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244 Cards in this Set
- Front
- Back
Three primary techniques for examining cells
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Microscopy, autoradiography, centrifugation
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Microscopy Types
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Compound Light = most common
diaphragm - controls amount of light Phase Contrast - allows for visualization of living organisms Electron - visibility down to atomic level |
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autoradiography used to...
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study biochemical processes
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plasmids
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small circular pieces of DNA in prokaryotes, replicate independently of bacterial chromosome
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glyoxysomes
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convert fats to usable fuel (sugars) for energy in plants until photosynthesis can be performed
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3 components to cytoskeleton
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microfilaments (made of actin)
intermediate filaments microtubules |
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four main types of tissue in body
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epithelial, connective, nervous, muscle
"C-MEN , seamen" |
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Cell Theory
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1. All living things composed of cells.
2. Cell = basic functional unit of life. 3. Cells come only from other cells. 4. Genetic material contained in DNA. |
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nucleoid region
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where DNA is found in prokaryotes
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cell adhesion molecules (CAMs)
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important in cell recognition
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nucleolus
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where rRNA is synthesized in nucleus in euks, not surrounded by a membrane
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lysosomes
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break down ingested material (cell garbage dump)
can participate in apoptosis |
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cristae
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increase surface area of mitochondria, folds of inner membrane
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mitochondrial matrix
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enclosed inner portion important in cellular respiration
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peroxisomes
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microbody that creates hydrogen peroxide and uses it to break down fats, important in detox liver rxns (alcohol)
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centriole
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bundle of microtubules used to organize spindle apparatus for mitosis ("highway system")
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actin
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important in muscle contraction where they interact with myosin
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microtubules
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hollow, polymers of tubulin proteins, involved in chromosomal separation during mitosis/meiosis, make up cilia and flagella
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intermediate filaments
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maintain overall integrity of cytoskeleton
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Mv't across membranes
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simple diffusion (includes osmosis)
facilitated diffusion active transport (needs ATP) endo- & exo- cytosis (needs ATP) |
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hypotonic
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less solutes than on other side of membrane
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hypertonic
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more solutes than on other side of membrane
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isotonic
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same amt of solutes on both sides of membrane, does not prevent mv't
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facilitated diffusion
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for large, polar, and/or charged molecules to move down electrochem gradient
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pinocytosis
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endocytosis of fluids and dissolved particles
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phagocytosis
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ingest of large solids, e.g. bacteria
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epithelial tissue
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cover body and line cavities, protect against invasion and desiccation
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connective tissue
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supports, provides framework for body, e.g. blood, adipose tissue, tendons
"the bra of the body" |
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nervous tissue
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primary cells = neurons
use electrochem gradients for cell signaling and coordinating control |
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muscle tissue types
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skeletal, smooth, cardiac
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capsid
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protein coat of virus
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obligate intracellular parasites
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descriptor of viruses
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virions
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new copies that a virus has made of itself using cell machinery
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bacteriophages
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viruses that specifically target bacteria, don't fully enter, just inject genetic material
polyhedral tail structure with tail fibers |
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virus genetic information forms
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circular or linear
single or double stranded DNA or RNA (may bring own polymerases and/or RNA replicase with them if they want to replicate & transcribe in cytoplasm) |
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Functions of smooth ER
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transport of materials throughout cell
lipid synthesis detoxification of drugs and poisons |
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ribosome function
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protein synthesis
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Differences bw prokaryotes and eukaryotes
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- euks have nucleus & membrane-bound organelles
- euks ribosomal subunit weights are 40s and 60s, proks ribosomal subunit weights are 30s and 50s |
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Enzyme function
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biological catalysts, lower activation E thus increasing rxn rate, pH & temp sensitive, specific
