Biology Flashcards
What are eukaryotic cell features?
- contains a true nucleus
- phospholipid bilayer membrane compartmentalizes function
- contains membrane bound organelles
What is the function of the nucleus? How is DNA organized?
Nucleus contains all genetic information
Linear DNA is wrapped around histones –> chromosome
Transcription occurs in the nucleus then exports RNA to cytoplasm through nuclear pores
Associated with centrioles
What is the function of the mitochondria? Structures? Evolution?
Generation of ATP
Structural components are an outer and inner membrane (convoluted for high SA) with a matrix
Thought to have evolved from prokaryotes b/c it does contain some of its own genes that replicate via binary fission
What is the function of the lysosome?
Contains hydrolytic enzymes to break stuff down and works with endosomes to transport
What is the function of the ER? Eukaryotic ribosome size?
Continuous with nuclear envelope
Rough ER: studded w/ ribosomes (protein translation)
Smooth ER: lipid synthesis and detoxification, transports to Golgi via vesicles
Ribosome 40S and 60S to form 80S combined
What is the function of the Golgi?
Post office of the cell, post-translational modifications occur here like localizing signals to cellular location or secretion
What is the function of the peroxisome?
Oxidative reactions like breakdown of fatty acids
What is the function of the cytoskeleton? What are its components?
Responsible for cell structure, shape, and transport
Microfilaments: actin! and responsible for cytokinesis
Intermediate filaments: keratin! cell adhesion, organelle anchoring
Microtubules: tubulin!
- transport pathway motor proteins (kinesin:
anterograde (away from cell body), dyenin: retrograde
(toward cell body))
- cell shape
- associated with centriole/centrosome/kinetochore for
anaphase
What is epithelial tissue?
Covers body and lines all cavities for protection with highly diverse function and multiple layers
- absorption, secretion, diffusion, filtration etc.
Ovaries are an example
What is connective tissue?
Bone, cartilage, tendon (muscle to bone), ligament (bone to bone), adipose tissue, blood
What are prokaryotic cell features? DNA?
Single celled organisms that contain no nucleus or membrane bound organelles
Transcription is done in the cytoplasm and ETC is done along the membrane
Circular DNA
What are the prokaryotic cell domains? Shape classifications?
Archaea and bacteria
Cocci (spherical), bacilli (rod), spirilli (spiral) describe cell shape
Aerobes vs. anaerobes?
Obligate aerobes: require oxygen for metabolism
Anaerobe: do no require oxygen to survive
Obligate anaerobe: cannot survive in oxygenate environments
Facultative anaerobe: can switch b/w using O and not using O
Aerotolerant anaerobe: tolerate O but doesn’t use
What is the structure of a prokaryotic cell? DNA? Ribosome?
Cell wall:
- outer barrier of cell that surrounds membrane
- responsible for structure
- associated w/ peptidoglycan
- gram-positive (purple, mostly peptidoglycan)
- gram-negative (pink/red, less peptidoglycan
Flagella:
- responsible for bacterial movement
DNA Structure:
- circular DNA
- also contains a plasmid for non-essential DNA
30S and 50S ribosomes combine to form 70S ribosome
What is binary fission? What are three types of genetic recombination for prokaryotes?
Binary fission: asexual reproduction of prokaryotic circular chromosomes
Genetic recombination: responsible for increasing diversity and evolution
- transformation: uptake from environment
- transduction: bacteriophages
- conjugation: bacterial-mating (sexual reproduction)
What are viruses? Structure? Genome?
Are acellular obligate parasites (not alive and rely on host cell machinery) that are tiny and way smaller than bacteria (can’t see on light microscope)
Structure:
- protein coat/capsid: w/ genetic material inside and a
- tail sheath/fibers: to inject genetic material into cell or
dock with cell for endocytosis
Genome:
- positive sense RNA: directly translated into proteins
- negative sense RNA: needs to synthesize
complementary strand that is translated
- retrovirus: RNA –> DNA that integrates with host
genome
What is the viral life cycle? Lytic cycle? Lysogenic cycle?
