Biology Keystone Review Notes

Biology Keystone Review

Introduction

• This packet prepares you for the Biology Keystone Test in 10th/11th grade.

• It's divided into major themes.

• Completing the packet diligently can exempt you from retaking the test.

• If the test score does not meet the state's expectations, it will need to be taken again.

Major Themes

• Themes of Life

• Organic Chemistry

• Cells and Cell Transport

• Energy

• Cell Reproduction & Genetics

• Protein Synthesis

• Evolution/Phylogeny

• Ecology

Each section includes vocabulary, content anchors, review questions, and practice test questions.

Themes of Life

Vocabulary

• Biology: Study of life.

• Biotechnology: Using living systems and organisms to develop or make products.

• Forensics: Scientific tests or techniques used in connection with the detection of crime.

• Homeostasis: Maintaining a stable internal environment.

• Homeostatic mechanism: Process that maintains homeostasis. Ex: Hypothalamus regulates temperature.

• Scientific law: A statement of fact meant to explain, in concise terms, an action or set of actions; generally accepted to be true and universal.

• Scientific mechanism: A natural or established process by which something takes place or is brought about. Ex: Natural selection/evolution.

• Organ: A group of tissues working together for a specific function.

• Organ system: A group of organs working together for a specific function.

• Organism: An individual living thing.

• Science: The intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment.

• System: A set of things working together as parts of a mechanism or an interconnecting network.

• Temperature: Degree or intensity of heat present in a substance or object.

• Theory: A well-tested explanation that unifies a broad range of observations and hypotheses, enabling accurate predictions about new situations.

• Hypothesis: A testable scientific explanation for a set of observations that can be supported or rejected.

• Eukaryote: Organism whose cells contain a nucleus and other organelles.

• Prokaryote: A microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles.

Concepts to Know: Characteristics of Life

1. Made of cells:

   • Smallest unit of an organism considered alive.

   • Can be unicellular (bacteria) or multicellular (humans).

2. Reproduce:

   • Asexual: New organism from one parent; offspring is a clone.

   • Sexual: Two cells from different parents unite to produce the 1st cell of a new organism.

3. Based on a universal genetic code:

   • Based on one molecule (DNA) that is almost identical in every organism.

   • DNA (Deoxyribonucleic Acid).

4. Grow and develop:

   • Growth: Increase in size of an organism.

   • Development: Progression through a life cycle.

5. Obtain materials and use energy:

   • Autotroph: Obtains energy from the sun.

   • Heterotroph: Obtains energy from consuming other organisms.

6. Respond to environment:

   • Examples: Find shelter from rain, hibernate, produce toxins.

7. Maintain a stable internal environment:

   • Homeostasis: Keeping internal conditions stable relative to external environment.

8. Change over time (evolve):

   • Populations evolve over time.

Structure and Function

• Central theme in biology, major groups of organisms have evolved particular body part "tool kits".

• Structures evolve to make particular functions possible.

• Examples:

  • Wings enable birds and insects to fly.

  • Legs enable horses to gallop, kangaroos to hop.

• Carnivore and herbivore skulls differ based on diet.

Levels of Organization

• Specialized cells of multicellular organisms are organized into organ systems.

• Tissue: A group of similar cells performing a particular function.

• Organ: Many tissues working together to complete complicated tasks.

• Organ system: A group of organs working together to perform a specific function.

• Cells are specialized for specific functions contributing to homeostasis.

Chemistry of Water

• Life is connected to water; Earth is nearly 75% covered in water.

• Water is composed of two hydrogen atoms and one oxygen atom (H_2O).

• Water is a polar molecule: one side is positively charged, the other negatively.

• Negative oxygen of one water molecule attracts positive hydrogen of another forming a hydrogen bond.

• Cohesion: Water sticking to water.

• Adhesion: Water sticking to something else.

• Hydrogen bonds give water:

  • High specific heat.

  • Cause it to expand upon freezing.

• Specific heat: Amount of energy to raise one gram of water 1 degree Celsius.

• Water expands when frozen, becoming less dense (ice floats).

• Specific heat and freezing point of water support life:

  • Ice insulates water underneath (moderates temperatures of the earth).

  • Water helps moderate temperatures on land; sweat cools us.

Scientific Method/Scientific Terms

• Inference: Arriving at a conclusion using background knowledge.

• Hypothesis: A testable statement based on observations.

• Control group: Stays the same.

• Experimental group: Is changed.

• Dependent variable: Measured.

