Zoology Notes PDF

THE CHEMISTRY OF LIFE FEEDBACK REGULATION FIVE UNIFYING THEMES -​ The output or product of a process regulates 1.​ Organization the interactions in the...

THE CHEMISTRY OF LIFE FEEDBACK REGULATION FIVE UNIFYING THEMES -​ The output or product of a process regulates 1.​ Organization the interactions in the body. 2.​ Information -​ NEGATIVE FEEDBACK: Most common form of 3.​ Energy & Matter regulation; a loop where the response 4.​ Interaction reduces the initial stimulus EX: insulin 5.​ Evolutions signaling. EMERGENT PROPERTIES -​ POSITIVE FEEDBACK: An end product speeds -​ Result from the arrangement & interaction of up its own production EX: blood clotting. parts within a system EVOLUTION -​ Characterize non biological entities as well -​ The concept that the organisms living on (ex. bicycle). Earth today are the modified descendants SYSTEMS BIOLOGY of common ancestors. -​ The exploration of a biological system by -​ The scientific explanation for both the analyzing the interactions among its parts. unity & diversity of organisms is the CELL concept that living organisms are -​ An organism’s basic unit. modified descendants of common -​ Lowest level of organization that can ancestors. perform all activities required for life. TAXONOMY -​ Enclosed by a membrane that regulates -​ A branch of biology that names & passage of materials between the cell and classifies species into groups of increasing its environment. breadth. GENETICS DOMAIN OF LIFE -​ Structures called chromosomes contain 1.​ BACTERIA - Most diverse & widespread genetic material prokaryotes. -​ in the form of DNA (deoxyribonucleic acid). 2.​ ARCHAEA - Live in Earth’s extreme -​ GENES: Encode info for building the environments such as salty lakes and molecules synthesized within the cell. boiling hot springs. -​ GENE EXPRESSION: The entire process by which the information in a gene directs the 3.​ EUKARYA - All eukaryotic organisms. manufacture of a cellular product (become ​ PLANTAE: terrestrial multicellular functional). eukaryotes. -​ GENOMICS: A large-scale analysis of DNA ​ FUNGI: nutritional mode of its sequences. members. -​ GENOMES: The entire library of genetic ​ ANIMALIA: multicellular eukaryotes instructions that an organism inherits. that ingest other organisms. BIOINFORMATICS ​ PROTISTA: unicellular eukaryotes & -​ The use of computational tools to store, some relatively simple multicellular organize, and analyze the huge volume of relatives. data that results from high-throughput NATURAL SELECTION methods.  -​ The idea that the environment 3.​ Nuclear Lamina - lines the envelope that is consistently selects for the propagation of composed of proteins and maintain the beneficial traits among naturally shape of the nucleus occurring variant traits in the population. 4.​ Nuclear Membrane - lipid bilayer (inner and -​ Could cause an ancestral species to give outer membrane of the envelope). rise to two or more descendant species. 5.​ Nucleolus - site of ribosomal RNA (rRNA) that is within the nucleus. -​ Causes evolutionary adaptation EX: Bats 6.​ Pores - can act as the ‘door’ as it regulates with wings. the entry and exit. -​ CHARLES DARWIN: Wrote On the Origin of RIBOSOMES Species by Means of Natural Selection ​ Made from rRNA + proteins. that discusses the theory of natural ​ Protein synthase. selection individuals in a population vary ​ Can be seen IN the cytosol as free in their traits which are heritable. ribosomes and BOUND to the endoplasmic THE CELL reticulum. CELL TYPES ENDOPLASMIC RETICULUM PROKARYOTIC EUKARYOTIC ​ Takes account for half of the cell’s total membrane. - Smaller - Bigger and more ​ SMOOTH - no ribosomes ROUGH - has - Has plasma complex ribosomes. membrane - Has plasma - Has cell wall membrane SMOOTH ROUGH - NO membrane - DNA in nucleus bound organelles - Cytoplasm - Lipid - Protein synthase - DNA at unbound between storage/synthesizer - Bound ribosomes region membrane and - Detoxifies poisons that secretes - Goes through nucleus and drugs glycoproteins binary fusion - Goes through - Metabolizes - Distributes vesicle - Has singular mitosis and meiosis carbohydrates transport chromosomes - Has double - Stores calcium - Membrane factory - 70s ribosomes chromosomes ions - 80s ribosomes GOLGI APPARATUS PARTS OF EUKARYOTIC CELLS ​ Contains flattened membranous sacs = PLASMA MEMBRANE cisternae. -​ Semi-preamble ​ Modifies E.R. products. -​ Helps with communication, transportation, ​ Manufactures macromolecules. and protection. ​ Stores and packages materials to transport THE NUCLEUS: INFORMATION CENTRAL vesicles. 1.​ Nucleus - contains most of the cell’s genes. ​ Trans (shipping) = circular, cis (receiving) = Most conspicuous organelle. long 2.​ Nuclear Envelope - encloses the nucleus LYSOSOMES and separates the nucleus from the ​ Made by E.R and Golgi A. cytoplasm.  ​ Membranous sac of hydrolytic enzymes = ​ Basal body - anchors the digest macromolecules. cilium or flagellum ​ Lysosomal enzymes work best in acidic ​ Dynein - a motor protein that areas of the lysosomes. drives the bending ​ Hydrolytic enzymes and lysosomal movements of a cilium or membranes are made by rough ER and flagellum then transferred to the Golgi apparatus for 2.