1) infection
- virus binds to receptor on cell surface
- either injects genetic material or is endocy-tosed
2) translation and progeny generation
- replicates in cell by its specific mechanism
3) release
- cell death and lysis spills virus everywhere
- or leaves through extrusion through membrane
Lytic cycle: replicates quickly and degrades host genome until it fills cell with virions and it lyses
Lysogenic cycle: integrates with host genome then gets triggered into the lytic cycle
Prions vs. virioids?
Prions: infectious misfolded proteins that can cause other proteins to misfold and can lead to aggregates
Virioid: plant pathogen
What are the cell cycle phases? Checkpoints?
1) G0: nothing happening, cell just living
2) G1 (interphase): cell growth
3) G1/S checkpoint: restriction point where cell cycle will arrest until DNA is repaired
4) S (interphase): DNA replication
5) G2 (interphase): more cell growth
6) G2/M checkpoint: another checkpoint to ensure no DNA damage
7) M (mitosis) and cell division
Proto-oncogene vs. oncogene?
Proto-oncogene: normal
Oncogene: cancerous
What are the steps of mitosis? End result?
Mitosis is the asexual division of somatic cells and results in two identical diploid daughter cells
1) interphase: preparing for division, cell growth, nuclear membrane disappears
2) prophase: chromatin condenses to chromosomes, spindle forms
3) metaphase: chromosomes line up at metaphase plate
4) anaphase: sister chromatids are pulled apart
5) telophase/cytokinesis: spindle disappears, nuclear membrane reforms, cells are separated
What are the steps of meiosis? End result?
Meiosis is the sexual division of gametocytes and results in four non-identical haploid gametes
Meiosis I
1) prophase I:
- homologous chromosomes synapse
- crossover occurs b/w homologous chromosomes
resulting in recombination
- single crossover: one part of arm, double crossover:
two parts of arm
2) metaphase I:
- homologous chromosomes line up at metaphase
plate
3) anaphase I:
- homologous pairs separate into sister chromatids
4) telophase I:
- cells are now haploid and have two sister chromatids
- two daughter cells
Meiosis II: essentially the same as mitosis where sister chromatids are separated resulting in four haploid daughter cells
What is nondisjuction?
Occurs during anaphase when chromosomes fail to separate so one cell has extra chromosomes and the other cell is missing a chromosome
X vs. Y chromosome? Male/female?
Male: XY
Female: XX
Y chromosome carries the SRY for testis
One X chromosome on a female is inactivated, both replicate but one replicates last
What is the male reproductive anatomy?
S emineferous tubules:
- sperm production (sertoli cells)
- testosterone proudction (leydig cells)
- located in the testes that are in the scrotum
E pididymis: sperm is stored here
V as deferens: sperm travels through here
Ejaculatory duct: sperm exits here
U rethra: sperm enters here to carry through penis
P enis: and out of the body
Sperm is nourished by seminal fluid = semen
Midpiece contains a lot of mitochondria for flagellal movement
What is the spermatogenesis process? When does it start?
Starts at puberty in the seminiferous tubules and produces cells of equal size
Spermatagonia –> primary spermatocyte –> secondary spermatocyte –> spermatozoa
What is the female reproductive anatomy?
Ovaries:
- produces estrogen (female characteristics) and
progesterone (endometrium stuff)
- ovulates eggs
Fallopian Tubes: cilia propels eggs forward into the…
Uterus: muscular cavity and site of fetal development
Cervix: lower end of uterus and connects to the vaginal canal
Vulva: collection of external anatomy
What is the oogenesis process? When does it start?
This whole process occurs prior to birth
Primary oocyte –> secondary oocyte –> ovum (uneven division, some have more cytoplasm than others)
What is the menstrual cycle?
