topic 2 key terms

Question 1

Fick’s Law of Diffusion

Answer 1

The law that relates the rate of diffusion to the concentration difference, surface area and membrane thickness using the following equation:
rate of diffusion = membrane SA x concentration difference/membrane thickness

Question 2

Alveoli

Answer 2

Small air sacs found in the lungs at the end of bronchioles which provide a large surface area for gas exchange.

Question 3

Fluid mosaic model

Answer 3

A model that describes membrane structure as a sea of mobile phospholipids studded with various proteins.

Question 4

Hydrophilic

Answer 4

A molecule which is attracted to water.

Question 5

Hydrophobic

Answer 5

A molecule which repels water.

Question 6

Integral membrane protein

Answer 6

A type of protein bound to the membrane with strong interactions

Question 7

Peripheral membrane protein

Answer 7

A type of protein that is weakly bound to the surface of the
membrane.

Question 8

Amphipathic

Answer 8

A molecule with both hydrophobic and hydrophilic parts.

Question 9

Phospholipid

Answer 9

A type of lipid formed by the condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group.

Question 10

Osmosis

Answer 10

The net movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration without the use of energy.

Question 11

Facilitated diffusion

Answer 11

The net movement of substances from a high concentration to a lower concentration (down their concentration gradient) through transport proteins without the use of energy.

Question 11

Active transport

Answer 11

The active movement of substances from a low concentration to a higher concentration (up their concentration gradient) with the use of energy in the form of ATP.

Question 12

Endocytosis

Answer 12

The bulk uptake of substances into a cell by invagination of the membrane to form a vesicle trapping the substances inside the cell with the use of energy in the form of ATP

Question 13

Exocytosis

Answer 13

The bulk transport of substances out of a cell using a vesicle that fuses with the plasma membrane using energy in the form of ATP

Question 14

Amniocentesis

Answer 14

Sampling the amniotic fluid to determine the sex of the foetus or any that may be present during development.

Question 15

Phospholipid

Answer 15

A type of lipid formed by the condensation of one molecule of glycerol, two molecules of fatty acid and a phosphate group.

Question 16

Osmosis

Answer 16

The net movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration without use of energy.

Question 17

Active transport

Answer 17

The active movement of substances from a low concentration to a higher concentration (up their concentration gradient) with the use of energy in the form of ATP.

Question 18

Facilitated diffusion

Answer 18

The net movement of substances from a high concentration to a lower concentration (down their concentration gradient) through transport proteins without the use of energy

Question 19

Endocytosis

Answer 19

The bulk uptake of substances into a cell by invagination of the membrane to form a vesicle trapping the substances inside the cell with the use of energy in the form of ATP.

Question 20

Amniocentesis

Answer 20

Sampling the amniotic fluid to determine the sex of the foetus or any abnormalities that may be present during development.

Question 21

Exocytosis

Answer 21

The bulk transport of substances out of a cell using a vesicle that fuses with the plasma membrane using energy in the form of ATP.

Question 22

Chorionic villus sampling

Answer 22

Sampling the placenta to test for any genetic diseases that may be present in the developing foetus.

Question 23

Cystic fibrosis (CF)

Answer 23

An autosomal recessive genetic disorder which causes the production of excess thick mucus.

Question 24

Dominant trait

Answer 24

A trait which is present if an individual has at least one copy of the gene.

Question 25

Gene

Answer 25

A sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain.✢

Question 26

Genotype

Answer 26

The genetic makeup of an organism.

Question 27

Heterozygote

Answer 27

An organism which has two different versions of the same gene.

Question 28

Incomplete dominance

Answer 28

A type of inheritance where a dominant allele does not completely mask the recessive allele and so the trait produced is a combination of both alleles.

Question 29

Homozygote

Answer 29

An organism which has two of the same versions of a gene.

Question 30

Monohybrid inheritance

Answer 30

A genetic cross between two homozygous organisms.

Question 31

Mutation

Answer 31

A change in the sequence of bases in a DNA molecule.

Question 32

Recessive trait

Answer 32

A trait which is only present when an individual has two copies of the gene and can be masked by a dominant gene.

Question 32

Pre-implantation genetic diagnosis (PGD)

Answer 32

A method used to diagnose diseases before implantation of the embryo into the uterus.

Question 32

Phenotype

Answer 32

The observable characteristics of an organism.

Question 32

Prenatal testing

Answer 32

Testing performed before childbirth to determine the overall health of the developing foetus.

Question 33

Polymers

Answer 33

Molecules made from a large number of monomers joined together.

Question 34

Amino acid

Answer 34

The monomers containing an amino group (NH2), a carboxyl group (COOH) and a variable R group that make up proteins.

Question 35

Monomers

Answer 35

The smaller units from which larger molecules are made

Question 36

Condensation reaction

Answer 36

A type of reaction that joins two molecules together with the formation of a chemical bond involving the elimination of a molecule of water

Question 37

Hydrolysis

Answer 37

Breaking a chemical bond between two molecules involving the use of a water molecule.

Question 38

Dipeptide

Answer 38

Molecules formed by the condensation of two amino acids.

Question 39

Polypeptide

Answer 39

Molecules formed by the condensation of many amino acids

Question 40

Enzyme

Answer 40

A protein molecule that acts as a biological catalyst and increases the rate of biochemical reactions.

Question 41

Fibrous protein

Answer 41

A class of long chain proteins that are generally insoluble in water and typically have structural roles.

Question 42

Globular protein

Answer 42

A class of spherical shaped proteins that are generally water soluble and typically have metabolic roles.

Question 43

Secondary structure

Answer 43

The local interactions of the amino acids in the polypeptide chain which causes folding.

Question 44

Tertiary structure

Answer 44

The way that the whole protein folds to make a three dimensional structure.

Question 45

Hydrogen bond

Answer 45

A type of weak bond formed between an electropositive hydrogen and an electronegative atom like oxygen or nitrogen.

Question 46

Haemoglobin

Answer 46

A type of conjugated globular protein used to transport oxygen that is made up of four polypeptide chains each containing a haem prosthetic group.

Question 47

Collagen

Answer 47

A type of fibrous protein that provides strength to many different cell types and makes up connective tissues.

Question 48

Enzymes

Answer 48

Biological catalysts that reduce activation energy.✢

Question 49

Intracellular enzyme

Answer 49

An enzyme that works within cells.

Question 50

Extracellular enzyme

Answer 50

An enzyme which works outside of cells.

Question 51

Ribosomal RNA (rRNA)

Answer 51

A type of RNA that makes up ribosomes.

Question 52

Ribosome

Answer 52

An organelle found in the cytoplasm of cells that carries out protein synthesis.