Kaplan Biology Unknown Concepts Flashcards
Why are viruses not living according to cell theory?
acellular, cannot reproduce without assistance from a host cell, and may use RNA as their genetic material
What are the main differences between eukaryotes and prokaryotes?
Eukaryotes
- membrane-bound organelles, a nucleus, and may form multi-cellular organisms
Prokaryotes
- do not contain membrane bound organelles; genetic material in single circular molecule of DNA located in nucleoid region
- smaller ribosomes, carry out ETC in their cell membranes
- divide via binary fission
What is the purpose of nucleolus?
synthesizes rRNA which make up ribosomes
What is the purpose of rough vs. smooth ER?
rough = continuous with nuclear envelope, studded with ribosomes to translate proteins destined for secretion
smooth = lipid + carbohydrate synthesis and detoxification
connects with Golgi: modified, packaged, and directed to locations
What do peroxisomes do?
contain hydrogen peroxide that breaks down long FA chains via B-oxidation
phospholipid synthesis + pentose phosphate pathway
What are the differences between microfilaments, microtubules, and intermediate filaments?
microfilaments: actin; structural protection for the cell
- cause muscle contraction with myosin
- form cleavage furrow during mitosis
microtubules: tubulin; pathways for motor proteins like kinesin and dynein to carry vesicles
- structure of cilia and flagella
- centrioles organize them to make mitotic spindle
intermediate: cell-cell adhesion; anchor organelles
- keratin, desmin
What are characteristics of epithelial tissues?
cover the body and line its cavities
- protect against invasion, absorption, secretion, sensation
- form parenchyma = functional part of organ
- polarized
What are the classes of epithelial tissues?
simple epithelia: 1 layer
stratified: many layers
pseudostratified: appear to have many, but have1 layer
cuboidal
columnar
squamous
What are the characteristics of connective tissue?
support the body and provide framework for epithelial cells
- form the stroma = support structure by secreting materials to form ECM
- bone, cartilage, tendons, ligaments, adipose, blood
What are the two domains of prokaryotes?
archaea: extremophiles, often use chemical sources of energy rather than light
- similarities to eukaryotes: start translation with methionine, similar RNA poly, histones
- similarities to bacteria: single circular chromosome, divide by binary fission
bacteria
What are the shapes of bacteria?
cocci: spherical
bacilli: rod
spirilli: spiral-shaped
How are bacteria classified through their metabolic processes?
1) Obligate aerobes: require O2
2) Facultative anaerobes: survive in environments with or without O2 and will toggle between metabolism
3) Aerotolerant anaerobes: cannot use O2 for metabolism, but can survive
4) Obligate anaerobes: can only carry out anaerobic metabolism, can’t survive in O2
How are bacteria classified by their cell walls?
Gram+ = thick cell wall composed of peptidoglycan and lipoteichoic acid
- PG, inner membrane
- purple
Gram - = thin cell wall composed of peptidoglycan and outer membrane containing phospholipids and lipopolysaccharides
- outer membrane, PG, inner membran
- red
What is chemotaxis?
have flagella that generate propulsion to move toward food or away from immune cells
What are plasmids?
carry extrachromosomal genetic material; may contain antibiotic resistance genes or virulence factors
plasmids can integrate into the genome are called episomes
How do bacteria undergo genetic recombination?
1) transformation: genetic material from the surroundings is taken up by the cell
2) conjugation: transfer of plasmid from one bacterium (F+) to another (F-) across a conjugation bridge (sex pilius) or part of genome from Hfr to a recipient (now can initiate)
3) transduction: bacteriophage vector
What are the phases of bacterial growth?
1) lag phase: adapt to new environment
2) exponential phase: exponential increase in growth
3) stationary phase: resources reduced, growth levels off
4) death phase: resources depleted
Describe viruses.