• Independent variable: Manipulated.

• Observation: Starts the research.

• Theory: Well-tested explanation unifying observations and hypotheses, enabling predictions.

Organic Chemistry

Vocabulary

• Adhesion: The clinging of one substance to a different substance.

• Cohesion: The linking together of like molecules, often by hydrogen bonds.

• Atom: The smallest unit of matter that retains the chemical properties of an element.

• Concentration: The amount of a substance per defined space.

• Biological macromolecules: Large polymers, such as carbohydrates, lipids, proteins, and nucleic acids.

• Monomer: The subunit that serves as the building block of a polymer.

• Freezing point: The temperature at which a liquid changes into a solid.

• Carbohydrate: A sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides).

• Amino acid: An organic molecule possessing both a carboxyl group and an amino group; amino acids serve as the monomers of polypeptides.

• Protein: A biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure.

• Macromolecule: A giant molecule formed by the joining of smaller molecules through a dehydration reaction.

• Lipid: One of a group of compounds, including fats, phospholipids, and steroids, that mix poorly, if at all, with water.

• Nucleic acid: A polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities.

• Enzyme: A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Catalyst: A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction.

• pH: A measure of the relative acidity or alkalinity of a solution, measuring the concentration of H^+ and OH^-.

• Molecule: Two or more atoms held together by covalent bonds.

• Specific heat: The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C.

• Organic molecule: Molecules that contain carbon and are found in living organisms.

Concepts to Know

Carbon's Properties

• Carbon has 4 electrons in its valence shell, enabling easy formation of four covalent bonds.

• Covalent bonds involve sharing of electrons between two atoms.

• Carbon can form long chains by forming several bonds in a row.

• Organic compounds contain carbon and variety is created by the partners that carbon can bond with.

• Properties include polarity: balance of charges in a molecule.

  • Polar: Charges are not balanced.

  • Nonpolar: Equal balance of charges.

Biological Macromolecules from Monomers

• Macromolecules are very large molecules, mostly polymers.

• Polymers are long chains of bonded groups; monomers link to form polymers.

• Dehydration synthesis generates water and forms polymers.

• Hydrolysis breaks apart polymers.

Macromolecules and Their Function

Carbohydrates: Structure and Function

• Broken down through hydrolysis to serve as fuel or a carbon source.

• Saccharide means sugar. Can be monosaccharides (1 sugar), disaccharides (2 sugars), or polysaccharides (more than 2 sugars).

• Glycolysis: Breaks down carbohydrates like glucose for cellular respiration.

• Cellular respiration generates energy (ATP). Produces 36 ATP.

Lipids: Structure and Function

• Nonpolar macromolecules made from long carbon chains.

• Can be fats, phospholipids, or steroids.

• Fats store large amounts of energy and compose cell membranes.

• Steroids made of four connected carbon rings with functional groups.

• Can be saturated (linear shape, single bonds) or unsaturated (nonlinear shape, double/triple bonds).

Proteins: Structure and Function

• Amino acid polymers essential to life.

• Amino acids have amino and carboxyl groups, made unique by the "R" group.

• Function determined by structure and conformation of the "R" group.

Nucleic Acids: Structure and Function

• Polymers of nucleotides consisting of pentose (hexagon shape) attached to a phosphate group (red in diagram) and nitrogen base (blue in diagram).

• Pentose can be deoxyribose (DNA) or ribose (RNA).

• DNA and RNA central to heredity, made unique by nitrogenous bases (cytosine, thymine, uracil, adenine, guanine).

Enzymes: Biological Catalysts

• Increase the rate of a reaction without being changed by the reaction.

• Substrates are the reactants on which enzymes work.

• Rate of reaction in both directions is increased by specific enzymes.

• Active site: Part of an enzyme that interacts with a substrate.

• Regulation (Activation): The process of turning enzymes on that occurs through regulation or activation.

• Induced means the body only produces the enzyme when it is needed.

• Deactivation can occur through allosteric or competitive inhibition.

  • In competitive inhibition, another chemical bonds with and blocks the active site.

  • In allosteric inhibition, another chemical bonds to the enzyme away from the active site, altering it.

Enzyme Reaction Rates Influenced by Temperature, pH & Substrate Concentration

• Temperature is a measure of kinetic energy (energy of motion).

  • Higher temperature means faster-moving particles.

  • Increased collisions between enzymes and substrates.

  • Enzymes do not function well above or below the optimal temperature.

