Reviewn #1 Flashcards
(28 cards)
SPONCHNa CaFe
Sulfur: Amino acids (proteins – disulfide bridges)
Phosphorus: Phospholipids, Nucleic acids (DNA and RNA – phosphate in the backbone), ATP
Oxygen: Amino acids (proteins), Carbohydrates, Lipids, Nucleic acids (DNA and RNA), aerobic respiration (final electron acceptor at end of ETC)
Nitrogen: Amino acids (proteins – amine groups), Nucleic acids (DNA and RNA – nitrogenous bases), ATP
Carbon: See previous slide
Hydrogen: Amino acids (proteins), Carbohydrates, Lipids, Nucleic Acids, respiration (reducing agent – shuttles electrons), photosynthesis (reducing agent – shuttles electrons)
Sodium: Osmoregulation (nephron in kidney), action potentials (nerve signals – sodium channels open, sodium ions rush INTO nerve cell causing depolarization)
Calcium: Muscle contraction (released from sarcoplasmic reticulum to bind to troponin to expose myosin binding sites), Nerve cell transmission (calcium channels open at axon terminal, calcium ions rush INTO nerve cell causing vesicles with neurotransmitter to bind with pre-synaptic membrane and “dump” neurotransmitter into synaptic cleft)
Iron: In cytochromes (proteins that make up the electron transport chain – respiration and photosynthesis), in hemoglobin (oxygen transport in blood)
Carbon
forms foundation for all organic molecules/ compounds – can form up to 4 covalent bonds (compounds containing carbon and found in living organisms)
Carbohydrates (building blocks/
monomers are saccharides – sugars
and starches)
Lipids (building blocks are glycerol
and up to 3 fatty acids – fats/ oils)
Proteins (building blocks are amino
acids – enzymes, antibodies etc.)
Nucleic Acids (building blocks are nucleotides – DNA, RNA, ATP)
Structure of Water
Water is polar (dipolar) and forms up to four hydrogen bonds with other water molecules
Hydrogen bonds are short-lived
attractions (they are ephemeral)
Thermal Properties (Due to Hydrogen Bonds)
High specific heat : stabilizes environments for life (around them and within them) – a large amount of heat only raises water’s temp. a small amount – heat energy used to break hydrogen bonds BEFORE individual water molecules heat up
High heat of vaporization: evaporative cooling for organisms (sweat, transpiration)
Cohesive and Adhesive Properties (due to hydrogen bonds)
High surface tension: organisms live on surface/ maintains lung structure (pleural membranes)
Transport in plants: Hydrogen bonds “stick” water molecules together (cohesion) and to other substances (adhesion - such as xylem walls) – allows movement (pull) of water through plants (transpiration)
Solvent Properties (due to polarity) – Universal solvent
Dissolves and transports polar/ hydrophilic substances - nutrients (organic compounds/ inorganic ions) etc. around/ through organisms
Sap in plants (water up xylem and sugars down phloem)
Blood in animals (glucose, amino acids, fibrinogen, hydrogen carbonate ions etc.)
Note: hydrophobic substances (cholesterol, fats, oxygen) have special means of transport in living systems (lipoproteins in blood, haemoglobin etc.)
Medium for metabolic reactions (Ex: glycolysis, DNA replication, transcription and translation, light-independent reactions, gas exchange/ clotting in blood plasma etc.)
Cell Theory
All living things made of cells
Cells = smallest fundamental unit of life
All cells arise from pre-existing cells
Evidence for the cell theory
Microscopes allow visualization of cells
NOTHING smaller than a cell found to survive (on OWN) – if not made of cells
Sterilization prevents cell growth (cells can only come from other cells) – Louis Pasteur
Exceptions to cell theory (NOS)
Multinucleate muscle cells and fungal hyphae, giant algae, viruses, first cell origins (spontaneous)
All Cells (including unicellular organisms) carry out basic functions of life:
Reproduction, growth, respiration (energy/ nutrients), cells, homeostasis, excretion, response, metabolism etc.