do not - affect overall ΔG - change equilibrium constant - Δ from rxn |
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substrate of enzymatic rxn
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molecule upon which enzyme acts
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active site of enzymatic rxn
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location within enzyme where substrate is held during rxn
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lock & key theory
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suggests enzyme active site (lock) is in appropriate conformation to bind to substrate (key)
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induced fit theory
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more accepted than lock & key theory
change in shape which takes a little E but ends up with lowered conformation energy, active site only truly complementary after substrate binds to enzyme |
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cofactor
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nonprotein molecules that aid enzymes
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apoenzymes
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enzymes without their cofactors
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holoenzymes
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enzyme with cofactor
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prosthetic groups
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tightly bound factors that connect to their enzyme
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coenzymes
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small organic groups that are cofactors for an enzyme
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Km = ? when rxn rate = ½ Vmax
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[S]= ? at ½ Vmax
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Michaelis-Menten eqn
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rate = (Vmax * [S]) / ([S] + Km)
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optimal pH of human blood
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7.4
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allosteric sites
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site different from active site that affects active site availability
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allosteric enzymes
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alternate bw an active and inactive form
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allosteric activators
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causes conformation shift in protein that favors substrate binding
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allosteric inhibitors
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cause conformational shift in protein that inhibits substrate binding
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Reversible inhibitions types
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competitive, noncompetitive, uncompetitive
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competitive inhibition
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only involves occupancy of active site
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noncompetitive inhibition
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involves allosteric site, both the substrate bound and non-substrate bound forms of protein can be inhibited
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uncompetitive inhibition
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involves allosteric and active site, substrate-bound protein can be inhibited allosterically
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irreversible inhibition
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active site made permanently unavailable or enzyme permanently altered
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zymogens
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inactive forms of enzymes, regulatory domain must be removed/altered to expose active site, e.g. caspases used in apoptosis
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autotrophs
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derive E from sun
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heterotrophs
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derive E by breaking down other organisms organic molecules
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Photosynthetic eqn
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6 CO₂ + 6 H₂O + E ➔ C₆H₁₂O₆ + 6 O₂
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Cell Respiration Eqn
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C₆H₁₂O₆ + 6 O₂ ➔ 6 CO₂ + 6 H₂O + E
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Intermediates used in glucose metabolism
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ATP, NAD⁺, FAD
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ATP
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generated during glucose metabolism
7 kcal/mol E released with each Pi that leaves |
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NAD⁺ & FAD
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coenzymes capable of accepting high-energy electrons during glucose oxidation
by accepting hydride ions, they are reduced to NADH & FADH₂, carried on inner mitochondrial membrane to ETC to get oxidized & produce ATP |
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glycolysis
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breaks down glucose into 2 smaller orgo mols in presence or absence of O₂
Inputs: 6C-glucose, 2 ATP, 2 NAD⁺ Outputs: 2 3C-pyruvate, 4 ATP, 2 NADH |
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substrate-level phosphorylation
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direct generation of ATP from ADP and Pi
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Net rxn of glycolysis
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Glucose + 2 ADP + 2 Pi + 2 NAD⁺ ➔ 2 Pyruvate + 2 ATP + 2 NADH + 2 H⁺ + 2 H₂O
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fermentation fxn
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to oxidize NADH for re-use, includes glycolysis step
reduces pyruvate to ethanol or lactic acid |
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alcohol fermentation rxn
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Pyruvate (3C) ➔ CO₂ + Acetaldehyde (2C)
Acetaldehyde + NADH + H⁺ ➔ Ethanol (2C) + NAD⁺ Typical rdxn of aldehyde to alcohol from orgo |
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Lactic acid fermentation rxn
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Pyruvate (3C) + NADH + H⁺ ➔ Lactic acid + NAD⁺
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Cori cycle
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when O₂ supply catches up to demand, lactic acid gets converted back to pyruvate
|
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oxygen debt
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amt of O₂ needed to catch back up to demand
|
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3 key phases of cell respiration
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pyruvate decarboxylation
citric acid cycle ETC |
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Pyruvate decarboxylation
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2 pyruvate(3C) + 2 CoA + 2 NAD⁺ ➔ 2 NADH + 2 Acetyl-CoA (2C) + 2 CO₂ (1C)
2 NAD⁺ mols reduced per glucose mol no need of O₂ itself but part of chain so O₂ must be present for other parts to make this part run |
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What E do we have in what forms after pyruvate decarboxylation?
