MCAT - BIO/BIOCHEM EXAM | QUESTIONS & ANSWERS (VERIFIED) | LATEST UPDATE | GRADED A+

1 MCAT - BIO/BIOCHEM EXAM | QUESTIONS & ANSWERS (VERIFIED) | LATEST UPDATE | GRADED A+ defunct mRNA translation in bacteria would... Correct Answer: prevent cells from replicating. lysogenic cycle Correct Answer: a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA Lytic phase or lytic cycle Correct Answer: phage replicates immediately, destroying the host cell (All phages carry out this life cycle) protein production Correct Answer: -proteins made at ribosomes -ribosomes on Rough ER make proteins that are excreted or attached to the cell membrane. The free ribosomes in the cytoplasm make proteins that stay in the cytoplasm. -new proteins produced at the rough ER are folded and processed ( chains are added) in the rough ER 2 -then they're transported to the Golgi apparatus in vesicles -at the Golgi apparatus the proteins undergo further processing ( chains are trimmed and more are added) -the proteins enter more vesicles to be transported around the cell proteins (found in mucus) move to the cell surface and are secreted. missense mutation Correct Answer: A base-pair substitution that results in a codon that codes for a different amino acid. nonsense mutation Correct Answer: A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein. frameshift mutation Correct Answer: mutation that involves the insertion or deletion of a nucleotide in the DNA sequence silent mutation Correct Answer: A mutation that changes a single nucleotide, but does not change the amino acid created. Schwann cells (PNS) 3 Correct Answer: Form myelin sheath in the peripheral nervous system Oligodendrocytes Correct Answer: Form myelin sheath in CNS temporal summation Correct Answer: occurs when a single presynaptic neuron releases neurotransmitters to generate the action potential spatial summation Correct Answer: occurs when multiple presynaptic neurons release neurotransmitters together to fire an action potential Glutamate Correct Answer: A major excitatory neurotransmitter; involved in memory. If the coding strand for a certain gene begins with 5' AGC CTT CGG CTG ACT GGC TGG, which of the following is a possible primer that researchers could use for amplification during reverse transcription PCR? Correct Answer: 5' AGC CTT CGG CTG ACT GGC TGG 3'. since we are given the coding strand - the mRNA produced will match it except that U will replace all T's. 4 The DNA primer that will match this mRNA be the same as the coding strand given. homologous recombination repair Correct Answer: information from the homologous chromosome/sister chromatid is used to correct the break photo reactivation repair Correct Answer: Photoreactivation is a prokaryotic process (still used in some eukaryotes) to reverse damage done by UV light; humans use a separate process. exonuclease Correct Answer: an enzyme that removes successive nucleotides from the end of a polynucleotide molecule endonuclease Correct Answer: An enzyme that cleaves its nucleic acid substrate at internal sites in the nucleotide sequence. Ribonuclease Correct Answer: enzyme that breaks down RNA Fertilization: how does a sperm cell reach a secondary oocyte? 5 Correct Answer: acrosome reaction. digestive enzymes are released that allow the nucleus of the sperm cell to enter the developing egg and glycoproteins surrounding the egg create a "mesh" that prevents other sperm cells from fertilizing it. stages of embryonic development (after fertilization and creation of a zygote) Correct Answer: 1. morula (16 cell ball) 2. blastocyst (fluid-filled sac in the middle) 3. gastrula (three germ cell layers) three layers of gastrula (and what they lead to) Correct Answer: ectoderm (skin, nervous system, sweat glands, hair, nails) mesoderm (connective tissue, blood, bone, muscles, gonads). endoderm (internal linings of GI tract, lungs, urinary bladder) Opsonization Correct Answer: Opsonization is the process by which antibodies bind to and recognize antigens on the surface of a pathogen. The antibodies then attract macrophages to phagocytose the invader. Macrophages Correct Answer: a type of white blood cell - Found within the lymph nodes, they are phagocytes that destroy bacteria, cancer cells, and other foreign matter in the lymphatic stream. 