1) folicular phase:
- sheds previous uterine lining
- increased FSH and LH and estrogen
2) ovulation:
- LH surge triggers ovulation
4) luteal phase:
- increased progesterone inhibits secretion of FSH, LH, and GnRH
5) menstruation:
- uterine lining sloughs off and GnRH is no longer
inhibited
OR
5) pregnancy:
- fertilization occurs, detected by hCG
6) menopause:
- results with loss of sensitivity to hormones causing ovarian atrophy
What are the three different types of cell junctions?
Desmosome: anchors cytoskeleton
Gap junction: cell-cell communication
Tight junction: direct connection, no leakage
What are the early developmental stages of a fetus?
Fertilization:
- occurs in the ampulla: wides part of fallopian tube
- sperm penetrates into egg forming a unicellular
zygote
- dizygotic/fraternal: two eggs by two sperm
- monozygotic/identical: one zygote splits into two
Cleavage:
- occurs during travel from fallopian tube to uterus
- undergoes rapid cell division (now considered an
embryo)
Blastulation:
- after division embryo is a mass of cells: morula
- morula develops into a hollow ball of cells: blastocyst
Implantation:
- in endometrium of uterus
- now connected to the placenta via umbilical cord
Gastrulation:
- germ layer formation
- selective transcription is responsible for differentiation
Neuralation:
- neural tube: CNS
- neural crest: PNS
What are the different germ layers?
ectoderm: skin and nervous system, adrenal medulla
mesoderm: circulatory, muscoskeletal, and excretory system (kidney here), adrenal cortex
endoderm: lining of internal organs
What are features of fetal circulation? Affinity? Arteries/veins?
Fetal hemoglobin has higher affinity for oxygen than adult hemoglobin
Umbilical artery: flows away from fetal heart and towards placenta (deoxygenated)
Umbilical vein: flows towards fetal heart from placenta (oxygenated)
Undifferentiated vs. totipotent vs. pluripotent vs. multipotent cells?
Undifferentiated: stem cells (self-renewal) have ability to differentiate into any cell
Totipotent: can differentiate into any cell type
Pluripotent: can differentiate into cells of any germ layer
Multipotent: can differentiate into cells of one germ layer
What are the three kinds of cell-cell signals?
Autocrine: act on same cell it was secreted from
Paracrine: acts of cells in local area
Endocrine: hormones travel through blood to distant tissue
What tissues types are regenerative?
Liver
Kidney to a certain degree
What are telomeres?
Highly repetitive sequences at the end of DNA that shorten with every round of replication
What is the function of a neuron? Structure?
Transmit electrical impulses then translated to chemical signals
Dendrites: receive incoming signals
Cell body/soma: houses nucleus
Axon hillock: integrates signals and site of action potential
Axon/myelin: propagates signals and insulates for better conduction (CNS: oligodendrocyte, PNS: schwann cells)
Synaptic cleft: area b/w pre/post synaptic neuron where neurotransmitters diffuse across
What is the function of other nervous system cells? Astrocyte? Ependymal? Microglia?
Astrocyte: maintains blood-brain barrier
Ependymal: maintains CSF
Microglia: immune system for the nervous system
What is the resting potential?
A negative potential difference (inside is negative, outside is positive) Na on the inside, K on the outside
Na/K ATPase establishes the equilibrium and leak channels maintain it
What is an action potential, steps?
An all or nothing impulse (when reaches threshold potential) starting from the axon hillock sent down axon and to synapse
Excitatory impulse causes voltage gated channels
1) increased permeability to Na, so Na channels open and influx (causes depolarization)
2) Na channels inactivate and K channels open
3) K efflux and repolarization
4) K stays open open too long so hyperpolarizes (refractory period: absolute is no firing, relative is firing if big stimulation beyond previous)
5) Na/K ATPase reequilibrates
What is the affect of length and area on conduction?
Increased length = increased resistance = decreased conduction
Increased area = decreased resistance = increased conduction
How are neurotransmitters released into the synapse after an action potential? How are they cleared?