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2 ATP (glycolysis)
2 NADH (glycolysis) 2 NADH (decarboxylation) |
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Citric Acid Cycle aka Krebs Cycle aka tricarboxylic acid cycle (TCA) info
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Each acetyl-CoA molecule ➔ 2 NADH & 1 FADH₂
2 turns / glucose molecule Each turn generates 1 ATP via substrate-level phosphorylation and a GTP intermediate. Does generate high-E electrons carried by NADH and FADH₂. Some ATP generated from GTP directly through substrate-level phosphorylation. |
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What E do we have in what forms after Krebs/TCA?
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2 ATP (glycolysis)
2 NADH (glycolysis) 2 NADH (decarboxylation) 6 NADH (TCA) 2 FADH₂ (TCA) 2 ATP (TCA) |
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oxidative phosphorylation
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·Process of releasing E from protons moving back through ATP synthases to convert ADP to ATP
·Produces more ATP during Krebs/TCA |
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Citric Acid Cycle aka Krebs Cycle aka tricarboxylic acid cycle (TCA) Rxn
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2 Acetyl-CoA + 6 NAD⁺ + 2 FAD + 2 GDP + 2 Pi + 4 H₂O ➔ 4 CO₂ + 6 NADH + 2 FADH₂ + 2 ATP + 4 H⁺ + 2 CoA
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cytochromes
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enzymes that are high energy electron carriers used in ETC, contain central iron atom
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cytochrome complexes
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Complex I. NADH dehydrogenase
Complex III. b-c1 complex Complex IV. cytochrome oxidase |
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FMN (flavin mononucleotide)
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part of complex I, given electrons by NADH, then passed to ...
carrier Q |
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carrier Q (ubiquinone)
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small hydrophobic, not an enzyme, passed electrons onto complex III
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Order of ETC
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Complex I (NADH dehydrogenase) & Complex II (succinate-Q oxidoreductase - FADH₂)
Carrier Q (ubiquinone) Complex III (b-c1 complex) Complex IV (cytochrome oxidase) (w/in IV, cytochrome a3 protein + 2 protons make H2O) |
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cytochrome a3
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protein in complex IV (cytochrome oxidase) that makes water with 2 protons
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Each NADH in ETC generates ___ molecules ATP?
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3
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Each FADH₂ in ETC generates ___ molecules ATP?
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2
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Where does FADH₂ molecules start in ETC?
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Complex II (succinate-Q oxidoreductase)
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proton-motive force
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the electrochemical gradient driving H⁺ passively back across the inner mitochondrial membrane into the matrix
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ATP synthases
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enzyme complexes that are channels for allowing charged H⁺s to move back down gradient
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Location of glycolysis
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cytoplasm
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location of fermentation
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cytoplasm
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location of pyruvate to acetyl-CoA
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mitochondrial matrix
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location of TCA cycle
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mitochondrial matrix
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location of ETC
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Inner mitochondrial membrane
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Fatty acids introduced catabolic pathway via what molecule at what stage?
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Acetyl-CoA introduced into Krebs cycle
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adding H reduces/oxidizes?
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reduces
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Fats stored in adipose tissue in what form?
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triglycerides
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β-oxidation
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generates acetyl CoA from fatty acids in cytoplasm, each round results in 1 NADH and 1 FADH₂
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transaminases
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remove amine moiety from amino acids resulting in α-keto acids which can then be converted to acetyl-CoA or are intermediates of TCA
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Steps in metabolism of fats
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1. Fatty acids activated in cytoplasm, requires 2 ATP
2. Transported to mitochondrial matrix to undergo β-oxidation 3. Each round of oxidation makes 1 NADH and 1 FADH₂, removes 2 C at a time from fatty acid chain |
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Steps in metabolism of proteins
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1. Removal of amine moiety from AAs by transaminases to make α-keto acids
2. α-keto acids converted to acetyl-CoA or are intermediates of TCA cycle and enter directly |
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binary fission
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type of asexual reproduction used by proks
|
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euk autosomal cells
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contain diploid (2n) chromosomes
|
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euk haploid
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aka germ cells
contain the n number of chromosomes |
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Interphase made up of...?