6 function of macrophages Correct Answer: tissue remodeling phagocytosis cytokine production and release antigen presentation microbicidal activity tumoricidal activity lymphocyte regulation inflammation and fever Eukaryotic cells Correct Answer: Contain a nucleus and other organelles that are bound by membranes. exception: erythrocytes (red blood cells) do not have a nucleus The basic function of the nucleus is to Correct Answer: compartmentalize and store DNA. Nuclear membrane/envelope Correct Answer: made of two sets of phospholipid bilayers. Surrounds the nucleolus and DNA. Controls what enters and leaves the nucleus. 7 nuclear pores function Correct Answer: protein complexes that act as "doors" for larger molecules to enter and exit the nucleus. Nucleolus function Correct Answer: Makes ribosomes Mitochondria Correct Answer: ATP production via: - beta oxidation of fatty acids (or amino acids) - oxidative phosphorylation (ETC and chemiosmosis) - citric acid cycle Aerobic cellular respiration is made up of three parts: Correct Answer: glycolysis, the citric acid (Krebs) cycle, and oxidative phosphorylation mitochondrial matrix Correct Answer: site of citric acid cycle inner membrane of mitochondria Correct Answer: Where does the electron transport chain take place? mtDNA (mitochondrial DNA) 8 Correct Answer: circular in structure and inherited maternally Lysosomes Correct Answer: garbage disposal system of the cell. stuff that comes outside the cell = endocytosis stuff from inside - autophagy Endoplasmic Reticulum Correct Answer: A cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another. rough - has ribosomes on surface smooth - no ribosomes Rough ER function Correct Answer: protein synthesis Smooth ER function Correct Answer: lipid synthesis and breakdown, production of steroid hormones, calcium ion storage, and detoxification where do proteins go after they are produced? Correct Answer: the golgi apparatus 9 what does the Golgi apparatus do with proteins? Correct Answer: modifies them and puts them in little cell Ubers (vesicles) Peroxisomes function Correct Answer: houses peroxides (like H2o2) that break down very long chain lipids into medium sized chain lipids that are then sent to the mitochondria for further processing. They also play a role in detoxifying substances like ethanol. Microfilaments Correct Answer: Long, thin fibers that function in the movement and support of the cell. Made of two strands of actin polymers. microtubules Correct Answer: Spiral strands of protein molecules (alpha tubulin and bet a tubulin) that form a tubelike structure. Make up cilia and flagella. involved in vesicular transport and organelle relocation in cells intermediate filaments Correct Answer: umbrella term for proteins that provide structural support and are involved in cellular adhesion processes. ex. keratin. 10 Centrioles Correct Answer: cylindrical structures made of tubulin that help organize the mitotic spindle Centrosome Correct Answer: A structure in animal cells containing centrioles from which the spindle fibers develop. Sphingolipids contain Correct Answer: amino alcohol sphingosine backbone instead of a glycerol (like phospholipids do) Cholesterol in the cell membrane does what? Correct Answer: regulates stiffness and flexibility of membrane in low and high temps Lipid rafts are Correct Answer: "boats" of cholesterol and sphingomyelins that can diffuse within the lipid bilayer. Aid in the fluidity of the membrane and regulate signaling processes. embedded proteins Correct Answer: are associated with only the interior/cytoplasmic or exterior/extracellular surface of the cell 11 Gap 0 (G0) Correct Answer: A resting phase where the cell has left the cycle and has stopped dividing. Interpase Correct Answer: cell prepares for division by 1) growth (G1 and G2) 2) DNA replication (S) steps in order are: G1, S, G2. G1 checkpoint - checks for DNA replication errors, commitment to division G2 checkpoint - checks again for damage after replication. if damage is round, pauses cell division until damage is repaired. Mitosis stages Correct Answer: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase Prophase (mitosis) Correct Answer: DNA condenses into sister chromatids. 