mcat Bio / Biochem Final Comprehensive

peptide hormones [insulin]

→ made up of amino acids [soluble]

→ polar, CANNOT pass membrane, use extracellular receptors like GPCR

→ modified and activated by the golgi / released via exocytosis

steroid hormones [estrogen, testosterone, cortisol]

→ non-polar, CAN pass through membrane

→ doesn’t dissolve must be carried by proteins

→ activate nuclear receptors

→ have direct action on DNA

amino-acid derivative hormones

share traits from both peptide and steroid hormones

→ catecholamines use GPCR / thyroxine bind intracellularly

g-protein coupled receptors

→ epinephrine binds to GPCR → activates G-protein → causes adenylyl cyclase to convert ATP to cAMP → causes protein kinase A to cause glycogen breakdown

phosphodiesterase deactivates cAMP

diabetes mellitus

type 1 → no insulin, glucose cannot enter cell

type 2 → desensitized insulin receptors, glucose cannot enter cell

hypothalamus hormones

GnRH → increases FSH and LH

GHRH → increases GH

TRH → increases TSH

CRH → increases ACTH

PIF (dopamine) → decreases prolactin

ADH and prolactin produced here

pancreas hormones

insulin → beta islets / decrease glucose

glucagon → alpha islets / increase glucose

somatostatin → beta islets / decrease insulin and glucagon

anterior pituitary hormones

FSH → spermatogenesis / ovarian follicle growth

LH → testosterone / induce ovulation

ACTH → release of glucocorticoids from adrenal cortex

TSH → release of thyroxine and triiodothyronine from thyroid

Prolactin → increase milk production

Endorphins → decrease pain

GH → increase growth in bone / glucose in blood

thyroid gland hormones

T4 and T3 → increase basal metabolic rate

Calcitonin → increase Ca2+ in bone / Ca2+ excretion in kidney

Calcitonin → decreases Ca2+ absorption in gut and blood

posterior pituitary hormones

ADH → decrease H2O output in urine / vasoconstriction

Oxytocin → increase uterine contractions, milk, bonding

positive feedback

adrenal cortex hormones

glucocorticoids → cortisol / cortisone → increase glucose / decrease protein synthesis & immune system

mineralocorticoids → aldosterone → increase BP, Na in blood, H2O in blood / decrease K+ in blood

androgens → converted to testosterone and estrogen

adrenal medulla hormones catecholamines

epinephrine & norepinephrine → increase HR and BP

air pathway

nostrils → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

please let those boys be able

surfactant REDUCES surface tension and prevents collapse in the lung

inhalation

increase lung volume and decreases lung pressure

exhalation

decreases lung volume and increases lung pressure

bicarbonate buffer

decreased pH → increased respiration blowing off CO2

increased pH → decreased respiration trapping CO2

electrical conduction

SA node → AV node → bundle of His → Purkinje Fibers

stab a big pickle

systole vs diastole

systole → ventricular contraction AV valves close

diastole → ventricular relaxation SV close

increased vs decreased blood pressure

increased → increased ANP

decreased → increased aldosterone / increased ADH

arteries

thick, muscular, elastic, helps propel blood forward

arterioles

small muscular arteries

capillaries

1 cell thick endothelial wall, easy diffusion of O2 & CO2 and waste

veins

thin wall, inelastic, does not have recoil, contains valves

erythrocytes

formed in bone marrow

→ no nucleus, mitochondria, or organelles

leukocytes

formed in bone marrow

granulocytes → nonspecific immunity [neutrophils, eosinophils, basophils]

agranulocytes → specific immunity [lymphocytes]

innate immunity

→ defenses that are always active but NON SPECIFIC

→ skin, mucus, stomach acid, tears, etc

adaptive immunity

→ defenses that take time to activate and are SPECIFIC to the invader

innate immune system [non-cellular defenses]

skin, mucus, lysozymes, complement system, interferons

innate immune system [cellular defense]

