General Biology 2 Midterms PDF

GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN BIOLOGY ENERGY SOURCES Scientific study of life...

GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN BIOLOGY ENERGY SOURCES Scientific study of life Producers A fraction of the organisms on Earth are found ○ Make own food using energy and simple raw materials from ○ Scientists constantly discover new species nonbiological sources ○ Extinction rates are accelerating EXAMPLE: Photosynthesis LIVING AND NONLIVING THINGS Consumers ○ Obtain energy and nutrients by feeing on other organisms Made out of same components EXAMPLE: Animals COMPONENTS: Atom RESPOND TO CHANGE ○ Fundamental building block of all matter Molecule Organisms sense and respond to change inside and outside themselves ○ An association of two or more atoms Homeostasis Unique properties of life emerge from the interactions of these components ○ Process by which an organism keeps its internal conditions within a COMPONENTS: range that favors survival by sensing and responding to change b Cell ○ Smallest unit of life RESPOND TO STIMULATION Organism Organisms sense and respond to stimulation ○ An individual EXAMPLE: Tickle ○ Consists of 1 or more cells GROW AND REPRODUCE LIFE’S LEVEL OF ORGANIZATION Organisms grow, develop, and reproduce Population - Group of individuals of a species in a given area Growth Community - All populations of all species in a given area ○ Increase in size, volume, and number of cells in multicelled Ecosystem - A community interacting with its environment species Biosphere - All regions of Earth that hold life Development ○ Process by which the first cell of a new individual becomes a multicelled adult HOW LIVING THINGS ARE ALIKE Reproduction ○ Process by which individuals produce offspring All living things have similar characteristics Inheritance ○ Require ongoing inputs of energy and raw materials ○ Transmission of DNA to offspring ○ Sense and respond to change DNA (Deoxyribonucleic acid) ○ Pass DNA to offspring ○ Carries hereditary information that guides development and other activities ENERGY AND NUTRIENTS ○ Source of life’s diversity One-way flow of energy through the biosphere and cycling of nutrients among organisms sustain life’s organization HOW LIVING THINGS DIFFER Energy Living things differ in observable characteristics ○ The capacity to do work Classification schemes help us organize what we understand about Earth’s Nutrient biodiversity ○ Necessary for survival, An organism can’t make for itself 1  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN Biodiversity - Scope of variation among living organisms Organisms can be grouped based on whether they have a nucleus Bacteria Nucleus - Saclike structure containing cell’s DNA Archaea Protists Plants PROKARYOTES Fungi Animals Single celled organisms in which DNA is not present in a nucleus Three-domain THIS INCLUDES: ○ The eukarya domain includes protists, plants, fungi, and animals Bacteria - Most numerous organisms on Earth Bacteria Archaea - More closely related to eukaryotes than to bacteria Archaea Eukarya EUKARYOTES IDENTIFYING SPECIES Organisms whose DNA is contained within nucleus Early naturalists classified species according to what they look like and THIS INCLUDES: where they live Protists - Simplest eukaryotes with great diversity Today’s biologists compare biochemical traits such as the DNA sequence Fungi - Eukaryotic consumer that breaks down food externally Ernst Mayr Plant - Usually a multicelled, photosynthetic producer ○ Biological Species Concept Animal - Multicelled consumer that ingest food or juices of other ○ Defined a species as one or more group of individuals that potentially organisms can interbreed, produce fertile offspring, and don’t interbreed with other groups TAXONOMY SCIENCE OF NATURE Practice of naming and classifying species Species Critical thinking ○ A unique kind of organism ○ Deliberate process of judging the quality of information before ○ Has a unique two-part scientific name consisting of its genus and accepting it species Science Genus ○ Systematic study of the observable world ○ Group of species that share a set of unique traits Hypothesis Taxon ○ Testable explanation for a natural phenomenon ○ A group of organisms that share a unique set of traits ○ Each taxon consists of next lower taxon SCIENTIFIC METHOD TAXONOMIC RANK: Domain Systematically making, testing, and evaluation hypotheses Kingdom Model Phylum ○ Analogous system used for testing hypotheses Class THE METHODS: Order Observation Family Hypothesis Genus Prediction - Statement based on a hypothesis Species Experiment - Test designed to support or falsify a prediction CLASSIFICATION SYSTEMS Analysis of Results Conclusion Six-kingdom THE EXPERIMENT: ○ Protist kingdom includes the most ancient multicelled and all 1. Variable - Characteristics that differs among individuals or overtime single-celled eukaryotes 2  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN 3. Control Group - Group not exposed to the independent variable being 2. Experimental Group - Groups of individuals who have certain tested characteristic or receive a certain treatment 4. Data - Test results MULTIPLICATION BY DIVISION Cells reproduce by dividing in two NATURE OF SCIENCE ○ Each descendant cell receives a full set of chromosomes and Scientists typically design experiments that will yield qualitative results