  • Enzyme denatures (breaks down) if too cold/hot.

• pH measures acidity; Enzymes function best at optimal pH level.

  • Enzyme may denature if conditions too acidic (low pH) or basic (high pH).

• Concentration measures substrate molecules present.

• Saturation is the concentration where the reaction rate is maximized.

Cells and Cell Transport

Vocabulary

• Cell: The basic structural and functional unit of all known living organisms.

• Tissue: A group of similar cells performing specific functions.

• Cell membrane (plasma membrane): The semipermeable membrane surrounding the cytoplasm of a cell.

• Nucleus: Control center of the cell that contains the cell's DNA.

• Ribosome: A cell structure that makes protein.

• Mitochondrion: Powerhouse of the cell that generates ATP via cellular respiration.

• Chloroplast: An organelle in plant cells that conducts photosynthesis.

• Protein synthesis: The process by which amino acids are linearly arranged into proteins.

• Active transport: The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

• Carrier (transport) proteins: Proteins that bind to molecules and transport them across the cell membrane.

• Concentration gradient: Gradual change in the concentration of solutes in a solution as a function of distance through a solution.

• Diffusion: Movement of molecules from an area of higher concentration to an area of lower concentration.

• Endocytosis: The process of taking in matter by a living cell by invagination of its membrane to form a vacuole.

• Endoplasmic reticulum: A network of membranes involved in protein and lipid synthesis.

• Endosymbiosis: A symbiotic relationship where one organism lives inside the other.

• Exocytosis: Process by which a cell releases large amounts of material.

• Facilitated diffusion: Movement of specific molecules across cell membranes through protein channels.

• Extracellular: Situated or taking place outside a cell or cells.

• Golgi apparatus: Organelle responsible for packaging and modifying proteins.

• Impermeable: Not allowing fluid to pass through.

• Intracellular: Located or occurring within a cell or cells.

• Organelle: A specialized subunit within a cell that has a specific function.

• Osmosis: Diffusion of water through a selectively permeable membrane.

• Passive transport: Movement of substances across a cell membrane without the use of energy by the cell.

• Plastids: Any of a class of organelles in the cells of plants and algae that contain pigment or food.

• Pumps (ion or molecular): Transmembrane proteins that move ions or small molecules across a plasma membrane against a concentration gradient.

• Unicellular: Made up of a single cell.

• Multicellular: Consisting of many cells.

Concepts to Know

Cell Theory

1. All living things are made of cells.

2. Cells are the basic units of structure and function in living things.

3. New cells are produced from existing cells.

Prokaryotic vs Eukaryotic Cells

1. Prokaryotic Cells:

   • Single-celled organisms that lack internal membrane-bound compartments.

   • Genetic material (DNA) is in a circular molecule (simple).

   • Example: bacteria.

   • Hypothesized that the first type of cells on earth were prokaryotic.

2. Eukaryotic Cells:

   • Cells with membrane-bound compartments with organelles such as the nucleus (more complex).

   • Examples: Animal and plant cells.

Cell Structures & Functions

• Cells are enclosed by a cell membrane (plasma membrane).

• Within the membrane is the nucleus and the cytoplasm.

• Within the cytoplasm are organized structures that perform specific functions - organelles.

Cell Membrane (Plasma Membrane) (A, P)

• Surrounds the cell.

• Determines which substances enter and exit the cell (selectively permeable or semipermeable).

• Composed of lipids (phospholipids) and proteins.

Nucleus (A, P)

• Control center for all cell functions.

• Contains chromosomes and at least one nucleolus.

• Nucleolus is the site of RNA synthesis and may produce ribosomes.

Cytoplasm (A, P)

• Material in the cell outside the nucleus, mainly water.

• Contains various organelles of the cell.

• Provides the environment in which the organelles carry on the life processes of the cell.

Mitochondria (A, P)

• Found in the cytoplasm.

• Most stages of cellular respiration occur here.

• Energy released during respiration is stored in ATP molecules.

Chloroplasts (P)

• Contain chlorophyll (green pigment) which carries on photosynthesis.

• Mitochondria & Chloroplast-Developed from prokaryotic cells (endosymbiotic theory)? Because they contain their own DNA.

Ribosomes (A, P)

• Small, dense granules.

• Found free in the cytoplasm and the nucleus and lining the membranes of some endoplasmic reticulum.

• Composed mainly of RNA.

• Centers of protein synthesis in the cell.

Endoplasmic Reticulum (A, P)

• Membrane-bound system of channels or tubes through which materials are transported within the cell.