macrophages, MHC-I, MHC-II, dendritic cells, natural killer cells, granulocytes

MHC-I

present in all nucleated cells

endogenous antigen to cytotoxic CD8 T-cells

MHC-II

present in professional antigen-presenting cells

exogenous antigen to helper CD4 T-cells

adaptive immune system [humoral immunity]

b-cells, antibodies, hypermutation, opsonization, agglutination, memory b-cells

antibodies

produced by plasma cells → activated by B-cells → contain two heavy and two light chains

opsonization

antigens mark pathogens for destruction

agglutination

pathogens clump together into insoluble complexes

adaptive immune system [cell - mediated ]

T-cells, positive/negative selection, helper T-cells, cytotoxic T-cells, surpressor T-cells, memory T-cells, allergic reactions

cytotoxic T cells

killer cells

respond to antigen on MHC-I and kill virally infected cells

helper T cells [CD4]

respond to antigens on MHC II

secrete interferon gamma

activate B-cells in parasitic infections

digestive pathway

mouth → pharynx → esophagus → stomach → small intestine → large intestine → rectum

secretory cells that line the stomach

chief cells → pepsinogen , activated by acidic environments

parietal cells → HCl and intrinsic factor, B12 absorption

G-cells → secrete gastrin, increases HCl secretion and gastric motility

feeding behavior hormones

ADH & Aldosterone → increase thirst

glucagon and ghrelin → increase hunger

leptin and cholecystokinin → increase satiety

urine pathway

Bowman’s space → proximal → descending → ascending → distal → collecting duct → renal pelvis → ureter → bladder → urethra

Bad Penguins Do Act Depressed and Cold

filtration of the kidney

bowman’s capsule moves solutes from blood → filtrate

secretion of the kidney

movement of solutes from blood → filtrate anywhere other than Bowman’s space

proximal tubule

bulk reabsorption of glucose, amino acids, salt, H2O

secretion of H+, NH3, K+, urea

descending limb [loop of Henle]

permeable to H2O but NOT salt

ascending limb [loop of Henle]

permeable to salt but NOT to H2O

distal convoluted tubule

responsive to aldosterone

site of salt reabsorption and waste product excretion

red fibers skeletal muscle

slow twitch

support dark meat

oxidative phosphorylation

white fibers skeletal muscle

fast-twitch

active white meat

anaerobic metabolism

sarcomeres

Z-lines → boundary of each sarcomere

M-line → middle of sarcomere

I-band → only actin

H-zone → only myosin

A-band → both actin and myosin [maintains constant size]

contraction / relaxation

depolarization → triggers Ca 2+ release → binds to troponin → exposes myosin-binding site → shortens sarcomere

relax when acetylcholine is degraded by acetylcholinesterase

taxonomic

kingdom, phylum, class, order, family, genus, species

transferase

move a functional group from one molecule to another

hydrolase

cleavage with the addition of H2O

lyases

cleavage without the addition of H2O and without the transfer of e-

isomerases

interconversion of isomers

ligases

join two large biomolecules

lipases

hydrolysis of fats k

kinases

add a phosphate group

phosphatases

remove a phosphate group

phosphorylases

introduces a phosphate group

competitive inhibition

inhibitor BINDS AT ACTIVE SITE

Vmax unchanged, Km increases

uncompetitive inhibition

inhibitor BINDS ONLY WITH THE ENZYME-SUBSTRATE COMPLEX

Vmax & Km decrease

noncompetitive inhibition

inhibitor binds with equal affinity to the ENZYME AND ENZYME SUBSTRATE COMPLEX

Vmax decreases and Km unchanged

cell adhesion molecules

cadherins → calcium dependent glycoproteins holding similar cells together

integrins → two membrane spanning chains permit cells to adhere to proteins in extracellular matrix

selectins → allow cells to carbohydrates on the surface other cells

Native PAGE

maintains protein’s shape

→ results are difficult to compare because the mass / charge ratio differs for each protein