​ Microfilaments - THINNEST. Actin and further processing. myosin, muscle cells have this. ​ Food x Lysosome = Phagocytosis 3.​ Intermediate filaments - In the ​ Recycling = autophagy middle. VACUOLES THE EXTRACELLULAR MATRIX (ECM) ​ Large vesicles made by E.R and Golgi A. ​ Animals lack cell walls but the ECM acts as 1.​ Food vacuoles - used to digest big its cell wall. things. ​ They are made by receptors and 2.​ Contractile vacuoles - in freshwater glycoproteins like collagen, proteoglycans, where it pumps out the water. and fibronectin. 3.​ Central vacuoles - for plant cells. ​ Bind receptor proteins in the plasma MITOCHONDRIA membrane called integrins (for ​ Site of cellular respiration. communication). ​ Similar to a bacteria (endosymbiont theory) CELL JUNCTIONS ​ Outer = smooth, Inner = membrane folded ​ Communicates through direct physical (cristae). contact ​ Cristae presents a large surface area for 1.​ Tight junctions - pressed together to enzymes that synthesize ATP. prevent leakage. ​ Has intermembrane space and 2.​ Desmosomes - fasten together like mitochondrial matrix > where some steps of sheets for anchor. cellular respiration catalyze. 3.​ Gap junctions - cytoplasmic PEROXISOMES channels for communicating. ​ Specialized metabolic compartments MEMBRANE STRUCTURE AND FUNCTION bounded by a single membrane. PLASMA MEMBRANE ​ Produce hydrogen peroxide > convert to ​ Separates cells from their surroundings. water. ​ Head = heart water, Tail = hate water. ​ Perform reactions with different functions. ​ FLUID MOSAIC MODEL - states that a CYTOSKELETON membrane is a fluid structure with a ​ Network of fibers that organizes structures "mosaic" of various proteins embedded in it. and activities in the cell. ​ Interacts with motor proteins = helps with movement in the cell. 1.​ Microtubules - THICKEST. Helps with cell division and control the beating of flagella and cilia.  OSMOSIS INTEGRAL PERIPHERAL -​ Water where two solutions with different PROTEINS PROTEINS solute concentrations interact. - Inside the - On the membrane -​ Low to high. membrane (hate - Sometimes TONICITY H2O) attaches to integral 1.​ Hypertonic - H > L, water goes out hence it - Monotopic, - For shrinks. Bitopic, & Polytopic. communication 2.​ Hypotonic - L > H, water goes in hence - For transportation turgid or bursting. FUNCTIONS OF THE CELL MEMBRANE 3.​ Isotonic - No movement. ACTIVE TRANSPORT 1.​ TRANSPORTATION ​ Does need ATP to work. ENDOCYTOSIS 1.​ Phagocytosis - “to eat”, they do solid. 2.​ Pinocytosis - “to drink”, they do liquid. EXOCYTOSIS -​ The movement of materials out of the cell. MEMBRANE POTENTIAL -​ The voltage difference across a membrane. -​ VOLTAGE - created by differences in the distribution of positive and negative ions across a membrane. PASSIVE TRANSPORT -​ ELECTROCHEMICAL GRADIENT - chemical ​ Doesn’t need ATP to do work. (ion concentration) and electrical force ​ TRANSPORT PROTEINS - speed the passive (effect of membrane potential on ion). movement of molecules across the plasma -​ ELECTROGENIC PUMP - transport protein that membrane. generates voltage across a membrane. ​ CARRIER PROTEINS - undergo a subtle -​ NaK = animal proton = plants, fungi, and change in shape that translocates the bacteria. solute-binding site across the membrane COTRANSPORT (binding then shapeshift). -​ Occurs when active transport of a solute DIFFUSION indirectly drives transport of other -​ Gas. substances. -​ High to low. 2.​ ENZYMATIC ACTIVITY -​ Facilitated Diffusion - need transport protein. ION CHANNELS (FD) -​ Channel proteins that transport ions that many are gated channels (open or close in response to a stimulus). AQUAPORINS (FD) -​ Channel proteins for water molecules. -​ A protein built into the membrane (in between) may be an enzyme with its active site (molecules attach for the enzyme to work with it) exposed to substances in the adjacent solution. -​ The active site faces outward or inward, depending on the reaction. This placement allows the enzyme to interact with substances (like nutrients or waste) near the membrane. 3.​ SIGNAL TRANSDUCTION -​ Some glycoproteins serve as identification tags that are specifically recognized by membrane proteins of other cells. This type of cell-cell binding is usually short-lived. -​ Glycoprotein = people proteins = guard 5.​ INTERCELLULAR JOINING -​ A receptor may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The external messenger (signaling molecule) -​ Membrane proteins of adjacent cells may may cause the protein to change shape, hook together in various kinds of junctions, allowing it to relay the message to the inside such as gap junctions or tight junctions. This of the cell, usually by binding to a type of binding is more long-lasting. cytoplasmic protein. 6.​ ATTACHMENT TO CYTOSKELETON AND ECM -​ Receptor protein has binding site > match shape with signaling molecule > signaling molecule binds to receptor like a puzzle > shape shift > allows signal to pass through 4.