|
G1, S, G2 stages
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G1 stage
|
aka presynthetic gap
cells create organelles for E and protein prdxn while doubling in size |
|
Restriction points
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G1 ➔ S
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S Stage
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aka synthesis
replication of genetic material making 2 identical chromatids bound at centromere, no Δ in ploidy 2x as much dna now as in G1 |
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Four phases of mitosis
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prophase (chromosomes condense, spindle forms)
metaphase (chromosomes align) anaphase (sister chromatids separate) telophase (new nuclear membranes form) |
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G2 stage
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aka post synthetic gap
quality control check |
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chromatin
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less condensed form of chromosomes during interphase
|
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centrioles
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specialized organelles made of tubulin, paired outside the nucleus in centrosome region, responsible for correct division
migrate to opposite poles during prophase and form spindle fibers made from microtubules |
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asters
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attachment points for chromosomes for separation during anaphase
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prophase
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chromosomes condense, centriole pairs separate, spindle apparatus forms, nuclear membrane dissolves, nucleoli become less dense, kinetochores appear at centromeres
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metaphase
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centriole pairs at opposite poles, kinetochore fibers interact with spindle apparatus to align chromosomes on metaphase plate
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anaphase
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centromeres split so each chromatid has its own, telomeres are last part of chromatids to separate, sister chromatids pulled apart by kinetochore fiber shortening
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telophase & cytokinesis
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spindle apparatus disappears, nuclear membrane re-forms, nucleoli reappear, chromosomes uncoil, resume interphase form
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Four forms of asexual reproduction
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binary fission
budding regeneration parthenogenesis |
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binary fission
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(think bacteria)
circular chromosome attaches to wall and replicates while cell grows in size, plasma membrane and cell wall grow inward along midline |
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budding
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equal replication followed by unequal cytokinesis
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regeneration
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accomplished via mitosis, parts regrowing into whole
|
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parthenogenesis
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process whereby adult organism develops from unfertilized egg, means number of chromosomes will be haploid in resulting offspring
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gametes
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specialized sex cells produced via meiosis
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mitosis results vs meiosis results
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mitosis- 2 identical diploid daughter cells (2n)
meiosis - 4 different haploid gametes (n) |
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gametocytes undergo ______ where somatic cells undergo _______.
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meiosis... mitosis
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reductional division
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First division during meiosis I generating haploid daughter cells
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equational division
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Second division during meiosis II resulting in separation of sister chromatids.
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synapsis
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first major difference bw meiosis and mitosis
during prophase I where homologous chromosomes come together and intertwine point of synapsis = chiasma exchange = crossing over |
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prophase I
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each chromosome has 2 sister chromatids at this stage so each pair contains 4 chromatids making a tetrad
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anaphase I
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homologous pairs separate to opposite cell sides
process known as disjunction = chromosome of paternal origin separates from maternal, either can end up in either daughter cell |
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telophase I
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each chromosome still consists of sister chromatids joined at centromere, the cells are haploid (once homologous chromosomes separate, only the n number of chromosomes is left; still 2 chromatids / chromosome)
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gonads
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produce sperm and ovum which fuse during fertilization to form a single-celled zygote in fallopian tubes
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testes
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primitive gonads develop into these in males, located in scrotum hanging below penis
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2 functional components of testes
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seminiferous tubes (sperm produced here, nourished by Sertoli cells)
interstitial cells (cells of Leydig) (secrete testosterone and other androgens) |
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Pathway of sperm from creation to ejaculation
|
"Seven Up"
Seminiferous tubules Epididymis Vas deferens Ejaculatory duct Urethra Penis |
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epididymis
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where sperm go as they mature and develop flagella, stored here until ejaculation
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seminal fluid produced by...
|
seminal vesicles (contribute fructose)
prostate gland (makes fluid mildly alkaline) bulbourethral gland seminal fluid + sperm = semen |
|
where does spermatogenesis occur?
|
seminiferous tubules
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spermatogonia
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diploid stem cells in males
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Steps of spermatogenesis
|
spermatogonia (2n) ➔
1° spermatocytes (2n) ➔ via meiosis I form.. 2° spermatocytes (n) ➔ via meiosis II form.. spermatids (n) ➔ spermatozoa (n) |
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How many sperm does one spermatogonium create?
