Chapter 6-8 biology review

• Plasma membrane
• Semifluid substance called cytosol
• Chromosomes (carry genes)
• Ribosomes (make proteins)

• No nucleus
• DNA in an unbound region called the nucleoid
• No membrane-bound organelles
• Cytoplasm bound by the plasma membrane

• DNA in a nucleus that is bounded by a membranous nuclear envelope
• Membrane-bound organelles
• Cytoplasm in the region between the plasma membrane and nucleus
• Eukaryotic cells are generally much larger than prokaryotic cells

• Sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
• The general structure of a biological membrane is a double layer of phospholipids

• contains most of the cell’s genes and is usually the most conspicuous organelle
• nuclear envelope encloses the nucleus, separating it from the cytoplasm

Has a higher surface to volume ratio, which facilities the exchange of materials into and out the cell

DNA is organized into discrete units

are particles made of ribosomal RNA and protein

• Nuclear envelope
• Endoplasmic reticulum
• Golgi apparatus
• Lysosomes
• Vacuoles

Smooth ER and Rough ER

• Synthesizes lipids
• Metabolizes carbohydrates
• Detoxifies drugs and poisons
• Stores calcium ions

• Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates)
• Distributes transport vesicles, proteins surrounded by membranes
• Is a membrane factory for the cell

• apparatus consists of flattened membranous sacs called cisternae
• Modifies products of the ER
• Manufactures certain macromolecules
• Sorts and packages materials into transport vesicles

• is a membranous sac of hydrolytic enzymes that can digest macromolecules
• 15. phagocytosis
• Some types of cell can engulf another cell by; this forms a food vacuole

are formed by phagocytosis

found in many freshwater protists, pump excess water out of cells

found in many mature plant cells, hold organic compounds and water

are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP

found in plants and algae, are the sites of photosynthesis

• are specialized metabolic compartments bounded by a single membrane
• produce hydrogen peroxide and convert it to water

• is a network of fibers extending throughout the cytoplasm
• It is composed of three types of molecular structures
• * Microtubules
• * Microfilaments
• * Intermediate filaments

thickest; organelle movement; secretory vesicles to plasma membrane; mitosis

thinnest (also called actin) –supports cell shape; microvilli; forms bridge with myosin for muscle contraction;cell contraction during cell cleavage; pseudopodia movement (amoeba and WBC)

• diameters in a middle range
• contains protein keratin
• reinforces position of nucleus

microtubules grow out from a near the nucleus

• Microtubules control the beating
• locomotor appendages of some cells

A motor protein, drives the bending movements of a cilium or flagellum

• Cell walls of plants
• The extracellular matrix (ECM) of animal cells
• Intercellular junctions
• 30. Cell wall of plants
• Prokaryotes
• The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water
• Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein

lack cell walls but are covered by an elaborate extracellular matrix (ECM)

• Support
• Adhesion
• Movement
• Regulation

Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact

• channels that perforate plant cell walls
• Through plasmodesmata, water and small solutes (and sometimes proteins and RNA) can pass from cell to cell

membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid (skin cells)

(anchoring junctions) fasten cells together into strong sheets (muscle cells to muscle cells)

(communicating junctions) provide cytoplasmic channels between

• 1. Rough endoplasmic reticulum
• 2. Smooth endoplasmic reticulum
• 3. Ribosomes
• 4.Central vacuole
• 5. Cytoskeleton
• * Microfilaments
• * Intermediate filaments
• * Microtubules
• 6. Chloroplast
• 7. Plasmodesmata
• 8. Wall of adjacent cell
• 9. cell wall
• 10. Plasma membrane
• 11. peroxisome
• 12. Mitochondrion
• 13. Golgi apparatus
• 14. Nucleus

• 1.Nucleus
• * Nucleus Envelope
• * Nucleolus
• * Chromatin
• 2. Plasma Membrane
• 3.Ribosomes
• 4. Golgi apparatus
• 5. Lysosomes
• 6. Mitochondrion
• 7. Peroxisome
• 8. Microvilli
• 9. Cytoskeleton
• * Microfilaments
• * Intermediate filaments
• * Microtubules
• 10. Centrosome
• 11. Flagellum
• 12. Endoplasmic Reticulum (ER)
• * Rough ER
• * Smooth ER

• 1. Cytosol fluid
• 2. Ribosome (male protein)
• 3. Flagella
• 4. Capsule -gel like
• 5. Cell wall -rigid
• 6. Plasma Membrane Cell Boundary
• 7. Nucleoid DNA (geometric info)
• 8. Pilli (sticks )

• tight junctions
• Desmosomes
• Gap junctions

• Transport
• Enzymatic activity
• Signal transduction
• Cell-cell recognition
• Intercellular joining
• Attachment to the cytoskeleton and extracellular matrix (ECM)

states that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it

Cells recognize each other by binding to surface molecules, often containing carbohydrates, on the extracellular surface of the plasma membrane