​ CELL-CELL RECOGNITION  -​ BIOENERGETICS - the study of how energy -​ Microfilaments or other elements of the flows through living organisms. cytoskeleton may be noncovalently bound FORMS OF ENERGY to membrane proteins that helps maintain ​ Energy is the capacity to cause change. cell shape and stabilizes the location of KINETIC ENERGY certain membrane proteins. -​ Associated with motion. -​ Proteins that can bind to ECM molecules HEAT/THERMAL ENERGY can coordinate extracellular and -​ Kinetic energy associated with random intracellular changes (outside-to-inside movement of atoms or molecules. communication system). POTENTIAL ENERGY SYNTHESIS AND SIDEDNESS MEMBRANES -​ Energy that matter possesses because of its -​ Membranes have distinct inside and outside location or structure. faces. CHEMICAL ENERGY -​ The asymmetrical distribution of proteins, -​ Potential energy available for release in a lipids, and associated carbohydrates in the chemical reaction. plasma membrane is determined when the THE LAW OF ENERGY TRANSFORMATION membrane is built by the ER and Golgi THERMODYNAMICS apparatus. -​ The study of energy transformations. METABOLISM AND CELLULAR RESPIRATION -​ An isolated system, such as that METABOLISM approximated by liquid in a thermos, is -​ The totality of an organism’s chemical isolated from its surroundings. reactions. -​ In an open system, energy and matter can -​ A metabolic pathway begins with a specific be transferred between the system and its molecule and ends with a product. surroundings. -​ Each step is catalyzed by a specific 1.​ Energy can be transferred and transformed, enzyme. but it cannot be created or destroyed. CATABOLIC ANABOLIC 2.​ Every energy transfer or transformation PATHWAYS PATHWAYS increases the entropy (disorder) of the universe. - Release energy by - Also known as -​ Entropy as a measure of molecular disorder, breaking down biosynthetic or randomness. The more randomly complex molecules - Consume energy arranged a collection of matter is, the to simpler to build greater its entropy. compounds. complicated molecules from FREE-ENERGY CHANGE simpler ones -​ Energy that can do work when temperature and pressure are uniform, as in a living cell. -​ Energy released from the downhill reactions -​ The concept of free energy can be applied of catabolic pathways can be stored and to the chemistry of life's processes. then used to drive the uphill reactions of -​ EXERGONIC REACTION - proceeds with a net anabolic pathways. release of free energy and is spontaneous (release).  -​ ENDERGONIC REACTION - absorbs free -​ FERMENTATION - uses substrate-level energy from its surroundings and is phosphorylation instead of an electron nonspontaneous. transport chain to generate ATP EQUILIBRIUM AND METABOLISM 2.​ CITRIC ACID CYCLE -​ Reactions in a closed system eventually -​ The citric acid cycle has eight steps, each reach equilibrium and then do no work. catalyzed by a specific enzyme. -​ Cells are not in equilibrium; they are open -​ The NADH and FADH2 produced by the systems experiencing a constant flow of cycle relay electrons extracted from food to materials. the electron transport chain. -​ A defining feature of life is that metabolism is 3.​ OXIDATIVE PHOSPHORYLATION never at equilibrium. -​ Following glycolysis and the citric acid -​ A catabolic pathway in a cell releases free cycle, NADH and FADH, account for most of energy in a series of reactions. the energy extracted from food. -​ Closed and open hydroelectric systems can -​ These two electron carriers donate electrons serve as analogies. to the electron transport chain, which CELLULAR RESPIRATION powers ATP synthesis via oxidative -​ RESPIRATION - the process that the body phosphorylation. uses to release energy from digested food (glucose) from the digestive system. -​ PROTEINS - digested to amino acids; amino -​ ELECTRON DONOR - reducing agent groups can feed glycolysis or the citric acid -​ ELECTRON RECEPTOR - oxidizing agent cycle -​ Some redox reactions do not transfer -​ FATS - are digested to glycerol (used in electrons but change the electron sharing in glycolysis) and fatty acids (used in covalent bonds. generating acetyl CoA) 1.​ GLYCOLYSIS -​ Glycolysis ("sugar splitting") breaks down CELL DIVISION glucose into two molecules of pyruvate. -​ The ability of organisms to produce more of -​ Glycolysis occurs whether or not O2 is their own kind best distinguishes living things present. from nonliving matter. -​ THE FATE OF PYRUVATE - Fermentation and -​ The continuity of life is based on the anaerobic respiration enable cells to reproduction of cells, or cell division. produce ATP without the use of oxygen. -​ Multicellular eukaryotes depend on cell -​ Without O2, the electron transport chain will division for development from a fertilized cease to operate. cell, growth, and repair. -​ In that case, glycolysis couples with -​ Most cell division results in daughter cells anaerobic respiration or fermentation to with identical genetic information, DNA. produce ATP. -​ The exception is meiosis, a special type of -​ ANAEROBIC RESPIRATION - uses an electron division that can produce sperm and egg transport chain with a final electron cells. acceptor other than Oxygen, for example -​ All the DNA in a cell constitutes the cell's sulfate. genome. INTERPHASE -​ A new nuclear envelope pops out and other 1.