1) contain genetic material, protein coat (capsid), sometimes lipid containing envelope
- single or double stranded DNA or RNA
- ssRNA can be + sense that can be translated by host cell or -, which required complementary strand via RNA replicase
2) obligate intracellular parasites
What are retroviruses?
contain ssRNA genomes from which complementary DNA strand is made using reverse transcriptase, which can be integrated into the genome
- HIV
How do viruses infect?
attaching to specific receptors, then enter by fusion with plasma membrane (endocytosis) or can inject their genome into the cell
What are the two lifecycles of bacteriophages?
lytic: produce massive numbers of new virions until the cell lyses
- “virulent”
lysogenic: virus integrates into the host genome, which reproduces along with the cell
- can enter lytic cycle in response to stimulus
What are prions? viroids?
prions: infectious proteins that trigger misfolding of other proteins; decrease solubility
viroids: plant pathogens and are small circles of RNA that can turn off genes
What are the five stages of the cell cycle?
G0: perform functions without preparing for division
G1: create organelles for energy and protein production, increase size
- checkpoint
S: DNA is replicated; sister chromatids = identical copies of each other
G2: cell growth and replication of organelles
- checkpoint
M: mitosis and cytokinesis occur, producing two genetically identical daughter cells
p53 = main checkpoint protein
What is the role of cyclins and and cyclin-dependent kinases (CDKs) in the cell cycle?
cyclins bind to CDKs, phosphorylating and activating transcription factors for genes required for next phase of the cell cycle
What are the 4 phases of mitosis?
1) prophase: chromosomes condense, nuclear membrane dissolves, nucleoli disappear, centrioles migrate, spindle apparatus begins to form
2) metaphase: chromosomes line up on metaphase plate
3) anaphase: sister chromatids separate
4) telophase: nuclear membrane reforms, spindle apparatus gone, cytosol and organelles split through cytokinesis
What happens in meiosis?
1) prophase I: homologues come together and intertwine during synapsis (4 chromosomes = tetrad), crossing over
- Mendel’s second law of Independent Assortment = inheritance of one allele has no effect on the likelihood of inheriting alleles for other genes
2) metaphase I: homologous chromosomes line up on opposite sides of metaphase plate
3) anaphase I: homologues pulled to opposite poles of cell
- Mendel’s first law of Segregation = one allele of each gene
4) telophase I: two sister chromatids; each cell is haploid (23 in humans)
meiosis II = sister chromatids separated, same as mitosis, producing 4, nonidentical sex cells
What do Sertoli cells and Leydig cells do in men ? How are they stimulated?
GnRH from the hypothalamus causes FSH and LH release
Men
FSH–Sertoli: nourish sperm
LH–Leydig: secrete testosterone
Women
FSH–development of ovarian follicles
LH–causes ovulation
stimulate production of estrogen and progesterone
What is the pathway of sperm through the male reproductive system?
SEVEN UP
seminiferous tubules–>epididymis–>vas deferens–>ejaculatory duct–> nothing –> urethra –> penis
List the order of names in developing sperm.
spermatogonium –> primary spermatocytes –> secondary spermatocytes –> spermatids –> spermatozoa
Pathway of an ova.
produced in follicles in the ovaries–>fallopian tube during ovulation–>uterus
Describe oogenesis in females.
at birth, all oogonia have undergone replication and are considered primary oocytes
- arrested in PROPHASE I
the ovulated egg is a secondary oocyte, arrested in metaphase II
fertilization completes meiosis II
Describe the menstrual cycle.
periodic growth and shedding of the endometrial lining.
1) follicular phase: FSH and LH secretion, follicle develops; estrogen is released to thicken endometrium
2) ovulation: sudden surge in LH when estrogen hits certain level, releasing ovum
3) luteal phase: LH causes the ruptured follicle to become corpus luteum, which secretes progesterone that maintains uterine lining
- high estrogen + progesterone
4) Menstruation: no fertilization; estrogen + progesterone drops
5) if fertilization does occur, then blastula produces hCG which maintains corpus luteum
- end of 1st trimester, placenta takes over progesterone
Describe the steps of fertilization.