How many ovum does one oocyte create? |
4
1 |
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Sperm parts
|
Head (containing genetic material)
Midpiece (to generate E from fructose) Flagellum (motility) Acrosome (cap over sperm head, derived from Golgi to penetrate ovum) |
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Ovaries
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female gonads that produce estrogen and progesterone, consisting of follicles (sacs) to nourish ova
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Fallopian tube
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aka oviduct, lined with cilia to usher egg along from peritoneal sac to uterus (site of fetal development)
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vaginal canal
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where sperm is deposited during intercourse and then moves through cervix into uterus
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primary oocytes
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pre-differentiated 2n cells in females frozen in prophase I
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Steps of oogenesis
|
1° oocyte (2n) ➔
via meiosis I, 2° oocyte (n) + polar body ➔ 2° oocyte gets frozen in metaphase II until fertilization ➔ fertilization leads to meiosis II ➔ ovum (n) |
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What is unequal cytokinesis in oogenesis?
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ample cytoplasm given to one daughter (2° oocyte) and nearly none to other (polar body)
|
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Cell layers surrounding oocytes
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zona pellucida
corona radiata Meiosis II triggered when sperm penetrate these. |
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zygote
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fused haploid cells resulting in restoration of diploid chromosome number during fertilization
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How does the sperm get inside the egg?
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1. Acrosomal enzymes digest corona radiata and penetrate zona pellucida.
2. Sperm hits cell membrane; acrosomal apparatus forms to penetrate. 3. Nucleus enters ovum. 4. Ovum undergoes cortical rxn with Ca2+ release leading to.. 5. Formation of fertilization membrane. (impenetrable to other sperm) |
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Upon ovulation, the oocyte is released into...
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the abdominal cavity near the entrance of the fallopian tubes.
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cleavage
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process of rapid mitotic cell division of the zygote, first cleavage officially creates an embryo
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Types of cleavage
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indeterminate (results in cells that develop into full organisms)
determinate (commits cells to differentiating) |
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Key time points in embryo development
|
1st cleavage - 32 hpf
2nd - 60 hpf 3rd - 72 hpf arrives at uterus hpf = hours post fertilization |
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morula
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solid mass of cells after several divisions during embryo development
|
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blastula
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formed by blastulation, characterized by fluid-filled cavity known as blastocoel
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blastocyst & 2 cell groups of it
|
mammalian blastula
1. trophoblast (surrounds blastocoel, gives rise to chorion & placenta) 2. inner cell mass |
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endometrium
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"soil" where blastocyst settles, settling promoted by progesterone which proliferates mucosal layer in uterus
|
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gastrulation
|
generation of 3 distinct cell layers in gastrula (indented 2 layer cup)
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Parts of gastrula
|
endoderm (inner cell layer and inside of cup)
ectoderm (outer cell layer) archenteron (cavity, later makes gut) blastopore (opening into archenteron) mesoderm (third middle layer) |
|
deuterosomes (humans) vs. protosomes
|
(d) blastopore = anus
(p) blastopore = mouth |
|
Ectoderm generates...
|
integument (skin, hair, nails, epithelium of nose mouth and anal canal, eye lens, nervous system
*adrenal medulla of kidney system |
|
Mesoderm generates...
|
Musculoskeletal system, circulatory system, excretory system, gonads, muscle and connective tissue coats of digestive & respiratory tracts
*kidneys |
|
Endoderm generates...