some cytoplasm Research experiment on subsets of a group, which may result in sampling ○ Before the cell’s nucleus divides, it must first replicate its error chromosomes Mitosis ○ Nuclear division mechanism that maintains the chromosome SAMPLING ERROR number in daughter cells ○ Used in growth, development, replacement of damaged or dead Difference between results obtained from a subset and results from the cells whole ○ Used as part of asexual reproduction Probability ○ Researchers try to design experiments carefully in order to minimize MITOSIS AND CELL CYCLE sampling error ○ Expressed as a percentage, of the chance that a particular outcome Cell Cycle will occur - Series of event from time a cell forms until its cytoplasm divides Statistically significant INCLUDES THREE PHASES: ○ Result that has a very low probability of occurring by chance alone Interphase Mitosis Cytoplasmic division SCIENTIFIC THEORIES INTERPHASE Hypothesis that has not been disproven after many years of rigorous testing Most of a cell’s activities occur in interphase Law of Nature Eukaryotic Cell Cycle ○ Scientific theory differs from law of nature ○ Interval between mitotic divisions when a cell grows ○ Phenomenon observed to occur in every circumstance without fail ○ Roughly doubles the number of its cytoplasmic components ○ Without a complete scientific explanation ○ Replicates its DNA Scope of Science THREE STAGES OF INTERPHASE: ○ Objective way of describing the natural world G1 ○ 1st interval (gap) of growth before DNA replication S HENRIETTA’S IMMORTAL CELLS ○ Interval of synthesis (DNA replication) Henrietta Lacks G2 ○ Died of cervical cancer more than 50 yrs ago ○ 2nd interval (gap) when the cell prepares to divide ○ Her cells live on in research laboratories HeLa Cells ○ Used to investigate cancer, viral growth, protein synthesis, effects of HOMOLOGOUS CHROMOSOMES radiation, and many other processes important in medicine and Members of a pair of chromosomes with the same length, shape, and genes research One member of a homologous pair Understanding cancer cells’ immortality ○ Inherited from the female parent and the other male parent ○ Understanding structures and mechanisms that cells use to divide Human body cells have 23 chromosome pairs ○ Except for a pairing of sex chromosomes (X,Y) 3  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN THE EUKARYOTIC CELL CYCLE PROPHASE Built-in checkpoints Duplicated chromosomes become visible as they condense Stop the cycle from proceeding until certain condition are met The nuclear envelope breaks up Spindle microtubules assemble and bind to chromosomes at the MITOSIS centromere Sister chromatids become attached to microtubules extending from Mitosis maintains chromosome number because: opposite ends of the cell ○ It distributes a complete set of chromosomes into two new nuclei ○ In G2, each chromosome consists of 2 replicated DNA molecules attached at the centromere (sister chromatids) ○ When sister chromatids are pulled apart, each becomes an individual chromosome in a new nucleus ○ When the cytoplasm divides, the two nuclei are packaged into two separate cells METAPHASE INTERPHASE All of the chromosomes are aligned in the middle of the cell - Interphase is not part of mitosis - The red spots in the plant cell nucleus are areas where ribosome subunits are being transcribed and assembled ANAPHASE Spindle microtubules separate from the sister chromatids and move them toward opposite sides of the cell EARLY PROPHASE Each sister chromatid has now become an individual, unduplicated chromosome Mitosis begins Transcription stops DNA begins to appear grainy as it starts to condense TELOPHASE The chromosomes reach opposite sides of the cell and loosen up 4  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN Mitosis ends when a new nuclear envelope forms around each cluster of CELL DIVISION GONE WRONG chromosomes Neoplasm - Accumulation of abnormally dividing cells Tumor - Neoplasm that forms a lump Oncogene - Any gene that helps transform a normal cell into a tumor cell Photo-oncogene - promote mitosis because mutation can turn them into oncogenes TUMOR SUPPRESSORS CYTOPLASMIC DIVISION Checkpoint gene products that inhibit mitosis since tumors form when they are missing A cell’s cytoplasm divides between late anaphase and the end of telophase Viruses such as HPV cause a cell to make proteins that interfere with its own forming two cells, each with its own nucleus tumor suppressors Mechanisms of cytoplasmic division differ between animal cells and plant cells CANCER IN ANIMAL CELLS Benign neoplasm A contractile ring pinches the cytoplasm in two ○ such as a mole is noncancerous A contractile ring of microfilaments contracts when its component proteins Malignant neoplasm are energized by ATP ○ Dangerous to health The cleavage furrow produced deepen until the cytoplasm is pinched in two ○ Can break free and invade other tissues (metastasis) Each new cell has its own nucleus, cytoplasm, and is enclosed by a plasma Cancer occurs when abnormally dividing cells of a malignant neoplasm membrane disrupt body tissues, physically and metabolically CHARACTERISTICS OF CANCER CELLS: IN PLANT CELLS Grow and divide abnormally Abnormal plasma membrane, cytoskeleton, chromosome number, and metabolism Microtubules guide vesicles from Golgi bodies and the cell surface to the Cells do not stay anchored properly in tissues