• Membranes may serve as sites of biochemical reactions.

• Two types:

  • Smooth.

  • rough (presence of ribosomes on the membrane, mainly in cells involved in protein synthesis). Found in cells involved in synthesis of nonprotein substances.

Golgi Apparatus (A, P)

• Made up of membrane-enclosed sacs, near the nucleus.

• Associated with the production of lysosomes and synthesis of secretions.

Lysosomes (A)

• Sacs of digestive enzymes.

• Keeps the enzymes separated from the rest of the cell contents until they are needed.

Vacuoles (A, P)

• Membrane-enclosed structures filled with water containing dissolved substances.

• Small in animal cells, large in plants.

• Pressure helps maintain the rigid structure of the plant cell and of the plant.

Centrosome (A, P) & Cell Wall (P)

• Centrosome: are small organelles found just outside the nucleus in animal cells.

• Cell Wall: Structure found outside the cell membrane of plant cells. Made up mostly of cellulose, provides support for the cell.

Cytoskeleton (A, P)

• Filamentous network of proteins that maintain and change cell shape and produce cell movements in animal and bacteria cells.

• In plants, it is responsible for maintaining structures within the plant cell, rather than whole cell movement.

• Main types of filaments: Microfilaments and Microtubules.

Two Types of Cellular Transport

The cell membrane is semipermeable: some substances can pass through it freely, while others cannot.

1. Passive Transport

   • Doesn't use energy

   • Moves from a high to low concentration

   • Examples:

     • Diffusion: Movement of particles from regions of higher density to regions of lower density across the cell membrane.

     • Facilitated Diffusion: Transport proteins help ions and polar molecules diffuse through the membrane.

     • Osmosis: Diffusion of water across a selectively permeable membrane.

2. Active Transport

   • Requires energy

   • Moves from a low to high concentration

   • Examples:

     • Endocytosis: Movement of a large substance into a cell by means of a vesicle.

     • Exocytosis: Movement of material out of a cell by means of a vesicle.

Sodium-potassium pump

• One of the most important carrier proteins in animal cells.

• In nerve cells the pump is used to generate gradients of both sodium and potassium ions.

• These gradients are used to propagate electrical signals that travel along nerves.

Energy

Vocabulary

• Photosynthesis: Process by which plants and other organisms use light energy to convert water and carbon dioxide into oxygen and glucose.

• Cellular respiration: The process that releases energy from food in the presence of oxygen.

• Electron transport chain: A series of protein complexes that transfer electrons from electron donors to electron acceptors via redox reactions, and couples this electron transfer with the transfer of protons (H+) across a membrane.

• ATP: The main energy source that cells use for most of their work.

Concepts to Know

• Life Needs Energy

  • Autotroph: Supplies itself (self-feed).

  • Heterotroph: Eats something (other-feed).

• Laws of Thermodynamics dictate that no energy can be created or destroyed, it can only change forms.

• Chemical bonds are literally energy.

• Short-term storage molecule that ALL life has evolved to use is adenosine triphosphate, or ATP.

• Catabolic Pathways: Break down molecules so that.

• Anabolic Pathways: Build up molecules.

• ATP is the go-between.

Cell Respiration

• The major way organisms harness energy.

• Large food molecules are taken in and ultimately the monosaccharide GLUCOSE is digested to capture its energy

• C6H{12}O6 + 6O2 -> 6CO2 + 6H2O + energy

• Aerobic Respiration: glycolysis -> Krebs cycle -> electron transport chain (ETC)

• Anaerobic Respiration: glycolysis -> fermentation

Steps of Cell Respiration

• It’s all about rearrangement.

• During glycolysis, glucose (6C) is broken in half so a little energy is released with that broken bond…it is put into making ADP into ATP.

• Whenever a bond breaks in this process, an electron and a hydrogen need to be accounted for. A molecule NAD+ picks them up to form NADH.

• The carbons will leave as CO2. The hydrogens and electrons were put into NADH.

• The MOST important part of Cell Respiration is the electron transport chain. All of the NADH that was formed so far drops off the electrons and the hydrogens at the inner membrane of the mitochondria (for eukaryotes).

• Electrons are a different form of energy and can power the protein channels to open (this is active transport).

• Building a gradient of H+ ions in this tiny mitochondrial space, the H+ build up and need to diffuse out, through a special channel called ATP synthase (this is passive transport). This molecule literally spins as H+ goes through it and makes ATP from ADP.