12 Centromere Correct Answer: where sister chromatids are held together kinetochore Correct Answer: A specialized region on the centromere that links each sister chromatid to the mitotic spindle. Metaphase Correct Answer: Chromosomes line up in the middle of the cell. checkpoint to make sure all kinetochores are attached well Anaphase Correct Answer: sister chromatids are pulled apart to opposite sides of the cell Telophase Correct Answer: a new nuclear envelope developed around each set of chromosomes and cell divides in two. Meiosis 1 Correct Answer: first round of division. results in to haploid daughter cells that contain sister chromatids prophase 1 13 Correct Answer: homologous chromosomes (maternal and paternal copies of a given chromosome) pair up with each other and cross-over metaphase 1 Correct Answer: homologous pairs line up at the center randomly anaphase 1 Correct Answer: homologous pairs are separated. each cell will get only a maternal or paternal copy of each chromosome. meiosis 2 Correct Answer: operates similarly to mitosis. sister chromatids are split up into two haploid daughter cells bacterial cells Correct Answer: no membrane bound organelles, no nucleus, circular genome bacteria shapes: cocci, bacilli, spirilla Correct Answer: cocci - spheres bacilli - rods spirilla - spirals obligate aerobic bacteria 14 Correct Answer: require oxygen obligate anaerobes Correct Answer: require oxygen-FREE environment facultative anaerobes Correct Answer: can live with or without oxygen gram-positive Correct Answer: turn purple in gram staining. have thick peptidoglycan cell walls Gram-negative bacteria Correct Answer: turn pink in gram staining, have thin wall with outer lipopolysaccharide layer prokaryotic ribosomes Correct Answer: smaller than eukaryotic ribosomes (70S vs 80S) transformation Correct Answer: DNA from environment transduction Correct Answer: virus-mediated gene transfer 15 conjugation Correct Answer: Sexual reproduction in bacteria Viruses are Correct Answer: obligate intracellular parasites. protein capsid coat around genetic material lytic cycle Correct Answer: a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses lysogenic Correct Answer: a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA. Prions Correct Answer: misfolded proteins that can cause other proteins to misfold. think: jess and Rory viroids Correct Answer: Infectious particles that cause disease in plants 16 Bacteriophage Correct Answer: viruses whose host cells are bacteria stop codons are Correct Answer: UAA, UAG, UGA start codon Correct Answer: AUG (methionine) complimentary base pairing Correct Answer: A-T/U G-C DNA coils around Correct Answer: histones Euchromatin Correct Answer: The less condensed form of eukaryotic chromatin that is available for transcription. Heterochromatin Correct Answer: Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed. 17 DNA polymerase Correct Answer: Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule. Reads 3-5, synthesizes 5-3 Ligase Correct Answer: An enzyme that connects two (okazaki) fragments of DNA to make a single fragment RNA polymerase II Correct Answer: Enzyme similar to DNA polymerase that binds to DNA and synthesizes an hnRNA (that is then modified to a mRNA strand) from the antisense or template strand of DNA 3 post-transcriptional modifications of hnRNA Correct Answer: 1) addition of a 3' poly A tail - protects the eventual mRNA from degradation in the cytoplasm 2) addition of a 5' cap to also prevent degradation and helps with export (unique to eukaryotes) 3) splicing non coding introns out and lighting exons together Translation 18 Correct Answer: occurs in the cytoplasm, assisted by the structure of ribosomes. mRNA to protein via tRNA which links codons to amino acids rRNA (ribosomal RNA) Correct Answer: type of RNA that makes up the major part of ribosomes 3 steps of translation Correct Answer: 1. initiation - mRNA binds to the small ribosomal unit. first tRNA binds to the start codon on the 5' of the mRNA strand. 2. elongate - ribosome reads the mRNA from 5' to 3' and synthesizes protein from N to C terminus. 