*Be able to calculate the linear magnification of drawings and the actual size of specimens in images of known magnification (bring a RULER!). Convert to same units 1st!
Magnification = Measured size (in drawing)/ Actual size (Mag = M/A) *PRACTICAL #1
Actual size = Measured size (in drawing)/ Magnification (A = M/Mag)
Cells are small to maintain a LARGE surface area and SMALL volume (SA/ V ratio)
Cells want to MAXIMIZE SA:V ratio (more surface area and less volume) – they want a LARGE SA/ V ratio!
Surface area = determines rate of exchange of materials (nutrients/ wastes)
Volume = influences metabolic reaction rate/ determines need of nutrients and amount of waste
As cell size increases, SA:V ratio decreases (cells divide when too large to maintain high SA:V ratio)
Multicellular organisms show emergent properties.
Interaction between component parts produces new properties: cell interactions produce new functions that individual cells could not undertake on own. (cells to tissues to organs etc.)
Cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.
All cells contain complete set of DNA (entire genome).
Different genes turned on/ off in different cells (making DIFFERENT PROTEINS/ making them different – differentiation to become more specialized/ distinct/ carry out unique tasks)
Stem Cells
Stem cells retain the capacity to divide and have the ability to differentiate along different pathways.
Stem cells = undifferentiated (pluripotent/ totipotent – can continuously divide and become any cell)
ne therapeutic use of stem cells (Ethics of stem cell use = NOS).
Stem cells harvested from embryos – destroys/ kills embryo! (OR placenta/ umbilical cord)
Exposed to biochemicals in lab to cause differentiation into desired cell type
Transferred to patients who need them (photoreceptor cells for Stargardt’s disease, blood cells for leukemia) – requires immunosuppression of patient first so do not reject/ monitoring for cancer following transfer
Prokaryotic Cells
Divide by binary fission (asexual reproduction)
Have organelles WITHOUT membranes around them
Mitochondria and Chloroplasts (Eukaryotic cells) thought to have originated from primitive prokaryotic cell that was engulfed (endocytosis) by a primitive predatory/ heterotrophic cell – Endosymbiotic Theory (Lynn Margulis)
Eukaryotic Cells
Have MEMBRANE-BOUND organelles (discrete structures that carry out specialized functions = allow compartmentalization/ increased efficiency)
Note: all cells have a cell/ plasma
membrane, ribosomes (no membrane),
cytoplasm, chromosomes/ DNA
Eukaryotic cells also contain:
-a cell (plasma) membrane
-cytoplasm
*Same functions as in prokaryotic cells (same structure = usually same function)
Cancer = uncontrolled cell division
Cancerous cells do NOT respond to cell cycle controls –
divide uncontrollably and produce masses of cells (tumors)
– can happen in ANY part of the body
Benign tumors = remain at original site or contained in membrane
Malignant tumors = invading surrounding tissue
Metastatic tumors = in blood; travel to other parts of body and form secondary tumors
Mitotic Index: # of cells in any stage of mitosis / total # of all cells
Cancerous tissues have higher mitotic indexes as cells divide faster/ out of control
Falsification of Theory of Vitalism
Theory of vitalism states that organic compounds can ONLY be made by living systems, which possess a “vital force”
In 1828, Frederick Woehler heated ammonium sulfate (inorganic salt) and created urea (an organic compound)
Artificial synthesis of urea falsified theory of vitalism
First cell origins
First cells must have arisen from non-living matter (abiogenesis). For
this to occur, the following is theorized to have happened:
1. There was non-living synthesis of simple organic compounds
2. These simple organic compounds became more complex polymers
3. Some polymers became self-replicating (enabling inheritance)
4. These molecules became packaged in membranes (protobionts)
Miller-Urey Experiments: Used system of closed flasks etc. to recreate
conditions of early earth and were able to generate simple organic
compounds from non-living matter
Discovery of Cyclins was “serendipitous” (a happy accident)
Two scientists studying gene expression in embryos accidentally discovered 3 proteins that varied in concentration at different times of cell cycle = cyclins discovered by chance!
