only requires 1 parent, and is basically just asexual reproduction The process of cloning is as follows: The nucleus is removed from a cell The nucleus is removed from a donor egg The nucleus from the cell is placed into the donor egg The new cell is stimulated with an electric shock, results in a zygote The resulting embryo is implanted into a mother organism, which is where it continues to grow Cloning is not used as often due to a high chance of failure as well as morale questions arising. Humans are illegal to clone due to these same reasons. Selective Breeding Selective breeding is the process where specific organisms with desired traits are bred together, in order to receive offspring with good traits. This process takes a lot of time, taking many generations, and is mostly up to natural selection for the traits Genetic Engineering Genetic engineering is a more modern technique, as it involves directly modifying the organism’s genetic information. This process is a lot faster than selective breeding, and is more accurate. Scientists isolate specific genes and insert them into the DNA of another organism ○ This can modify or create new traits My notes: Mutation is any change in the DNA code Missense and frameshift are NOT the same, Missense is when a single nucleotide is SUBSTITUTED, frameshift is when a nucleotide is INSERTED or DELETED Mutated codons don't always code for a different amino acid Chromosomes are found in the nucleus autosomes are chromosomes that contain genes for characteristics that are unrelated to sex there are 23 chromosomes in human sex cell Primarily inherit genetic information through the fusion of gametes Unit 3: Inheritance (like maybe the hardest unit?) (nvm unit 4 is a lil harder) (i think) Notes Key Concepts: 3.1 Asexual reproduction creates identical offspring, limiting adaptability ○ Less growth due to offspring being a literal clone Sexual reproduction generates diverse offspring, increasing survival chances in changing environments ○ More growth due to the combination of genes from 2 different parents 3.2 Gregor mendel’’s groundbreaking experiments with pea plants laid the foundation for modern genetics Discovered that traits are controlled by pairs of genes, each with different versions called alleles. ○ Each individual has 2 version ○ Dominant and Recessive traits Dominant hides the recessive trait Mendel’s laws include the Law of Segregation, which states that allele pairs separate during gamete formation, and the Law of Independent Assortment, which explains that genes for different traits are inherited independently ○ They also CANT affect another trait 3.3 Punnett squares are a special tool used to predict the offspring from a cross between 2 parents In a punnett square, the possible offspring are represented by the letters in the boxes, with one factor coming from each parent Genotype is the genetic code, whilst phenotype is the physical appearance. Genotype ratio counts each genotype type, while phenotype ratio counts each visible trait 3.4 The Mendelian pattern of inheritance and expression does not apply to all traits Codominant traits, incompletely dominant traits, and polygenic traits do not follow simple Mendelian patterns of inheritance. ○ Does not follow Gregor Mendel’s laws on inheritance, more complex Content: Sexual Reproduction Sexual reproduction is a type of reproduction where 2 parents do the big bang to make an offspring  Results in the offspring having a genetic make up of both parents mixed, half and half from each Pros ○ Allows the growth of genetic diversity ○ Allows evolution Cons ○ Takes a longer time to reproduce/grow ○ Longer time to find a mate Asexual Reproduction Asexual reproduction is a type of reproduction where the child is a identical copy of its parent Results in the offspring having the exact same genetic make up Pros ○ A lot more rapid and fast ○ Could potentially reproduce indefinitely if met with right conditions Cons ○ Less variety of genes/less growth of genetic diversity ○ Not much/slower evolution Gregor Mendel Conducted experiments on the topic of heredity, widely popular due to his theories on heredity. Conducted experiments using pea plants to learn more about the laws of heredity and inheritance. The person that laid the foundation of modern genetics Discovered rules on dominant and recessive alleles that control traits within the pairs of genes Created the Law of Segregation and the Law of Independent Assortment ○ S = Allele pairs separate during gamete formation ○ IA = Genes for different traits are inherited independently Used pea plants for his experiments due to them being easily manageable and grew fast ○ Did this by removing the anther (male flower part) off some pea