Action potential causes the release of calcium which triggers exocytosis of neurotransmitter filled vesicles, neurotransmitters diffuse across synapse and bind to receptors
Neurotransmitters can be cleared by reuptake, enzymatic breakdown, or diffusion out of the synapse
What is the nervous system organization?
Nervous system is divided into the CNS and PNS
CNS is divided into the brain and spinal cord
PNS is divided into autonomic and somatic branches
Somatic branch is responsible for sensory and motor functions (voluntary)
Autonomic (involuntary) branch is divided into sympathetic (fight/flight) and parasympathetic (rest/digest)
Sensory vs. motor vs. interneurons?
Sensory neurons are also afferent neurons and send signals from receptors to the spinal cord and brain
Motor neurons are also efferent neurons and send signals from the brain and spinal cord to muscles/glands
Interneurons are the most abundant and connect all neurons
White matter vs. grey matter?
White matter: myelinated
Grey matter: cell body/unmyelinated parts
What are the vertebral divisions of the spinal cord?
Brain –> brain stem –> cervical –> thoracic –> lumbar –> sacral
Protected by the vertebral column
White matter outside, grey matter inside
Cell body in the DRG
What is the fight/flight response?
Increased HR, BG, bronchodilation, vasoconstriction, pupillary dilation
What is the reflex arc?
Happens at the level of the spinal cord instead of impulses traveling all the way to the brain
Like the knee jerk
How does the endocrine system work? Endocrine vs. exocrine glands?
Endocrine glands secrete hormones into the bloodstream that then travel to distant tissue where they bind to receptors inducing a change
Endocrine gland: secrete directly into bloodstream (ductless)
Exocrine gland: secrete into a duct first
Peptide vs. steroid hormones?
Peptide:
- amino acids
- packaged into vesicles and released by exocytosis
- polar/charged so cannot diffuse through membrane
so bind extracellular receptors and triggers a second
messenger/signal cascade
- b/c they are polar they are soluble in bloodstream
- rapid/short lived affect
Steroid:
- cholesterol derivative
- non-polar so can diffuse through membrane so bind
intracellular receptors
- affect comes by altering transcription of particular
genes
- b/c they are non-polar they are not water soluble so
require a carrier in bloodstream
- slow/long-lived affect
What are amino acid derivative hormones?
tyrosine derivatives
thyroid hormones, epi/norepi (catecholamines), melatonin
Direct vs. tropic hormones?
Direct hormones act directly on target tissue versus tropic hormones act through an intermediary hormone (hypothalamus hormones)
What is the hypothalamus? Location? Mechanism of action?
Function: serves as link b/w nervous and endocrine system by regulating pituitary gland via tropic hormones
Location: in forebrain above pituitary and below thalamus
Action: paracrine release into portal system that links pituitary glands
How is the posterior pituitary connected to the hypothalamus?
Connected via neurons to the hypothalamus
Oxytocin and ADH/vasopressin (posterior pituitary hormones) are synthesized in the hypothalamus but secreted by the posterior pituitary
Where are the lungs located? What is the pathway of air into the lungs?
Lungs are located in the thoracic cavity are surrounded by pleura in the pleural space
1) air enters through the nares where it is filtered by mucous membranes and hair
2) then travels into the pharynx (air and food), over the epiglottis and into the larynx (air only)
3) then travels down the trachea and into bronchi –> bronchioles –> alveoli where capillaries area
Lungs can excrete water by humidifying air!
What is the role of surfactant around the alveoli?
Surfactant reduces surface tension and prevents alveoli from collapsing
Inhalation vs. exhalation process?
Inhalation
- diaphragm contracts to expand thoracic cavity
- that causes increased volume so decreased pressure
- that negative pressure differential b/w lungs and
atmosphere forces air in (NEGATIVE PRESSURE
VENTILATION)
Exhalation
- diaphragm relaxes
- lungs decrease in volume so pressure increases
- that forces air out
Total lung capacity? Residual volume? Vital capacity? Tidal volume? Expiratory reserve volume? Inspiratory reserve volume?