• * proposed a sandwich model in which the phospholipid bilayer lies between two layers of globular proteins
• * Later studies found problems with this model, particularly the placement of membrane proteins, which have hydrophilic and hydrophobic regions
• * In 1972, S. J. Singer and G. Nicolson proposed that the membrane is a mosaic of proteins dispersed within the bilayer, with only the hydrophilic regions exposed to water

• * Phospholipids in the plasma membrane can move within the bilayer
• * Most of the lipids, and some proteins, drift laterally
• * Rarely does a molecule flip-flop transversely across the membrane

determine most of the membrane’s specific functions

• nonpolar) molecules, such as hydrocarbons, can dissolve in the lipid bilayer and pass through the membrane rapidly
• is the tendency for molecules to spread out evenly into the available space

• * is the boundary that separates the living cell from its surroundings
• * The plasma membrane exhibits selective permeability, allowing some substances to cross it more easily than others
• * Membranes have been chemically analyzed and found to be made of proteins and lipids
• * Scientists studying the plasma membrane reasoned that it must be a phospholipid bilayer
• 9. selective permeability
• allowing some substances to cross the plasma membrane more easily than others

• * are the most abundant lipid in the plasma membrane
• * Phospholipids are amphipathic molecules, containing hydrophobic and hydrophilic regions

Membrane carbohydrates may be covalently bonded to lipids

Membrane carbohydrates may be covalently bonded to proteins

• * CO2, simple diffusion
• * Glucose, facilitated transport in most tissues
• * H+, active transport
• * O2, simple diffusion
• * H2O, simple diffusion (through the protein aquaporin)

• * Temperature
• * Fatty acid chain length in constituent lipids
• * The presence of cis carbon-carbon double bonds
• * The presence of cholesterol
• * Hydrophobic interactions between neighboring lipids

• * allow passage of hydrophilic substances across the membrane
• * is specific for the substance it moves
• * Channel proteins& Carrier proteins
• * Small molecules and water enter or leave the cell through the lipid bilayer or

have a hydrophilic channel that certain molecules or ions can use as a tunnel. Are also called aquaporins facilitate the passage of water

bind to molecules and change shape to shuttle them across the membrane

Yes for the substance it moves. Different transport move different things.

• * is the tendency for molecules to spread out evenly into the available space
• * Although each molecule moves randomly, diffusion of a population of molecules may be directional
• * At dynamic equilibrium, as many molecules cross the membrane in one direction as in the other
• 20. Concentration gradient
• * the region along which the density of a chemical substance increases or decreases
• * No work must be done to move substances down the concentration gradient

The diffusion of a substance across a biological solute moves down its concentration gradient, and the transport requires no energy membrane no energy is expended by the cell to make it happen

• * is the diffusion of water across a selectively permeable membrane
• * Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentration is equal on both sides

is the ability of a surrounding solution to cause a cell to gain or lose water

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

Solute concentration is greater than that inside the cell; cell loses water

Solute concentration is less than that inside the cell; cell gains water

• * (Hypotonic solution) swells until the wall opposes uptake; the cell is now turgid (firm)
• * (Isotonic) the cell becomes flaccid (limp), and the plant may wilt
• * (hypertonic) plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal effect called plasmolysis (Shrivel)
• 28. why a carrot left on the counter overnight becomes limp.
• due to the relatively low humidity around the counter, water would diffuse (via osmosis) out of the carrot, down the concentration gradient, this makes the carrot flaccid (limp) as plasmolysis occurs due to the lack of water.

• * transport proteins speed the passive movement of molecules across the plasma membrane
• * Channel proteins provide corridors that allow a specific molecule or ion to cross the membrane
• * Channel proteins include Aquaporins, for facilitated diffusion of water
• * Ion channels that open or close in response to a stimulus (gated channels)
• * Facilitated diffusion is still passive because the solute moves down its concentration gradient, and the transport requires no energy
• 30. Active transport
• * moves substances against their concentration gradients
• * requires energy, usually in the form of ATP
• * is performed by specific proteins embedded in the membranes
• * Active transport allows cells to maintain concentration gradients that differ from their surroundings
• 31. sodium-potassium pump
• is one type of active transport system, it exchanges Na+ for K + across the membrane of animal cells.

a chemical used throughout the body to transfer and hold energy. It is made of a nucleotide (adenine).

• * is a transport protein that generates voltage across a membrane
• * help store energy that can be used for cellular work

The main electrogenic pump of plants, fungi, and bacteria is a

occurs when active transport of a solute indirectly drives transport of other solutes

How large molecules, such as polysaccharides and proteins crosses the membrane (requires energy)

• * transport vesicles migrate to the membrane, fuse with it, and release their contents
• * Many secretory cells use exocytosis to export their products

• * the cell takes in macromolecules by forming vesicles from the plasma membrane
• * Endocytosis is a reversal of exocytosis, involving different proteins

• * Phagocytosis (“cellular eating”)
• * Pinocytosis (“cellular drinking”)
• * Receptor-mediated endocytosis

a cell engulfs a particle in a vacuole

binding of ligands to receptors triggers vesicle formation