plants in order to remove self pollination ○ In order to conduct these experiments, he took the anthers off of some pea plants and fertilized different plants with them Via his experiments, he found out the laws of dominant and recessive traits, as well as on how to predict how the traits of offspring will turn out Dominant x recessive plant == dominant/recessive mix D/R mix x D/R mix == D/D, D/R, R/R (1:2:1 ratio) ○ D = Dominant ○ R = Recessive Uhhhhhh Traits do not affect other traits ○ Ex. eye color does not affect skin color Punnett Squares: A tool to find/predict the traits that the offspring might inherit from a cross between 2 parents Genotypes:  ○ A set of genes that an organism has; genetic information, dominant or recessive alleles ○ Homozygous = same 2 traits (dominant x dominant | recessive x recessive) ○ Heterozygous = hybrid (dominant x recessive) Phenotype ○ Physical appearance of an organism, the visible traits To make a Punnett Square: Form a 2 by 2 square Take the genotype from the first parent and place them on the top of the box, separate the alleles by the lines Take the genotype of the second parent and place them on the right of the box, separate the alleles by the lines Pull one allele from each parent down into each box ○ Repeat until all boxes are full EX: G G GG GG G Gg Gg g 2:2 ratio, full dominant x dominant/recessive EX 2: g g Gg Gg G gg gg g 2:2 ratio, full recessive x dominant/recessive EX 3: G g GG Gg G Gg gg g 1:2:1 ratio, full dominant x dominant/recessive x full recessive  Read carefully when questions about these pop up, or just draw them on a piece of scratch paper (details) Ratio of chances can either be classified by phenotype (dominant or recessive), or by genotype (dominant x recessive, dominant, recessive) Different types of inheritance? Idk what to put Codominance ○ A form of inheritance where both alleles in a heterozygous (hybrid genotype) organism is fully expressed ○ Can see both types of phenotype ex. White and black spotted cow/type AB blood NOT MIXED Incomplete Dominance ○ Incomplete dominance is an inheritance pattern where the phenotype of a heterozygous (hybrid genotype) organism is blended/mixed ○ Can see a mix of both phenotypes ex. red/white flower parents == pink flower Polygenic Trait ○ A polygenic trait is a phenotype that is controlled by multiple genes ○ Multiple genes control it ex. Eye color, height, skin color Co and Incomplete dominance are not a part of Mendelian inheritance (Gregor Mendel’s laws on inheritance), where it follows a strict dominant/recessive order. Unit 3: Inheritance (final stretch) Notes Key Concepts: 4.1 Fossils are the remains of organisms that were preserved in the earth, and they are mostly found in the sedimentary rock layer because these stocks form at low temperatures and pressures Scientists use relative dating and absolute dating to determinant he age of fossils, with older fossils found in deeper layers of the earth's sedimentary rock ○ Relative dating is the way to find an estimate of the fossils age ○ Absolute dating is the way to find the exact age of the fossil The fossil record and the geologic time scale provide information about when and how long organisms have existed on Earth 4.2 Variation: Individuals in a population are different from one another, which allows for survival in changing environments ○ Different traits within the gene pool Natural Selection: Organisms with traits that help them survive are more likely to pass those traits to the next generation Adaptation: Over time, species change to better fit their environment ○ This can either be more traits, removal of traits, or just a improvement of a good trait 4.3  Homologous structures suggest common ancestry, while analogous structures indicate similar selective pressures driving similar adaptation ○ Homologous structures == body parts in species that are similar to another species through shared ancestry ○ Analogous structures == body parts that have the same function as other species but aren't related through ancestry Biological molecules, like DNA sequences, reveal a species relativity to other species Biogeographical patterns offer clues about species relationships ○ Biogeographical == how species are placed around the earth 4.4 Phylogeny is the evolutionary history of a group of related organisms. It is represented by a phylogenetic tree that shows how species are related to each other through common ancestors A clade is a group of organisms that includes an ancestor and all of its descendants. It is a phylogenetic classification, based on evolutionary relationships. Content: Fossils Fossils are the remains of plants and animals that have lived a LONG time ago, and are made up of either: Bones or