MCAT Biology 2
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- What is a phospholipid made of?
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phosphate group
2 fatty acid chains
glycerol - glycoproteins
- proteins containing a carbohydrate portion
- micelle
- Spherical structure formed when amphipathic molecules spontaneously aggregate in aqueous solution, turning polar ends toward the solution and nonpolar ends toward each other
- Difference between Prokaryote and Eukaryote Plasma Membrane
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E-contains steroids like cholesterol
P-contains only steroid like hopanoids - Membrane model
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Fluid Mosaic model in which parts can only move laterally.
The membrane is asymmetrical.
Fluidity moderated by cholesterol. - Types of prokaryotes
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Archaea--like bacteria and eukaryotes, extreme environments
Bacteria--peptidoglycan cell walls - What do organisms require in order to grow and what are the types?
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1. Carbon: autotrophs ( fix CO2) or heterotrophs (organic molecules)
2. Energy: chemotrophs (organic/inorganic matter) or phototrophs (light)
3. Electrons from H+ usually: - What can acquire energy from an inorganic source other than light?
- Prokaryotes: lithotrophs (electrons acquired from inorganic matter) or organotrophs (electrons acquired from organic matter)
- Nitrification
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Bacteria fix nitrogen
requires 2 genera of chemoautotroph prokaryotes - Characteristics of the Structure of Prokaryotes
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No nucleus, only a single double stranded molecule of DNA twisted around histones in supercoils forming a nucleoid
Two major shapes: cocci (round) and bacilli (rod shaped). Also spirilla (rigid) and spirochete (gave rise to flagella).
no complex, membrane bound organelles
contain both RNA and DNA, so have ribosomes - Electrical Gradient
- points in the direction a + charge would move
- Semipermeability depends upon...
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size and polarity
larger size and more polar = less permeable
ex. natural membrane more permeable to water than sodium--charge difference outweighs size difference - Integral/intrinsic membrane proteins
- transverse the membrane and create holes that facilitate leakage or passive diffusion of water.
- Transport or carrier membrane proteins
- designed to facilitate diffusion of specific molecules across the membrane
- facilitated diffusion
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Occurs down the electrochemical gradient.
Makes the membrane selectively permeable b/c it's able to distinguish b/w size and charge...so permeability depends on lipid solubility and size
Requires carrier proteins. - Active transport
- Against gradient...requires energy (ATP)
- Bacteriophage
- type of bacteria that has a tail, base plate, tail fiber, capsid, and DNA or RNA and infects bacteria
- Virion
- mature virus outside host
- Virus
- capsid protein coat and contains DNA or RNA, require hosts’ machinery to reproduce
- Bacterial Envelope
- Includes the cell wall (preventing bursting), periplasmic, and capsule
- Hypertonic
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cytosol more aqueous than environment
most bacteria are hypertonic - Isotonic
- cytosol contains the same amount of particles as the environment
- hypotonic
- cytosol contains less particles
- Peptidoglycan
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Makes up the bacterial cell wall
Polymer disaccharide chains connected by amino acides.
Elastic and porous, and antibiotics weaken it. - Gram Staining
- Staining technique used to ID bacteria.
- Gram-positive Staining
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thick peptidoglycan cell wall prevents gram stain from leaking out = purple
cell wall 4 times thicker than PM - Gram negative staining
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Thin cell wall doesn't retain stain.
Phospholipid bilayer outside cell wall that is more permeable. - flagella
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long, hollow, rigid, helical cylinders made from the globular protein flagellin.
Rotate counterclockwise to propel bacterium in a single direction...tumbling
Propelled by a hydrogen gradient (not ATP). - Bacterial Reproduction & Recombination
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No sexual reproduction and do not undergo meiosis or mitosis.
Genetic Recombination by conjugation, transformation, and transduction.
Reproduce also by binary fission (no recombination). - Binary fission
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Bacterial Reproduction:
circular DNA is replicated (DNA polymerase) and cell divides
genetically identical daughter cells - Conjugation
- On Bacteria with the F plasmid with the gene coding for the sex pilus (allowing connection for DNA passage)
- R plasmid
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donates resistance to certain antibiotics.
can be transferred in conjugation. - Transformation
- Proces by which bacteria may incorporate DNA from their external environment into their genome (S & R bacteria)
- Transduction
- host DNA incorporated into a virion, so it injects foreign DNA into a new host instead of virulent DNA
- Endospores
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Bacterium divides within its cell wall and then one side engulfs the other..forming an ultra-resistant spore...occurs in conditions of lack of nutrients
Germination triggered by nutrients. - Characteristics of Fungi
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Eukaryotic heterotrophs that obtain energy by absorption not ingestion (external digestion)
Saprohpytic--feed on decayed matter
Also eat living matter
Septa-cell wall made of chitin
1n dominant
Mitosis takes place in the nucleus
multicellular (except yeast)
Consist of a tangled mass of mycelium or branched hyphae - Sexual Reproduction in Fungi
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Occurs between hyphaie from two mycelia of different mating types.