3. terminate - stop codon is encountered. ribosome disassembles, polypeptide is released. binding sites for elongation Correct Answer: A - next tRNA-amino acid complex to bind P - peptide bond to existing chain E - detachment site translocation mutation Correct Answer: mutation in which one part of one chromosome breaks off and attaches to another 19 Aneuploidy Correct Answer: A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number. Hardy-Weinberg equilibrium criteria and equation Correct Answer: criteria: 1) diploid sexual reproduction 2) random mating 3) large population 4) random distribution of alleles by sex 5) no mutations 6) no migration p + q = 1 p^2 + 2pq +q^2 = 1 where: p = the frequency of allele A q = the frequency of allele a p2 = the frequency of individual AA q2 = the frequency of individual aa 2pq = the frequency of individual Aa 20 stabilizing selection Correct Answer: Natural selection that favors intermediate variants by acting against extreme phenotypes directional selection Correct Answer: Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve disruptive selection Correct Answer: form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle molecular clock hypothesis Correct Answer: Since random errors accumulate on the genome at a relatively fixed rate, the extent to which two genomes are different can be used to figure out how long ago they shared a common ancestor. ex. emergence and spread of HIV in humans. stem cells are capable of being: - totipotent - pluripotent - multipotent 21 describe what each means Correct Answer: totipotent - can become any type of cell* pluripotent - can become any of the three germ layers* multipotent - can become several types of cells (but not as broad as totipotent) example is adult stem cell. *only embryonic stem cells can be totipotent/pluripotent. Operons are a genetic feature of prokaryotes. Describe them and what they do/how they can be controlled: Correct Answer: clusters of genes that are usually transcribed together. these genes have a promoter that is either suppressed or promoted based on the needs of the cell. under positive control: activator stimulates transcription of these genes under negative control: repressor prevents transcription lac operon Correct Answer: a type of negatively controlled operon, specifically negatively inducible. example of lab operon in e coli: E. coli has the ability to metabolize glucose and the lac operon allows it to ALSO be able to metabolize lactose. Problem is, lactose is energetically expensive to metabolize 22 so it's better to only have the lab operon operate when necessary. This is why the lac operon is usually repressed and when glucose is low and lactose is available, the operon is activated. trp operon Correct Answer: trp operon is negatively repressible. when tryptophan is present, it binds to the operon's repressor and the repressor prevents the operon from expressing the gene that will produce more tryptophan. promoters and enhancers (in eukaryotes) Correct Answer: promoters: upstream DNA sequences that initiate transcription enhancers: DNA sequences that allow increased transcription transcription factors Correct Answer: proteins that regulate expression by binding to specific DNA sequences histone acetylation Correct Answer: increases transcription DNA methylation Correct Answer: decreases transcription 23 siRNA and miRNA Correct Answer: decrease protein synthesis restriction enzymes Correct Answer: cut DNA at specific points - leading to blunt and sticky ends that can be recombined plasmid and bacteriophage vectors are used to Correct Answer: transfer/amplify recombinant DNA electrophoresis Correct Answer: separates DNA/RNA by size hybridization Correct Answer: used in southern, northern, and western blotting to detect specific DNA, RNA, and protein sequences Sanger sequencing method Correct Answer: uses dideoxynucleotides to terminate synthesis and electrophoresis to analyze fragment size PCR 24 Correct Answer: used to make multiple copies of a small amount of DNA in a short amount of time; uses primers. central nervous system is comprised of Correct Answer: brain and spinal cord peripheral nervous system Correct Answer: A division of the nervous system consisting of all nerves that are not part of the brain or spinal cord. divided into autonomic and somatic nervous systems somatic nervous system Correct Answer: voluntary moments via skeletal muscles autonomic NS Correct Answer: involuntary responses via the sympathetic and parasympathetic systems glial cells Correct Answer: cells in the nervous system that support, nourish, and protect neurons. oligodendrocytes, Schwann cells, ependymal cells, satellite cells, astrocytes, and microglia. 