MCDB 1B Midterm Exam Biology Outline PDF

MCDB 1B Scope of Midterm Two Outline Annotation Lecture 9: Identify the level of biological organization within animals and how these systems interact with one another to sustain life. Cells organized into tissues > tissues organized into organs > organ systems > organism List four...

MCDB 1B Scope of Midterm Two Outline Annotation Lecture 9: Identify the level of biological organization within animals and how these systems interact with one another to sustain life. Cells organized into tissues > tissues organized into organs > organ systems > organism List four types of animal tissues (muscle, nervous, epithelial, and connective) and explain their overall function. -​ Epithelial tissues: Sheets of densely packed cells that are specialized to protect structures and to secrete and absorb ions and organic molecules -​ Connective tissues: Connect, surround, anchor and support for attachment, mechanical strength, or communication between cells and tissues -​ Muscle tissues: Made up of cells specialised to shorten or contract to generate force for body movement -​ Nervous tissues: Initiate and conduct electrical signals from one part of the animal’s body to another Discuss how the concept of homeostasis applies to the internal environment of animals. Homeostasis is a process that reduces the stimulus to an animal's environment by bringing the system back to a stable state in the face of a changing external environment and varying internal activity. Stimulus > sensor > control center > effector > response Compare and contrast positive and negative feedback loops and how they do or do not contribute to the maintenance of homeostasis in animals. Positive feedback loop: amplifies effects and drives process to completion, blood clotting in mammals Negative feedback: dampens effects, homeostasis - regulates the pH, internal temperature, and glucose levels of an animal's system Lecture 10: Describe the advantages and disadvantages of the major forms of nitrogenous waste generated by animals. Urea:  -​ Semi toxic allowing it to be stored in the body temporarily, less energy for excretion -​ Requires energy to synthesize in the urea cycle, more water is needed for excretion Ammonia: -​ Very soluble in water, easy to secrete in aquatic environments, minimal energy to produce -​ Highly toxic and requires large amounts of water for dilution, must be continuously excreted Uric Acid: -​ Insoluble in water allowing excretion as a paste and aiding in water conservation, non-toxic and can be stored in the body without harming tissues -​ Most energy required to produce, can lead to metabolic disorders without proper excretion Describe the general processes of filtration, reabsorption, secretion, and excretion. Filtration: filtering of blood to form a solution (filtrate) Reabsorption: reclaiming valuable solutes and water from the filtrate to the blood Secretion: adding additional nonessential solutes and waste from blood to filtrate Excretion: filtrate containing nitrogenous waste released by the body as urine Recognize common structural and functional features of mammalian kidneys. Renal artery, Renal cortex, Renal medulla, Nephron ** Nephron: -​ Function: filtration, reabsorption, secretion -​ Structure: Renal Corpuscle (site of filtration), renal tubule and collecting duct (reabsorption and secretion) Lecture 11: Describe how the structural features of different parts of the nephron relate to specific functions in the formation of urine. Renal Corpuscle (site of filtration): -​ Filtration; blood fluids = source for urine to create filtrate Renal tubule -​ Made of proximal tubule, loop of henle and distal tubule -​ Site of secretion (transports extra toxins into urine) and reabsorption (returns materials back to blood) -​ Proximal tubule: reabsorbs useful solutes from initial filtrate to the blood, helps regulate blood pH  -​ Loop of Henle (descending and ascending limb): creates a solute concentration gradient from cortex to medulla, reabsorbs additional water and ions from filtrate to blood using the countercurrent multiplication system -​ Ascending Limb: not permeable to water, passively and actively secretes NaCl -​ Descending Limb: highly permeable to water, water passively moves out -​ Distal Tubule: in cortex, fine tunes water and ion homeostasis with more reabsorption and secretion, more pH regulation with secretion of H+ and reabsorption of HCO3- Collecting Duct: site of urine processing, starts in cortex and passes through medulla, empties into ureter -​ Permeability controlled by antidiuretic hormone (ADH), when present in the blood the number of water channels (aquaporins) is increased = concentrated urine, when absent it decreases & dilutes urine Explain how and why ions and molecules move in response to concentration gradients. Ions and molecules use active transport and passive diffusion to move in response to concentration gradients. During diffusion, ions move from areas of high concentration to areas of low concentration without an energy input. During active transport, molecules move against the concentration gradient from low to high concentration, requiring an energy source. Osmosis is a specific type of diffusion that moves water molecules against a semi permeable membrane, from lower solute concentration to higher solute concentration aiming to equalize solute concentrations on both sides of the membrane. Explain how antidiuretic hormone (ADH) mediates