Total lung capacity: max volume of air in lungs
Residual volume: minimum volume of air in lungs
Vital capacity: difference b/w TLC and RV
Tidal volume: volume of air in a normal breath
ERV: volume of additional air that can forcibly exhaled after normal breath
IRV: volume of additional air that can be forcibly inhaled after normal breath
How is breathing regulated?
Chemoreceptors sensitive to CO2 concentration and pH buffering
CO2 + H2O <> H2CO3 <> HCO3- + H+
H2CO3 = carbonic acid HCO3 = bicarbonate
What are the four functions of the respiratory system?
1) gas exchange
2) thermoregulation
3) immune function
4) pH control
What is the immune function of the respiratory system?
Nasal cavity hairs trap pathogens and contain lysozymes that break down peptidoglycan (bacteria)
Mucus lines airways and can trap pathogens for expulsion or swallowing to digestion
Alveoli contains macrophages
What is the pathway of blood through the cardiovascular system?
1) deoxygenated blood flows through the SVC and IVC into the RA
2) RA fills into the RV via the tricuspid AV valve
3) RV pumps blood to lungs via pulmonary artery and through semilunar valve
4) blood oxygenates in the lungs and returns via pulmonary vein to LA
5) LA fills into LV via bicuspid/mitral/AV valve
6) LV pumps blood to aorta through semilunar aortic valve
R side is pulmonary circulation
L side is system circulation
What is the electrical conduction pathway of the heart?
1) starts at the SA node in the RA
2) depolarization causes both atria to contract simultaneously
3) signal reaches the AV node where it is delayed to allow ventricles to fill completely
4) AV node signal travels down the bundles of His and Purkinjie fibers that distributes signal to ventricles
- intercalated discs have gap junctions for coordinated contraction
Vagus nerve supplies parasympathetic signal
What is systole vs. diastole in contraction? What is cardiac output equation?
Systole: ventricular contraction / closing of AV valves to pump out blood
Diastole: ventricular filling / closing of semilunar valves
BP is systole / diastole
CO = HR⋅SV
Arteries vs. arterioles vs. capillaries vs. venules vs. veins? What are portal systems?
Blood flow travels arteries –> arterioles –> capillaries –> venules –> veins
Arteries: pumps blood away from heart, is highly muscular and elastic so has high resistance and high pressure to overcome
Arterioles: connect arteries and capillaries
Capillaries: single endothelial cell layer makes for easy diffusion to perfuse tissues (most area so least resistance)
Venules: connect capillaries to veins
Veins:
- lowest pressure
- returns blood to the heart
- less muscular and elastic so can accommodate more
volume
- valves prevent back flow
- surrounded by skeletal muscle that supplies force on
movement to push blood to heart
Portal systems: blood travels through two capillary beds instead of just one before returning to heart (liver, hypothalamus, kidney)
What is the composition of blood? Different cell types?
Liquid/plasma (with nutrients, salts, gases, hormones, proteins)
Cells
- erythrocytes (RBC’s): oxygen transport from
hemoglobin, lack organelles (nucleus, mitochondria
etc.) so there’s room for hemoglobin
- leukocytes (WBC’s): granulocytes and agranulocytes
- thrombocytes (platelets): blood clotting
Cells are synthesized from hematopoetic stem cells in bone marrow
What are blood antigens? Allelic dominance? Rh factor
Blood antigens are surface proteins expressed on RBC’s that serve as targets for the immune system
A & B: co-dominant
O: recessive
O is universal donor and AB is universal recipient
Rh factor is another surface protein where (+) is dominant to (-), plays an important role maternal-fetal circulation as during birth that blood can mix and trigger an immune response
Oxygen vs. carbon dioxide carried in blood?
Oxygen is carried by hemoglobin, a four subunit, cooperative binding protein)
Carbon dioxide is transported in blood as bicarbonate
In oxygenation graph (partial pressure, pH) what does a left and right shift mean?