because plasma membrane adhesion division plane proteins are defective or missing Vesicles and their wall-building contents fuse into a disk-shaped cell plate The cell plate ○ grows and forms a cross-wall between the two new nuclei TELOMERES Develops into two new cell walls, separating the descendant cells Noncoding DNA sequences at the ends of eukaryotic chromosomes ○ Provide buffer against loss of more valuable DNA MITOSIS AND CANCER Under normal circumstances, eukaryotic chromosomes shorted by about 100 nucleotides per replication cycle Gene expression controls ○ Too-short telomeres trigger a checkpoint that halts the cell cycle ○ Determines when a cell divides and when it does not ○ May relate to setting an organism’s lifespan Products of checkpoint genes ○ Monitor whether a cell’s DNA has been copied completely, whether it is damaged, and whether enough nutrients are available If a problem remains uncorrected, and other checkpoint proteins may cause the cell to self-destruct 5  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN ○ A nuclear envelope forms around each set, so two haploid nuclei SEX AND ALLELES form Paired genes on homologous chromosomes often vary slightly in DNA sequence Alleles ○ Are forms of a gene that encode slightly different versions of that gene’s product Offspring of sexual reproducers inherit new combinations of alleles, which is the basis of new combinations of traits ADVANTAGES OF SEX Asexual reproduction PHASES OF MEIOSIS II ○ Offspring arise from one parent Prophase II ○ Offspring are genetic clones ○ The chromosomes condense Sexual reproduction ○ Spindle microtubules attach to each sister chromatid as the nuclear ○ Offspring inherit genes from two parents envelope breaks up ○ Diversity offers a better chance of surviving an environmental Metaphase II challenge or harmful mutations ○ The duplicated chromosomes are aligned midway between spindle ○ Beneficial mutations spread quickly poles Anaphase II MEIOSIS IN SEXUAL REPRODUCTION ○ Sister chromatids separate ○ The unduplicated chromosomes head to the spindle poles Meiosis Telophase II ○ Halves the parental chromosome number by sorting the ○ A complete set of chromosomes clusters at both ends of the cell chromosomes into new nuclei twice ○ A new nuclear envelope forms around each set, so 4 haploid nuclei ○ Basis of sexual reproduction form ○ Gives rise to new combination of alleles in offspring ○ Duplicated chromosomes of a diploid nucleus are distributed into 4 haploid nuclei PHASES OF MEIOSIS I ○ Prophase I ○ Homologous chromosomes condense, pair up, and swap segments ○ Spindle microtubules attached to them as the nuclear envelope breaks up Metaphase I MEIOSIS MIXES ALLELES ○ Homologous chromosome pairs are aligned between spindle poles Meiosis shuffles parental combinations of alleles, introducing variation in ○ Spindle microtubules attach the two chromosomes of each pair to offspring opposite spindle poles ○ Crossing over in prophase I Anaphase I ○ Random assortment in metaphase I ○ All of the homologous chromosomes separate and begin heading Crossing over toward the spindle poles ○ Recombination between non-sister chromatids of homologous Telaphase I chromosomes which produce new combination of parental alleles ○ A complete set of chromosomes clusters at both ends of the cell 6  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN FROM GAMETES TO OFFSPRING SEGREGATION OF GENES Sexual reproduction involves the fusion of reproductive cells (gametes) from two parents Gametes ○ Haploid ○ Arise by division of immature reproductive cells (germ cells) At fertilization, two haploid gametes fuse and produce a diploid zygote, ○ first cell of a new individual PATTERNS OF INHERITANCE MENACING MUCUS Cystic fibrosis ○ Most common fatal genetic disorder in the U.S. ○ Caused by a deletion in the CFTR gene PUNNETT SQUARES CF allele ○ Persists at high frequency despite devastating effects Calculates the probability of the genotype and phenotype of offspring of ○ Only homozygous for the CF allele have the disorder crosses MONOHYBRID CROSS TRACKING TRAITS Cross in which individuals with different alleles of a gene are crossing Mid 1800s Frequency at which two traits appear in the second generation provides ○ Genes and chromosomes were unknown information about dominant relationship between two alleles Gregor Mendel’s experiment Dominant trait will have a 3:1 phenotype ratio ○ With pea plants established principles of inheritance DIHYBRID CROSSES INHERITANCE Showed inheritance of trait did not affect inheritance of other traits Organisms breed true for a trait because they carry identical alleles of genes Experiment in which individuals with different alleles of two genes are governing that trait crossed Homozygous Monohybrid cross ○ Identical alleles of a gene ○ dominance relationships between alleles are revealed Heterozygous Independent assortment ○ Unidentical alleles of a gene ○ A gene tends to be distributed independently of how other genes Genotype are distributed ○ Particular set of alleles carried by an individual Phenotype CONTRIBUTION OF CROSSOVERS ○ Observable traits Two genes located close together on the same chromosome tend to be Dominant allele inherited together ○ When its effect masks that of a recessive allele paired with it When two genes on the same chromosome are far apart, crossing over MENDELIAN INHERITANCE PATTERNS occurs more