​ G1 - Growth and increase of size occur organelles too. along with the production of important -​ Chromosomes uncoil (less condense) molecules (mitochondria). -​ Two new cells. 2.​ S - DNA replication. Prophase, Metaphase, and Anaphase II 3.​ G2 - Preparation. -​ Undergo the same way as mitosis but the 4.​ G0 - If the cell does not receive the difference is that two cells are undergoing go-ahead signal, it will exit the cycle, the process at the same time. switching into a nondividing state. Telophase II MITOSIS PHASE -​ Undergo the same as mitosis but 4 cells 1.​ Prophase instead. -​ Chromatin condenses to chromosomes. ​ Gametes are produced during meiosis. -​ Nuclear envelope disappears. CANCER -​ Division and disintegration of organelles. -​ Cancer cells do not respond normally to the -​ Spindle fibers grow and move. body's control mechanisms. 2.​ Metaphase -​ TRANSFORMATION: Process where a normal -​ Alignment of chromosomes in the middle. cell is converted to a cancerous cell. -​ **Prometaphase = chromosomes are thick -​ Cancer cells that are not eliminated by the and shorter. immune system form tumors, masses of 3.​ Anaphase abnormal cells within otherwise normal -​ Separation of chromatids. tissue. 4.​ Telophase -​ BENIGN TUMOR: A lump if abnormal cells -​ A new nuclear envelope pops out and other remain only at the original site. organelles too. -​ MALIGNANT TUMOR: Invade surrounding -​ Chromosomes uncoil (less condense) tissues and can metastasize, exporting 5.​ Cytokinesis cancer cells to other parts of the body, -​ Separation of cytoplasm. where they may form additional tumors. MEIOSIS PHASE -​ Localized tumors may be treated with 1.​ Interphase I high-energy radiation, which damages the -​ Preparation. DNA in the cancer cells. -​ Chromosomes duplicate. -​ To treat metastatic cancers, 2.​ Prophase I chemotherapies that target the cell cycle -​ Chromosomes pair up, making tetrad this is may be used. called synapsis. TERMINOLOGIES -​ When synapsis occurs, they do crossover -​ Living organisms are distinguished by their where they exchange genetic information. ability to reproduce their own kind. 3.​ Metaphase I -​ HEREDITY: The transmission of traits from one -​ Alignment of tetrad as pairs. generation to the next. 4.​ Anaphase I -​ VARIATION: is demonstrated by the -​ Separation of tetrad, 1 side has 1 partner of differences in appearance that offspring 1 pair. show from parents and siblings. 5.​ Telophase I  -​ GENETICS: is the scientific study of heredity -​ Contate sugre set of chromosomes and is and variation. haploid (n), we have 23. -​ Genes are the units of heredity and are -​ Each set of 23 consists of 22 autosomes and made up of segments of DNA. a single sex chromosome. -​ Genes are passed to the next generation MENDELIAN GENETICS via reproductive cells called gametes What principles account for the passing of traits (sperm and eggs). from parents to offspring? -​ Most DNA is packaged into chromosomes. -​ BLENDING HYPOTHESIS: The idea that -​ Humans have 46 chromosomes in their genetic material from the two parents somatic cells, all cells of the body except blends together (like blue and yellow paint gametes and their precursors. blend to make green). -​ LOCUS: A gene's specific position along a -​ PARTICULATE HYPOTHESIS: The idea that chromosome. parents pass on discrete heritable units ASEXUAL & SEXUAL (genes). Mendel documented a particulate -​ In asexual reproduction, a single individual mechanism through his experiments with passes all of its genes to its offspring without garden peas. the fusion of gametes. Mendel discovered the basic principles of heredity -​ A clone is a group of genetically identical by breeding garden peas in carefully planned individuals from the same parent. experiments -​ In sexual reproduction, two parents give rise -​ CHARACTER: Heritable feature that varies to offspring that have unique combinations among individuals (such as flower color). of genes inherited from the two parents. -​ TRAIT: Each variant for a character, such as HUMAN CHROMOSOMES purple or white color for flowers. -​ Human somatic cells have 23 pairs of -​ Other advantages of using peas chromosomes. ​ Short generation time. -​ KARYOTYPE: An ordered display of the pairs ​ Large numbers of offspring. of chromosomes from a cell. ​ Mating could be controlled where -​ HOMOLOGOUS plants could be allowed to CHROMOSOMES/HOMOLOGS: The two self-pollinate or could be cross chromosomes in each pair. pollinated. -​ Chromosomes in a homologous pair are the Mendel mated two contrasting, true-breeding same length and shape and carry genes varieties, a process called hybridization controlling the same inherited characters -​ P GENERATION: The true-breeding parents. (eye color). -​ F1 GENERATION: The hybrid offspring of the P -​ Each pair of homologous chromosomes generation. includes one chromosome from each -​ F2 GENERATION: Produced when F1 parent. individuals self-pollinate or cross- pollinate -​ The 46 chromosomes in a human somatic with other F1 hybrids. cell are two sets of 23: one from the mother The Law of Segregation (Mendel Experiment) and one from the father. -​ Each organism has two alleles for a trait, but -​ A diploid cell (2n) has two sets of these alleles separate (segregate) during chromosomes, we have 46.  