|
epithelial linings of digestive & respiratory tracts, lungs, parts of liver, pancreas, thyroid, bladder, distal urinary and reproductive tracts
|
|
neurulation
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creation of nervous system, occurs post gastrulation formation of 3 germ layers
|
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Steps of neurulation
|
1. Notochord
2. Neural folds surrounding neural groove 3. Fusion into neural tube (gives rise to central nervous system) 4. Neural crest cells (at top of folds) migrate outward to form peripheral nervous system 5. Ectodermal cells form cover |
|
Specialized structures for fetal nutrient/gas xchange?
|
placenta (formed from chorion)
umbilical cord (provides chorion attachment & nutrition for fetus) |
|
chorion
|
develops from trophoblast cells
extra-embryonic membrane chorionic villi eventually grow into placenta and support gas exchange |
|
3 extra-embryonic membranes
|
allantois (surrounded by amion)
amnion (filled with amniotic fluid) yolk sac (site of early blood vessel development) |
|
fetal shunts
|
keep blood within heart and away from fetus lungs
1. foramen ovale (connects right and left atria, pushed by pressure differential opposite of adults) 2. ductus arteriosus (shunts leftover blood from pulmonary artery to aorta) |
|
ductus venosus
|
reroutes blood returning from placenta to inferior vena cava instead of the liver
|
|
arteries vs. veins
|
Arteries take blood Away from heart
Veins take blood towards (veni, vedi, vici) |
|
First trimester
|
major organs begin to develop
heart starts beating at about 22 days skeleton starts to harden embryo becomes fetus by about 8 weeks |
|
Second trimester
|
lots of growth
starts moving lengthening of toes and fingers |
|
Third trimester
|
rapid growth, further brain development
antibodies selected and transferred in via active txport less active, less room |
|
Birth
|
coordinated by prostaglandins & peptide hormone oxytocin
3 phases: 1. cervix thins, amniotic sac ruptures 2. strong uterine contractions 3. afterbirth = placenta & umbilical cord expelled |
|
Placenta releases what hormones?
|
LH (luteinizing hormone)
hCG (human chorionic gonadotropin) estrogen |
|
What can cross placental barrier?
|
Smaller molecules such as ethanol, drugs, and hormones.
|
|
induction
|
influence of a specific group of cells on the differentiation of another group of cells
|
|
Blood pressure in inferior vena cava after birth..?
|
Blood pressure decreases, causing decrease in pressure in right atrium.
|
|
true-breeding plants
|
offspring will only ever have same traits as parents
|
|
Mendel's Law of Segregation
|
1. genes have alternate forms (alleles)
2. An organism has 2 alleles for each gene, one from each parent. 3. 2 alleles segregate during meiosis, resulting in gametes carrying only one allele for any inherited trait. 4. If 2 alleles differ, one will be dominant, the other recessive. |
|
F (filial) generation
|
F1, F2, etc. mark what generation we're looking at. F1 = P (parent) generation.
|
|
other term for test crosses
|
back crosses
|
|
Mendel's (2nd Law) Law of Independent Assortment
|
Each gene's inheritance/assortment is independent of inheritance of other genes. True only for unlinked genes.
|
|
TtPp self-cross gives what phenotypic ratios?
|
9:3:3:1
|
|
How do you determine likelihood of two unlinked traits both happening?
|
Probability of one * probability of other = likelihood
|
|
genetic map
|
1 map unit corresponds to 1% chance of recombination occurring
|
|
Four variations on mendelian genetics
|
incomplete dominance (color mix result 1:2:1 distribution)
codominance (complete expression of both genes) penetrance (all or nothing) & expressivity (variable) inherited disorders |
|
hemizygous
|
where males express an x-linked mutation, cuz they only got one x chromosome
|
|
pedigrees
|
males = squares
females = circles affected = shaded carrier = half shaded |
|
aneuploid
|
individuals with diploid chromosome number other than 46
|
|
nondisjunction
|
most common cause for aneuploidy
|
|
deletion
|
can result in...
duplication (fragment joining homologous chromosome) translocation (joining another chromosome) inversion (joining back in where it was but backwards) |
|
homozygous dominant crossed with heterozygous gives what phenotypic ratio?