frequently between them ○ They tend to assort independently When homologous chromosomes separate during meiosis, the gene pairs on those chromosomes separate Each gamete that forms carries only one of the two gene of a pair 7  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN BEYOND SIMPLE DOMINANCE ○ Shows whether a trait is associated with a dominant or recessive Incomplete dominance allele ○ Condition in which one allele is not fully dominant over another, so ○ Shows whether a trait is on an autosome or sex chromosome the heterozygous phenotype is intermediate between the two homozygous phenotypes (Ex. Red and white parental plants with pink TYPES OF GENETIC VARIATION offsprings) Genetic abnormality Codominant ○ An uncommon version of a heritable trait that does not result in ○ Refers to two alleles that are both fully expressed in heterozygous medical problems individuals (Ex. Blood types in humans) EXAMPLES: Polydactyly PLEIOTROPY Presence of six fingers on a hand Single genes influence multiple traits Web between two toes ○ Mutations in the gene’s product affect all the traits Genetic disorder Mutations in pleiotropic genes ○ A heritable condition that results in a syndrome of mild or severe ○ sickle cell anemia, cystic fibrosis, and Marfan syndrome medical problems EXAMPLE: EPISTASIS Cystic fibrosis Effect in which a trait is influenced by the products of multiple genes HUMAN GENETIC DISORDERS (Ex. Labrador retriever coat color) Some dominant or recessive alleles on autosomes or the X chromosome are COMPLEX VARIATIONS IN TRAITS associated with genetic abnormalities or disorders Mutations, interactions among genes, and environmental conditions can affect one or more steps in a metabolic pathway, and contribute to variation in AUTOSOMAL DOMINANT ALLELE phenotypes Expressed in homozygotes and heterozygotes CONTINUOUS VARIATION EXAMPLE: Achondroplasia A range of small increments of phenotype in a trait that is influenced by the AUTOSOMAL RECESSIVE ALLELE products of multiple genes ○ The more genes and other factors that influence a trait, the more Expressed only in homozygotes continuous the distribution of phenotype Only people homozygous for a recessive allele on an autosome have the Often associated with short tandem repeats associated trait. ○ Series of 2-6 nucleotides repeated many times in a row within EXAMPLE: Albinism regions of DNA Bell curve ○ Curve that results when the range of variation in a continuous trait is X-LINKED RECESSIVE DISORDERS plotted against frequency in a population Alleles on the X chromosome are inherited and expressed differently in HUMAN GENETIC ANALYSIS males and females Males Pedigrees ○ transmit X-linked alleles to their sons ○ Standardized charts illustrating phenotypes of family members Females and their genetic connections ○ pass X-linked alleles to male and female offspring ○ Used to study inheritance patterns in humans EXAMPLE: Red-green color blindness 8  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN CHROMOSOME NUMBER CHANGES ANIMAL CELLS Polyploid Called eukaryotic cells ○ Having three or more of each type of chromosome characteristic of ○ Much larger and complex the species Nucleus ○ Common in flowering plants ○ Genetic material is contained inside ○ Some insects, fishes, and other animals Organelles Nondisjunction ○ Has a lot of internal and surface structures ○ The failure of chromosomes to separate normally during meiosis or Animal cells lack cell walls mitosis Organelles and other internal structures provide a division of labor and allow the cells to work much more efficiently Generally more active and have higher metabolism than other kingdoms AUTOSOMAL CHANGE Require more energy Trisomy 21 (Down Syndrome) Almost all energy is the product of aerobic respiration inside mitochondria ○ Only autosomal trisomy that allows human to survive to adulthood Make use of proteins for structure, movement, nerve impulses, and ○ Affected individuals tend to have certain physical features and metabolism impairments ANIMAL TISSUES ○ Nondisjunction leads to trisomy 21 increases with age of the mother Group of cells becomes specialized to do one or a few tasks very well Tissues CHANGE IN SEX CHROMOSOME NUMBER ○ Are groups of similar cells performing similar functions Usually associated with learning difficulties, speech delays, and motor skill TYPES OF ANIMAL TISSUES impairment Female sex chromosome abnormalities: ○ Turner syndrome (XO) ○ XXX syndrome EPITHELIAL TISSUES Male sex chromosome abnormalities: Most primitive animal tissue ○ Klinefelter syndrome (XXY) Forms outer coverings of animals ○ XYY syndrome Lines the inner and outer surfaces of all organs Consists of cells fitted tightly together GENETIC SCREENING Potential parents who may be at risk of transmitting a harmful allele to offspring FUNCTIONS OF EPITHELIAL TISSUES have screening or treatment options Protection Obstetric sonography ○ From microbes, physical injury, water loss ○ May reveal defects associated with a genetic disorder Absorption Other tests performed before birth carry risks of miscarriage or injury to ○ Of food, water, etc. in the intestine fetus Transport ○ Amniocentesis ○ Sometimes have cilia that move things along a tube ○ Chorionic villi sampling (CVS) Filtration ○ Fetoscopy ○ In kidneys WAYS OF IMAGING A HUMAN FETUS: Gas exchange Conventional Ultrasound ○ Lungs 4D Ultrasound Secretion Fetoscopy ○ From