1) sperm + ovum join in the ampulla of the fallopian tube
2) sperm uses acrosomal enzymes to penetrate the corona radiata and zona pellucida
3) once it contacts oocyte’s plasma membrane, sperm injects its pronucleus
4) when first sperm penetrates, Ca2+ ions are released, stopping polyspermy = cortical reaction
How do fraternal twins happen? identical?
dizygotic = fertilization of two eggs by two different sperm
monozygotic = splitting of zygote in two
What are the steps that happen after the zygote is formed?
1) cleavage: early mitotic divisions with no change in overall volume, forming morula
2) blastula forms: inner cell mass + trophoblast (placenta)–> implants into the endometrium with chorion villi
3) embryo is connected to the placenta by the umbilical cord, which has two arteries and one vein
4) gastrulation: germ layers establish
- ectoderm: epidermis, hair, nails, and epithelia of the nose, mouth, anal canal, and nervous system (lens of eye too), !adrenal medulla!
- mesoderm: musculoskeletal, circulatory, and excretory systems; gonads, muscular + connective tissue layers of the digestive/respiratory systems, and the !adrenal cortex!
- endoderm: epithelial linings of respiratory/digestive tracts and parts of the pancreas, thyroid, bladder
5) neurulation
- neural tube: CNS
- neural crest cells: PNS, melanocytes in skin, others.
What are teratogens?
interfere with development causing defects or death to the embryo
- alcohol, drugs, viruses, bacteria
What is determination and differentiation?
determination: commitment to specific cell lineage from uneven distribution of cellular material during mitosis by morphogens
differentiation: selective transcription in a cell to take on characteristics appropriate for its cell line
What are the different types of stem cells?
totipotent: can differentiate into all cell types
pluripotent: differentiate into all three of the germ layers
multipotent: differentiate only into a specific subset of cell types
What is juxtacrine signaling?
direct stimulation of adjacent cells
What is incomplete regeneration?
newly formed tissue is not identical in structure or function to the tissue that was injured or lost
Compare fetal hemoglobin (HbF) to adult.
HbF: higher affinity for oxygen to assist in the transfer into the fetal circulatory system
What does the placenta do?
1) nutrient, gas, and waste exchange occurs here
2) barrier serves as immune protection; antibodies are transferred to baby
3) secretes estrogen, progesterone, and hCG
Describe fetal circulation.
umbilical arteries carry deoxygenated blood from fetus to placenta; umbilical vein carries oxygenated blood from placenta back to fetus
3 shunts:
1) foramen ovale connects right atrium to left atrium, bypassing lungs
2) ductus arteriosus: connects pulmonary artery to aorta, bypassing lungs
3) ductus venosus: connects umbilical vein to inferior vena cava, bypassing liver
Describe what happens in each trimester and birth.
1) organogenesis: heart, eyes, gonads, liver, limbs, brain
2) tremendous growth, movement begins, the face becomes human, digits elongate
3) rapid growth and brain development continue, transfer of antibodies to fetus
4) 40 weeks ! Birth: cervix thins, amniotic sac ruptures, uterine contractions (oxytocin + prostaglandins)
List the glial cells and their functions.
1) Oligodendrocytes: myelinate axons in CNS
2) Schwann cells: myelinate axons in the PNS
3) Astrocytes: nourish neurons and form blood-brain barrier
4) microglia: phagocytic cells that ingest and break down waste products and pathogens in CNS
5) Ependymal cells: line ventricles and produce CSF
What is the difference between nerves and tracts?
individual axons are bundled into nerves and tracts
nerves: carry multiple types of information, including sensory, motor, or both
- cell bodies cluster together to form ganglia in the PNS
tracts: only carry one type of information
- cell bodies cluster to form nuclei in the CNS
How is the resting membrane potential maintained?
-70 mv maintained by selective permeability of ions and Na+/K+ ATPase (3 Na+ out/2 K+ in)
What is temporal and spatial summation?
temporal: single neuron rapidly fires signals to post synaptic neuron
spatial: multiple neurons simultaneously send signals to postsynaptic neuron
What are the ways a NT is cleared from the postsynaptic receptors?
enzymatically be broken down (acetylcholinesterase), absorbed back into presynaptic cell by reuptake channels (serotonin, dopamine, norepinephrine), or NT diffuses out of synaptic cleft (NO)
What affects the speed of action potential propagation?
shorter axon length, greater cross-sectional area decreases resistance, myelin prevents loss of electric signal
What is white and grey matter?