25 types of neurons Correct Answer: multipolar (including interneurons and motor), bipolar, pseudounipolar resting potential of a neuron Correct Answer: -70mV Stages of an action potential Correct Answer: 1) depolarization, sodium rushes into the cell 2) at +40mV, sodium channels close and potassium channels open. potassium rushes out of the cell, depolarizing it. 3) cell hyper polarizes below -70mV, making it hard to generate a new action potential at this time. 4) cell re-establishes resting state potential. steps in the release of a neurotransmitter Correct Answer: 1)action potential reaches end of axon 2) calcium rushes in to the pre-synaptic axon terminal, which sends vesicles containing NTs into the synaptic cleft. 3) NTs bind to the post-synaptic membrane of next neurons. peptide hormones 26 Correct Answer: made from amino acids chains and are hydrophillic. Cannot diffuse through plasma membranes so they interact with receptors to send their message along. fast, short acting effects. steroid hormones Correct Answer: derived from cholesterol. lipohilipc. Can and do diffuse thru the membrane. delayed onset, longer lasting effects. steroid hormones that affect sex Correct Answer: estrogen, testosterone, progesterone steroid hormones that affect salt Correct Answer: aldosterone, a mineralcorticoid steroid hormones that affect sugar Correct Answer: cortisol, a glucocorticoid negative feedback Correct Answer: common in the body. products inhibit upstream steps. maintains homeostasis positive feedback 27 Correct Answer: rare in the body. downstream products upregulates upstream steps. pushes body towards extreme state - ex. oxytocin in labor/childbirth insulin Correct Answer: decreases blood glucose. which A protein hormone secreted by the pancreas that is essential for the metabolism of carbohydrates and the regulation of glucose levels in the blood. glucagon Correct Answer: A protein hormone secreted by pancreatic endocrine cells that raises blood glucose levels; an antagonistic hormone to insulin. which hormones increase calcium? which decrease it? Correct Answer: increase: PTH & vitamin D decrease: calcitoninn which hormones increase fluid retention Correct Answer: ADH and aldosterone which hormones decrease fluid retention/increase excretion Correct Answer: ANP cortisol 28 Correct Answer: stress hormone released by the adrenal cortex. increases glucose levels. long-term stress epinephrine Correct Answer: Neurotransmitter secreted by the adrenal medulla in response to stress. Also known as adrenaline. increases glucose in fight or flight response. short term stress. which hormones increase metabolic rate Correct Answer: T3 AND T4 tropic hormones Correct Answer: hormones that stimulate other glands to release their hormones path of sperm Correct Answer: seminiferous tubules -> epididymis -> vas deferens -> ejaculatory duct -> urethra -> penis. "SEVEN UP" N stands for nothing. path of eggs Correct Answer: ovaries -> Fallopian tube if fertilization occurs: -> zygote/morula/blastocyst goes to uterus -> pregnancy -> childbirth 29 if no fertilization: -> uterine lining shed during menstruation spermatogenesis Correct Answer: where: testes what: spermatogonial stem cells -> spermatogonia (2n) -> primary spermatocytes (2n) -. secondary spermatocytes (n) -> spermatids -> spermatozoa Where do sperm mature? Correct Answer: epididymis oogenesis Correct Answer: oogonia -> primary oocyte --> secondary oocyte + polar body -> ovum + polar body primary oocytes are halted at prophase 1 at birth, meiosis 1 is completed in the very to form secondary oocyte, which is then arrested at metaphase II. Meiosis II is completed at fertilization. Where does fertilization occur? Correct Answer: fallopian tubes 30 menstrual cycle phases Correct Answer: 1. follicular phase - follicle develops that grows the little bb oocyte 2. ovulation - release of egg 3. luteal phase - follicle turns into corpus luteum that tells uterus to start thickening 4. menstruation - uterine endometrium from previous cycle is shed 5. proliferative pase - endometrium develops again 6. secretory phase - endometrium ready for implantation 1-3: ovarian cycle 4-6: uterine cycle hcG Correct Answer: human chorionic gonadotrophin hormone. if