Topic 2 - Genes and Health Defintions

Alveoli

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

Fluid mosaic mode

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

Hydrophilic

A molecule which is attracted to water.

Hydrophobic

A molecule which repels water.

Integral membrane protein

A type of protein bound to the membrane with strong interactions.

Peripheral membrane protein

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

Amphipathic

A molecule with both hydrophobic and hydrophilic parts.

Phospholipid

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

Osmosis

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

Active transport

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.

Facilitated diffusion:

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.

Endocytosis

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.

Exocytosis

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.

Amniocentesis

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

Chorionic villus sampling

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

Cystic fibrosis (CF);

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

Dominant trait

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

Gene

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

Genotype

The genetic makeup of an organism.

Heterozygote

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

Homozygote

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

Incomplete dominance:

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.

Monohybrid inheritance

A genetic cross between two homozygous organisms.

Mutation

A change in the sequence of bases in a DNA molecule

Phenotype

The observable characteristics of an organism.

Pre-implantation genetic diagnosis (PGD)

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

Prenatal testing

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

Recessive trait

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

Amino acid:

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

Polymers

Molecules made from a large number of monomers joined together

Monomers

The smaller units from which larger molecules are made

Condensation reaction

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

Hydrolysis

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

Dipeptide

Molecules formed by the condensation of two amino acids.

Polypeptide

Molecules formed by the condensation of many amino acids.

Enzyme

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

Fibrous protein

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

Globular protein

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

Secondary structure

The local interactions of the amino acids in the polypeptide chain.

Tertiary structure

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

Hydrogen bond

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

Haemoglobin

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

Collagen

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

Enzymes

Biological catalysts that reduce activation energy.✢

Intracellular enzyme

An enzyme that works within cells.

Extracellular enzyme

An enzyme which works outside of cells.

Ribosomal RNA (rRNA)

A type of RNA that makes up ribosomes.

Ribosome

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