Biology Test 4
Disease
-Abnormality in the body's normal processes that significantly impairs normal function -Major causes include blood vessel issues, cancers, infections, inflammation -Systemic disease *Affects entire body -Local disease *Restricted to one part of the body -Acute disease *Occurs suddenly *Usually short duration -Chronic disease *Long term, less severe *Develops slowly -Cancers are a group of disorders in which the usual controls of cell division fail, resulting in the production of abnormal cells that invade and destroy healthy tissue.
Reptiles: Amniotic Egg 3
-Living reptiles excluding birds are ectothermic, meaning their body temperature is the same as that of the external environment. -Fish and amphibians are also ectothermic. -Reptiles try to regulate their body temperature by exposure to the sun when in need of warmth or by hiding in shadows if they need cooling off
Integumentary System
-The Integumentary System *Skin *Accessory organs **Hair **Nails **Sweat glands **Oil glands Functions of the integumentary system -Protects underlying tissues from trauma, -pathogen invasion, and water loss -Helps to regulate body temperature -Synthesizes vitamin D -Contains sensory receptors - awareness of surroundings
Macroevolution and Speciation
Macroevolution is evolution on a large scale. SPECIES is defined as a group of organisms that are capable of interbreeding and are isolated reproductively from other organisms. The Process of Speciation SPECIATION has occurred when one species gives rise to two species. ALLOPATRIC SPECIAITON occurs when populations become separated by a geographic barrier and gene flow is no longer possible. SYMPATRIC SPECIATION occurs when a single population divides into two reproductively isolated groups without being geographically isolated. ADAPTIVE RADIATION Darwin's finches provide an example of adaptive radiation, the proliferation of a species by adaptation to different ways of life.
Disorders of the Skin
-Human skin can be traumatized and is prone to certain infections. -Its dryness, slightly acidic pH, and the presence of dead cells in the outermost layers make skin resistant to many pathogens -Certain cancers can arise, usually from UV ray damage. -Dermatitis - skin inflammation - can arise from chemicals or allergic reactions. -Acne is common disorder of the face, shoulders, chest and back that usually occurs in adolescence. *These locations have the greatest density of sebaceous glands. -During puberty, certain hormones increase and also cause increased sebum production. -As sebum is blocked from exiting the gland, more Propionibacterium acnes, a very common skin bacteria, grows as well. -An inflammatory response (pimple) follows. -Warts are small areas of skin proliferation caused by the human papillomavirus. -Warts can occur at any age; non-genital warts most commonly occur between ages 12 and 16. -Warts generally harmless and disappear without treatment. -Warts can cause cosmetic disfigurement . -Several treatments can be utilized
Evolutionary Trends Among the Chordates
-Nonvertebrate chordates Tunicates and lancelets do not have vertebrae -Vertebrate chordates Fishes, amphibians, reptiles, birds, mammals cartilaginous fish: first to develop jaws *Some early bony fish had lungs -Amphibians were the first to have joint appendages These were also the first to invade land -Lobe-finne fishes from the Devonian era had fleshy appendages with bones homologous to those o terrestrial vertebrates *these are believed to be ancestral to amphibians -Reptiles and mammals had terrestrial adaptations for reproduction *Amnion and extraembryonic membranes support the embryo and prevent it from drying as it develops
Diversity of Birds
-The majority of birds can fly (eagles, geese). -Some birds are flightless (emus, penguins, ostriches). -Birds are traditionally classified based on beak and foot type. *Also based on their habitat and behavior -Bird orders: *birds that prey with notched beaks and sharp talons *shorebirds with long, slender, probing beaks and long stilt-like legs *woodpeckers with sharp, chisel-like beaks and grasping feet *waterfowl with broad beaks and webbed toes
Monotremes
-have a cloaca - terminal region of digestive tract that serves as a common chamber for feces, excretory wastes, and sex cells -lay hard-shelled amniotic eggs -secrete milk onto body surface (both males and females) *babies lick up the milk -Exist only in Australia *spiny anteaters and duck-billed platypus
Bird Anatomy and Physiology air circulation
1. inhalation: air enters posterior air sacs 2. exhalation begins: air enters lung 3.exhalation continues: air enters anterior air sacs 4. exhalation ends: air exits anterior air sacs birds and crocodiles have a four chambered hear and separate pulmonary and systematic circuits.
Gene Mutations
A GENE MUTATION is a permanent change in the sequence of bases in DNA. Gene mutations can lead to malfunctioning proteins in cells. CAUSES OF MUTATIONS ERRORS IN REPLICATION DNA replication errors are a rare source of mutations because DNA polymerase proofreads the new strand. MUTAGENS Environmental influences called mutagens, which include radiation and certain organic chemicals, cause mutations in humans. TRANSPOSONS are specific DNA sequences that have the ability to move within and between chromosomes, which can alter the expression of neighboring genes. EFFECTS OF MUTATION ON PROTEIN ACTIVITY The result can be a completely new sequence of codons and nonfunctional protein. NONFUNCTIONAL PROTIENS A single nonfunctioning protein can have a dramatic effect on phenotype, because enzymes are often a part of metabolic pathways.
Reptiles: Amniotic Egg 2
Adaptations for reproduction on land -The male penis passes sperm directly into the female . -Fertilization is internal; female possess the shelled eggs. -The amniotic egg made development on land possible and eliminated the need for swimming larval stage. *The egg provides the embryo with O2, food, and water *It removes nitrogenous wastes. *It prevents the egg from drying out and from mechanical injury.