implantation happens, hCG maintains the corpus luteum which maintains progesterone and maintains pregnancy. air to lungs pathway Correct Answer: nasal/oral cavity > pharynx > trachea > bronchi > bronchioles > alveoli pleura Correct Answer: Membrane surrounding the lungs surfactant 31 Correct Answer: cover alveoli to decrease surface tension and prevent collapse negative pressure breathing Correct Answer: diaphragm contracts, expanding lungs; greater volume = lower pressure, air comes in from outside function of ciliated cells in trachea Correct Answer: trap particulate matter and push it up to either be expelled or swallowed basic point of respiration Correct Answer: carbon dioxide produced as a waste product of metabolism needs to be exhaled, oxygen for aerobic respiration needs to be inhaled Blood contains what? Correct Answer: plasma (non-cellular component) platelets (thrombocytes) white blood cells (leukocytes) erythrocytes (red blood cells) describe erythrocytes Correct Answer: lack nuclei and membrane-bound organelled biconcave shape 32 have hemoglobin arteries to veins (from the heart and back to the heart) Correct Answer: aorta > arteries > arterioles > capillaries > venules > veins > venae cavae basic cardiovascular anatomy Correct Answer: venae cava > right atrium > tricuspid valve > right ventricle > pulmonary semilunar valve > pulmonary artery > capillaries > pulmonary veins > left atrium > bicuspid/mitral valve > left ventricle > aortic semilunar valve > aorta > systemic circulation Hemoglobin affinity for oxygen Correct Answer: more oxygen present > more likely hemoglobin is to bind to oxygen. H+ ions allosterically regulate Hb by stabilizing the T form, which has lower affinity for oxygen. 2,3BPG also causes Hb to have lower affinity for oxygen hemoglobin curve shifts Correct Answer: higher temp (cells working harder, needing more oxygen), higher BPG, higher CO2, lower pH > shift to the right where Hb has less affinity to oxygen so easier to unload oxygen to cells lower temp, lower BPG, lower CO2, higher pH > shift left 33 (in capillaries) hydrostatic pressure drops as Correct Answer: you move from the arterial end of the capillary bed to the venous end basic path of food thru the digestive system Correct Answer: oral cavity > esophagus > stomach > small intestine (duodenum, jejunum, ileum) > large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colon), rectum. pH of stomach Correct Answer: low due to gastric acid pH of small intestine Correct Answer: slightly basic bile is produced by () and stored in () Correct Answer: produced by liver stored by gallbladder function of bile Correct Answer: emulsify fats by physically breaking large fat globules into smaller ones 34 (digestion) pancreas secretes () to the small intestine Correct Answer: digestive enzyme and bicarb small intestine function Correct Answer: Absorbs most nutrients; Main absorption organ of the digestive tract what increases the surface area of the small intestine and its ability to absorb Correct Answer: villi and microvilli large intestine Correct Answer: Absorbs water and forms feces. also absorbs microbe-generated substances like vitamin K and short chain fatty acids carbs through the digetive tract Correct Answer: salivary amylase in mouth pancreatic amylase in small intestine monosaccharides are also absorbed in small intestine hepatic portal vein for liver processing bloodstream proteins through the digestive tract 35 Correct Answer: pepsin in stomach > various peptidases in small intestine; isolated amino acids and some dipeptides absorbed in small intestine > hepatic portal vein for liver processing > blood stream fats thru the digestive tract Correct Answer: lingual lipase starts digesting triglycerides > pancreatic lipase continues > bile salts in small intestine emulsify > absorbed in small intestinal cells > lacteals in villi > drain into lymphatic system as chylomicrons > bloodstream Fat soluble vitamins Correct Answer: A, D, E, K water soluble vitamins Correct Answer: B and C function of vitamin A Correct Answer: To improve vision and keeping skin & healthy. Function of Vitamin D Correct Answer: -Helps absorb calcium -Keeps teeth and bones strong -Found in dairy products and eggs 36 function of vitamin K Correct Answer: blood clotting vitamin c function Correct