CNS
- white matter = myelinated axons
- grey matter = unmyelinated cell bodies and dendrites
Brain: white is deeper than gray
Spinal cord: grey is deeper than white
- cervical, thoracic, lumbar, sacral
Which side of the spinal cord do sensory and motor neurons enter?
sensory: dorsal side
motor: ventral
What is the difference between somatic and ANS?
Somatic: motor neuron goes directly from spinal cord to muscle without synapsing
ANS: preganglionic neuron + postganglionic neuron, then stimulates target tissue
What is the difference between monosynaptic and polysynaptic reflex arcs?
mono: sensory (afferent) neuron fires directly onto motor (efferent) neuron
poly: sensory neuron may fire onto a motor neuron as well as interneurons that fire onto other motor neurons
Describe peptide hormones.
composed of amino acids from larger precursor proteins
polar, cannot pass through plasma membrane, but travel freely through bloodstream
bind to receptors + trigger second messengers
fast onset, short lived
ADH, insulin
“in/ine”
Describe steroid hormones.
derived from cholesterol, can pass through membrane, but need carriers through blood
bind to intracellular receptors, the complex binds to DNA, altering transcription of gene
slow onset, long lived
“one, ol, oid”
Describe amino acid-derivative hormones.
modified amino acids
- epinephrine, norepinephrine, T3/T4
What is the difference between direct and tropic hormones?
Stimulates other endocrine glands to release additional hormones vs. major effects on non-endocrine tissues
What are the hypothalamus –> anterior pituitary hormones.
1) GnRH –> FSH = ovarian follicles + spermatogenesis, LH = ovulation + testosterone
2) GHRH –> GH (direct) = growth of bone and muscle, raises blood glucose
3) TRH–> TSH = synthesis and release of T3/T4
4) CRF –> ACTH = synthesis and release of glucocorticoids from adrenal cortex
5) prolactin: milk production
- inhibited by dopamine
6) endorphins: natural pain killers
FLAT = tropic
PEG = direct
What are the hypothalamus–>posterior pituitary direct hormones.
ADH (vasopressin) = low blood volume, increased water reabsorption via AQP2 channels
Oxytocin = uterine contractions
- positive feedback loop
What does the thyroid produce?
T3 and T4: contain iodine
- increase basal metabolic rate
calcitonin: decreases plasma Ca2+ concentration by promoting Ca2+ excretion, decreasing reabsorption, and promoting storage in bones
What does PTH do?
- increases blood calcium concentration by decreasing excretion, increasing bone resorption
- activates vitamin D, Ca2+ and phosphate reabsorption from the gut
What hormones does the adrenal cortex produce?
1) glucocorticoids: cortisol and cortisone; increase blood glucose, reduce protein synthesis, inhibit immune system, stress response
2) mineralocorticoids: aldosterone; sodium reabsorption + water reabsorption
- regulated by renin-angiotensin system (drop BP)
3) sex hormones: testosterone + estrogen
salt, sugar, sex
What hormones does the adrenal medulla produce?
catecholamines: epi and norepi; glycogenolysis, increase in basal metabolic rate, increase HR, dilate bronchi
What hormones does the endocrine pancreas secrete?
alpha cells make glucagon: raises blood glucose by stimulating protein and fat degradation, glycogenolysis, and gluconeogenesis
beta cells make insulin: lowers blood glucose levels by stimulating glucose uptake by cells and promoting glycogen, fat, and protein synthesis
delta cells make somatostatin: inhibits insulin and glucagon secretion
What does the pineal gland release?
melatonin = circadian rhythm
Other organs that release hormones?
stomach/intestine = secretin, gastrin
kidneys = erythropoietin (produce erthyrocytes)
heart = ANP for high BP
What is the pathway of air when you breathe?
nares –> pharynx (warmed + humidified) –> larynx –> trachea –> bronchi –> bronchioles –> alveoli
What does surfactant do?
reduces surface tension at the liquid-gas interface in the alveoli, preventing collapse
Describe inhalation and exhalation processes.