Adipose Tissue and Reticular Connective Tissue
Adipose Tissue -Fibroblasts enlarge and store fat and become adipocytes. -Used for *Energy storage *Insulation against heat loss or gain *Organ protection -Found beneath the skin, around the kidneys and surface of the heart Reticular Connective Tissue -Forms the supporting meshwork of lymphatic tissue -Found in lymph nodes, spleen, thymus and bone marrow Adipose Tissue Fibroblasts enlarge and store fat
Gene Linkage
All the alleles on one chromosome form a LINKAGE GROUP(tend to be inherited together and do not show independent assortment)
Amphibians: Jointed Appendages
Amphibians (class Amphibia) -Class name means living on land and water -Includes salamanders, frogs, toads, newts *Caecilians are fossorial wormlike amphibians that are limbless, and spend most of time underground. -Characteristics include *Jointed appendages (other than in caecilians) *Four limbs *Eyelids to keep eyes moist *ears (a tympanum) to pick up sound waves *larynx for vocalization Class Amphibia -Larger brain than in fish relative to body size -small lungs in adults *gas exchange also occurs across moist skin -Three-chambered heart *Two atria and a ventricle -Amphibious lifestyle *larval stages in water, adults on land *reproduction generally occurs in water
Evolution of Humanlike Hominins
Bipedalism is an anatomy suitable for standing erect and walking on two feet. *Characteristic that separates modern humans -Initial debate regarding hominid evolution due to climate change in which forests were replaced by grassland 4 MYA has given way to the belief that early hominids lived in forests. -Recent fossil findings suggest hominids may have begun to walk upright as early as 7 MYA. *Fossil evidence limited to a part of the back of the skull
Feathered Reptiles
Birds (class Aves) -Sizes range from the hummingbird at 1.8g to the ostrich at a weight of 160kg. -The fossil record, as well as molecular data, provides evidence that birds evolved from reptiles -Birds are now considered part of Reptilia. *Feathers are modified scales; legs of birds have scales *Amniote egg with a hard shell instead of leathery eggs of reptiles
Blood
Blood -Unlike other types of connective tissue, the matrix (i.e., plasma) is not made by the cells. -Functions *Transports nutrients and oxygen and removes carbon dioxide and wastes. *Helps distribute heat. *Plays role in fluid, ion and pH balance. *Protects against disease. *Blood clotting protects against fluid loss -Components of Blood *Plasma - 55% of volume **Variety of inorganic and organic substances dissolved or suspended in water *Formed elements - 45% of volume **Red blood cells (erythrocytes) **White blood cells (leukocytes) **Platelets (thrombocytes) -Red blood cells (erythrocytes) *Small, biconcave, disk-shaped cells that lack a nucleus *Contain hemoglobin for transport of oxygen -White blood cells (leukocytes) *Larger cells with a nucleus *Fight infection in different ways Platelets (thrombocytes) -Cell fragments involved with blood clotting *Help to form a plug that seals damaged blood vessels *Injured tissues release molecules to stimulate the clotting process
Body membranes 2
Body Membranes -Line cavities and the internal spaces of organs and tubes that open to the outside -Mucous Membranes *Line tubes of the digestive, respiratory, urinary, and *reproductive systems *Made of an epithelium overlying loose fibrous connective tissue *Goblet cells produce mucus **Protective function Serous Membranes -Line thoracic and abdominal cavities -Made of epithelium and loose fibrous connective tissue -Secrete watery fluid for lubrication -Carry specific names according to location *Pleurae - lines thoracic cavity and lungs *Pericardium - encloses heart *Peritoneum- lines abdominal cavity and covers organs **Mesentery supports abdominal organs and attaches them Synovial membranes -Made of loose connective tissue -Line freely movable joints -Secrete synovial fluid Meninges -Line the dorsal cavity -Protect brain and spinal cord -Made of connective tissue
Bone
Bone -The most rigid connective tissue -Extremely hard matrix-formed from *Calcium salts deposited around collagen fibers **Give bone rigidity *Protein fibers **Provide elasticity and strength -Two types of bone tissue Compact Spongy Compact bone -Forms shafts of long bones -Consists of cylindrical structures called osteons -Central canal of each osteon surrounded by rings of hard matrix -Located in spaces called lacunae Spongy bone -Contains many bony bars and plates, separated by irregular spaces -Found in ends of long bones -Though lighter, still designed for strength
Bony fishes 2
Bony fishes -lobe-finned fishes *evolved into the amphibians **coelocanths are living fossils *had fleshy appendages could be adapted for locomotion on land *most had lungs
Bony Fishes
Bony fishes (class Osteichthyes) -Ray-finned fishes most commonly eaten -Characteristics *Paired fins supported by bony rays *Swim bladder for buoyancy *Streamlined shape *Bony scales for protection *Water pumped across gills **Enters through mouth, exits out the gill slits *Blood pumped by a two-chamber heart through single-circuit circulatory system
Changes in Chromosomal Structure
CHROMOSOMAL MUTATIONS occur when chromosomes break and fail to reunite correctly. A DELETION occurs when a single break causes a chromosome to lose an end piece or when two simultaneous breaks lead to the loss of an internal chromosomal segment. In a DUPLICATION, a chromosomal segment is repeated in the same chromosome or in a nonhomologous chromosome. A TRANSLOCATION is the exchange of chromosomal segments between two nonhomologous chromosomes. An INVERSION occurs when a segment of a chromosome is turned 180 degrees
Cartilage
Cartilage -Specialized form of dense fibrous connective tissue -Commonly forms smooth surfaces that allow bones to slide against one another in joints -Cells lie in small chambers called lacuna, separated by solid, but flexible matrix -Three types of cartilage *Hyaline, elastic, and fibrocartilage Hyaline: the most common type -Contains very fine collagen fibers -Found in the nose and ends of long bones and ribs -Forms rings in the walls of respiratory passages -Parts of the fetal skeleton become bone from this tissue Elastic: higher proportion of elastic fibers, so more flexible -Framework of outer ear Fibrocartilage: contains strong collagen fibers -Found in structures that withstand tension and pressure such as the pads between vertebrae