Bone fragments Imprints or footprints Preserved remains (like inside ice or amber) Fossils are usually found in the Sedimentary layer of earth Fossils are usually found in his layer due to it being made up of sand, mud, and other materials that are perfect at protecting the organism remains ○ It is also due to the fact that materials may have eroded the land near where the organism died in order to transport it make it slowly get covered over time Fossil Records are nearly the same thing as fossils, data/study on fossils There are 2 methods to find out how old fossils actually are Absolute Dating: ○ This is the method to find the exact age of the fossil, the more precise way ○ Involves measuring the amount of radioactive decay in the rocks or fossil Relative Dating: ○ This is the method to find an estimated age of the fossil, usually used to find where to place the fossil in a general timeline. ○ Involves looking at the position of the fossil in rock layers. Deeper the layer, the older the fossil Natural Selection Natural selection is the idea that a scientist named Darwin had concluded after visiting an island filled with birds. Natural selection is in 4 big parts: Variation: Not all individuals are the same ○ Each bird has different traits Struggle to Survive: Food, water, and space become limited, which creates competition  Survival of the Best Fit: Traits that help survival become more common over many generations ○ Mainly due to the fact that traits that dont help survival become nearly wiped out of the population Change over Time: The population evolves as more individuals inherit helpful traits ○ The traits that support survival slowly improve over generations Essentially, the ones who are best suited to survive within their environment are the ones who prosper, and improve the generations to come. Here is a real life situation: Before the drought: Finches had both small, large, round, and pointed beaks. The small and pointy beaked birds thrived due to there being many small and soft seeds. During the drought: Small seeds slowly disappeared, and instead the large, tough seeds remained. Finches with larger or rounder beaks were able to thrive over the small-beaked finches. After the Drought: The next generation of finches overall had larger beaks than average Summary: Natural selection is the process where the best fit survives and passes down the best fit traits onto the next generation. (also variation is VERY important) Evidence of evolution: To find evidence of evolution throughout history, there are a few things that scientists study, being: Comparative Anatomy Comparative Anatomy is the study of the anatomy of different species to see their similarities and differences Basically just comparing the structure of a skeleton between different organisms, such as comparing the arms of a human, dog, chicken, and bird to see its differences and similarities Embryology and Development Embryology and development is the process of how a human embryo evolves and grows inside the womb The process of how we grow after the egg is fertilized Fossil Record Fossil record is a document full of everything that was found fossilized Basically data of fossils and remains that have been persevere, a collection of fossil data DNA Comparison DNA comparison is when you take the genetic code of an organism to compare it to another organism to see how related they are to one another Just comparing the DNA of different organisms, such as comparing human DNA to bat DNA Species Distribution Species distribution is the study how species are spatially placed around the earth Where species are placed on earth, simple Phylogeny Phylogeny is the evolutionary history of a group of related organisms. It is represented by a phylogenetic tree:  Basically a family tree comprised of different species, and shows how they are related via evolution One way of classifying organisms that shows phylogeny is by using the clade (cladogram). A clade (cladogram) is a group of organisms that includes an ancestor and all of its descendants. These are based on cladistics Cladistics is the method of comparing traits in related species to determine ancestor-descendant relationships Cladograms is a tree where it starts from the oldest ancestry, than keeps going up the evolutionary tree with said evolution/difference between each species (ex. legs/wings) Clade is the group of organisms that are similar to phylogenetic trees, however focus more on the branching order and shared characteristics Phylogenetic trees are similar to cladograms but focus more on time, evolutionary changes, and extinct species Phylogenetic == general timeline Cladogram == group of related species Ian are yuo copying everything good iddea