gamete formation (meiosis), so each An organism's traits do not always reveal its genetic gamete receives only one allele. composition due to the different effects of dominant -​ When Mendel crossed contrasting, and recessive alleles true-breeding white- and purple-flowered -​ PHENOTYPE: Physical appearance. pea plants, all of the F1 hybrids were purple. -​ GENOTYPE: Genetic makeup. -​ When Mendel crossed the F1 hybrids, many EX: Flower color in pea plants. PP of the F2 plants had purple flowers, but and Pp plants have the same some had white. phenotype (purple) but different ​ A ratio of about three to one, purple genotypes. to white flowers, in the F2 generation. -​ Only the purple flower factor was affecting flower color in the F1 hybrids. ​ Purple flower color a dominant trait and the white flower color a recessive trait. -​ The factor for white flowers was not diluted or destroyed because it reappeared in the F2 generation. The Testcross -​ A dominant phenotype could be either homozygous dominant or heterozygous. -​ If any offspring display the recessive -​ Mendel observed the same pattern of phenotype, the mystery parent must be inheritance in six other pea plant heterozygous. characters, each represented by two traits. -​ MONOHYBRID CROSS: A cross between -​ "Heritable factor" = gene. heterozygotes following one character. PUNNETT SQUARE: Can show possible combinations The Law of Independent Assortment of sperm and egg. -​ Developed by Mendel using a dihybrid cross CAPITAL LETTER: Dominant Allele. (following two characters at the same time). LOWERCASE LETTER: Recessive Allele -​ It states that each pair of alleles segregates HOMOZYGOUS BB bb: An organism with two independently of each other pair of alleles identical alleles for a character. during gamete formation. HETEROZYGOUS Bb: An organism that has two -​ Applies only to genes on different, different alleles for the gene controlling that non-homologous chromosomes or those far character. apart on the same chromosome.  -​ Genes located near each other on the -​ Dominant alleles are not necessarily more same chromosome tend to be inherited common in populations than recessive together. alleles. Crossing two true-breeding parents differing in two EX: One baby out of 400 in the United States characters is born with extra fingers or toes. -​ Produces dihybrids in the F1 generation. -​ The allele for this unusual trait is dominant to -​ Heterozygous for both characters. the allele for the more common trait of five -​ DIHYBRID CROSS (Cross between F1 digits per appendage. dihybrids): Can determine whether two -​ In this example, the recessive allele is far characters are transmitted to offspring as a more prevalent than the population's package or independently. dominant allele. Inheritance patterns are often more complex than -​ MULTIPLE ALLELES: Most genes exist in predicted by simple Mendelian genetics populations in more than two allelic forms = -​ The relationship between genotype and 1 gene many variations. phenotype is rarely as simple as in the pea EX: The four phenotypes of the ABO blood plant characters. group in humans are determined by three -​ Many heritable characters are not alleles determined by only one gene with two -​ PLEIOTROPY: Most genes have multiple alleles. phenotypic effects, a property called -​ However, the basic principles of segregation pleiotropy. One gene affects more than one and independent assortment apply even to observable trait. more complex patterns of inheritance. EX: Sickle-Cell Disease > -​ COMPLETE DOMINANCE: Occurs when -​ SICKLE-CELL DISEASE: In homozygous phenotypes of the heterozygote and individuals, all hemoglobin is abnormal. dominant homozygote are identical. -​ Symptoms include physical -​ INCOMPLETE DOMINANCE: The phenotype weakness, pain, organ damage, and of F1 hybrids is somewhere between the paralysis. phenotypes of the two parental varieties. -​ Heterozygotes are usually healthy -​ CODOMINANCE: Two dominant alleles but may suffer some symptoms. affect the phenotype in separate, -​ Heterozygotes are less susceptible to distinguishable ways. the malaria parasite (an The Relation Between Dominance and Phenotype advantage). -​ A dominant allele does not subdue a -​ Some traits may be determined by two or recessive allele; alleles don't interact that more genes. way. -​ EPISTASIS: A gene at one locus alters the -​ Alleles are simply variations in a gene's phenotypic expression of a gene at a nucleotide sequence. second locus (Dependent on another gene). -​ For any character, -​ One gene determines the pigment color dominance/recessiveness relationships of (with alleles B for black and b for brown). alleles depend on the level at which we -​ The other gene (with alleles E for color and e examine the phenotype. for no color) determines whether the Frequency of Dominant Alleles pigment will be deposited in the hair.  -​ POLYGENIC INHERITANCE: Additive effect or Multifactorial Disorders product of two or more genes on a single -​ Many diseases, such as heart disease, phenotype. Many genes = 1 diabetes, alcoholism, mental illnesses, and allele/phenotype cancer have both genetic and -​ Skin color in humans is an example of environmental components. polygenic inheritance. -​ No matter what our genotype, our lifestyle A Mendelian View of Heredity and Variation has a tremendous effect on phenotype. -​ An organism's phenotype includes its Locating Genes Along Chromosomes physical appearance, internal anatomy, -​ Mendel's "hereditary factors" were purely physiology, and behavior. abstract when first proposed. -​ An organism's phenotype reflects its overall -​ Today we can show that the genotype and unique environmental history. factors-genes—are located on -​ Many human traits follow Mendelian chromosomes. patterns of inheritance. -​ The location of a particular gene can be Pedigree Analysis seen by tagging isolated chromosomes with -​ PEDIGREE: A family tree that describes the a fluorescent dye that highlights the gene. inter-relationships of parents and children -​ Biologists began to see parallels between across generations. the behavior of Mendel's proposed -​ Inheritance patterns of particular traits can hereditary factors and chromosomes. be traced and described using pedigrees. Chromosome theory of inheritance: Linkage and -​ Pedigrees can also be used to make Chromosomes predictions about future offspring. -​ The first solid evidence associating a specific Recessively Inherited Disorders gene with a specific chromosome came in -​ Many genetic disorders are inherited in a the early 20th century from the work of recessive manner. Thomas Hunt Morgan. -​ Range from relatively mild to -​ These early experiments provided life-threatening. convincing evidence that the chromosomes -​ Show up only in individuals homozygous for are the location of Mendel's heritable the allele. factors. -​ CARRIERS: Heterozygous individuals who -​ Morgan's discovery of a trait that correlated carry the recessive allele but are with the sex of flies was key to the phenotypically normal. development of the chromosome theory of -​ Albinism is a recessive condition inheritance. characterized by a lack of pigmentation in -​ In humans and some other animals, there is skin and hair. a chromosomal basis of sex determination. Dominantly Inherited Disorders There are two varieties of sex chromosomes: -​ Some human disorders are caused by a larger X chromosome and a smaller Y dominant alleles. chromosome. -​ Dominant alleles that cause a lethal disease -​ A person with two X chromosomes develops are rare and arise by mutation. as a female, while a male develops from a -​ Achondroplasia is a form of dwarfism zygote with one X and one Y. caused by a rare dominant allele.  -​ SEX-LINKED GENE: A gene that is located on -​ ANEUPLOIDY: Results from the fertilization of either sex chromosome. gametes in which nondisjunction (failure of -​ X chromosomes have genes for many paired chromosomes to move to opposite characters unrelated to sex, whereas most poles of the spindle during mitosis or Y-linked genes are related to sex meiosis)occurred. Offspring with this determination. condition have an abnormal number of a -​ X-linked recessive disorders are much more particular chromosome. common in males than in females. -​ Breakage of a chromosome can lead to Some disorders caused by recessive alleles on the four types of changes in chromosome X chromosome in humans. structure; Deletion, Duplication, Inversion -​ Duchenne muscular dystrophy. and Translocation. -​ Linked genes tend to be inherited together -​ DOWN SYNDROME (Trisomy 21): An because they are located near each other aneuploid condition that results from three on the same chromosome. copies of chromosome 21. -​ LINKED GENES: Genes located on the same -​ KLINEFELTER SYNDROME: The result of an chromosome that tend to be inherited extra chromosome in a male, producing together. XXY individuals. -​ The genetic findings of Mendel and Morgan -​ TURNER SYNDROME: Produces X0 females, relate to the chromosomal basis of who are sterile; it is the only known viable recombination. monosomy in humans. Only one X. -​ PARENTAL TYPES: Offspring with a phenotype -​ CRI DU CHAT: Severely intellectually matching one of the parental phenotypes. disabled and has a catlike cry; individuals -​ RECOMBINANTS: Offspring with nonparental usually die in infancy or early childhood. phenotypes (new combinations of traits). -​ Certain cancers, including chronic -​ A 50% frequency of recombination is myelogenous