Inhalation: diaphragm + external intercostal muscles expand the thoracic cavity (contract), increasing volume of intrapleural space, decreasing intrapleural pressure
- difference in pressure expands the lungs, dropping the pressure + drawing air in from the environment
Exhalation
- passive: relaxation of muscles of inspiration and elastic recoil of lungs
- active: internal intercostal muscles and abdominal muscles can be used to forcibly decrease the volume of thoracic cavity, pushing out air
What happens in emphysema?
destruction of alveolar walls, reduced elastic recoil during exhalation
- air gets trapped, increasing RV and TLC
What is total lung capacity, residual volume, vital capacity, tidal volume, expiratory reserve volume, and inspiratory reserve volume?
TLC: max volume of air in the lungs when one inhales completely
- everything added together
RV: volume of air remaining in the lungs when one exhales completely
VC: TV + IRV + ERV
TV: volume of air inhaled or exhaled in normal breath
ERV: volume of additional air that can be forcibly exhaled after normal exhalation
IRV: volume of additional air that can be forcibly inhaled after normal inhalation
How is ventilation regulated?
medulla oblongata
- chemoreceptors respond to high CO2 concentrations and low O2 concentrations in the blood
What does lysozymes, macrophages, mucosal cells, and mast cells do?
lysozymes: nasal cavity and saliva; attacks PG cell walls of Gram+ bacteria
macrophages: engulf and digest pathogens
mucosal cells: IgA antibodies
mast cells: antibodies on their surface that can promote release of inflammatory chemicals
- allergic reactions
Describe blood flow in the heart.
right atrium –> tricuspid valve –> right ventricle –> pulmonary valve –> pulmonary artery –> lungs –> pulmonary vein –> left atrium –> mitral valve –> left ventricle –> aortic valve –> aorta –> arteries –> arterioles –> capillaries –> venules –> veins –> vena cava –> right atrium
Formula for cardiac output.
CO = stroke volume * HR
Compare arteries, capillaries, and veins.
arteries: thick, highly muscular structures with elastic quality
- arterioles = highest pressure + resistance
capillaries: one cell thick walls, gas + solute exchange
- high individual pressure, but parallel network lower overall pressure
veins: inelastic, thin-walled; able to stretch and accommodate large volume of blood without recoiling
- low pressure, high compliance
Describe the three common portal systems in the body.
blood passes through two capillary beds in series
1) hepatic: gut to liver
2) hypophyseal: hypothalamus to anterior pituitary
3) renal: glomerulus to vas recta
Describe the composition of blood
55% liquid = plasma
- aqueous mixture of nutrients, salts, respiratory gases, hormones, blood proteins
45% cells
- erthyrocytes: red blood cells; lack mitochondria, nucleus; hemoglobin
- leukocytes: white blood cells; granular = neutrophils, eosinophils, and basophils nonspecific immunity; agranulocytes = lymphocytes and monocytes specific immunity
- platelets: required for coagulation
Describe the different blood types.
A and B alleles are codominant, while O allele is recessive
Blood types: A, B, AB, O
- O is universal donor because they don’t express either antigen and don’t initiate an immune response, but they can only receive O
- AB blood is universal recipient because no blood antigen is foreign
- people have antibodies for the allele they do not have
most common = O+
least common = AB-
What is the Rh factor?
surface protein expressed on RBCs
Rh+ = presence, dominant, can receive either + or - blood
Rh- = absence, only receive - blood
erthyroblastosis fetalis: mother is Rh - and baby is Rh +, mother makes antibodies against baby
How is blood pressure maintained?
baroreceptor + chemoreceptor reflexes
- low BP: promotes aldosterone and ADH release
- high BP: promotes ANP release from heart cells
What is the difference between hydrostatic and osmotic pressure?