homozygous recessive crossed with heterozygous gives? |
3:1
1:1 |
|
cytoplasm vs. cytosol
|
area contained by plasma membrane but excluding nucleus
vs. fluid component of that area — "sol"ution (all of inside of proks) |
|
glycosylation
|
process that takes place in golgi where proteins are modified with sugar groups
|
|
movement of cilia vs. flagella
|
whip-like
wave-like |
|
intercellular junctions
|
tight (membranes of neighboring cells attached)
anchoring (eg desmosomes, in cells subject to mech stress) gap (direct connxn bw cytoplasms of 2 cells formed by connexins) |
|
gram-positive
|
bacteria with thick cell wall made of peptidoglycan
|
|
gram-negative
|
bacteria with thinner cell wall sandwiched b/w layers of periplasm & coated with lipopolysaccharide and protein
|
|
bacteria shapes
|
cocci - round/spherical
bacilli - rod-shaped spirilla - curly |
|
polycistronic
|
mRNA's in proks that contain more than one coding region
|
|
methods by which proks txfer genetic material
|
transformation (DNA taken up from environment)
transduction (via virus, generalized (all chromosome of another bacterium) & specialized (piece of chromosome with viral mix)) conjugation (via temporary connection of extended sex pili forming conjugation bridge) |
|
Hfr cells
|
"High frequency of recombination" cells
Proks that have recombination of genetic material with F plasmid integrated into chromosome |
|
retroviruses
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need reverse transcriptase to copy DNA from RNA (not found in animal cells), then gets integrated and txcribed to make mRNA
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Methods of bacteriophage reprdxn
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lytic cycle (virus takes control of host cell machinery)
lysogenic cycle (integrates viral DNA into bacterial genome in prophage form, remains dormant) |
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fungi
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cell walls of chitin
heterotrophs multicell ones have hyphae, the whole = mycelium mushrooms molds (some reproduce asexually) yeasts (unicellular, reproduce via budding) lichens (symbiotic mix of algae and fungi) |
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fungi reproduction
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asexual - earlier, haploid spores= sporangia or conidia
sexually - later, 2 haploid nuclei in plasmogamy (fusion) -dikaryotic stage, followed by karyogamy in diploid stage |
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Endoskeleton structure info
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axial (skull, vertebral columns, ribcage: i.e. basic framework)
appendicular (arms, legs, pelvic & pectoral girdles) 2 major components: cartilage & bone |
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Cartilage
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Made of chondrin matrix secreted by chondrocytes.
("chondro-" always relates to cartilage) relatively avascular |
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Two Bone types
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Compact bone ➔ gives strength
Spongy/cancellous bone ➔ lattice structured w/spicules known as trabeculae |
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Bone marrow
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Red - Filled w/hemapoietic cells (generates blood)
Yellow - mostly fat, relatively inactive poiesis (Gr. root) = "to make" |
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Long bones
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Characterized by cylindrical shafts (= "diaphyses", full of marrow) & dilated ends (= "epiphyses", sponginess for dispers° of F)
Compact on outside, separat° from inside with epiphyseal plate (site of growth) Fibrous sheath = periosteum ➔important for growth/repair Pic 6.2 |
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Bone matrix
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Source of bone strength
orgo cmpnts: collagen, glycoproteins inorgo cmpnts: Ca, P, OH form hydroxyapatite crystals Continuous bone re-modeling, vascular & enervated Structure: osteons = Haversian systems Pic 6.3 |
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Haversian system
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Makes up bone matrix
aka osteons osteons encircle Haversian canals which is surrounded by circles of lamellae Spaces = lacunae which house osteocytes (mature bone cells involved in bone maintenance interconnected by canaliculi) |
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Bone formation
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via hardening of cartilage = endochondral ossification
Also formed through intramembranous ossification (from embryonic connective mesenchymal tissue) |
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Key concept: Bone remodeling
What builds? What resorbs bone? |
Osteoblasts build bone.