Cartilaginous Fishes
Cartilaginous fishes (class Chondricthyes) -This class is made up of sharks, skates, and rays. -Skeletons comprised of cartilage instead of bone -Sharks vary in size. *Dogfish shark used in biology labs is relatively small *whale sharks are largest -Skates and rays are flat fishes, and live partly buried in sand *feed on mussels, clams and various crustaceans How do sharks and rays detect prey? 1. they can sense electric currents in water *even basic muscle contractions of animals 2. The use a series of pressure-sensitive cells along both sides of body called a LATERAL LINE SYSTEM 3. They have a keen sense of smell, with an enlarged part of the brain associated with this sense *Distances up to 1/3 of a mile
Types of Tissues
Cells are composed of molecules; a tissue has similar types of cells; an organ contains several types of tissues; and several organs make up an organ system. A tissue is composed of similarly specialized cells that perform a common function in the body. Four Types of Tissues in the Human Body Epithelial: covers body surfaces and lines cavities Connective: supports and binds body parts Muscular: moves the body and its parts Nervous: receives stimuli, processes that information, and conducts impulses
Theory of Evolution
Charles Darwin proposed the theory of evolution after his observations of geological formations and species variation during his five-year voyage on the HMS Beagle. EVOLUTION proposes that species arise, change, and become extinct due to natural forces. Darwin's predecessor, LAMARCK, developed the theory of INHERITANCE OF ACQUIRED CHARACTERISTICS, which that states that the environment can bring about inherited change. Changes to an organism's visible characteristics, or PHENOTYPE, acquired during an organism's lifetime do not result in genetic changes that are heritable based on Lamarck. *However, Darwin's theory of natural selection states that: individual organisms within a species exhibit variation that can be passed from one generation to the next, organisms compete for available resources, individual organisms within a population differ in terms of their reproductive success, organisms become adapted to conditions as the environment changes
Connective Tissue
Connective Tissue -Binds organs together -Provides support and protection -Fills spaces -Produces blood cells -Stores fat Connective tissue cells are separated by matrix, noncellular material that varies in consistency. *Solid, semisolid, or liquid Composition of nonfluid matrix Fibers: *Collagen: protein that gives flexibility and strength *Elastic: protein that is not as strong as collagen, but more elastic *Reticular: thin, highly branched fibers that form supporting network
DNA Structure
DEOXYRIBONUCLEIC ACID (DNA) IS THE GENETIC MATERIAL OF LIFE, it is able to store information that pertains to the development, structure, and metabolic activities of the cell or organism, and is stable so that it can be replicated with high accuracy during cell division and be transmitted from generation to generation. The brief history of the Genetic Material (1920-1950's) ... Experiments by Griffith in the late 1920s led investigators to look for the transforming substance in bacteria to determine the chemical nature of the genetic material. By the 1940s scientists recognized that genes are on chromosomes and that chromosomes contain both proteins and nucleic acids. In 1944 Avery, MacLeod and McCarty published a paper concluding that DNA is the genetic material based on their experiments. An experiment by Hershey and Chase in the early 1950s firmly established DNA as the genetic material. Learn Structure of DNA The STRUCTURE of DNA was determined by Watson and Crick in the early 1950s. DNA is a chain of nucleotides, two strands of alternating phosphate and sugar molecules form a DOUBLE HELIX, which are held together by hydrogen bonding.
Environmental Influences
Environmental factors, such as NUTRITION OR TEMPERATURE, can also influence the expression of genetic trait. Investigators try to determine what percentage of various human traits is due to NATURE (INHERITANCE) and what percentage is due to NURTURE (THE ENVIORNMENT)
Evidence of Evolution
Evolution is all the changes that have occurred, due to differential reproductive success, in living organisms over geological time. Evolution is said to be one of the great unifying theories of biology. Why? The word "theory" is reserved for those conceptual schemes that are supported by a large number of observations and have not yet been found lacking. For example, information from the fossil record, bio geography, comparative anatomy, comparative embryology, and comparative biochemistry may all be interpreted to support the hypothesis that all living things are descended from a common ancestor. The diversity of life occurs because living things are adapted to different ways of life. 1. FOSSIL EVIDENCE- FOSSILS are the remains and traces of past life or any other direct evidence of past life. Geological Timescale Table 27.1 (know which periods belong with which eras) As a result of studying strata, scientists have divided Earth's history into eras, and then periods and epochs. The absolute dating method relies on radioactive dating techniques to assign an actual date to a fossil. 2. BIOGRAPHICAL EVIDENCE BIOGRAPHY is the study of the distribution of the range and distribution of plants and animals in different places throughout the world. MASS EXTINCTIONS Extinction is the death of every member of a species. During mass extinctions, a large percentage of species become extinct within a relatively short period of time. So far, there have been five major mass extinctions; and supposedly we are in the 6th mass extinction 3. ANATOMICAL EVIDENCE Structures that are anatomically similar because they are inherited from a common ancestor are called HOMOLOGOUS STRUCTURES. In contrast, ANALOGOUS STRUCTURES serve the same function, but are not constructed similarly, nor do they share a common ancestry. VESTIGIAL STRUCTURES are anatomical features that are fully developed in one group of organisms but that are reduced and may have no function in similar groups. 4. BIOCHEMICAL EVIDENCE When the degree of similarity in DNA nucleotide sequences or the degree of similarity in amino acid sequences of proteins is examined, the more similar the DNA sequences are, generally the more closely related the organisms are.