hydrostatic: pressure of fluid within the blood vessel
- forces fluid out at arteriolar end of capillary bed
osmotic: pressure drawing water towards solutes
- draws fluid back in at the venule end of capillary bed
What causes a decreased affinity for oxygen in hemoglobin?
high PaCO2, high [H+], low pH, high temperature, high concentration of 2,3-BPG, exercise causes a rightward shift in dissociation curve
- left shift in fetal hemoglobin bc needs to pull O2 off maternal Hb
What is the coagulation cascade?
when endothelial lining of blood vessel is broken, collagen and tissue factor are exposed
- collagen sensed by platelets and begin to clump
- tissue factor sensed by coagulation factors which activate prothrombin to form thrombin, which converts fibrinogen into fibrin
What is the difference between innate and adaptive immunity?
innate: defenses are always active, but can’t target a specific invader ~ non-specific
- macrophages, dendritic cells, neutrophils, natural killer cells
adaptive: defenses that take time to activate, but target a specific invader and can maintain an immunologic memory ~ specific
- T-cells + B-cells
Where is the immune system?
1) bone marrow produces WBCs and RBCs
2) spleen (location of blood storage + activates B-cells that turn into plasma cells) and lymph nodes (where immune cells communicate + mount attack)
3) thymus is site of T-cell maturation
What are the acellular components of the innate immune system?
1) skin: physical barrier and secretes defensins (antimicrobial compounds)
2) mucus: traps pathogens, can be expelled with ciliated cells
3) lysozyme: tears and saliva; antibacterial
4) stomach acid
5) complement system punches holes in cell walls of bacteria
6) interferons given off by virally infected cells to prevent replication
What are the cellular components of the innate immune system?
1) macrophages ingest pathogens and present them on MHC molecules; secrete cytokines
- MHC-I: present in all nucleated cells and displays endogenous antigen to cytotoxic T-cells
- MHC-II: professional antigen-presenting cells (macrophages, dendritic cells) and display exogenous antigen to helper T-cells
2) Dendritic cells: antigen presenting cells on the skin
3) Natural killer cells: attack cells not presenting MHC molecules (cancer, virally infected cells)
4) Granulocytes: neutrophils, eosinophils, and basophils
- neutrophils: ingest bacteria
- eosinophils: allergic reactions and invasive parasitic infection; release histamine, causing inflammatory response (increased leakiness from vasodilation)
- basophils: allergic reactions (related to Mast cells in the skin)
What is humoral immunity? How does it work?
centered on antibody (immunoglobulins) production by plasma cells, which are activated by B-cells
- antibodies target specific antigen; contain two heavy and two light chains and variable/constant regions
- cells may be given signals to change the isotopes of antibody (IgM, IgD, IgG, IgE, IgA)
- can opsonize pathogens (mark for destruction), cause agglutination (clumping) into complexes ingested by phagocytes, or neutralize pathogens
- memory B-cells wait for second exposure and can mount more rapid + vigorous response
What is cell-mediated (cytotoxic) immunity?
centered on the function of T-cells
- mature in the thymus
- helper T-cells (CD4+): respond to antigen on MHC-II and coordinate rest of immune system, secreting lymphokines = increase recruitment + activity of other immune cells —-> LOST in HIV
- cytotoxic T-cells (CD8+): respond to antigen on MHC-I and kill virally infected cells , better at targeting intracellular infections (viral)
- suppressor T-cells: tone down immune response
- memory T-cells: similar to memory B-cells, wait for secondary exposure to the same antigen
What happens in an allergic reaction?
nonthreatening exposures incite inflammatory response
What is the difference between active and passive immunity?
active: activation of B-cells to produce antibodies to an antigen prior to exposure
- vaccines
passive: transfer of antibodies to an individual
What does the lymphatic system do?
equalizes fluid distribution, transports fats and fat soluble compounds in chylomicrons, and provides site for mounting immune response
What is the pathway of food?