Conjugation bridge formed and the tips of the hyphae produce gametes which forms the zygote, aka zygospore.
Zygospore then separates from hyphae and remains dormant till activated by appropriate environmental conditions, where it undergoes meiosis->haploid cells
Occurs when conditions are bad - Eukaryotic Nucleus
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Contains DNA, which cannot leave the nucleus.
Double phospholipid bilayer
RNA exits nuclear pores - Nucleolus
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In the nucleus
where the subunits of ribosomes are assembled - Endocytosis
- Phagocytosis and pinocytosis and receptor mediated (clathrin coated pit)
- Endoplasmic Reticulum
- Continuous with the PM. Separates the cytosol from the ER lumen.
- Rough ER
- Where transcription and tagging of protein occurs..then small transport vesicles bud off and carry proteins across the cytosol to the golgi
- Golgi
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series of flattened membrane bound sacs
organizes and concentrates proteins recieved from rER as they are shuttled across the cisterna
Proteins expelled as secretory vesicles or released as lysosomes - secretory vesicles
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may contain enzymes or growth factors
release contents through exocytosis - lysosomes
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contain acid hydrolases that break down macromolecules within a cell
pH 5 - Smooth ER
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lacks ribosomes
tubular
makes and stores fat
lipid (steroid, cholesterol) synthesis
produces tryglycerides and store them as fat droplets
oxidize foreign substances
detoxifies - Adipocytes
- cells containing fat droplets
- peroxisomes
- vesicles in the cytosol
- Filaments of the Cytoskeleton
- microtubules and microfilaments
- Microtubules
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larger than microfilaments
rigid hollow tubes made from the protein tubulin
involved in flagella and cilia construction and spindle apparatus - Vitamin A
- precursor to all the pigments in rods and cones
- Lense in the Eye
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converging lens
object outside focal length
image on the retina is real and inverted - Fovea
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small point on the retina containing mostly cones
point on the retina where vision is most acute - Iris
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colored portion of the eye that creates the pupil
circular and radial muscles
when contracted, the pupil dilates (in the dark) - Ciliary Muscles
- When relaxed, they flatten the lense making it less powerful, which moves the focal point away from the lens
- Cerebellum
- controls finely coordinated muscular movements
- Medulla oblongata
- Controls involuntary breathing movements
- Knee jerk reflex
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governed by the spinal cord
sensory neurons (located dorsally) receive signals from the environment and motor/efferent neurons carry signals to the muscle/gland (synapse ventrally on the spinal cord) - epinephrine and norepinephrine
- neurotransmitters in the postsynaptic of the sympathetic nervous system
- Cochlea
- where pressure waves are converted to neural signals
- Peptide Hormones
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water soluble, move freely through the blood but hard to diffuse through cell membrane
use second messenger or membrane receptor
manufactured in the rER as preprohormones - Anterior Pituitary Hormones
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FSH, LH, ACTH, TSH, Prolactin, hGH
peptide hormones - Posterior Pituitary Hormones
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ADH and oxytocin
peptide hormones - Parathyroid Hormones
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PTH
peptide hormones - Pancreatic Hormones
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Glucagon and insulin
peptide hormones - Steroid hormones
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derived from or similar to cholesterol
formed in the smooth ER
lipids--require transport through blood
combine with receptor in cytosol (diffuse through membrane)
acts on transcription levels
from adrenal cortex, gonads, or placenta
ex. aldosterone, cortisol, estroge, glucocorticoids, etc. - Hormones of adrenal cortex
- glucocorticoids and mineral corticoids
- 3 types of hormones
- steroid, tyrosine, and peptide
- Tyrosine derivative hormones
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formed by enzymes in the cytosol or rough ER
thyroid hormones (diffuse thru membrane) and catecholamines (bind to membrane) - Adrenal Medulla Hormones
- catecholamines: epinephrine and norepinephrine
- Thyroid hormones
- T3 and T4