Processes of Evolution
Five Agents of Evolutionary Change The opposite of the five Hardy-Weinberg conditions can cause evolutionary change. 1. Mutations - which are genetic changes, are the only source of new variation in a population. 2. Genetic drift - refers to changes in the allele frequencies of a gene pool due to the random meeting of gametes during fertilization. Genetic drift has greater effects in smaller populations because there are fewer gametes to sort. The bottleneck effect and the founder effect are both examples of genetic drift. 3. Gene Flow - is the movement of alleles among populations when individuals or their gametes migrate from one population to another and breed in that new population. 4. Nonrandom Mating - occurs when individuals are selective about choosing a mate with a preferred trait. 5. Natural selection is the process that allows some individuals, with an advantage over others, to produce more offspring. Evolution by natural selection requires individual variation, inheritance, overproduction, and differential reproductive success. The fitness of an individual is measured by the number of fertile offspring produced throughout its lifetime.
Anatomy and Physiology of Birds 2
Flight requires acute sense organs and a well-developed nervous system. -Good vision and developed brain -Excellent muscle reflexes -Enlarged brain region for instinctive behavior An enlarged portion of the brain is responsible for instinctive behavior. -Ritualized courtship before mating -Strong parental care of young unable to fly -Seasonal migration over very long distances
Gene Therapy
GENE THERAPY is the insertion of genetic material into human cells for the treatment of genetic disorders and various other human illnesses
Gregor Mendel
Gregor Mendel developed the basic principles of inheritance after performing a series of experiments. He kept careful and complete records of plant crosses and concluded that the plants transmitted distinct factors to offspring. The factors that control traits are called genes and genes are found on chromosomes. Chromosomes are fond in pairs, called homologous chromosomes, one of which is from the mother, the other from the father; they are similar in the types of genes they contain. Alternate forms of a gene for the same trait are called ALLELS.
Organ Systems
Human body is organized into 11 organ systems -Integumentary -Cardiovascular -Lymphatic and Immune -Digestive -Respiratory -Urinary -Skeletal -Muscular -Nervous -Endocrine -Reproductive
Jawless Fishes
Jawless fishes (superclass Agnatha) -Cylindrical body shape with smooth, scaleless skin -No jaws or paired fins -Hagfish and lampreys are two groups of living jawless fishes *Hagfish are scavengers *Lampreys are parasitic **Mouth modified to form a sucker **attach to other fish **water moves in and out of gills directly and not through mouths as in other fish
Milestones in Vertebrate Evolution
Jaws allowed for predation. (Shark) Limbs allowed for locomotion (salamander) Amnion and shelled egg allowed for reproduction on land (chamaelo)
DNA Cloning
Knowledge of DNA biology has led to our ability to manipulate the genes of organisms. GENETIC ENGINEERING is when we clone genes and then use them to alter the GENOME (complete genetic makeup of an organism) of viruses and cells. -THE CLONING OF A GENE GENE CLONING is the production of many identical copies of a single gene. TRANSFENIC ORGANISMS are those with foreign DNA or genes inserted into them; they are frequently used to produce a product desired by humans. RECOMBINANT DNA (rDNA) TECHNOLOGY contains DNA from two or more different sources. To make rDNA, a researcher needs a VECTOR, a piece of DNA that can be manipulated such that foreign DNA can be added to it. THE POLYMERASE CHAIN REACTION (PCR) can create billions of copies of a segment of DNA in a test tube in a matter of hours. DNA ALALYSIS DNA FINGERPRINTING (W/GEL ELECCTROPHORESIS), STR (short tandem repeats) profiling, and other applications of PCR can be used to determine the differing sequences of DNA nucleotides that exist between individuals. These techniques have many uses, including identification in forensics.
