Chapters 12, 6, and 7 Test Review

Chapter 12

1. Describe the structural organization of the prokaryotic genome and the eukaryotic genome

   Eukaryotic cells have a set number of characteristic chromosomes in each nucleus, and they can have somatic cells or gametes (sex cells). Eukaryotic cells also contain chromatin, a DNA-protein combination that condenses. Prokaryotic cells are haploid (single, not double) and float around the cell without a nuclear envelope. .

2. List the phases of the cell cycle; describe the sequence of events during each phase

   G1- “Growth 1”

   S Phase - Synthesis, chromosomes are duplicated

   G2- “Growth 2”

3. List the phases of mitosis and describe the events characteristics of each phase

   Prophase- Assembly of spindle microtubules begins in centrosome, centrosome duplicates and moves to opposite ends of the cell, and an aster extends from each centrosome.

   Prometaphase- spindle microtubules attach to the kinetochores

   Metaphase- chromosomes are lined up at the metaphase plate

   Anaphase- sister chromatids separate and move along kinetochore microtubules to opposite ends of the cell when kinetochore ends depolymerize, and nonkinetochore microtubules from opposite poles push against one another to elongate the cell\

   Telophase- Genetically identical daughter cells form at opposite ends

4. Draw or describe the mitotic spindle, including centrosomes, kinetochore microtubules, nonkinetochore microtubules, and asters.

   Mitotic spindle- microtubules that control chromosome movement

   centrosome- microtubule organizing center

   kinetochore microtubules- microtubules that attach to the centromeres of chromosomes

   nonkinetochore micortubules- kinetochores that don’t attach to the chromosomes, and instead push against one another

   aster- a radial array of short microtubules

5. Compare cytokinesis in animals and plants

   Animals- cytokinesis occurs by cleavage, forming a cleavage furrow.

   Plants- a cell plate forms, which later forms a new cell wall

6. Describe the process of binary fission in bacteria and explain how eukaryotic mitosis may have evolved from binary fission

   The chromosome replicates at the origin of replication and the two daughter cells actively move apart; ??

7. Explain how the abnormal cell division of cancerous cells escapes normal cell cycle controls

   Cancer cells escape normal cell cycle controls by making their own growth factor, convey a growth factor signal without a growth factor being present, or may have an abnormal cell cycle control system.

8. Distinguish between malignant, benign, and metastatic tumors

   Benign tumor cells remain at the original site, malignant tumor cells invade surrounding tissues, and metastatic tumors export cancer cells to other parts of the body.

Chapter 6

1. Distinguish

   Magnification v. Resolution: magnification is making small objects larger, while resolution is clarity/distinguishing objects

   Prokaryotic v. Eukaryotic: Eukaryotic cells have a DNA-containing nucleus, a nuclear envelope, membrane bound organelles, and cytoplasm bound by the plasma membrane. Prokaryotic cells have DNA in an unbound nucleiod, no membrane bound organelles, and no cytoplasm bound by a membrane.

   Free v. Bound Ribosomes: Free ribosomes synthesize proteins used in the cytoplasm, while bound ribosomes synthesize proteins inserted into the membranes, organelles, or secreted from the cell

   Smooth v. Rough ER: Smooth ER lacks ribosomes and synthesizes lipids, metabolizes carbs, detoxifies poison, and stores calcium. The rough ER has bound ribosomes and it secretes glycoproteins, distributes transport vesicles, and is a membrane factory.

2. Describe the structure and function of the components of the endomembrane system.

   Nuclear Envelope: encloses the nucleus, separating from cytoplasm

   Endoplasmic Reticulum: half of all membrane is continuous with nuclear envelope; the smooth ER synthesizes lipids, metabolizes carbs, detoxifies poisons, and stores calcium while the Rough ER secretes glycoproteins, distributes transports vesicles, and is a membrane factory.

   Golgi Apparatus: Contains flattened membrane sacs (cisternae), and it modifies ER products, manufactures macromolecules, and sorts/transports materials into transport vesicles.

   Lysosomes: Membranous sac of hydrolytic enzymes; digests macromolecules, hydrolyze macromolecules, and can can conduct autophagy (Enzyme powered enzyme organelle recycling). Can also release digestive enzymes for apoptosis.

