BIOL 1001 Midterm Exam Study Guide (CHAPTER 5)

The currently accepted model of cell membrane structure, depicting the membrane as a mosaic of protein molecules suspended in a fluid bilayer of phospholipid molecules.

fluid mosaic model

flexible, selectively permeable barrier that surrounds all living cells, separating the internal cytoplasm from the external environment

structure of a plasma membrane

help the cell communicate, transport materials, and maintain its structure

-transport channels

-receptors

-enzymes

-ID Tags

functions of different proteins embedded in the plasma membrane.

the diffusion of free water across a selectively permeable membrane

osmosis

Passive transport: the diffusion of a substance across a membrane, using no energy.

Diffusion: the random movement of particles that results in the net movement of a substance down its concentration gradient from a more concentrated region to a less concentrated region

Exocytosis: exports bulky materials via transport vesicles that fuse with the plasma membrane and release their contents outside the cell.

how substances are transported across the membrane

A transport protein in the plasma membrane of an animal, plant, or microorganism cell that facilitates the diffusion of water across the membrane (osmosis).

aquaporin

differentiate simple diffusion from facilitated diffusion

Simple diffusion moves small, nonpolar molecules directly through the cell membrane, while facilitated diffusion moves larger or charged molecules through protein channels.

differentiate exocytosis from endocytosis

Endocytosis brings large materials into a cell by engulfing them in a membrane vesicle, while exocytosis expels materials out of the cell by fusing a vesicle with the plasma membrane

differentiate passive transport from active transport

passive transport moves substances along a concentration gradient without using cell energy, while active transport moves substances against a gradient using cellular energy (ATP)

where does the water move if the cell is hypotonic?

water moves into the cell

where does the water move of the cell is isotonic?

water moves in and out of the cell at the same rate. Causes no net movement of water into or out of the cell.

where does the water move if the cell is hypertonic?

water moves out of the cell and into the surrounding solution.

what is the role of enzymes and co-factor?

enzymes speed up reactions by lowering the activation energy barrier

cofactors bind to the active site and function in catalysts.

Discuss the effect of competitive and non-competitive inhibitor on an enzyme.

Competitive inhibitors bind directly to the active site of an enzyme to block the substrate.

Non-competitive inhibitors bind to a separate allosteric site to change the enzyme's shape

a method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

Ex: ATP Regulation: Adenosine triphosphate (ATP) provides energy for cells. When ATP levels get too high, ATP acts as an inhibitor on the enzymes that break down glucose to make energy, slowing down synthesis.

feedback inhibition

process by which an animal (or any organism) keeps its internal environment relatively stable even when the external environment fluctuates widely.

Ex: When you are cold: Blood vessels constrict to conserve core heat, and muscles trigger rapid contractions (shivering) to generate warmth

homeostasis