the final composition of urine. ADH increases water permeability in the collecting ducts and distal convoluted tubule. It acts on the aquaporins which allow water into the collecting duct cells. The increase in permeability allows for reabsorption of water into the bloodstream concentrating the urine. -​ When blood osmolarity is high (e.g., when dehydrated), ADH is released to increase water reabsorption, which dilutes the blood and restores normal osmolarity. -​ Conversely, when blood osmolarity is low (e.g., after drinking too much water), ADH release is suppressed, and the kidneys excrete more diluted urine to restore balance. Lecture 12: List three types of muscle tissue found in vertebrates, and describe where they are found in the body. Skeletal muscle: moves bones and maintains posture -​ Attached to bones by tendons, found in limbs face and neck  Smooth muscle: controls movement of substances through internal organs -​ Found in hollow organs; airways, blood vessels, digestive tract, bladder Cardiac muscle: pumps blood through the heart -​ Found only in heart Identify the structural components of a muscle down to the level of a sarcomere. -​ Muscle fiber: a single muscle cell, made of lots of myofibrils, myofibrils made of many sarcomeres -​ Sarcomeres are made of thick (myosin) and thin (actin) cytoskeleton filaments, they are the basic contraction unit of skeletal muscles found between the two z-lines Explain the sliding filament mechanism of muscle contraction. During a muscle contraction the sarcomere gets shorter. This is done by having filaments with the molecules actin & myosin slide on each other, shortening the length of the muscle cells. -​ Thick filaments (myosin) remain stationary, while thin filaments (actin) slide, pulling on the z lines and shortening the sarcomere -​ The sliding occurs because myosin heads repeatedly grab onto actin and pull Explain how the interaction between, tropomyosin, and troponin complex, myosin, and actin help to regulate muscle contraction. -​ Regulatory proteins are bound to actin filaments, aiding in muscle contraction -​ Tropomyosin: covers the site where myosin heads bind to actin, prevent interaction between actin and myosin -​ Troponin complex: bonds to calcium to move tropomyosin off the binding sites so the actin and myosin can form cross bridges, high Ca2+ = muscle contractions, low Ca2+ inhibits contractions Describe the structural features of the neuromuscular junction and the role of acetylcholine and calcium in regulating a skeleton muscle contraction. -​ An action potential in the neuron opens voltage gated calcium channels -​ Calcium influx into the neuron causes the release of acetylcholine -​ Acetylcholine binds to receptor proteins on the muscle fiber causing a muscle action potential The NMJ is a synapse where a motor neuron communicates with a skeletal muscle fiber and initiates a muscle contraction. -​ The end of the neuron contains vesicles filled with ACh, when action potential reaches the terminal it trigger the release of ACh into the synaptic cleft -​ Synaptic cleft: a gap between the motor neuron terminal and the muscle fiber membrane, the diffusion of ACh across this space binds receptors on the muscle cell -​ Motor End Plate: contains sodium gated ion channels that allow sodium to enter the muscle cell and trigger an action potential Explore the role of the sarcoplasmic reticulum and transverse tubules in muscle contraction of skeletal muscle fibers. Structures in skeletal muscle fibers: -​ Sarcoplasmic reticulum: specialized form of endoplasmic reticulum that acts as a calcium reservoir -​ Transverse tubules: infoldings in the plasma membrane of the muscle fibers that are able to conduct action potentials Lecture 14: Explain the role of sensory receptors in detecting environmental stimuli, differentiate their types (e.g., mechanoreceptors, chemoreceptors), and describe how they transmit sensory input to the central nervous system. -​ Sensory receptors respond to specific stimuli by transmitting signals through specific pathways (axons) that the central nervous system, decodes processes and responds in a motor output 1.​ Ion channels in sensory receptors open when confronted with a stimulus 2.​ At the axon the graded response produces action potentials in the sensory receptor 3.​ The action potentials travel to the brain, interprets where they come from and their frequency Describe how mechanoreceptors in the ear detect sound and maintain equilibrium, focusing on the roles of hair cells, fluid movement, and the structures of the ear. 1.​ Outer ear funnels sound into the auditory canal 2.​ Sound waves cause the eardrum to vibrate 3.​ Movement of the eardrum (tympanic membrane) cause the bones of the middle ear to vibrate against the oval window of the cochlea, create pressure waves in the fluid inside the cochlea (travel from upper vestibular canal to the lower tympanic canal) 4.​ Waves are dissipated when they strike the round window 5.​ Waves cause the vibration of the basilar membrane  6.