Reptiles: Amniotic Egg
Land adaptations -Body covered with scales to protect against desiccation and against predators -Well-developed sense organs - snakes have a tongue modified as sense organ -Well-developed lungs protected by a rib cage *negative pressure when rib cage expands draws air into lungs -Three-chambered heart (division between ventricles is usually incomplete) *In some organisms oxygenated and deoxygenated blood is mixed
Loose Fibrous and Dense Connective Tissue
Loose fibrous connective tissue -Supports epithelium and many internal organs -Forms a protective covering enclosing many internal organs *Muscles, blood vessels, and nerves -Found in the lungs, arteries, and urinary bladder Dense fibrous connective tissue -Contains many collagen fibers packed together -Found in structures such as *Tendons - connect muscles to bones *Ligaments - connect bones to other bones Both loose and dense connective tissue have cells called fibroblasts -Separated by a jellylike matrix with collagen and elastic fibers
Mammals: Hair and Mammary Glands
Mammals (class Mammalia) -Also evolved from reptiles -Chief characteristics are body hair and milk-producing mammary glands -Almost all are endothermic - hair provides insulation against heat loss -Very efficient respiratory and circulatory systems, similar to birds High level of care for the young -The young are born alive (except monotremes) after a period of development in the uterus. -Internal development shelters the young. -Mammary glands enable females to nurse their young with a nutrient-rich food source. -Nursing also creates a bond to offspring that ensures parental care after birth Mammals classified as monotremes, marsupials, or placentals
Pedigree Analysis and Genetic disorders
Many traits and disorders are genetic in origin and follow Mendel's laws. PATTERNS OF INHERITANCE A PEDIGREE is a chart of a family's history with regard to a particular genetic trait. Males are disignated by squares and females by circles. Individuals with the trait, the affected individuals, are usually shaded. PEDIGREES FOR AUTOSOMAL DISORDERS- It is possible to decide if an inherited condition is due to an autosomal dominant or recessive allele by studying a pedigree. A PERSON is a carrier if they are unaffected but capable of passing on a genetic trait or disorder. -AUTOSOMAL RECESSIVE DISORDERS Inheritof the two recessive alleles is required vefore an autosomal recessive disorder will appear. Examples include TAY-SACHS DISEASE, CYSTIC FIRBROSIS, PHENYLKETONURIA, and SICKLE CELL DISEASE. -AUTOSOMAL DOMINANT DISORDERS Inheritance of only one dominant allele is necessary for an autosomal dominant genetic disorder to appear. Examples include MARFAN SYNDROME and HUNTINGTON DISEASE
Microevolution
Many traits can change temporarily in response to a varying environment, these are not evolutionary changes. Microevolution pertains to evolutionary change within populations. Example = Microevolution in the Peppered Moth Population genetics is the field of biology that studies the diversity of populations at the level of the gene. A POPULATION is all the members of a single species that occupy a particular area at the same time and that interbreed and exchange genes. The GENE POOL refers to the alleles of all genes in all individuals in a population. Hardy-Weinberg Equilibrium A population in which allele frequencies do not change over time is said to be in genetic or Hardy-Weinberg equilibrium-a stable, nonevolving state. The principles of the Hardy-Weinberg equation indicate that allele frequencies in a gene pool will remain at equilibrium after one generation of random mating in a large, sexually reproducing population as long as five conditions are met: 1) no mutations, 2) no genetic drift, 3) no gene flow, 4) random mating, 5) no selection.
Marsupials
Marsupials -Begin development within female's body -Are born very immature -Complete development within a pouch near the mother's abdomen *Attach to nipples of mammary glands within the pouch and continue to develop -Mainly found in Australia due to adaptive radiation *Kangaroo and koalas *Virginia opossum - only marsupial species north of Mexico
Muscular Tissue
Muscular Tissue -Composed of cells called muscle fibers *Muscle fibers contain actin and myosin filaments *Interaction accounts for sliding movements -Types of Muscle Tissues *Skeletal *Smooth (visceral) *Cardiac Skeletal Muscle -Cylindrical, long and multinucleated -Striated due to alternating light and dark bands -Usually attached by tendons to bones of the skeleton -Contraction is under voluntary control which causes bones of the skeleton to move at joints
Mutations Can Cause Cancer
Mutations Can Cause Cancer The development of cancer involves a series of accumulating mutations that can be different for each type of cancer. Mutations in tumor suppressor or proto-oncogenes often lead to cancer. Why does a person inherit a risk for cancer but does not actually inherit cancer? Not all people who inherit an altered gene will develop cancer. A person who inherits a mutated gene is more likely to get cancer; therefore they have an increased risk. However, they do not actually inherit the cancer, just the mutated gene CHARACTERISTICS OF CANCER CELLS Cancer cells are genetically unstable, they do not correctly regulate the cell cycle, they escape the signals for cell death and can survive and proliferate elsewhere in the body.
Accessory Organs of the Skin
Nails -Protect distal part of digits and help pry things open and pick up small objects *Nail root - growth occurs from this epithelial tissue **Becomes keratinized as they grow outward *Nail body - the visible part of the nail *Cuticle - protects nail root *Lunula - white half-moon at base result of thick layer of cells Hair Follicles -Extend from dermis through epidermis -Form from epidermal cells in hair root -Become keratinized and die as they are pushed away from root -Contracting arrector pili muscles cause "goose bumps" if frightened or feeling cold Oil Glands -Associated with hair follicles -Secrete sebum to lubricate hair and skin Sweat Glands -Some open into hair follicles, others onto skin -Assist in modifying body temperature by evaporating heat stored in the fluid
Anatomy and Physiology of Birds
Nearly every anatomical feature of a bird can be related to its ability to fly -The forelimbs are modified as wings. -Hollow, very light bones contain air cavities. -A beak has replaced jaws with teeth. -Large sternum aids attachment of flight muscles -Lobular lungs form air sacs to increase the efficiency of gas exchange. *Air sacs also lighten the body for flying. Bird anatomy -A four-chambered heart completely separates O2-rich and O2-poor blood. -Birds are endothermic, like mammals, and maintain a constant internal temperature due to metabolic heat. *Feathers also help maintain body temperature. -Birds have no bladder and excrete uric acid in a semi dry state.