oral cavity–> pharynx –> esophagus –>stomach –> small intestine –>large intestine –>rectum
What does the enteric nervous system do?
in the wall of alimentary canal and controls peristalsis; upregulated by parasympathetic nervous system
What promotes hunger? thirst? satiety?
hunger: glucagon and ghrelin
thirst: ADH and aldosterone
satiety: leptin and CCK
What enzymes are produced in the oral cavity?
salivary amylase + lipase
What does each cell in the stomach produce?
mucous cells: bicarbonate rich mucus
chief cells: pepsinogen
parietal cells: HCL and intrinsic factor (absorb Vitamin B12)
G-cells: secrete gastrin that increases HCL secretion
What are the important enzymes/hormones in the small intestine?
1) disaccharidases: sucrase, maltase, lactase
2) peptidases: aminopeptidase, dipeptidase
3) enteropeptidase: activates trypsinogen and procarboxypeptidases
4) secretin stimulates release of pancreatic juices and slows motility
5) CCK stimulates bile release from the gallbladder
What does the pancreas produce?
pancreatic amylase (carbs), pancreatic peptidases (trypsinogen, chymotrypsinogen, carboxypeptidases A/B = proteins), and pancreatic lipase = fats
What does the liver do?
1) synthesizes bile: emulsifies fats, making them more soluble and increasing SA
2) processes nutrients: glycogenesis, glycogenolysis, storage/mobilization of fats, and gluconeogenesis)
3) produces urea: remove N from body
4) detoxifies chemicals
5) synthesizes clotting factors
What is bile made out of ?
bile salts: emulsify fats
pigments: bilirubin, from breakdown of Hb
- jaundice
cholesterol
How does absorption work?
water soluble compounds (monosaccharides, amino acids, vitamins, small fatty acids) enter capillary bed in villi
fat-soluble compounds (fats, cholesterol) enter the lacteal (lymphatic system)
small + large intestine absorb water
Describe the blood flow through the kidney.
renal artery –> afferent arterioles –> glomeruli –> efferent arteriole –> vasa recta –> renal vein
What is the musculature of the bladder like?
lining called detrusor muscle
2 sphincters
- internal urethral: parasympathetic control
- external urethral: skeletal muscle and is under voluntary control
Describe filtration, secretion, and reabsorption by the kidney.
filtration: movement of solutes from blood to filtrate at Bowman’s capsule
secretion: movement of solutes from blood to filtrate after Bowman’s capsule
reabsorption: movement of solutes from filtrate to blood
Function of the segments of the nephron.
proximal convoluted tubule: bulk reabsorption of glucose, amino acids, soluble vitamins, salt, and water
descending limb of loop of Henle: permeable to water but not salt
- vas recta and nephron move in opposite directions, creating countercurrent multiplication that allows for max reabsorption of water
ascending limb of the loop of Henle: permeable to salt, not water; filtrate becomes hypotonic to the blood
distal convoluted tubule: responsive to aldosterone; salt reabsorption
collecting duct: responsive to aldosterone and ADH
What does aldosterone and ADH do in the kidney?
When BP is low…
Aldosterone: renin-angiotensin system that increases reabsorption of Na+ in the distal convoluted tubule and collecting duct, increasing water reabsorption
- does not change blood osmolarity
ADH: increasing the permeability of the collecting duct to water, increasing its reabsorption
- lowers blood osmolarity
What are the main layers of the skin?
hypodermis (fat and connective tissue), dermis (2 layers, sensory cells), and epidermis (5 layers)
- melanocytes produce melanin to protect skin from DNA damage
- keratinocytes produce keratin
What are the three types of muscle?