​ Vibrations bend the stereocilia attached to hair cells against the tectorial membrane which release neurotransmitters causing sensory neurons to send action potentials Compare the sensory pathways of hearing and equilibrium, highlighting the types of stimuli they process and how the brain interprets them for sound perception and balance maintenance Hearing: -​ Takes place in the cochlea that is composed of chambers separated by membranes, this part of the inner ear turns vibrations into electrical impulses recognized as sound -​ Inside the cochlea > basilar membrane that reads and communicates sound to the nervous system. On top is the organ of corti that contains hair cells that open sodium channels releasing an influx of sodium, generating gated potentials and action potentials Equilibrium: -​ Takes place in the vestibular apparatus made of three semicircular canals that contain different fluids which each detect a different type of head movement -​ Sacs at the base are full of hair cells that sense this fluid movement and communicate to your brain which direction your head is turned Lecture 15: Describe the anatomy of the eye and olfactory structures, explaining the roles of key components (e.g., cornea, lens, retina, and olfactory epithelium) in detecting visual and chemical stimuli Eye Structure: -​ Pupil: photons of light enter the eye -​ Retina: photons strike the retina passing through layers of neurons -​ Photoreceptors: rods and cones Olfactory Structure: -​ Olfactory epithelium: specialized tissue in the upper nasal cavity -​ Olfactory receptor neurons: detect airborne odor molecules and convert them into neural signals -​ Supporting cells: provide structural and metabolic support -​ Basal cells: act as stem cells, regenerating olfactory neurons -​ Olfactory Receptors: Embedded in membranes of receptor neurons, proteins bind odor molecules triggering a signal transduction process -​ Olfactory bulb: At base of brain, receives signals from receptor neurons and processes odor information before sending it to higher brain regions  -​ Olfactory Tract & Cortex: Signals from the bulb are relayed to the cortex as well as the limbic system Explain how the eye focuses light onto the retina and how photoreceptors convert light into neural signals. Focussing light: -​ Cornea provides the eyes refractive power, bends incoming light rays to help focus them -​ Iris adjusts the size of the pupil to control the amount of light entering the eye -​ Lens fine tunes focus by changing shape, the ciliary muscles adjust curvature -​ Retina is where images are projected at the back of the eye, light sensitive tissue Phototransduction: converting light into neural signals -​ Photoreceptors contain photopigments that when photons hit they change shape (isomerizes from cis to trans retinal) -​ Structural change causes opsin to activate transducin -​ Transducin activates phosphodiesterase which converts cyclic GMP to GMP -​ Light: less cGMP = sodium channels closed (hyperpolarized cell) -​ Dark: more cGMP = sodium channels open (depolarized cell) -​ Change in glutamate levels alters the response of bipolar cells that transmit signals to ganglion cells which generate action potentials -​ Signals sent via the optic nerve where they are processed in the visual cortex Analyze how olfactory receptors detect chemical signals and transduce them into neural signals processed by the brain -​ The olfactory epithelium is located in the epithelial tissue of the nasal cavity, each sensory neuron contains long cilia with receptor proteins that bind odorant molecules to G-proteins -​ When they bind to receptor this triggers signal transduction by G protein which converts ATP to cAMP -​ Increased cAMP opens cyclic gated sodium channels, allowing Ca and Na ions to enter the cell -​ Influx of Ca2+ further activates Cl- channels amplifying depolarization of the neuron -​ Depolarization triggers an action potential that travels along the nerve to the brain Lecture 16: Explain the processes of genetic sex determination (e.g., XX or XY) and how key players like the SRY gene, hormones, and other factors contribute to the biological spectrum of sex development Determined genetically at fertilization where the presence of an xx or xy chromosome pair sets a pathway for development. The SRY gene is the sex determining region on the Y chromosome that triggers male development by initiating the formation of testes (without SRY ovaries develop).  The Wnt4/B-catenin signaling pathway supreses SOX9 in XX gonads and promotes ovary development. It plays a repressive role in testis formation and is necessary for ovarian differentiation. The SRY gene on the Y chromosome initiates SOX9 activation, which promotes formation of testes by further regulating factors like FGF9 and PGDS Analyze how the hypothalamus, pituitary, and gonads coordinate to regulate gametogenesis and reproductive cycles, emphasizing the role of hormones such as GnRH, FSH, LH, estrogen, progesterone, and testosterone -​ The hypothalamus releases GnRH promoting the anterior pituitary to release FSH and LH stimulating gonadal activity and sex hormone production -​ FSH stimulates sertoli cells to nourish developing sperm while LH triggers Leydig cells to produce testosterone and androgens -​ Testosterone inhibits hormones through feedback on the hypothalamus and pituitary Evaluate the biological spectrum of sex development and discuss the genetic, hormonal, and anatomical factors contributing to conditions like Androgen Insensitivity Syndrome (AIS) and Congenital Adrenal Hyperplasia (CAH) -​ AIS: 46,XY karyotype but are completely unresponsive to androgens like testosterone, no functional ovaries, normal/high testosterone levels but ineffective due to receptor variations -​ CAH: 46,XX enzyme differences leading to higher androgen production, genitalia may be atypical, excess androgen exposure before birth