Nervous Tissue
Nervous tissue contains neurons (nerve cells) and is present in the brain and spinal cord -A neuron is a specialized cell with three structures. *Dendrites - processes that that conduct signals toward the cell body *Cell body - contains the cytoplasm and nucleus *Axon - a process that conducts nerve impulses away from the cell body **May have myelin sheath to increase speed Neuroglia -Outnumber neurons nine to one -Support and nourish neurons -Four types in the brain ( do not memorize this) *Microglia: engulf bacterial and cellular debris *Astrocytes: provide nutrients *Oligodendrocytes: form myelin sheaths *Ependymal cells: line fluid-filled spaces of brain and spinal cord
Nonvertebrate Chordates
Nonvertebrate chordates do not develop a vertebral column from the notochord -Lancelets (subphylum Cephalochordata) *knife-shaped bodies a few centimeters long *live in shallow coastal waters *retain all four chordate characteristics as an adult *segmentation is present -muscles are segmentally arranged -nerve cord has branches
Epithelial Tissue
On external surfaces, epithelial tissue protects the body from injury, drying out, and possible invasion by microbes. On internal surfaces, epithelial tissue carries out both protective and specific functions. Glandular epithelium secretes a product Gland - can be single or multiple cells Exocrine glands - secrete products into ducts Endocrine glands - secrete product into bloodstream *Pancreas is both an exocrine and endocrine gland
Law of Segregation
On the basis of his studies Mendel formulated the LAW OF SEGREGATION, which states that each individual has two factors for each trait, which separate during formation of the gametes and each gamete contains only one factor from each pair of factors. Fertilization gives each new individual two factors for each trait.
Control of Gene Expression
Only certain genes are active in cells that perform specialized functions, such as nerve, muscle, gland, and blood cells. The activity of selected genes accounts for the specialization of cells. Gene expression is controlled in a cell, and this control accounts for its specialization
Sex Linked Inheritance
Out of 23 pairs of chromosomes, 22 are called AUTOSOMES and the 23rd pair is the SEX CHROMOSOMES, so named because they differ between the sexes. In humans, males have the sex chromosomes X and Y, and females have two X chromosomes. Traits controlled by genes on the sex chromosomes are said to be sex-linked . The Y chromosome from the father often does not carry an allele for a trait found on the X chromosome. SEX-LINKED ALLELES When considering X-linked traits, the allele on the X chromosome is shown as a letter attached to the X chromosome. PEDIGREES FOR SEX-LINKED DISORDERS Most sex-linked disorders are carried on the X chromosome. More males than females have the disorder because recessive alleles on the X chromosome are always expressed in males. The Y chromosome lacks an allele for the disorder. X-LINKED RECESSIVE DISORDERS OF INTEREST Color blindness, Duchenne muscular dystrophy, fragile X syndrome, and hemophilia are examples of X-linked recessive disorders.
The inheritance of a single trait
PHENOTYPE: individuals actual appearance GENOTYPE: the alleles the chromosomes carry that are responsible for that trait. A capital letter indicates a DOMINANT ALLELE and a lowercase letter indicates a RECESSIVE ALLELE. In simple dominance meanse that this allele will mask the expression of the recessive allele when they are together in the same organism (others are codominance-blood type; incomplete dominance-flower colors...) If two members of the alleic pair are the same, the organism is said to be HOMOZYGOUS. If they are different, the organism is said to be HETEROZYGOUS.
Chordates
Phylum Chordata characteristics at some time in the life cycle -Notochord - dorsal supporting rod, replaced by vertebral column during development in vertebrates -Dorsal tubular nerve cord - nerve cord containing a fluid-filled canal -Pharyngeal pouches - final development depends on the adult chordate -Most vertebrates have pharyngeal pouches only in embryonic development. -Postanal tail - extends beyond the anus
Placental Mammals
Placental Mammals are majority of mammals -Extraembryonic membranes of reptilian egg are modified for internal development. -Development occurs within the uterus. -The chorion contributes to the fetal part of placenta. -Portions of the uterine wall contribute the maternal part. -Materials are exchanged between fetal and maternal blood. Adaptations for active life on land (except marine mammals) -Limbs that allow rapid movement -Lungs expanded by rib cage and a diaphragm -Four-chambered heart -Constant internal body temperature -Body-insulating hair -Well-developed brain, enlarged due to expansion of cerebral hemispheres Differentiated teeth -Incisors and canines have cutting edges for capturing and killing prey, at the front of the mouth. -Premolars and molars chew food, on the sides of the mouth. The shape and size of teeth may be associated with food types eaten by the mammal . -Herbivore - eats vegetation -Carnivore - eats meats -Omnivore - eats both meat and vegetation Placental mammals are classified by methods of obtaining food and mode of locomotion. -Order Chiroptera: bats; wings supported by digits for flight -Order Perissodactyla: horses; long, hoofed legs for speed -Order Cetacea: whales; paddle-like forelimbs
Primates
Primates (order Primates) -Most adapted to an arboreal life (in trees) *Limbs are mobile *Hands and feet have five digits *Many have opposable thumbs and big toes (not humans) Benefits of this adaptation *Powerful and precise grip *Easier to reach food and bring to the mouth *Improves grasping and releasing tree limbs in locomotion A shortened snout allows the eyes to move to the front of the head. -Depth perception is improved. Primates active during day have the ability to see colors. -Both rod and cone cells are present. The brain gets larger and more complex as it evolves. -Increased cerebral cortex size is associated with learning, memory, thought, and awareness. -The portion of brain associated with smell shrinks. -Portions associated with sight increase. One offspring per birth interval is the norm. -More difficult to care for offspring while moving from limb to limb -Leads to extended period of juvenile dependency and emphasis on learned behavior and complex social interactions Two suborders exist. -Strepsirhini (lemurs, aye ayes, bush babies and lorises) -Haplorhini (monkeys, apes and humans
Body Cavities and Body Membranes
Referring to anatomical parts of humans, certain standard terms are used based on the upright position (standing position) -Ventral or anterior refers toward the front -Dorsal or posterior refers toward the back -Superior means toward the head -Posterior means toward the feet -Medial is closer to the body midline -Lateral is away from the body midline Human body divided into cavities -Ventral Cavity or Coelom *Thoracic cavity Lungs and heart -Abdominal cavity *Separated from thoracic cavity by diaphragm *Stomach, liver, spleen, gallbladder, and most of the small and large intestines -Pelvic cavity *Bladder, rectum, internal reproductive organs Dorsal Cavity -Cranial cavity - within the skull *Contains the brain -Vertebral canal - made of the vertebrae *Contains the spinal cord
Vertebrates: Reptiles and Mammals Reptiles: Amniotic Egg
Reptiles (class Reptilia) -Extinct reptiles include mammal-like reptiles and dinosaurs -evidence suggests birds are "living dinosaurs" -today's reptiles include turtles, alligators, snakes, lizards, and birds.