Left shift = high affinity
Right shift = low affinity (dumps oxygen into tissues)
What is hydrostatic vs. osmotic pressure?
Hydrostatic: same as blood pressure, pushes fluid out of vessels
Osmotic: results from solute concentrations, pulls fluid into vessels
Innate vs. adaptive immune system?
Innate: non-specific, always active against infections but doesn’t target specific pathogens
Adaptive: specific, targets a specific pathogen
- humoral: antibodies
- cytotoxic cell-mediated: t-cell destruction
What is the function of the bone marrow? Spleen? Thymus? Lymph nodes in the immune system?
Bone marrow: produces erythrocytes, thrombocytes, leukocytes (WBC’s) via hematopoesis
Spleen: storage of B cells/antibodies
Thymus: responsible for T-cell development that is involved in cell-mediated immunity (adaptive/humoral)
Lymph nodes: where immune cells start attack from
What’s the function of the skin, respiratory system, GI tract as non-cellular and non-specific defense?
Skin: acts as a physical barrier to pathogens
Respiratory system: pathogens can be trapped and expelled or digested
GI tract: stomach acid can kill most pathogens, also is populated by gut microbiota which prevents pathogen colonization
What’s the function of macrophages, natural killer cells, and granulocytes as cellular and non-specific defense?
Macrophages:
1) phagocytizes (eats) invader via endocytosis
2) digests invader w/ enzymes
3) surface antigen presentation for adaptive immune system recognition
4) cytokine release
Natural Killer Cell: initiates apoptosis of infected cells
Granulocytes:
- neutrophils: phagocytic
- eosinophils: histamine
- basophils: mast cells
What is humoral immunity? What cell produces antibodies? Antibody structure? Antibody function?
Associated with antibodies that are produced by B-cells in the bone marrow
Antibodies are Y-shaped with the tip being the variable region (antibody binding area because it’s specific)
Antibodies attract macrophages, clump pathogen together, and block their ability to invade tissues
What is cytotoxic immunity? What structure develops T-cells? What are the different types of t-cells?
T-cells are synthesized in the thymus
helper t cells: coordinate and recruit other immune cells
cytotoxic t-cells: kill infected cells
suppressor/regulatory t-cells: dampen immune response after infection is gone
memory t-cells: for next infection
What is autoimmunity?
Normally self-recognizing (to body’s own antigens) immune cells are destroyed
But when the immune system fails to recognize self-antigens it attacks them as if they are foreign particle/pathogen
Active vs. passive immunization?
Active: immune system is stimulated to produce antibodies by injection of weakened or killed antigens (vaccine) note for vaccine that it should not target a general function or it will be toxic, target something unique to pathogen so it affects pathogen only
Passive: a transfer of antibodies to individual (think maternal/fetal)
What is the function of the lymphatic system?
Circulates lymphatic fluid
Associated with immune system in pathogen exposure
Fluid distribution
Fat transport
Lymph ducts drain into veins! and interstitial fluid is b/w lymph capillaries and veins
Mechanical vs. chemical digestion?
Mechanical: physical breaking of large particles into smaller particles
Chemical: enzymatic cleavage of chemical bonds
What is the pathway of food through the GI system?
1) oral cavity: chewing and salivary lipase
2) pharynx: which directs food to epiglottis and into
3) esophagus: connects pharynx with stomach, food moves down through peristalsis and past sphincter
4) stomach: then through pyloric sphincter to..
5) small intestine
6) large intestine
7) rectum
What is the role of the stomach in digestion? pH environment? Enzymes?
Highly acidic environment with pepsin used to digest food
Stomach is also protected by a thick mucus lining to prevent autodigestion
What is the role of the small intestine? pH environment? Enzymes? What are its parts? How does nutrient absorption work?
Basic environment with trypsin to digest but is mostly for nutrient absorption
Duodenum: chemical digestion
Jejunum: absorption
Ileum: absorption
Villi and microvilli increase surface area of epithelial cells that are connected to capillaries
What is bile? Role in digestion? What is bilirubin?