leukemia (CML),are caused observed for any two genes on different by translocations of chromosomes. chromosomes. MOLECULAR BASIS OF INHERITANCE -​ CROSSING OVER (HOMOLOGOUS): Morgan HISTORY discovered that genes can be linked, but -​ In 1953, James Watson and Francis Crick the linkage was incomplete, because some introduced an elegant double-helical recombinant phenotypes were observed. model for the structure of deoxyribonucleic -​ Alterations of chromosome number or acid, or DNA. structure cause some genetic disorders. -​ DNA is the substance of inheritance and is -​ Large-scale chromosomal alterations in the most celebrated molecule of our time. humans and other mammals often lead to -​ Hereditary information is encoded in DNA spontaneous abortions (miscarriages) or and reproduced in all cells of the body. cause a variety of developmental disorders. -​ This DNA program directs the development Human Disorders Due to Chromosomal Alterations of biochemical, anatomical, physiological, -​ Large-scale chromosomal alterations in and (to some extent) behavioral traits. humans and other mammals often lead to Evidence That DNA Can Transform Bacteria spontaneous abortions (miscarriages) or cause a variety of developmental disorders  -​ The discovery of the genetic role of DNA -​ DNA molecules are made up of two strands, began with research by Frederick Griffith in forming a double helix. 1928. -​ Complementary base pairing: -​ He mixed heat-killed remains of the ​ A - T (U) pathogenic strain with living cells of the ​ G - C harmless strain, some living cells became -​ Each nucleotide attaches to the 3-prime pathogenic (transformation). end via the phosphate group. Evidence That Viral DNA Can Program Cells -​ Anti-parallel. -​ More evidence for DNA as the genetic DNA REPLICATION material came from studies of viruses that -​ Since the two strands of DNA are infect bacteria. complementary, each strand acts as a Additional Evidence That DNA Is the Genetic template for building a new strand in Material replication. -​ Erwin Chargaff reported that DNA -​ In DNA replication, the parent molecule composition varies from one species to the unwinds, and two new daughter strands are next and the number of A and T bases are built based on base-pairing rules. equal and the number of G and C bases are equal. STRUCTURE OF DNA -​ Nucleotides are the building blocks of DNA. Four Nitrogenous Bases -​ Replication begins at particular sites called Purine origins of replication, where the two DNA -​ Adenine strands are separated, opening up a -​ Guanine replication "bubble". Pyrimidine -​ At the end of each replication bubble is a -​ Cytosine replication fork, a Y-shaped region where -​ Thymine new DNA strands are elongating. -​ Uracil -​ HELICASE: Enzymes that untwist the double helix at the replication forks. -​ SINGLE-STRAND BINDING PROTEINS: Bind to and stabilize single-stranded DNA. -​ TOPOISOMERASE: Corrects "overwinding" -​ DNA can be damaged by exposure to ahead of replication forks by breaking, harmful chemical or physical agents such as swiveling, and rejoining DNA strands. cigarette smoke and X-rays; it can also -​ SHORT RNA PRIMER: The initial nucleotide undergo spontaneous changes. strand. -​ In nucleotide excision repair, a nuclease -​ PRIMASE: Enzymes can start from scratch cuts out and replaces damaged stretches and add nucleotides one at a time using the of DNA. parental DNA as a template. TRANSCRIPTION & TRANSLATION -​ RNA is the bridge between genes and the proteins for which they code -​ TRANSCRIPTION: The synthesis of RNA using information in DNA. It produces messenger RNA (mRNA). -​ TRANSLATION: The synthesis of a polypeptide, using information in the mRNA. -​ RIBOSOMES: The sites of translation. -​ RNA synthesis is catalyzed by RNA polymerase, which pries the DNA strands apart and joins together the RNA nucleotides. -​ The RNA is complementary to the DNA -​ DNA POLYMERASES: Enzymes catalyze the template strand. elongation of new DNA as they add -​ RNA polymerase does not need any primer. nucleotides only to the free 3-prime end of -​ RNA synthesis follows the same base-pairing a growing strand; therefore, a new DNA rules as DNA, except that uracil substitutes strand can elongate only in the 5' to 3' for thymine. direction. -​ LEADING STRAND: Along one template strand of DNA, the DNA polymerase synthesizes a leading strand continuously, moving toward the replication fork. -​ LAGGING STRAND: To elongate the other new strand, called the lagging strand, DNA polymerase must work in the direction away from the replication fork. -​ OKAZAKI FRAGMENTS: The lagging strand is synthesized as a series of segments which are joined together by DNA ligase. -​ DNA polymerases proofread newly made DNA, replacing any incorrect nucleotides. -​ In mismatch repair of DNA, repair enzymes correct errors in base pairing.  -​ The mRNA base triplets, called codons, are read in the 5' → 3' direction. -​ Each codon specifies the amino acid (one of 20) to be placed at the corresponding position along a polypeptide. -​ Translation is a complex process in terms of its biochemistry and mechanics. -​ A cell translates an mRNA message into protein with the help of transfer RNA (tRNA). -​ Enzymes in the eukaryotic nucleus modify -​ tRNAs transfer amino acids to the growing pre-mRNA (RNA processing) before the polypeptide in a ribosome. genetic messages are dispatched to the -​ Molecules of tRNA are not identical cytoplasm. ​ Each carries a specific amino acid -​ Each end of a pre-mRNA molecule is on one end. modified in a particular way. ​ Each has an anticodon on the other ​ The 5' end receives a modified end; the anticodon base-pairs with a nucleotide 5' cap. complementary codon on mRNA. ​ The 3' end gets a poly-A tail. -​ Ribosomes facilitate specific coupling of -​ Most eukaryotic genes and their RNA tRNA anticodons with mRNA codons in transcripts have long noncoding (introns) protein synthesis. stretches of nucleotides that lie between -​ The two ribosomal subunits (large and small) coding (exons) regions. are made of proteins and ribosomal RNA -​ RNA splicing removes introns and joins (rRNA). exons, creating an mRNA molecule with a -​ A ribosome has three binding sites for tRNA: continuous coding sequence. ​ P SITE: Holds the RNA that carries the growing polypeptide chain. ​ A SITE: Holds the tRNA that carries the next amino acid to be added to the chain. ​ E SITE: The exit site, where discharged tRNAs leave the -​ In some cases, RNA splicing is carried out by ribosome. spliceosomes. The Three Stages of Translation Initiation 1.​ In the first step of translation, a small ribosomal subunit binds to both the mRNA and a specific initiator tRNA, which carries the amino acid methionine. 2.​ Then the small subunit moves along the mRNA until it reaches the start codon (AUG).  3.​ Proteins called initiation factors bring in the -​ If a mutation has an adverse effect on the large subunit that completes the translation phenotype of the organism the condition is initiation complex. referred to as a genetic disorder or Elongation hereditary disease. -​ In the elongation stage of translation, amino acids are added one by one to the previous amino acid at the C-terminus of the growing chain. -​ Each addition involves several proteins called elongation factors and occurs in a three-step cycle. -​ NUCLEOTIDE-PAIR SUBSTITUTION: Replaces one nucleotide and its partner with another pair of nucleotides. -​ SILENT MUTATIONS: Have no effect on the amino acid produced by a codon because of redundancy in the genetic. -​ NONSENSE MUTATIONS: Change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein. Termination -​ Insertions and deletions are additions or -​ Termination occurs when a stop codon in losses of nucleotide pairs in a gene. the mRNA reaches the A site of the -​ These mutations have a disastrous effect on ribosome. the resulting protein more often than substitutions do. -​ FRAMESHIFT MUTATION: Produced when insertion or deletion of nucleotides that may alter the reading frame occurs. -​ A nucleotide-pair deletion that causes a frameshift mutation can result in extensive MUTATIONS missense mutations. -​ MUTATIONS: Changes in the genetic -​ 3 NUCLEOTIDE-PAIR DELETION: No frameshift material of a cell or virus. but one amino acid is missing. -​ POINT MUTATIONS: Chemical changes in just TRANSCRIPTION & TRANSLATION IN A NUTSHELL one base pair of a gene. -​ The change of a single nucleotide in a DNA -​ In order to make proteins, the gene template strand can lead to the production sequences or codes should be read by of an abnormal protein. ribosomes but since ribosomes are outside the nucleus and DNA is huge, it will make a  small copy through mRNA to make a piece 4.​ Keeps adding amino tRNA till we get 3 to be of the gene be read. able to detach the first, leaving us with only -​ mRNA is single stranded or a copy of a its amino acid. single gene. 5.​ Once stop and finished, the amino acid chain will detach from the ribosome. TRANSCRIPTION 6.​ Fold up and form a protein. -​ It starts with the DNA that is double-stranded. 1.​ RNA Polymerase binds the DNA before the desired gene starts. 2.​ The strands separates and the RNA Polymerase will then move along through the DNA and read the codes to be able to create a copy for mRNA. It reads like of the DNA says A then mRNA would be U and G for DNA that would be C for mRNA. 3.​ The bottom strand the enzyme moved along is called the template strand. 4.​ After covering the gene, RNA Polymerase detaches while the DNA closes, finally with an mRNA ready to leave the nucleus. SPLICING 1.​ Spliceosomes bind at GU sequence. 2.​ RNA looped and 3 more biind to split and remove the intron by cleaved at A branch site. 3.​ At AG, the two exons are ligated together. TRANSCRIPTION 1.​ With sets of 3 bases (codon) = codes for a specific amino acid. 2.​ The mRNA binds with the ribosome and is ready to build proteins by adding amino acids one at a time. 3.​ The amino acids are brought to the ribosome by a molecule called tRNA = has amino acid at the top and anticodon (complementary to codon) at the bottom.