Membrane Models
There are different models of membrane structure
Scientific evidence is used to falsify one model (Davson-Danielli) and accept another (Singer-Nicolson/ Fluid Mosaic Model)
Davson-Danielli model was a “lipo-protein sandwich” (a layer of lipids sandwiched between two protein layers). Based on an electron micrograph image.
Davson-Danielli Model Falsified and Singer-Nicolson/ Fluid Mosaic Model Accepted by:
A. Membrane proteins found to contain hydrophobic portions/ non-polar amino acids (could not form a continuous layer in contact with water so must be embedded in membrane)
B. Membrane proteins found to be able
to move (fluid) within the membrane
(not in a fixed position)
C. Globular proteins found within/
passing through entire membrane
structure (so not just on outsides –
proteins are integral AND peripheral).
Water versus Methane
Differ in THERMAL properties, even though they have similar structures (similar mass/ size/ valence structure). WHY?!? Water is POLAR and can form HYDROGEN BONDS!
Formula:
W: H20
M: CH4
Freezing Point:
W: 0
M: -182.5
Boiling Point
W: 100
M: -161
Heat Capacity
W: 4.186
M: 2.20
Reasons Cells Divide (TOAD):
Tissue repair/ replacement
Organism growth
Asexual reproduction (binary fission – bacteria/ vegetative propagation or stem cuttings in plants)
Development (from a fertilized egg – embryonic development)
Also, cells divide when SA/ V ratio is too small
The “life of a cell” is the Cell Cycle: (“Shipmate” –She)
*Somatic (body) cells are diploid (2n = 2 copies of each chromosome = 2 parents)
*Go through mitosis to produce 2, genetically identical daughter cells
Interphase:
— G1 (growth, protein production, metabolic reactions etc.)
— S (synthesis – DNA replication – copied chromosomes attached at centromere; copies called “sister chromatids”)
— G2 (growth, protein production, duplicating organelles etc.)
Mitosis (and cytokinesis):
1. Prophase (nuclear membrane disappears, chromosomes condense and become visible, mitotic spindle forms)
2. Metaphase (chromosomes , as sister chromatids, line up individually (NOT as homologous pairs) along MIDDLE of cell)
3. Anaphase (centromeres split, sister chromatids separate; one copy of each chromosome pulled to opposite ends of cell by mitotic spindle fibers)
4. Telophase (nuclear membranes begin to reform and cytoplasm divides – cytokinesis – forming two IDENTICAL, diploid (2n = 2
copies of each chromosome) daughter cells)
Note: In animal cells, cytokinesis happens by means of a cleavage furrow, and in plants a cell plate (new cell wall, formed by vesicles) causes cytokinesis
Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes.
- Phospholipids have hydrophilic heads (polar) and hydrophobic (nonpolar) tails – amphipathic molecules
Hydrophilic heads attracted to water and hydrophobic tails repelled by water - Phospholipid bilayer (TWO layers) forms with polar heads toward/ in contact with water on both sides of the membrane (cytoplasm and extracellular fluids) and tails away from water (in the center of the bilayer)
- Hydrophobic interactions between tails and hydrophilic interactions between heads and water stabilizes membrane structure
- Interactions of phospholipids allow membrane fluidity (breaking/ remaking of membrane in endo- and exocytosis
Carbon
-forms foundation for all organic molecules/ compounds – can form up to 4 covalent bonds (compounds containing carbon and found in living organisms)
-Carbohydrates (building blocks/monomers are saccharides – sugars and starches)
- Lipids (building blocks are glycerol and up to 3 fatty acids – fats/ oils)
- Proteins (building blocks are amino acids – enzymes, antibodies etc.)
- Nucleic Acids (building blocks are nucleotides – DNA, RNA, ATP)