   Vacuoles: food vacuoles store food and fuses with lysosome, contractile vacuoles pump out excess water, and central vacuoles hold food and water

   Plasma Membrane: double phospholipid bilayer allowing water, nutrients, and waste to pass

3. Briefly explain the role of mitchondria, chloroplasts, and peroxisomes.

   Mitochondria: conducts cellular respiration to make ATP

   Chloroplasts: conducts photosynthesis

   Peroxisomes: oxidative, producing hydrogen peroxide and making it oxygen

4. Describe the function of the cytoskeleton.

   The cytoskeleton maintains cell shape, produces motility with motor proteins, they guide organelle movement and chromosome movement during mitosis, etc.

5. Compare the structure and functions of microtubules, intermediate filaments, and microfilaments.

   Microtubules are the largest (25nm), they grow out of the centrosome, shape the cell, guide organelle movement, and separate chromosomes. Intermediate filaments are medium (8-12nm), are more permanent, and support cell shape while fixing organelles in place. Microfilaments, the smallest (7nm) are twisted double chains of actin subunits, and they make the cortex to support cell shape and function in cellular motility (with myosin).

6. Explain how the ultrastructure of cilia and flagella relate to their functions.

   They have basal bodies that anchor them, and dyenin arms to grab, move, and release outer microtubules, and allows for their bending movement.

7. Describe the structure of the plant cell wall.

   The primary cell wall is thin and flexible, and the secondary wall is more rigid and is between the membrane and primary cell wall. The middle lamella connects primary cell walls.

8. Describe the structure and roles of the extracellular matrix.

   The extracellular matrix is made of glycoproteins like collagen, proteoglycogens, and fibronectin. ECM proteins bind to integrins in the membrane. The functions of the ECM include support, adhesion, movement, and regulation.

9. Describe four different intercellular junctions

   Plasmodesmata: Channels through cell walls that pass water, small solutes, and sometimes proteins + RNA

   Tight Junctions: Membranes of neighboring cells pressed together to prevent leakage of extracellular fluid

   Desmosomes: Fastens cells into sheets

   Gap Junctions: Cytoplasmic channels between adjacent cells

Chapter 7

1. Define the following terms: amphipathic molecules, aquaporins, diffusion

   Amphipathic Molecules: Molecules with hydrophilic and hydrophobic regions

   Aquaporins: Water passage channels in the membrane (passive osmosis)

   Diffusion: Tendency for molecules to spread out in available space

2. Explain how membrane fluidity is influenced by temperature and membrane composition

   As temp. decreases, membranes switch from fluid to solid, and membranes with high unsaturated fats are more fluid than membranes with high saturated fats. Cholesterol also restrains phospholipid movement as higher temps., but it prevents tight packing and maintains fluidity at low temps. (Note: Fluid Mosaic Model)

3. Distinguish

   Peripheral v. Integral Membrane Proteins: Peripheral proteins are on the surface, while integral proteins penetrate the hydrophobic core.

   Channel v. Carrier Proteins: Channel proteins allow for things to passively move straight through while maintaining a constant shape, while carrier proteins change shape in order to transport molecules.

   Osmosis v. Facilitated Diffusion v. Active Transport: Osmosis is the diffusion of water, facilitated diffusion speeds up the passive movement of molecules across the membrane via transport molecules, and active transport requires energy (ATP) to occur.

   Hypertonic v. Hypotonic v. Isotonic: Hypertonic solutions have more solute, hypotonic solutions have less solute, and isotonic solutions have equal solute concentrations.

4. Explain how transport proteins facilitate diffusion

   They speed up the passive movement of molecules down their concentration gradient, often with carrier or channel proteins.

5. Explain how an electrogenic pump creates voltage across a membrane, and name 2 electrogenic pumps.

   It creates voltage by moving ions against their concentration gradient, and two examples are sodium-potassium pumps and proton pumps.

6. Explain how large molecules are transported across a cell membrane

   In exocytosis, transport vesicles migrate to the membrane to fuse with it, and release their contents. Conversely, endocytosis is when the cell takes in macromolecules by forming vesicles from the plasma membrane. Examples of endocytosis include phagocytosis, pinocytosis, and receptor-mediated endocytosis.