glands that secrete various substances 9  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN Nerve cells CONNECTIVE TISSUES ○ Are able to conduct impulses to send signals throughout the The most widespread and abundant type of tissue in animals animal body Most diverse in structure and function Stem cells Most are heavily vascularized ○ Most adults retain some kinds of embryonic cells called stem cells Have an abundance of matrix ○ Can later differentiate into replacement cells and tissues Fibers composed mainly of collagen FUNCTIONS OF NERVOUS TISSUES FUNCTIONS OF CONNECTIVE TISSUES To sense internal and external environmental changes Glue Coordination and control of muscles and glands ○ Areolar tissue Support and Movement ANIMAL TISSUE AND ORGANS ○ Bone and cartilage GROWING REPLACEMENT PARTS Nutrient storage ○ Bone and adipose Stem Cell Temperature Homeostasis ○ Unspecialized cell can divide and create more stem cells or ○ Fat for heat production and cold insulation differentiate to become a specialized cell type Transport ○ Each type of adult stem cell normally differentiates into a limited ○ Blood and lymph variety of cells ○ An embryonic stem cell is pluripotent or can become any type of body cell MUSCLE TISSUES Human Embryonic Stem Cells Elongated cells, spindle shaped, up to 1 ft long ○ Must be induced to differentiate before they can be used in medical Muscle Cells treatments ○ Generally stop dividing at birth ○ But can expand greatly in volume ANIMAL STRUCTURE AND FUNCTION All animals are multicelled, and nearly all have cells organized as tissue FUNCTIONS OF MUSCLE TISSUES Tissue ○ Collection of one or more specific cell types and often an Movement extracellular matrix ○ Voluntary movements such as swimming or running ○ Can actively perform a specific task or tasks ○ Internal involuntary movements such as the pumping of the heart, peristalsis of the digestive organs TYPES OF TISSUE Posture Characterized by the types of cells it includes and their proportions Heat Generation Epithelial ○ Used for movement ○ Cover body surfaces and line internal cavities Connective NERVOUS TISSUES ○ Hold body parts together and provide structural support Muscle Are also elongated into long fibers ○ Move the body and its parts ○ Typically large cell body with one or more long fibers extending from it Nervous Grouped together to form extensive interconnected network of wires that ○ Detect stimuli and relay information extend throughout the body Each tissue is characterized by the types of cells it includes and their proportions 10  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN Cells are connected by junctions and have no matrix between them LEVELS OF ORGANIZATION TYPES OF EPITHELIAL TISSUE Simple Squamous Epithelium ORGAN AND ORGAN SYSTEMS ○ Lines vessels of cardiovascular and lymphatic system, makes up Organs walls of air sacs in lungs ○ Animal tissues are organized into organs ○ Allows substance to cross by diffusion ○ Structural unit composed of two or more tissues to carry out specific Stratified Squamous Epithelium tasks ○ Outer layer of skin, lining of the mouth, esophagus, anal canal, and Organ System vagina ○ Organs and other components that interact physically or ○ Protection chemically in a common task Single Columnar Epithelium All structural levels interact in processes that keep condition in the internal ○ Lines the stomach, intestine, and airways environment within levels that cells can tolerate ○ Absorbs secretes materials Homeostasis Single Cuboidal Epithelium ○ Process of maintaining favorable conditions inside the body ○ Lines kidney tubules, ducts of some gland, oviducts Single Columnar Epithelium ○ Absorbs, secretes, moves materials ○ Lines the stomach, intestine, and airways EPITHELIUM GLANDS ○ Absorbs secretes materials Single Cuboidal Epithelium Cluster of epithelial cells that secretes a substance that function outside the ○ Lines kidney tubules, ducts of some gland, oviducts cell ○ Absorbs, secretes moves materials Exocrine Gland ○ Secretes milk, sweat, saliva, oil, or some other substance through a duct onto an internal or external surface EVOLUTION OF STRUCTURE AND FUNCTION Endocrine Gland Structural traits ○ Ductless gland that secretes hormones into a body fluid ○ Evolve by natural selection ○ Existing structures are modified over a generation in ways that CONNECTIVE TISSUE better adapt their bearers to their environment Most abundant tissue in a vertebrate body New structures evolve by modifying existing ones ○ Animal tissue with extensive cellular matrix ○ Evolutionary remodeling often results in body plans that are less than ○ Bind, support, strengthen, protect, and insulate other tissues optimal ○ Range from soft connective tissues to specialized bone tissue, cartilage, adipose, tissue, and blood ANIMAL TISSUE EPITHELIAL TISSUE TYPES OF CONNECTIVE TISSUE Sheetlike animal tissue with one free surface exposed to some body fluid or Soft connective tissues the environment - Hold body parts in place 11  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN Fibroblast MUSCLE TISSUES ○ Main cell type in soft connective tissue ○ Secretes collagen and other components of extracellular matrix Contact in response to signals from nervous tissue, and help move the body or parts of it TWO TYPES OF SOFT CONNECTIVE TISSUES: Loose ○ With relatively few fibroblasts and fibers scattered in its matrix TYPES