SDS - PAGE

denatures the proteins and masks the native charge making the comparison of the size more accurate

→ functional protein cannot be recaptured from the gel

chromatography

separates protein mixtures on the basis of their affinity for a stationary phase / mobile phase

column chromatography

uses beads of a polar compound [ stationary ] with a nonpolar solvent [ mobile ]

ion-exchange chromatography

charged column and a variably saline eluent

size-exclusion chromatography

larger molecules elute first because they are not trapped in the small pores

affinity chromatography

bound receptor or ligand and an eluent with free ligand / receptor for the protein of interest

prokaryotes DO NOT have a nucleus, instead they have a region called the NUCLEOID where DNA can be made

nucleolus function

makes ribosomes → ribosomes important for connecting amino acids

rough ER vs smooth ER

rough ER → accepts mRNA to make proteins

smooth ER → detoxification and creation of lipids

golgi apparatus characteristics

→ only in eukaryotes

→ COPI : golgi → rough ER [anterograde]

→ COP II : rough Er → golgi [retrograde]

→ clathrin : plasma membrane → ← golgi

gram positive vs gram negative

gram positive → PURPLE, thick peptidoglycan / lipoteichoic acid cell wall

gram negative → PINK / RED, thin peptidoglycan cell wall & outer membrane

eukaryotes vs prokaryotes

eukaryotes → ETC in mitochondria, LARGE ribosomes, reproduce via MITOSIS

prokaryotes → ETC in cell membrane, SMALL ribosomes, reproduce via binary fission

cytoskeleton components

microfilaments → actin [cell motility]

intermediate filaments → keratin and desmin [structural support]

microtubules → tubulin [centriole, moving things within cell]

tissue types

simple → one layer

stratified → multiple layers

pseudostratified → one layer looks like two

columnar → long and narrow

squamous → flat, scale like

genetic recombination

transformation → genetic information from environment

conjugation → transfer of genetic information via conjugation bridge [ F factor ]

transduction → transfer using [virus] bacteriophage

transposons → genetic information that can insert / remove itself

virus characteristics

viruses can have DNA or RNA

be single or double stranded

single stranded DNA can be positive [translated by host] or negative [RNA replicase synthesizes the complimentary strand]

cell cycle

G1 → makes mRNA and proteins

G0 → cell enters if it DOES NOT need to divide

G1 checkpoint → P35 is in charge

S → DNA is replicated

G2 → cell growth [makes organelles]

G2 checkpoint → check cell size & organelles

mitosis PMAT

prophase → DNA condenses, centrioles move to opposite poles, nuclear envelope dissolves

metaphase → chromosomes meet in the middle

anaphase → sister chromatids separate and move to opposite poles

telophase → chromosomes decondense, nuclear membrane forms, enters cytokinesis

meiosis PMAT x2

metaphase I → instead of each half of a chromosome being pulled apart, they cross over resulting in genetic recombination

anaphase I → allows for disjunction [law of segregation]

telophase I → two haploid daughter cells of unequal sizes form

telophase II → four haploid daughter cells are formed

reflex arc

monosynaptic → sensory → motor

polysynaptic → sensory → interneuron → motor

you can send signals temporally or spatially

temporally → same space / different time

spatially → different space / same time

action potential [ 3 Na+ out / 2K+ in] ATPase

depolarization → Na+ in

repolarization → K+ out

hyperpolarization → K+ leak channels open, some voltage gated K+ open

refractory period → neuron no longer excitable

synapse

action potential → Ca 2+ into cell → synaptic vesicle → docking protein → neurotransmitter → neurotransmitter bound to receptor

neurotransmitter removed via either breakdown by enzymes, reuptake, or diffusion out of cell

for every glucose molecule that undergoes glycolysis, there is a net production of 2 ATP molecules and 2 NADH molecules

genes found extra chromosomally are self replicating