Answer: -production and maintenance of collagen -enhances immune response -does not prevent colds -assists in iron absorption -antioxidant vitamin b function Correct Answer: coenzymes basic urination path Correct Answer: nephron: glomerulus > capsular space of bowman's capsule > proximal convoluted tubule > loop of henle, distal convoluted tubule > collecting duct collecting duct -> minor calyx > major calyx > renal pelvic > ureters > urinary bladder > urethra 2 major functions of nephron Correct Answer: filtering various substances in blood regulating fluid/salt content of urine 37 How does the Loop of Henle reduce liquid volume in urine Correct Answer: concentrates in descending limb and then removes solutes in ascending limb Aldosterone function Correct Answer: causes kidneys to retain sodium to increase blood pressure, water retention. increase Na reabsorption = increase water reabsorption = increase plasma volume of blood = increase blood pressure antidiuretic hormone (ADH) Correct Answer: increases water retention = increases plasma volume in blood = increase blood pressure Atrial natriuretic peptide (ANP) Correct Answer: decreases sodium reabsorption = decreases water reabsorption = decreases plasma volume of blood = decreases blood pressure function of excretory system Correct Answer: regulates blood pressure, pH, excretion of nitrogenous wastes 38 Antigen Correct Answer: any substance that stimulates immune responnse antibody Correct Answer: y shaped molecule that recognizes antigens and allows immune response to be mobilized. has two heavy and two light chains linked by disulfide bonds Major Histocompatibility Complex (MHC) Correct Answer: Group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances. MHC class I Correct Answer: expressed in all nucleated cells, shows fragments of proteins from inside cell. can be thought of as internal quality check. abnormal in cases of viral infections or turmoigenesis. CD8+ T cells destroy MHC class II Correct Answer: expressed in some immune cells, shows fragments of antigens from external invaders that have been engulfed. cd4+ helper T cells recruit response. Cytokines Correct Answer: signaling proteins that help in immune response/inflammation 39 interferons Correct Answer: type of cytokines that specialize in response to viruses B cells Correct Answer: differentiate into plasma cells for antibody production. produced in bone marrow and are activated in lymphatic organs or tissues. t cells Correct Answer: mature in thymus through positive/negative selection. CD4+ helper T cells Correct Answer: coordinate response to abnormal MHC class II cd8+ cytotoxic T cells Correct Answer: kill cells with abnormal MHC class I suppressor (regulatory) T cells Correct Answer: moderate immune reaction when response has been insufficient memory t cells Correct Answer: "remember" previous antigens anatomy of immune system 40 Correct Answer: bone marrow, lymphatic system, spleen, thymus, and other lymphatic tissues lymphatic system function Correct Answer: regulates fluid balance, is home for lymphocytes (b and T cells), drains fats from digestive system into blood stream, returns substances from interstitial space to circulation cartilage Correct Answer: avascular, connective tissue ligaments Correct Answer: tough tissue connecting bones to bones tendons Correct Answer: tough tissue connecting muscles and bones bone types Correct Answer: long, flat, irregular, short synovial joinnts Correct Answer: bones connected by lubricated synovial cavity (elbow) 41 cartilaginous joints Correct Answer: bones connected by cartilage (vertebral discs) fibrous joints Correct Answer: bones connected by fibrous connective tissues (skull bones) diarthrosis Correct Answer: freely movable joint Amphiarthrosis Correct Answer: slightly movable joint Synarthrosis Correct Answer: immovable joint matrix of bone Correct Answer: minerals, collagen, water. calcium/phosphate reservoir Osteoblasts Correct Answer: build bone Osteoclasts are Correct Answer: cells that break down bone matrix 42 PTH Correct Answer: increase calcium from bone calcitonin Correct Answer: decrease calcium in blood by inhibiting osteoclast activity Bone marrow function Correct Answer: (hematopoiesis) produces new red blood cells skeletal muscle Correct Answer: striated, multi-nucleated, red (slow twitch) fibers contains myoglobin, specialize in long-lasting actions requiring oxidative metabolism. white (fast twich fibers contain less myoglobin and specialize in short Burts of action primarily using glycolysis smooth muscle Correct Answer: involuntary non-striated uninucleated can undergo myogencic activity (contraction in absence of nervous stimulation) cardiac muscle 43 Correct Answer: involuntary, striated, usually uninucleate. sinoatrial node sets pace of contractions. intercalated dics/gap junctions allow signals to spread muscle contraction Correct Answer: sliding actin/myosin filaments. ATP required to dissociate actin and myosin. ATP -> ADP to "cock" myosin head; calcium binds to troponin which moved tropomyosin not allow actin and myosin to bind. Pi is released to generate power stroke sacromere Correct Answer: contractile unit of muscle I-band (thin filaments, H zone (thick filaments), distances between M lines (center of H zone) and Z lines (center of I band) contract. A band (entire area where thick filaments are present) stayed the same during contraction Layers of skin (Superficial to deep) Correct Answer: epidermis, dermis, hypodermis (subcutaneous) epidermis contains Correct Answer: dead keratinocytes that provide physical protection melanocytes and Merkel cells (for touch) dermis contains Correct Answer: capillaries, lymph vessels, hair follicles, sweat glads, sensory cells 44 recombination frequency Correct Answer: larger RF = farther apart parapatric speciation Correct Answer: occurs when segments of two distinct populations overlap. due to environmental differences, these segments may develop into two species but individuals in the overlapping areas can typically still interbreed peripatric speciation Correct Answer: subtype of allopatric speciation that happens when one of the two populations is much smaller than the other sympatric speciation Correct Answer: occurs without a physical barrier. allopatric speciation Correct Answer: occurs when populations, or parts of the same population, are separated by a physical barrier. what is the principal stabilizing force and the secondary contributing factor that maintain the structure of the DNA double helix 45 Correct Answer: hydrophobic interactions between stacked bases and hydrogen bonding between complementary bases what is stronger, AT or GC bonds? Correct Answer: GC bonds - 3 hydrogen bonds rather than 2 Which of the following genetic abnormalities can occur only during meiosis? I. Substitution II. Frameshift III. Nondisjunction Correct Answer: III only! substitution = replication frameshift = replication Myoglobin Correct Answer: An oxygen-storing, pigmented protein in muscle cells. Has greater affinity for oxygen than does hemoglobin because it maintains oxygen reserve in muscles. Because it is monomeric - it does not have the coopertivity that hemoglobin does so its curve cannot be sigmoidal. instead, it will resemble more of a rectangle hyperbolic curve with how quickly it gets saturated by oxygen. 46 base form of vitamin A (the form our bodies absorb it) Correct Answer: retinol retinol (vit A) is converted into what molecule that then aids in vision? Correct Answer: retinal retinol can be oxidized into what compound? Correct Answer: retinoid acid vitamin B1 name Correct Answer: Thiamine vitamin B2 name Correct Answer: riboflavin vitamin b3 name Correct Answer: Niacin SNOW DROP mnemonic Correct Answer: S= southern blotting -> DNA= D N= Northern Blotting -> RNA = R O= nothing 47 W= western blotting -> protein = P gel electrophoresis Correct Answer: Procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel Blotting techniques Correct Answer: Blotting techniques allow for the identification of target fragments of DNA, RNA, or protein. An easy way to remember the blotting techniques is SNOW DROP Southern - DNA Northern - RNA Western - Proteins DNA microarray Correct Answer: research tool used to study gene expression SDS-PAGE Correct Answer: Type of chromatography used to separate proteins based on mass. larger proteins don't travel as far as smaller ones 48 adherent junctions Correct Answer: actin to cells tight juctions Correct Answer: blood brain barrier gap junctions Correct Answer: cell to cell anchoring junctions Correct Answer: fasten cells together into sheets