Review #1 Flashcards
Explain water’s properties and their importance to life.
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.)
Explain the endosymbiotic theory (origin of eukaryotic cells from prokaryotic cells - including evidence to support this idea).
Eukaryotic cells are believed to evolved from aerobic prokaryotes that were engulfed via endocytosis. The engulfed cells remained undigested and contributed new functionality to the engulfing cell (it became an organelle). Evidence that supports this theory are the existence of the chloroplast and mitochondria. Both organelles have traits such as:
- Membrane (a double membrane) - Antibiotics (show susceptibility) - DNA (have naked and circular DNA) - Division (occurs via a fission-like process) - Ribosomes (have 70S ribosomes)
Explain the cell cycle (make sure you can identify stages of the cell cycle in images/diagrams too).
Somatic cells are diploid (2n = 2 copies of each chromosomes). They go through MITOSIS to produce 2 GENETICALLY IDENTICAL daughter cells.
Interphase:
- G1 (Monitors potential growth conditions (nutrients, etc.). Assess level of DNA damage from UV, etc.)
- S (Synthesis - DNA replication - copied chromosomes attached at centromere; copies called “sister chromatids”).
- G2 (Monitors state of pre-mitotic cell (suitable size, etc). Identifies and repairs any DNA replication errors).
Mitosis (and cytokinesis):
- 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 the MIDDLE of the cell).
- Anaphase (centromeres split, sister chromatids separate; one copy of each chromosome pulled to opposite ends of the cell by mitotic spindle fibers).
- Telophase (nuclear membranes begin to reform and cytoplasm divides - cytokinesis - forming two IDENTICAL, diploid (2n) daughter cells). In animals, cytokinesis happens by means of a cleavage furrow. In plants, it occurs by means of a cell plate (new cell wall, formed by vesicles).
Explain the different types of passive transport (including examples).
Passive (movement of particles from high (HYPERTONIC) to low (HYPOTONIC) concentration (down the concentration gradient) - toward equilibrium - to create an isotonic solution).
- Diffusion: small, nonpolar molecules move through membrane from higher (hypertonic) to lower (hypotonic) concentration (nonspecific protein channels allow small, polar ions to diffuse - example: gasses in alveoli in lungs). - Osmosis: diffusion of water molecules to balance solute concentrations (moves from low solute to high solute concentration). - Facilitated Diffusion: diffusion of large molecules through SPECIFIC protein channels (pores) in the membrane (proteins change shape to facilitate this movements).
Outline what a mitotic index is and what information it can give you about a tissue.
The mitotic index is the measure of the proliferative status of a cell population (number of dividing cells). The mitotic index will be elevated during growth and repair processes. It also acts as a prognostic tool for cancer, as cells in cancerous tissue uncontrollably divide faster and don’t respond to cell cycle controls.
Outline the properties of phospholipids that are important in membrane structure.
- The bilayer is held together by weak hydrophobic interactions between the tails.
- Individual phospholipids can move within the bilayer (fluidity and flexibility).
- Amphipathic properties restrict passage of certain substances (semi-permeable).
Outline the cell theory (including exceptions).
HINT: To know muscle fiber structure as an exception.
Living organisms are composed of cells (or cell products). The cell is the smallest unit of independent life. Cells can only arise of pre-existing cells. However, exceptions to the cell theory include; muscle fibers, which are composed of cells that are fused and multinucleated, giant algae, unicellular organisms that are very large in size, and aseptate hyphae, which lack partitioning and have a continuous cytoplasm.
Outline the process of cell differentiation.
All cells of a multicellular organism contain an identical genome - each cell contains the entire set of genetic instructions for that organism. Differentiation involves the expression of some genes and not others in the cell’s genomes (selective gene expression). The activation of different genes within a given cell will cause it to develop differently from other cells (cell specialization).
What is the formula for magnification?
Magnification (Mag) = Measured (M) / Actual (A)
Explain the different types of active transport (including examples).
Active (movement of particles from low to high concentration (against a concentration gradient) - requires proteins pumps and ATP):
- Sodium/Potassium Pump: maintains resting potential in nerve cells (pumps 3 sodium OUT and 2 potassium IN - against their concentration gradients).
Explain endocytosis and exocytosis.
Endocytosis (requires ATP) - Vesicles move large substances INTO cell (invagination of membrane; pinches off to form vesicle around large solid substances (phagocytosis) or large amounts of liquid (pinocytosis)
Exocytosis (requires ATP) - Vesicles (from RER then to Golgi apparatus) move toward and fuse with cell membrane, dumping contents into extracellular space (secretion – molecules/ substances EXIT the cell)
What is the formula for the mitotic index?
Mitotic index = # of cells in any stage of mitosis / total # of all cells