OF MUSCLE TISSUES ○ Most abundant issue 1. Skeletal muscle tissue ○ Consists of fibroblasts widely scattered in a secreted matrix ○ Attaches to bones to move body parts Dense ○ Voluntary, striated, multiple nuclei ○ Connective tissue with many fibroblasts and collagen fibers in its 2. Cardiac muscle tissue matrix ○ Makes up the heart wall ○ May have regular or irregular arrangement ○ Involuntary, striated, single nuclei ○ Stronger than loose connective tissue 3. Smooth muscle tissue Specialized Connective Tissues ○ Lines blood vessels and other hollow organs TYPES OF SPECIALIZED CONNECTIVE TISSUES: ○ Involuntary, not striated, single nuclei 1. Cartilage Connective tissue with cells surrounded by a rubbery matrix of glycoproteins and collagen fibers NERVOUS TISSUES Cushions joint Allows a body to detect and respond to internal and external changes 2. Adipose Tissue ○ Detects stimuli, integrates information Connective tissue with fat-storing cells ○ Controls actions of muscles and glands Stores energy, cushions and protects, insulates Neurons (excitable cells) 3. Bone Tissue ○ Transmit electrical signals along the plasma membrane With cells surrounded by a calcium-hardened matrix ○ Communicates with other cells through chemical signals Supports and moves the body Neuroglia Produces blood cells ○ Support and protect the neurons 4. Blood Fluid connective tissue Transport medium ORGANS Cells and platelets form inside bones, transport oxygen, help blood Tissues are organized into organs such as the heart, stomach, liver, eyes, clot, have immune function kidneys, lungs, and skins Liquid plasma transports gasses, nutrients, wastes Most organs include all four tissue types Many human organs are located in body cavities ○ Thoracic cavity, abdominal cavity, pelvic cavity ○ Cranial activity, spinal activity SKIN Largest organ Protects the body Helps make vitamin D Detects changes in the outside environment Skin contains all four tissue types 12  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN Respiratory System STRUCTURE OF HUMAN SKIN ○ Takes in oxygen necessary for aerobic respiration Epidermis ○ Expels carbon dioxide released by this pathway ○ Outermost, epithelial skin layer Digestive System ○ Contains melanin ○ Takes in food and water Dermis ○ Breaks food down and absorbs needed nutrients, then eliminates ○ Deep layer of skin consisting of connective tissue with nerves and food residues blood vessels running through it Urinary System Hypodermis ○ Maintains volume and composition of blood ○ Layer of loose connective tissue and adipose tissue below skin, ○ Excretes excess fluid and wastes containing larger blood vessels Reproductive System ○ Female: Produces eggs; nourishes and protects developing ORGAN SYSTEM offspring Work cooperatively to carry out reproduction and survival tasks ○ Male: Produces sperm and transfers them to female All vertebrates have the same 11 types of organ system REGULATING BODY TEMPERATURE HUMAN ORGAN SYSTEMS Homeostasis ○ Process of keeping conditions in a body within a tolerable range for Integumentary System the body’s cells ○ Protects body from injury, dehydration, pathogens ○ Brain receives signals from sensory receptors and coordinates ○ Moderates temperature responses ○ Excretes some wastes ○ Detects external stimuli Negative feedback Nervous System ○ A mechanism in which a specific change stimulates a responses ○ Detects external and internal stimuli that reverses the change ○ Coordinates responses to stimuli ○ Integrates body activities Temperature Regulation Endocrine system ○ Endotherms maintain a stable body temperature ○ Secretes hormones that control activity of other organ systems ○ Ectotherms temperature fluctuates with environment Muscular System ○ Moves the body and its parts ○ Produces heat Skeletal System ○ Supports and protects body parts ○ Site of muscle attachment ○ Produces red blood cells ○ Stores minerals Circulatory System ○ Distributes materials and heat through the body ○ Helps maintain pH Lymphatic System ○ Collects and returns tissue fluid to the blood ○ Defends the body against infection and cancers 13  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN EARLY LIFE FORMS AND THE VIRUSES ○ RNA may have served as the first material of inheritance HUMAN MICROBIOME ○ RNA served a dual role, as a genome and as a catalyst Microbiome ○ The types of microorganisms supported by humans ○ Most are harmless or beneficial to humans ORIGIN OF CELL MEMBRANES ○ A small minority are human pathogens The current mix of species in and on you depends on a variety of factors, Laboratory simulations show how fatty acid membranes enclosing RNA might such as diet, and that in turn affects your health have formed on early Earth ○ Example: a diet rich in grains selects for species such as Prevotella Protocell copri, which is associated with rheumatoid arthritis ○ A membrane-enclosed collection of interacting molecules that can take up material and replicate ○ Possible ancestors of cellular life ON THE ROAD TO LIFE Proposed sequence for evolution of cells Earth’s early atmosphere likely contained water vapor, carbon dioxide, 1. Inorganic molecules (self-assemble on Earth and in space) hydrogen, and nitrogen – but no oxygen gas 2. Inorganic monomers (self-assemble in aquatic environments on Oxygen gas is reactive – if it had been present, complex compounds could Earth) not have formed and persisted 