Bile is a cholesterol derivative
It has hydrophobic and hydrophilic regions so emulsifies fats and cholesterol into micelles so they are water-soluble
Bilirubin is a bile pigment that is processed and excreted by liver also is a hemoglobin byproduct
What is the role of the pancreas in digestion?
It synthesizes and releases many digestive enzymes directly to the small intestine
- amylase, peptidase, lipase
What is the role of the liver?
Produces bile to store in the gallbladder or secrete directly to small intestine
Also processes blood from the abdomen for detoxification
Produces albumin (blood carrier protein) and clotting factors
Is also involved in sugar and fat storage (so regulates BG levels and oncotic pressure)
What is the role of the gallbladder?
It functions for bile storage
The common bile duct connects the liver, gallbladder, and small intestine
What is the role of the large intestine? Parts?
Functions for water reabsorption
Consists of the cecum, colon, and rectum
What is the first step in nephron function?
Filtration
- blood from the glomerulus is filtered into Bowman’s
capsule
- that occurs because hydrostatic pressure in the
glomerulus is high
- no proteins or cells should be in filtrate
What is the pathway through the nephron? Where are the structures located?
Proximal convoluted tubule
- filtrate enters here after filtration
- amino acids, glucose, vitamins, salts are reabsorbed
- H+, urea, NH3, K+ is secreted into filtrate
Descending loop of Henle
- only permeable to water moving out
Ascending loop of Henle
- only permeable to salts moving out
Distal convoluted tubule
- More reabsorption of salts and water
- More secretion of H+, K+, and NH3
Collecting duct
- concentrates urine through water reabsorption
Tubules are located in the cortex
Loops and collecting duct are located in the outer medulla (upper), inner medulla (bottom)
What are the two main hormones that regulate blood pressure? Mechanism?
Aldosterone: secreted by the adrenal cortex and acts on the DCT and collecting duct
- reabsorb Na+ so water follows
- K+ secretion
- responds to low BP
ADH/vasopressin: secreted by the posterior pituitary and acts on the collecting duct
- directly reabsorb more water via aquaporins
- responds to high plasma osmolarity
What are the layers of the skin?
Epidermis
- outermost layer
- merkel discs: respond to light touch
- innervated by nerves
Dermis
- middle layer
- meisner corpuscle: respond to vibration + pressure
- innervated by nerves
Hypodermis
- inner layer of connective tissue
How does thermoregulation through the skin work?
Sweating
- evaporation of water (sweat) absorbs body heat for
cooling
- so vasodilation for more evaporative cooling
Can excrete water!
Skeletal muscle vs. smooth muscle vs. cardiac muscle? In terms of voluntary, nucleated, striated?
Skeletal muscle: - voluntary (somatic NS) - striated (actin and myosin arranged into sarcomeres) - troponin is involved - multinucleated Slow twitch: - aerobic (oxidative) - high myoglobin and mitochondria Fast twitch: - anaerobic (non-oxidative, so glycolysis only instead) - less myoglobin and mitochondria
Smooth muscle:
- involuntary (autonomic NS)
- not striated
- mononucleated
Cardiac muscle
- involuntary (autonomic NS)
- striated
- troponin involved
- mononucleated
- intercalated discs w/ gap junctions
What is the sarcomere?
The contractile unit of muscle made of up of a thick filament: myosin, and a thin filament: actin, troponin, tropomyosin
What is the muscle contraction cycle? MEPP, powerstroke? How does relaxation occur?
MEPP:
1) motor neuron sends signal to muscle via NMJ
2) acetylcholine is released into synapse and binds to receptors on sarcolema causing depolarization across t-tubules
3) signal reaches SR and Ca is released
4) Ca binds to troponin causing tropomyosin to shift revealing the myosin binding site on actin
Powerstroke:
1) Hydrolysis of ATP bound to myosin to ADP + Pi recocks myosin head
2) Myosin binds to actin
3) ADP + Pi is released and powerstroke occurs
4) ATP binds to myosin detaching it from actin
Relaxation:
1) acetylcholine is degraded
2) sarcolema repolarizes
3) Ca release ceased and reuptake occurs
4) myosin binding sites re-covered
What is tetanus?