Osteoclasts resorb/destroy bone. |
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Joints
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Made of connective tissue (like bone & cartilage)
2 Major varieties = Movable & immovable Movable ("hinges") strengthened by ligaments, make up synovial capsule that encloses joint cavity. Articular cartilage & synovial fluid help w/lube. Immovable ("braces") = in skull |
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Three types of muscle
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skeletal, smooth, cardiac
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Skeletal muscle
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Enervated by somatic nervous system.
Basic contractile unit = sarcomere Put end to end = myofibrils Surrounded by covering of sarcoplasmic reticulum (SR, specialized ER) Sarcoplasm = modified cytoplasm in cells Cell membrane = sarcolemma, capable of generating action potential Connected to system of T-tubules, oriented ⊥ to myofibrils. |
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Contrast red & white fibers.
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Part of skeletal muscle.
Red (slow twitch, high myoglobin content (binds strongly to O₂) & white fibers (fast twitch, anaerobic). |
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Sarcomere structure
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Basic unit of muscle fiber.
Made of thick (organized bundles of myosin) & thin (made up of actin, troponin, & tropomyosin) filaments. Z-lines define sarcomere boundaries (reason for striat°) M-line runs down sarcomere ctr. I-band, exclusively thin bands H-zone, exclusively thick filaments A-band (size remains constant, "A"ll of thick fibers) contains thick filaments in entirety even where overlap w/thin |
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Contraction (of muscle cells) steps
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1. Initiation (signal via motor neuron to nerve terminal/synaptic bouton, releasing NT into synapse -neuromuscular jxn)
2. Shortening of sarcomere (Massive release of Ca²⁺, binding and exposing myosin-binding sites on actin (Pic 6.8), free glob heads move toward & bind exposed actin sites, allowing myosin to give actin a pull, power stroke E given by ATPase activity) Pic 6.10 3. Relaxation (once SR receptors no longer active, Ca²⁺ falls ** ATP required for both contraction & release |
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Muscle stimulus
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all-or-none response, must reach threshold value
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Tonus
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constant state of low-level muscle contraction, necessary for some voluntary & involuntary muscles
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Periods of a muscle twitch
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Latent (time bw reaching threshold & contraction onset)
(refractory period - absolute (∅ response ∅ matter the input) & relative (calls for higher input than normal to get response)) Contraction (, relaxation |
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Frequency summation & tetanus
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Freq summation = freq / prolonged stim leading to combined contractions
If no time to relax = tetanus |
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Key concept: smooth muscle
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exhibits myogenic activity = responds to nervous system input but doesn't require external signals to contract
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Smooth muscle
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controlled by autonomic nervous system
Have single, centrally placed nuclei. Capable of longer & more sustained contractions. |
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Cardiac muscle
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uninucleate & involuntary
striated May also have myogenic activity. |
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Energy reserves
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Muscles can get E from common places but also...
Creatine phosphate - stores allow for immed creat° of ATP Myoglobin - holds onto O₂ more tightly than hemoglobin, helps keep aerobic metabolism going |
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Connective tissue
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To bind & support other tissues.
Contains three types of proteinaceous fibers: Collagenous (collagen, tensile strength) Elastic (elastin, give resilience) Reticular (branched woven fibers, join C.T. to adjoining) 2 Major cell types: Fibroblasts (secrete components of xtracell fibers) Macrophages (engulf bacteria & dead cells) |
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Dense connective tissue
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High proportion of collagenous fibers organized in parallel bundles (great tensile strength)
Form tendons (attach muscle to bone) & ligaments (hold bones together at joints) |
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Origin
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End of muscle attached to stationary bone.
In limb muscles, corresponds to proximal end. |
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Insertion
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End of muscle attached to bone that moves during contraction.
In limb muscles, corresponds to distal end. |
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Synergistic muscles
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Assist principal muscles during movement.
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Classification of muscles by mv't type coordinated.
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Flexor (contract to ↓ ∠ of joint)
Extensor (contract to straighten joint) Abductor (moves a part of the body away from midline) Adductor (moves a part of the body towards midline) |