Chapter 5-6

Question 1

Fluid mosaic model

Answer 1

The cell membrane consists of a fluid formed by a bi-layer of phospholipids, with embedded proteins forming a mosaic patchwork of semi permeability.

Question 2

Receptor proteins

Answer 2

Most are glycoproteins that span the plasma membranes. Messenger molecules such as hormones bind to these initiating a cell response.

Question 3

Connection proteins function

Answer 3

Anchoring of cell membrane in various ways. Maintain cell shape by linking the membrane with cytoskeleton. Also link adjacent cells.

Question 4

Diffusion is the process of;

Answer 4

Movement of solutes from high concentration to low concentration.

Question 5

Facilitated diffusion and three types of transport proteins;

Answer 5

Carrier proteins
Channel proteins
Aquporins

Question 6

Define osmosis

Answer 6

The diffusion of water across a semi-permeable membrane in response to gradients of concentration, pressure and temp.

Question 7

Solutions with equal concentrations of solute and thus equal concentrations of water are described as;

Answer 7

Isotonic

Question 8

When comparing 2 solutions, the hypertonic solution is;

Answer 8

The solution with the higher solute concentration.

Question 9

Hypotonic is to be;

Answer 9

A less concentrated solution and therefore water content.

Question 10

When comparing 2 solutions, the hypotonic solution is;

Answer 10

The solution with the lower solute concentration.

Question 11

Cells maintain concentration gradients by using;

Answer 11

Active transport

Question 12

Two types of endocytosis

Answer 12

Pinocytosis and phagocytosis

Question 13

A very small patch of plasma membrane dimples inwards as it takes in a small amount of extra cellular fluid. Virus cells can be taken up by a cell through this process;

Answer 13

Pinocytosis

Question 14

Large particles, sometimes entire organisms moved into a cell through a large pocket of cell membrane. (Engulfing)

Answer 14

Phagocytosis

Question 15

Aquaporin

Answer 15

A selective channel for water molecules, (extremely small). Amino acids that line the walls have slight positive charges repelling ions but attracting water molecules.

Question 16

Adhesive junctions

Answer 16

Specialised groups of proteins that link cells to one another within tissues.

Question 17

Desmosome

Answer 17

An adhesive junction which join cells in tissues that are repeatedly stretched (skin, intestines and the heart).

Question 18

Tight junctions

Answer 18

Span the plasma membrane at corresponding sites. As if stitched together.

Question 19

Gap junction proteins

Answer 19

Consist of protein channels interconnecting the cytosol of adjacent cells. (Plasmodesmata)

Question 20

Plasmodesmata function

Answer 20

Are gap junctions that link nearly all adjacent plant cells and allow movement of large molecules between them.

Question 21

Energy

Answer 21

Capacity to do work

Question 22

Work

Answer 22

The transfer of energy to an object that causes the object to move.

Question 23

Potential energy

Answer 23

Stored energy, including the elastic energy stored in a compressed spring or a drawn bow.

Question 24

Chemical energy

Answer 24

A type of potential energy, stored in for example; batteries and biological molecules.

Question 25

Kinetic energy

Answer 25

Heat or thermal, x-rays or light.

Question 26

First law of thermodynamics;

Answer 26

Energy can be neither be created nor destroyed by ordinary processes.

Question 27

The second law of thermodynamics;

Answer 27

When energy is converted from one form to another the amount of useful energy decreases. For example losses in heat.

Question 28

Entropy

Answer 28

A tendancy toward the loss of complexity, order and useful energy.

Question 29

Reactants;

Answer 29

A combination of molecules of which are not yet broken down into other forms yet.

Question 30

Exogernic or exothermic

Answer 30

If there is an overal release of heat in a reaction.

Question 31

Endergonic or endergonic

Answer 31

If a reaction requires a net input of energy.

Question 32

Electron carriers

Answer 32

Energy transport mechanisms.

Question 33

Catalyst

Answer 33

Speed up the rate of a reaction by reducing it’s activation energy. Enzymes are biological catalysts.

Question 34

Active site

Answer 34

A pocket on an enzyme, location of binding to a molecule (the substrate) to help push it towards a reaction.

Question 35

Substrate

Answer 35

A molecule that is yet to be reacted with, one of which an enzyme can bind to to push it towards a reaction.

Question 36

Metabolism of a cell;

Answer 36

Is the sum of all a cells chemical reactions.

Question 37

Metabolic pathways of cells;

Answer 37

Sequence of reactions of a cells metabolism. From molecule to molecule by different enzymes respectively.

Question 38

Competitive inhibition

Answer 38

A substance that is not the enzymes normal substrate can also bind to the active site.

Question 39

noncompetitive inhibition

Answer 39

a molecule binds to a site on the enzyme that is distinct from the active site. This causes the active site to change shape and become una- vailable, making the enzyme unable to catalyze the reaction

Question 40

allosteric regulation (form of noncompetetive inhibition)

Answer 40

the same enzyme is ei- ther activated or inhibited by molecules binding to an allo- steric site on the enzyme; these sites are always distinct from the active site. Enzymes regulated in this manner are called allosteric enzymes.

Question 41

feedback inhibition

Answer 41

an important form of allosteric regulation, the activity of an enzyme near the beginning of a metabolic pathway is inhib- ited by the end product.

Question 42

poisons and drugs can impact:

Answer 42

enzymes and their functions. both non competitive; heavy metals etc. and competetive; nerve gas.

Question 43

Function of Penecillin

Answer 43

destroys bacteria by competitively inhibiting an enzyme that is needed to syn- thesize bacterial cell walls.

Question 44

Environmental conditions affect on enzymes

Answer 44

pH, salt concentration, and temperature, can promote or inhibit enzyme function by altering or preserving the enzyme’s three-dimensional structure.