We Can Observe Selection at Work
Researchers have recorded the evolution of traits in natural populations over decades. HUMANS AS AGENTS OF EVOLUTION Humans can artificially modify desired traits in plants and animals by selecting to breed individuals with preferred traits, thereby increasing the frequency of desired traits. This type of human-controlled breeding is called ARTIFICIAL SELECTION. EVOLUTION IN NATURAL POPULATIONS Recent research on the Galápagos finches demonstrates that evolutionary change can sometimes be observed within the time frame of a human life span.
Changes in Chromosome Number
Sometimes individuals are born with either too many or too few chromosomes, most likely due to nondisjunction during meiosis. NONDISJUNCTION occurs during meiosis when either the homologous pair or the sister chromatids fail to separate. DOWN SYNDROME The most common autosomal trisomy seen among humans is trisomy 21, also called Down syndrome. This syndrome has particular characteristics that are easily recognized. Persons with Down syndrome usually have three copies of chromosome 21 because the egg had two copies instead of one. CHANGES IN SEX CHROMOSOME NUMBER An abnormal sex chromosome number is the result of inheriting too many or too few X or Y chromosomes. TURNER SYNDROME Females with Turner syndrome have only one sex chromosome, an X. KLINEFELTER SYNDROME Klinefelter syndrome results when a male inherits two X chromosomes and one Y chromosome and develops severe symptoms. POLY-X FEMALES A poly-X female has more than two X chromosomes. JACOBS SYNDROME XYY males, who have Jacobs syndrome, can only result from nondisjunction during spermatogenesis.
Systematics
Systematics is the study of the evolutionary history of biodiversity, it is a quantitative science that uses characteristics of living and fossil organisms, or traits, to infer the evolutionary relationship among organisms. Classification= is the process of naming and assigning organisms or groups of organisms to a taxon. Taxonomy is the branch of systematic biology concerned with identifying, naming, and classifying organisms. A taxon is the general name for a group containing an organism or group of organisms that exhibit a set of shared traits). Taxonomists use several categories, taxons, of classification: species, genus, family, order, class, phylum, kingdom, and domain. Phylogenetics is the branch of systematic biology that studies the evolutionary relatedness among groups of organisms, which can be arranged in a phylogeny. Cladistics is one method phylogeneticists use to construct a phylogeny called a cladogram. Branches in a cladogram are called clades, which contain a most recent common ancestor and all its descendants. Only shared derived traits, which are shared among all individuals, define a clade. LINNEAN CLASSIFICATION VERSUS PHYLOGENETICS In many instances Linnaean classification is not consistent with new understandings about phylogenetic relationships. Therefore some phylogeneticists have proposed the International Code of Phylogenetic Nomenclature (PhyloCode), which sets forth rules to follow in naming of clades. Three Domain Classification System - A domain is a classification category higher than the kingdom. The two prokaryote groups were classified into the DOMAIN BACTERIA and the DOMIAN ARCHAEA. The DOMAIN EUKARYA contains kingdoms for all eukaryotes, including protists, animals, fungi, and plant.
Fishes: First Jaws, Then Lungs
The first vertebrates were jawless fish -They wiggled through the water and sucked up food from the ocean floor. -Today there are three groups of fish - jawless fish, cartilaginous fish, and bony fish *The two latter groups have jaws - tooth-bearing structures in the head that evolved from gill arches *Fishes are adapted to life in water **sperm and eggs released into water, fertilization external **zygote develops into swimming larval form
Gamete Formation
The gametes have only one allele for each trait in accordance with Mendel's law of segregation. ONE-TRAIT CROSSES. A PUNNETT SQUARE can be used to keep track of all the alleles in one-trait, or MONOHYBRID cross; every possible coominatiion of gamets occurs within the squares; in monohybrid testcross with the F2 generation expect a 3:1 phenotype ratio with simple dominance. THE ONE-TRAIT TESTCROSS In a TESTCROSS an organism showing the dominant phenotype, but unkown genotype, is crossed with homozygous recessive individual to determine its genotype.
DNA Replication
The process of copying one DNA double helix into two identical double helices is called DNA replication. DNA replication is termed semiconservative because a new double helix has one conserved old strand and one new strand. Messenger RNA DNA serves as the template for messenger RNA (mRNA), which carries the informatiON from DNA to the ribosomes in the cytoplasm. Transfer RNA Transfer RNA (tRNA) transfers amino acids to the ribosomes to form proteins
Gene Expression
The process of using a gene sequence to synthesize a protein is called gene expression. Gene expression relies on several different forms of RIBONUCLELIC ACID (RNA) and requires two processes called TRANSCRIPTION and TRANSLATION. Transcription During transcription, a segment of the DNA called a gene serves as a template for the production of an RNA molecule. Messenger RNA The purpose of messenger RNA (mRNA) is to carry genetic information from the DNA to the ribosomes for protein synthesis. TRANSLATION Translation is the second process by which gene expression leads to protein synthesis. THE GENETIC CODE The genetic code is a triplet code and each triplet of nucleotides is called a codon. The genetic code is just about universal in all living organisms. RIBOSOMES Ribosomes are composed of many proteins. A ribosome moves down the mRNA molecule producing a protein. TRANSLATION REQUIRES THREE STEPS The codons of an mRNA base pair with the anticodons of tRNA molecules carrying specific amino acids. The process of translation must be extremely orderly so the amino acids are sequenced correctly.