• After passing the electron down the chain to make the gradient happen (which is known as chemiosmosis), the electron has to go somewhere. It would cause damage in your cell otherwise. Oxygen is there to pick it up and combine it with the hydrogens to make….WATER.

Photosynthesis

• Occurs in photosynthetic autotrophs (plants, algae, some bacteria); in the chloroplast of eukaryotes.

• Has 2 major steps: the light reaction and the Calvin cycle.

• The Calvin Cycle is the part that makes the sugar. Carbon dioxide comes into a plant (via leaf stomata) and is joined together with other carbons in the cell to ultimately make glucose (6 carbons).

• 6CO2 + 6H2O + energy -> C6H{12}O6 + 6O2

Cell Reproduction & Genetics

Vocabulary

• Allele: Different forms of a gene.

• Cell cycle: The series of events that take place in a cell leading to its division and duplication.

• Chromosomes: Thread-like structures located inside the nucleus of animal and plant cells made of protein and a single molecule of DNA.

• Cloning: The process of producing genetically identical copies of an organism.

• Co-dominance: A form of inheritance wherein the alleles of a gene pair in a heterozygote are fully expressed.

• Crossing over: The exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

• Cytokinesis: The cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.

• DNA replication: The biological process of producing two identical replicas of DNA from one original DNA molecule.

• Dominant inheritance: A pattern of inheritance in which one allele masks the effect of another.

• Gamete: A mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

• Gene: A unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

• Gene splicing: A type of genetic recombination in which DNA is intentionally broken and recombined using laboratory techniques.

• Gene therapy: The transplantation of normal genes into cells in place of missing or defective ones in order to correct genetic disorders.

• Gene recombination: The production of offspring with combinations of traits that differ from those found in either parent.

• Genetic engineering: The deliberate modification of the characteristics of an organism by manipulating its genetic material.

• Genetics: The study of heredity and the variation of inherited characteristics.

• Incomplete dominance: A form of inheritance in which one allele for a specific trait is not completely dominant over the other allele.

• Inheritance: The process by which heredity information is passed from parents to their offspring.

• Interphase: The resting phase between successive mitotic divisions of a cell, or between the first and second divisions of meiosis.

• Meiosis: A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

• Mitosis: A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

• Multiple alleles: Three or more forms of a gene that code for a single trait.

• Nondisjunction: The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

• Polygenic trait: A trait whose phenotype is influenced by more than one gene.

• Recessive inheritance: A pattern of inheritance in which an allele is only expressed when two copies are present.

• Semiconservative replication: Each resulting cell will have a complete set of DNA molecule.

• Sex-linked trait: A trait associated with a gene that is carried only by the male or female parent.

• Genetically modified organism: An organism whose genetic material has been altered using genetic engineering techniques.

• Genotype: The genetic constitution of an individual organism.

• Phenotype: The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Concepts to Know

Cell Cycle

The Cell cycle is the period of time from the beginning of one cell division to the beginning of the next.

• A cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cell cycle again.

• Consists of 4 phases

  • M phase: Mitosis - the division of the cell nucleus and cytokinesis.

  • G1: Intense growth and activity.

  • S phase: Copying of chromosomes.

  • G2: Intense growth and activity.

• Interphase - time between two cell divisions:

  • Broken into 3 phases: G1, S, G2.

    • G1: cells do most of their growing, increasing in size and synthesizing new proteins and organelles.

    • S: chromosomes are duplicated and the synthesis of DNA molecules takes place.

    • G2: Organelles and proteins required for cell division are produced.

Mitosis

Biologists divide the events of mitosis into 4 phases: prophase, metaphase, anaphase, and telophase

1. Prophase: 1st and longest phase of mitosis (50-60% of total time).

   • Chromosomes become visible.

   • Centrioles separate and take up positions on opposite sides of the nucleus.

   • Plants do not have centrioles.

   • Nucleolus disappears.

   • Nuclear envelope breaks down.

2. Metaphase: 2nd phase of mitosis.

   • Chromosomes line up along the center of the cell.

   • Microtubules connect the centromere of each chromosome to the poles of the spindle.

3. Anaphase: 3rd phase of mitosis.

   • Centromeres that join the sister chromatids split

   • Chromatids separate and become individual chromosomes

   • Chromatids get pulled apart, to the poles of the spindle.

   • Ends when they stop moving.

4. Telophase: 4th phase of mitosis.

   • Chromosomes become loose and begin to disperse.