3. Organic polymers (interact in early metabolism, self-assemble as vesicles, first genome) 4. Protocells (in an RNA world are subject to selection that favors a ORIGIN OF BUILDING BLOCKS OF LIFE DNA genome) 5. DNA-based cells Lightning fueled atmospheric reactions ○ 1950s: Stanley Miller produced organic compounds from a mixture of gasses in a spark chamber ORIGIN OF THREE DOMAINS Delivery from space via meteorites ○ Amino acids, sugars, and nucleotide bases have been found in Evidence of early life: meteorites that fell to Earth - Comparing genes of living organisms indicates that the common ancestor of Reactions at deep-sea hydrothermal vents all organisms lived about 4 billion years ago ○ Amino acids form spontaneously in a simulated vent environment Stromatolites - Earliest fossil cells are found in rocks that date to about 3.5 billion years ago ORIGIN OF METABOLISM ORIGIN OF BACTERIA AND ARCHAEA Organic polymers may have formed on clay-rich tidal flats Bacteria and Archaea diverged about 3.5 billion years ago ○ Positively-charged organic molecules stick to negatively-charged clay ○ By 2.7 billion years ago, one lineage of bacteria (cyanobacteria) particles on tidal flats, and become concentrated by evaporation began to carry out photosynthesis by the oxygen-releasing pathway Iron–sulfur world hypothesis Oxygen then accumulated in the air and water ○ Early metabolic reactions may have taken place on the surface of ○ Provided a selective pressure for oxygen thriving organisms to rocks rich in iron sulfide near deep-sea hydrothermal vents spread ○ Ozone gas then formed and accumulated as the ozone layer ORIGIN OF GENETIC MATERIAL ORIGIN OF EUKARYOTES DNA is the genetic material in modern cells, but self-replicating ribozymes Eukaryotes first appear in the fossil record about 1.8 million years ago (RNA) may have stored the first genetic material The nucleus and endomembrane system probably evolved from infoldings of RNA world hypothesis the plasma membrane 14  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN ○ Some eukaryotic organelles (mitochondria and chloroplasts) may Lysogenic pathway have evolved from bacteria by endosymbiosis ○ Virus becomes integrated into the host’s chromosome and is passed on to the next generation VIRUSES A noncellular infectious particle that can replicate only inside a living host cell PLANT VIRUSES Consists of nucleic acid (DNA or RNA) inside a protein coat consisting of Typically nonenveloped, with a helical structure and a genome of protein subunits bonded in a repeating pattern single-stranded RNA In many viruses that infect animals, the protein coat is enclosed within a viral Disease vector envelope ○ Organism that transmits a pathogen from one host to the next ○ A layer of cell membrane derived from the host cell in which the viral ○ Many viral plant diseases pass through sucking insect vectors particle formed VIRUSES AND HUMAN HEALTH Some viruses are beneficial to human health Others are human pathogens ○ Most produce mild symptoms and only brief effects ○ Others remain in the body in a latent state, and can reawaken later on (Ex: herpesviruses) ○ Some may cause cancer (Ex: human papillomavirus (HPV) A. Tobacco mosaic virus, a helical virus that infects tobacco and related plants. B. An adenovirus, a polyhedral virus that infects animals. The 20-sided coat encloses HIV (THE AIDS VIRUS) double-stranded DNA. C. A herpesvirus, an enveloped virus that infects animals. The envelope is derived HIV (human immunodeficiency virus) from a host cell. ○ An enveloped RNA virus that replicates inside human white blood cells VIRAL REPLICATION ○ Viral RNA and enzymes enter host cell ○ Reverse transcriptase converts viral RNA into DNA, which is A virus’s structure is adapted for infection and replication within a specific type integrated into host chromosome and transcribed along with host of host genes Nearly all viral replication cycles include the same key steps: ○ Host cells make new viral RNA and proteins, and assemble new viral ○ Virus attaches to protein on host cell membrane particles which bud from cell ○ Viral genome enters cell ○ Viral genes direct cell to replicate viral DNA or RNA and proteins; components self-assemble ○ New viruses bud or burst from host cell BACTERIOPHAGES Nonenveloped virus that infects bacteria ○ Replicate in bacteria by two pathways: lytic and lysogenic Lytic pathway ○ Virus replicates in its host and quickly kills it by breaking off plasma membrane (lysis) 15  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN ○ Cell wall gives the cell a characteristic shape (coccus, spirillum, EBOLA bacillus) An enveloped RNA virus that emerged in Africa ○ Cell wall may be covered with a secreted capsule ○ Identified in 1976 ○ Bacterial flagella or pili allow cells to move ○ Infects fruit bats and nonhuman primates ○ Kills more than half of those it infects NEW FLUS Influenza viruses that cause flu: ○ Enveloped RNA viruses ○ Mutate quickly; reverse transcriptase makes frequent replication errors ○ Repair enzymes and proofreading activity do not operate during reverse transcription New strains also arise by viral reassortment REPRODUCTION AND GENE TRANSFER ○ Swapping of genes between related viruses that infect a host at the Binary fission same time ○ Asexual reproduction that forms two identical descendant cells A new flu vaccine is produced every year because of mutations