1) skeletal: support and movement, propulsion of blood in venous system, and thermoregulation
- striated, under voluntary control, polynucleated
- divided into red (slow-twitch) fibers that carry out oxidative phosphorylation and white (fast-twitch) fibers that use anaerobic metabolism
2) smooth: respiratory, reproductive, cardiovascular, and digestive systems
- nonstriated, autonomic control, and is uninucleated
- myogenic activity = contraction without neural input
3) cardiac: contractile tissue of the heart
- striated, autonomic control, and is uninucleated
- myogenic activity; connected by gap junctions
What is a sarcomere?
basic contractile unit of striated muscle
- thick (myosin) and thin (actin) filaments
- troponin + tropomyosin on thin filaments block myosin binding sites until Ca2+ binds
- ADP + Pi leave, causing power stroke
attach end to end to become myofibrils, and each muscle fiber has many
- surrounded by SR
What are the muscles additional oxygen reserves ?
creatine phosphate transfers phosphate group to ADP
myoglobin is a muscular O2 reserve
What are the types of bone? How are they connected to everything else?
1) compact: strength, dense; made up of osteon = concentric rings of matrix called lamellae
2) spongy or cancellous: lattice-like structure filled with bone marrow
epiphysis = end of bone with growth plate responsible for linear growth
periosteum: layer of connective tissue that surrounds bone
tendons: attach to muscles
ligaments: bones
What are bones made of?
collagen, glycoproteins, and other peptide; hydroxyapatite
- osteoblasts make bone; calcitonin increases this
- osteoclasts resorb bone; parathyroid hormone and vitamin D increases this
How do bones form in fetus?
endochondral ossification: from cartilage
intramembranous ossification: undifferentiated tissue (skull)
Which amino acids have more than 1 chiral center?
threonine and isoleucine have 2
What is the difference between penetrance and expressivity?
penetrance: proportion of population with given genotype who express the phenotype
expressivity: varying phenotypic manifestations of a given genotype
What are Mendel’s two laws?
1) segregation: organism has two alleles for each gene which segregate during meiosis, resulting in gametes that carry one allele for the trait
2) independent assortment: inheritance of one allele does not affect the probability of inheriting an allele for a different trait
- non-independent assortment = linked genes
What are the different types of nucleotide mutations?
- point: single substitution
- frameshift: moving 3-letter transcriptional frame
- silent: no effect on protein
- missense: substitution of one amino acid for another
- nonsense: substitution of a stop codon
- Indels: shift in reading frame
What are the different types of chromosomal mutations?
- deletion: large segment of DNA is lost
- duplication: segment of DNA is copied multiple times
- inversion: segment of DNA is reversed
- insertion: segment of DNA is moved from one chromosome to another
- translocation: segment of DNA is swapped with a segment of DNA from another chromosome
What is genetic leakage?
flow of genes between species through hybrid offspring
ex) horse + donkey = mule; can’t reproduce because of odd number of chromosomes
ex) beefalo: cattle + bison = reproductive
What is genetic drift?
composition of gene pool changes as a result of chance
What is the founder effect?
results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes
What are the phenotypic ratios for monohybrid and dihybrid crosses?
monohybrid = 3:1
dihybrid = 9:3:3:1
What is recombination frequency?
likelihood of two alleles being separated during crossing over in meiosis
- smaller the percentage, the closer together they are
What is the Hardy-Weinberg Principle?
if a population is:
1) very large (no genetic drift)
2) no mutations
3) mating is random
4) no migration
5) genes are equally reproductive
then allele frequencies will remain constant
p + q = 1 ===allele
p^2 + 2pq + q^2 = 1 ===genotype
turn the percentages into decimals
What is the modern synthesis model?
accounts for mutation and recombination as mechanisms of variation and considers differential reproduction to be the mechanism for reproductive success
What is inclusive fitness?
success is based on # of offspring, success in supporting offspring, and the ability of offspring to support others
What are the different types of selection?
1) stabilizing: keeps phenotypes in a narrow range
2) directional: moves average phenotype toward one extreme
3) disruptive: moves towards two different extreme phenotypes, can lead to speciation
4) adaptive radiation: rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche
What is a species?
largest group of organisms capable of breeding to form fertile offspring
- reproductively isolated from one another
What are the three types of evolution?
1) divergent: when two species sharing common ancestor become more different
2) convergent: two species NOT sharing a common ancestor evolve to become more similar
3) parallel: two species sharing common ancestor evolve in similar ways