   • Nuclear envelope reforms.

   • Spindle breaks apart.

   • Nucleolus reappears.

   • Cytokinesis: Division of the cytoplasm.

Meiosis

• Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half and homologous chromosomes in a diploid cell are separated.

• Involves two distinct stages: meiosis I and meiosis II.

• One diploid cell becomes 4 haploid cells.

• Homologous - two sets of chromosomes (one from mom and one from dad):

  • If a cell has both sets of chromosomes = diploid (2n).

  • Gametes with only one set of chromosomes = haploid (n).

• Meiosis I - prior to meiosis I, each chromosome is replicated:

  • Chromosomes line-up similar to mitosis, except the homologous chromosomes for a tetrad (4 chromatids).

    • Occurs during prophase I, crossing over may occur (exchange of alleles between homologous chromosomes, produces new combinations of alleles).

  • Homologous chromosomes separate and two new cells are formed.

• Meiosis II - cells from meiosis I enter meiosis II

  • Cell does not undergo chromosome replication.

  • Anaphase II - chromatids separate.

• Nondisjunction - failure of homologous chromosomes to separate during meiosis.

  • Abnormal numbers of chromosomes may find their way into gametes, a disorder chromosome numbers may result.

DNA replication

Ensures that each resulting cell will have a complete set of DNA molecule
During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template against which the new strand is made à called semiconservative replication.

Protein Synthesis

Vocabulary

• Transcription: The synthesis of RNA from a DNA template.

• Translation: The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of "language" from nucleotides to amino acids.

• Translocation: The movement of a ribosome along messenger RNA (mRNA) during protein synthesis.

• Chromosomal mutation: A change in the chromosome structure, resulting in new gene combinations.

• Deoxyribonucleic acid: A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins.

• Frameshift mutation: A mutation occurring when nucleotides are inserted or deleted from a gene and the number of inserted or deleted bases is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.

• Gene expression: The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.

• Mutation: A change in the nucleotide sequence of an organism's DNA or in the DNA or RNA of a virus.

• Point mutation: A change in a gene at a single nucleotide pair.

The Central Dogma

• DNA -> RNA -> Protein

• All life uses A,C,T,G in double-stranded base pairs.

• This is also the key to understanding a single common ancestor.

• The ACTGs of DNA can be read by enzymes to create a triplet codon that is interpreted into 20 amino acids to make very diverse proteins.

DNA

• Contains DNA: it is a SELF-REPLICATING molecule.

• DNA replicates itself (via DNA polymerase and other enzymes) in a semi-conservative manner.

• Adenine pairs with Thymine (A = T).

• Guanine pairs with Cytosine (G = C).

• The bonds between the base pairs are hydrogen bonds.

DNA structure

• Nucleic Acid (polymer) is made of nucleotides (monomer).

• A nucleotide is made of: a sugar (Deoxyribose), a phosphate group, and a nitrogenous base (A-T, G-C).

DNA Replication

Circular replication forks (prokaryotes) vs linear replication forks (Euk).

RNA

• RNA (ribonucleic acid) is the intermediate between DNA and protein.

• Transcription is the process of making RNA from DNA (via the enzyme RNA polymerase).

• RNA Polymerase scans the genome for the promoter region of DNA (the start signal).

• A single-stranded copy of RNA is made of the DNA gene, where U is complementary to A instead of T.

• Transcription and Translation occur simultaneously in the cytoplasm for prokaryotes, with no editing needed.

• Eukaryotic messageRNA has EXONS (expressed message) and INTRONS (in-between message).

• Introns get spliced (cut out) of the mRNA to make the mature transcript.

Translation

Matching an amino acid to the messageRNA in order to make the protein code.

• The mRNA leaves the nucleus à cytoplasm (in eukaryotes).

• Message is read at the ribosome.

• mRNA is read 3 letters at a time AUG is the start signal 1 Codon (3 letter message) is translated into 1 amino acid.

• TransferRNA molecule has one end (anticodon) that matches the mRNA. Each anticodon specifies an amino acid. There are 20 amino acids.

• The amino acids are bonded together as peptide chains…which fold into proteins.

Mutations

• A change in DNA sequence.

• Point Mutations: Change one or two base pairs.

Evolution

Vocabulary

• Evolution: The process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

• Natural selection: The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

• Speciation: The formation of new and distinct species in the course of evolution.

• Genetic drift: Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

• Competition: Interaction of organisms or species in which both require a resource that is in limited supply.

• Extinction: The state or process of a