Review set 1 Flashcards
Structure of water
Water is polar (dipolar) and forms up to four hydrogen bonds with other water molecules
Water’s Properties: 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 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
Water’s Properties: 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)
Water’s Properties: 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
Water is used in living systems to
MAKE AND BREAK chemical bonds
Condensation
creating larger molecules by removing water
Hydrolysis
hydro = water, lysis = “slice/dice;” breaking): water is added to break bonds/ break larger molecules into smaller pieces (ex: digestive processes)
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
Exceptions to cell theory
Muscle cells because Muscle cells fuse to form fibres that may be very long Consequently, they have multiple nuclei despite being surrounded by a single, continuous plasma membrane.
Basic functions of life
Reproduction, growth, respiration (energy/ nutrients), cells, homeostasis, excretion, response, metabolism
Stem cells…
retain the capacity to divide and have the ability to differentiate along different pathways.
One therapeutic use of stem cells
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 cell
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 engulfe
Eukaryotic cells
Have MEMBRANE-BOUND organelles
Compare Prokaryotic and Eukaryotic
Similarities: Both have DNA,Both have a cell membrane, Both have cytoplasm/ carry out all functions of life, Both contain ribosomes
Differences:
Prokaryote Eukaryote
DNA is naked (no proteins) DNA associated with proteins (histones)
DNA is circular DNA is linear
DNA in nucleoid DNA in nucleus
DNA does NOT contain introns DNA contains many introns
No membrane-bound organelles/ no mitochondria Membrane-bound organelles/ mitochondria
70S ribosomes 80S ribosomes
Smaller (size less than 10um) Larger (size more than 10um)
Structure of Membrane
Phospholipids have hydrophilic heads (polar) and hydrophobic (nonpolar) tails
Hydrophilic heads attracted to water and hydrophobic tails repelled by water
Phospholipid bilayer 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
Functions of Membrane Proteins
TRACIE
T- Transport R- Receptors A- Anchorage C- Cell recognition or Identification I- Intercellular connections E- Enzymatic connection
Type of Transport: Passive
Movement of particles from high (HYPERTONIC) to low (HYPOTONIC) concentration
Different types of Passive transport
Diffusion, Osmosis, Facilitated Diffusion
Diffusion:
small/ nonpolar molecules move through membrane from higher (hypertonic) to lower (hypotonic) concentration (nonspecific protein channels allow small, polar ions to diffuse
Osmosis
diffusion of water molecules to balance solute concentrations
Facilitated Diffusion
diffusion of large molecules through SPECIFIC protein channels (pores) in the membrane (proteins change shape to “facilitate” this movement)
Type of Transport: Passive
Movement of particles from low to high concentration
Sodium/ Potassium Pump: maintains resting potential in nerve cells
Cell Cycle
Interphase then Mitosis
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
Prophase, Metaphase, Anaphase, and Telophase
Prophase
nuclear membrane disappears, chromosomes condense and become visible, mitotic spindle forms
Metaphase
chromosomes, as sister chromatids, line up individually (NOT as homologous pairs) along MIDDLE of cell
Anaphase
centromeres split, sister chromatids separate; one copy of each chromosome pulled to opposite ends of cell by mitotic spindle fibers
Telophase
nuclear membranes begin to reform and cytoplasm divides – cytokinesis – forming two IDENTICAL, diploid (2n = 2 copies of each chromosome) daughter cells
Reasons a cell would divide
TOAD- Tissue repair, Organism Growth, Asexual reproduction, Development
Cancer
uncontrolled cell division- do NOT respond to cell cycle controls–divide uncontrollably and produce masses of cells- Cancerous tissues have higher mitotic indexes as cells divide faster/ out of control
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 cellsWater vs Methane
Water higher on everything