When frequent muscle contractions occur so there is no muscle relaxation
Tendon vs. ligament?
Tendon: muscle to bone
Ligament: bone to bone
Osteoclast vs. osteoblast?
Osteoclasts chew bone and releases calcium
Osteoblasts build bone and uses calcium
What is the growth plate?
Area filled with mitotic cells that contribute to growth but past puberty the growth plates are closed
Genotype vs. phenotype?
Genotype: genetic combination of alleles
Phenotype: observable traits
Complete dominance vs. co-dominance vs. incomplete dominance?
Complete dominance: normal, one dominant and one recessive allele where the dominant masks the recessive
Co-dominance: both alleles are expressed simultaneously
Incomplete dominance: express a mixture of both alleles
Penetrance vs. expressivity?
Penetrance: the proportion of population w/ a given genotype who actually express the phenotype
Expressivity: different manifestations of the same genotype across population (think diseases)
What is the key factor in evolution and adaptation that precedes it?
Diversity and variation also that evolution and adaptation is a population-level affect
Point mutation vs. frame shift mutation?
Point mutation: one nucleotide swap for another
- silent: no effect on final protein b/c of degeneracy/3rd
pair wobble
- missense: one amino acid substitution in final protein
- nonsense: results in a premature stop codon (UAA,
UGA, UAG)
Frameshift mutation: an insertion or deletion of a nucleotide results in a shift of the three codon reading frame
Genetic leakage vs. genetic drift?
Leakage: gene flow b/w species that can result in hybrid offspring
Drift:
- changes in composition of gene pool due to chance
- these changes will be more pronounced and have
greater effect in smaller populations
- founder effect: small population finds itself in isolation
and inbreeding occurs (which increases likelihood for
recessive disease in offspring)
- generally causes a reduction in genetic diversity so
decreased fitness
What is important to know about x-linked diseases? mitochondrial diseases?
X-linked diseases are much more common in males b/c they are XY (so any recessive disease will do it)
Mitochondrial/cytoplasmic diseases exhibit maternal transmission
What is the Hardy Weinberg equilibrium equation? Assumptions?
p^2 + 2pq + q^2 = 1 and p + q = 1
p^2 = homozygous dominant 2pq = heterozygous dominant q^2 = homozygous recessive
1) large population
2) no mutations
3) random mating
4) no migration
5) genes are equal
What is natural selection?
Organisms produce offspring and some chance variations w/ in individuals may be heritable, those individuals w/ more favorable variations are more likely to survive and reproduce
POPULATIONS EVOLVE NOT INDIVIDUALS
Stabilizing vs. directional vs. disruptive selection?
Stabilizing: selection towards the middle
Directional: selection towards an extreme
Disruptive: selection away from the middle and for two extremes (separate)
What is speciation?
Formation of new species through evolution
Divergent vs. parallel vs. convergent evolution?
Divergent: independent development of dissimilar characteristics in two or more lineages sharing a common ancestor (finches) / adaptive radiation
Parallel: related species evolve in similar ways for a long period of time
Convergent: independent development of similar characteristics in two or more lineages not sharing a common ancestor (dolphins/sharks)
Analogous vs. homologous structure?
Analogous: structures with same function
Homologous: structures with different function
What is an imprinted gene?
Genes expressed in parents in a specific manner
How to analyze a pedigree?
Male = square Female = circle Highlighted = affected
1) determine if sex-linked or autosomal
- if x-linked recessive or y-linked it will be in males only
2) determine dominant or recessive
- dominant: appears in every generation, and the union
of two affected can have unaffected offspring
- recessive: skips generations, union of two unaffected
can have affected offspring