Conjugation ○ Transfers a small ring of non chromosomal DNA (plasmid) to another individual through a sex pilus Transformation ○ Takes up DNA from its environment Transduction ○ Viruses move genes from one host cell to another BINARY FISSION AND GENE EXCHANGE BACTERIA AND ARCHAEA Prokaryotes constitute two distinct lineages Bacteria ○ Well-known and widespread group of cells that do not have a nucleus Archaea ○ More closely related to eukaryotes than to bacteria ○ Many types live in extreme habitats ○ No nucleus STRUCTURE AND FUNCTION Typical bacterial cell ○ No nucleus or other organelles ○ Cytoplasm contains ribosomes and a single, circular prokaryotic chromosome (DNA) 16  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN METABOLIC DIVERSITY FLAGELLATED PROTOZOANS Autotrophs obtain carbon from carbon dioxide (CO2) Heterotrophic lineage of unwalled, single-celled protists that have one or more − Photoautotrophs use light energy flagella − Chemoautotrophs remove electrons from inorganic molecules such as − A layer of proteins (pellicle) below the cell membrane provides shape hydrogen sulfide or methane Both free-living and parasitic species Heterotrophs obtain carbon from organic molecules − Photoheterotrophs get energy from light, and carbon from small organic molecules − Chemoheterotrophs obtain both energy and carbon by breaking down carbohydrates, lipids, and proteins − Decomposers break down organic molecules into inorganic ones DOMAIN ARCHAEA 1. Extreme thermophiles − Organisms that live in very high-temperature environments such as hydrothermal vents 2. Extreme halophiles FORAMINIFERANS − Organisms that live in high salt concentrations, such as in a California lake Single-celled predators that secrete calcium carbonate shells 3. Methanogens − Remains contribute to limestone and chalk − Anaerobic organisms that produce methane gas − Planktonic forams may have photosynthetic protists living in their − Live in swamps, sediments, and animal guts cytoplasm Plankton − Community of tiny drifting or swimming organisms DOMAIN BACTERIA Photosynthetic bacteria (cyanobacteria) CILIATES − Release oxygen into the atmosphere − Nitrogen-fixing bacteria make nitrogen available to photosynthesizers by ▪ Single-celled heterotrophs that use cilia to move and feed nitrogen fixation ▪ Most ciliates are predators in seawater or fresh water Nitrogen and hydrogen combine to form ammonia ▪ Some live in guts of mammalian grazers and Decomposers break organic material into inorganic subunits − Recycles nutrients in wastes and remains − Includes lactate fermenters Bacteria also cause many common diseases PROTISTS A eukaryote that is not a fungus, plant, or animal Now being assigned to groups that reflect evolutionary relationships − Most are single-celled, but some are multi celled species − Nearly all live in water or moist habitats, including host tissues 17  GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN DINOFLAGELLATES AMOEBAS ▪ Aquatic single cells that move with a whirling motion ▪ Single-celled heterotrophic amoebozoans that move and feed by extending ▪ Typically have cellulose plates and two flagella pseudopods ▪ May be heterotrophic or photosynthetic ▪ Live in aquatic habitats and animal bodies ▪ Some are bioluminescent: light-producing ▪ Some cause human disease ▪ Example: Entamoeba histolytica DINOFLAGELLATES AND ALGAL BLOOMS ▪ Algal bloom PLASMODIAL AND CELLULAR SLIME MOLDS ▪ Population explosion of single-celled aquatic organisms such as dinoflagellates ▪ Plasmodial slime mold ▪ Caused by nutrient-enriched water ▪ Heterotrophic protist that moves and feeds as a multinucleated mass ▪ Depletes oxygen and suffocates aquatic animals ▪ Forms a fruiting body in unfavorable conditions ▪ Some dinoflagellates produce toxins that sicken people and directly ▪ Cellular slime mold kill aquatic organisms ▪ Heterotrophic protist that usually lives as a single-celled predator, but cells aggregate and form a fruiting body in unfavorable conditions APICOMPLEXANS ▪ Parasitic protist that enters and lives inside the cells of its host ▪ Example: Plasmodium ▪ Apicomplexan species that causes malaria WATER MOLDS, DIATOMS, AND BROWN ALGAE ▪ Water mold (oomycotes) ▪ Heterotrophic protist that forms a mesh of nutrient-absorbing filaments ▪ Most decompose organic materials in aquatic habitats; some are pathogens of fish or plants ▪ Diatoms are single-celled, with a two-part silica shell; marine diatoms form diatomaceous deposits ▪ Brown algae are multicelled, ranging in size from microscopic filaments to giant kelps, the largest protists RED ALGAE ▪ Single-celled or multicelled photosynthetic protists with red accessory pigments (phycobilins) that allow them to live at great depths ▪ Red algae have many commercial uses CHOANOFLAGELLATES ▪ Nori, agar, carrageenan ▪ “Collared flagellate” GREEN ALGAE ▪ Each cell has a long flagellum surrounded by a ring of filaments reinforced with actin ▪ Single-celled, colonial, or multicelled photosynthetic protist ▪ Cell extends pseudopods to capture food, which is digested within the ▪ Most closely related to land plants cell body ▪ Include fresh water and marine species ▪ Most live as single cells; some form colonies ▪ Some grow other damp surfaces; some partner with ▪ Thought to be the closest living relatives of animals 18 GENERAL BIOLOGY 2 STUDENT’S ADVISORY BOARD | PEER TUTORING PROGRAM \ BY LARA CUNANAN 19