Mendel's laws
The science of genetics explains the process of inheritance and also why there are variations between offspring from one generation to the next
Regions of the Skin
The skin has two regions -Epidermis *Consists of stratified squamous epithelium **Basal cells produce new cells that harden and flatten as they are pushed to the surface by cells forming underneath them. **Keratin is a protein that hardens and waterproofs cells. **Melanocytes produce the pigment melanin which provide protection against UV radiation. Dermis -Fibrous connective tissue beneath epidermis -Contains collagen fibers that help prevent overstretching and tearing. -Contains elastic fibers that maintain tension, but also stretch to allow movement. -Contains blood vessels that nourish the skin. -Contains sensory receptors for touch, pain, pressure, temperature. Subcutaneous layer -Components *Loose connective tissue *Adipose tissue which stores fat **Thermal insulation against heat loss or gain **Energy storage
Beyond Simple Inheritance Patterns
There are types of inheritance patterns other than simple dominant or recessive inheritance INCOMPLETE DOMINANCE INCOMPLETE DOMINANCE occures when the hetoerozygote is intermediate between the two homozygotes (ex. haircolor); FAMILIAL HYPERCHOLESTEROLEMIA is an incompletely dominant disorder. CODOMINANCE occurs when alleles are equally expressed in hetorozygote. MULTIPLE ALLELE INHERITANCE: even though a gene may exist in several allelic forms, each person has only two of the possible alleles. ABO BLOOD TYPES Three allels for the same gene control the inheritance of ABO blood types, they determine the presence or absence of antigens on red blood cells. POLYGENIC INHERITANCE occurs when a trait is governed by two or more genes (set of alleles). The result is a conintuos variation of phenotypes. Example=SKIN COLOR...skin color is the result of pigmentation produced by cells called melanocytes in the skin and is an example of a polygenic trait that is likely controlled by many pairs of alleles. A bell-shaped curve is a common identifying characteristic of a polygenic trait.
Junctions Between Epithelial Cells
Tight junction - forms an impermeable barrier because adjacent plasma membrane proteins actually join Gap junction - forms when two adjacent plasma membrane channels join Adhesion junction - adjacent plasma membranes do not touch but are held together by intercellular filaments firmly attached to cytoplasmic plaques
Biotechnology Products
Transgenic bacteria, plants, and animals are often called GENETICALLY MODIFIED ORGANSIMS (GMOs), and the products they produce are called BIOTECHNOLOGY products. TRANSGENEIC BACTERIA Recombinant DNA technology is used to produce transgenic bacteria, which express a cloned gene. Examples include insulin, human growth hormone, tissue plasminogen activator and hepatitis B vaccine. TRANSGENIC BACTERIA Foreign genes have been introduced into plant cells. Foreign genes transferred to cotton, corn, and potato strains have made these plants resistant to pests. TRANSGENIC ANIMALS Techniques have been developed to insert genes into the eggs of animals. Gene pharming is the use of transgenic farm animals to produce pharmaceuticals; genes that code for therapeutic and diagnostic proteins are incorporated into an animal's DNA, and the proteins appear in the animal's milk.
Nonvertebrate Chordates 2
Tunicates (subphylum Urochordata)-tunicates squirt water when their siphons are disturbed -they live in the ocean and are filter-feeders -the larva is bilaterally symmetrical and has all four chordate characteristics -adults are sessile, thick-walled, sac-like organisms *the only chordate characteristics remaining in the adults are pharynx and gill slits
Vertebrates: Fishes and Amphibians
Vertebrates (subpylum Vertebrata) have all four chordate characteristics at some time in their life history -The embryonic notochord is replaced by vertebral column with individual vertebrae -The individual vertebrae provides evidence of vertebrate segmentation (strong, jointed endoskeleton). -The skeleton also protects internal organs and is a place of muscle attachment. -Together, the skeletal and muscular systems permit rapid and efficient movement -Two pairs of appendages -High degree of cephalization and complex sense organs -Evolution of jaws provided variety of biological roles -Complete digestive tract and large coelom -Closed circulatory system -Efficient respiration from water or air -Kidneys used for excretion and water regulation -Separate sexes and usually sexual reproduction -Reproduction on land possible due to evolution of the amnion *Many reptile species and a few mammals lay shelled eggs. *In placental mammals, development occurs in the uterus.
Inheritance of Two Traits
When the homologues separate during meiosis, each gamete relieves one member from each pair of homologues. The homologues separate independently. INDEPENDENT ASSORTMENT Mendel's second law is the LAW OF INDEPENDENT ASSORTMENT. It states that after each pair of factors separates independently, all possible combinations of factors is dependent of the random arrangement of homologous pairs at the equator during metaphase I. TWO-TRAIT CROSSES A DIHYBRID genotype is when the indiviual is heterozygous in two regards. A 9:3:3:1 phenotype ratio is always expected for a dihybrid cross when simple dominance is present.