Basis of Life

Question 1

Temperature and enzymes

Answer 1

As temperature increases the rate of enzyme action increases, until an optimum temperature is reached. After optimal temperature heat alters the shape of the active site of the enzyme molecule and deactivates it leading to a rapid drop in rate

Question 2

pH and enzymes

Answer 2

Optimal pH, above and below that activity declines. Maximal activity of many human enzymes occurs around 7.2.

Question 3

Reaction rate

Answer 3

Concentrations of substrate and enzyme greatly affect the reaction rate

Question 4

Competitive Inhibition

Answer 4

A similar molecule is present in a concentration comparable to the concentration of the substrate, it will compete with the substrate for binding sites on the enzyme and interfere with enzyme activity

Question 5

Noncompetitive Inhibition

Answer 5

Substance that forms strong covalent bonds with an enzyme and consequently may not be displaced by the addition of excess substrate, irreversible

Question 6

Hydrolysis

Answer 6

digest large molecules into smaller components

Question 7

Lactase

Answer 7

hydrolyzes lactose to the monosaccharides glucose and galactose

Question 8

Proteases

Answer 8

Degrade proteins to amino acids

Question 9

lipases

Answer 9

break down lipids to fatty acids and glycerol

Question 10

Cell Theory

Answer 10

All living things are composed of cells
Cell is the basic functional unit of life
Chemical reactions of life take place inside the cell
Cells arise only from pre-existing cells
Cells carry genetic information in the form of DNA, passed from parent cell to daughter cell

Question 11

Fluid Mosaic Model

Answer 11

The cell membrane consists of a phospholipid bilayer with proteins embedded throughout. Lipids and many of the proteins can move freely within the membrane

Question 12

Plasma membrane

Answer 12

Readily permeable to small nonpolar hydrophobic molecules and small polar molecules. Small charged particles are usually able to cross the membrane through protein channels. Charged ions and larger charged molecules cross the membranes with the assistance of carrier proteins.

Question 13

Nucleus

Answer 13

Controls activities of the cell, surrounded by a nuclear membrane, contains DNA. Ribosomal RNA synthesis occurs in the nucleolus

Question 14

Ribosome

Answer 14

Site of protein production and are synthesized by the nucleolus. Free ribosomes are found in the cytoplasm and bound ribosomes line the outer membrane of the endoplasmic reticulum

Question 15

Endoplasmic Reticulum

Answer 15

Network of membrane enclosed spaces involved in the transport of materials throughout the cell, especially materials destined to be secreted by the cell

Question 16

Golgi apparatus

Answer 16

receives vesicles and their contents from the smooth ER, modifies them, repackages into vesicles and distributes them to the cell surface by exocytosis

Question 17

Mitochondria

Answer 17

Sites of aerobic respiration within the cell and hence the suppliers of energy. Each contains an outer and inner phospholipid bilayer

Question 18

Vacuoles/Vesicles

Answer 18

Membrane bound sacs involved in the transport and storage of materials that are ingested, secreted, processed or digested by the cell

Question 19

Centrioles

Answer 19

involved in spindle organization during cell division and are not bound by a membrane. Plant cells do not have centrioles.

Question 20

Lysosomes

Answer 20

Membrane bound vesicles that contain hydrolytic enzymes involved in intracellular digestion. Break down material ingested by the cell.

Question 21

Cytoskeleton

Answer 21

Supports the cell, maintains its shape and functions in cell motility. Composed of microtubules, microfilaments, and intermediate filaments.

Question 22

Microtubules

Answer 22

hollow rods made up of polymerized tubulin that radiate throughout the cell and provide it with support. Provide framework for organelle movement. Cilia and flagella are specialized arrangements of microtubules that extend from certain cells and are involved in cell motility and cytoplasmic movement.

Question 23

Microfilaments

Answer 23

Solid rods of actin, important in cell movement as well as support. Muscle contraction is based on the interaction of actin with myosin. Move materials across plasma membrane.

Question 24

Simple Diffusion

Answer 24

net movement of dissolved particles down their concentration gradients, requires no external source of energy

Question 25

Osmosis

Answer 25

Simple diffusion of water from a region of lower solute concentration to a region of higher solute concentration.

Question 26

Hypertonic

Answer 26

When the cytoplasm of a cell has a lower solute concentration than the extracellular medium, water will flow out of the cell, cell will shrivel (PLASMOLYSIS)

Question 27

Hypotonic

Answer 27

If the extracellular environment is less concentrated than the cytoplasm of the cell, water will flow into the cell causing it to swell and lyse.

Question 28

Facilitated Diffusion

Answer 28

Passive transport, net movement of dissolved particles down the concentration gradient through special channels or carrier proteins in the cell membrane, does not require energy.

Question 29

Active Transport

Answer 29

Net movement of dissolved particles against their concentration gradient with the help of transport proteins, requires energy. Carrier molecules aid in the regulation of the cell’s internal content of ions and large molecules.

Question 30

Energy Independent Carriers

Answer 30

Facilitate the movement of compounds along a concentration gradient.

Question 31

Symporters

Answer 31

active transport, move two or more ions or molecules

Question 32

Antiporters

Answer 32

Active transport, exchange one or more ions for another ion or molecule

Question 33

Pumps

Answer 33

Active Transport, energy dependent carriers, require ATP

Question 34

Endocytosis

Answer 34

process in which the cell membrane invaginates, forming a vesicle that contains extracellular medium.

Question 35

Pinocytosis

Answer 35

Endocytosis, ingestion of the fluids or small particles

Question 36

Phagocytosis

Answer 36

Endocytosis, engulfing of large particles. Particles may bind to receptors on the cell membrane

Question 37

Exocytosis

Answer 37

Vesicle within the cell fuses with the cell membrane and releases its contents to the outside. Can play an important role in cell growth and intercellular signaling.

Question 38

Brownian movement

Answer 38

Intracellular Circulation, kinetic energy spreads small suspended particles throughout the cytoplasm of the cell

Question 39

Cyclosis or streaming

Answer 39

Intracellular Circulation, circular motion of cytoplasm around the cell transports molecules

Question 40

Endoplasmic Reticulum,

Answer 40

Intracellular Circulation, provides channels throughout the cytoplasm and provides direct continuous passageway from the plasma membrane to the nuclear membrane

Question 41

Diffusion

Answer 41

Extracellular Circulation, if cells are in direct or close contact with the external environment, can serve as a sufficient means of transportation for food and oxygen from the environment to the cell. Diffusion is important for the transport of materials between cells and the interstitial fluid that bathes the cells.

Question 42

Circulatory System

Answer 42

Extracellular Circulation, for complex animals whose cells are too far from the external environment to transport materials by diffusion, generally includes vessels to transport fluid and a pump to drive circulation.