Unit 1 Biology

Cell Membrane

Cell Membrane

Controls the entry and exit of molecules from cell. Is selectively permeable and found in all cells

Cell Wall

Supports the cell and prevents it from bursting. Made of cellulose in plant cells but of different materials in fungal and bacterial cells.

Cellulose

Structural carbohydrate which plant cell wall is made from.

Chloroplast

Structure containing chlorophyll and is the site of photosynthesis.

Cytoplasm

Jelly-like liquid containing cell structures and the site of many chemical reactions in the cell. Found in all cells

DNA

Deoxyribonucleic Acid - The substance in chromosomes that carries genetic (hereditary) information.

Mitochondria

The site of aerobic respiration in plant, animal and fungal cells

Nucleus

The structure that controls cell activity and contains DNA within its chromosomes, found in plant, animal and fungal cells.

Plasmid

Circular genetic material present in bacterial cells and used in genetic engineering.

Ribosome

Site of protein production. Found in all cells

Vacuole

Structure containing cell sap found in fungal and plant cells.

Active transport

The movement of molecules from an area low concentration to an area high concentration against a concentration gradient. This process requires energy and uses membrane proteins to actively pump the molecules.

Concentration gradient

The difference in concentration of a substance between two areas separated by a selectively permeable barrier.

Diffusion

The passive movement of molecules a higher to lower concentration, down a concentration gradient.

Osmosis

The movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane.

Passive transport

The movement of molecules down a concentration gradient that does not require energy Examples are diffusion and osmosis.

Phospholipid

Type of Lipid. The major component of the cell membrane.

Plasmolysed

A description of a plant cell that has become shrunken due to water loss. Cytoplasm detaches from cell wall.

Selectively permeable

A membrane that controls the movement of molecules depending on their size.

Protein

Substance composed of chains of amino acids. A component of the cell membrane along with phospholipids

Turgid

A description of a plant cell that has become swollen due to water gain. Does not burst due to the cell wall.

Amino acids

The components (building blocks) that make up proteins.

Bases

The units that make up the genetic code of DNA and mRNA e.g. Adenine, Guanine, Cytosine, Thymine on DNA.

Complementary

Pairing together i.e. DNA base pairing. (A-T and C-G).

Double helix

A description of the unique 'twisted-ladder' shape of DNA molecules.

Gene

A section of DNA that codes for the production of a protein.

mRNA

The substance that carries a complementary copy of the genetic code from DNA in the nucleus to the ribosomes for protein to be made.

Protein

Substance composed of chains of amino acids.

Ribosome

Site of protein production.

Genetic code

Information carried on DNA/genes needed to make proteins. The information is a code in the form of a sequence of bases

Active site

Area on the surface of an enzyme that a substrate binds with. The shape of the active site is complementary to its specific substrate.

Antibody

Type of protein that is involved in defending animals from microorganisms, such as viruses, that invade the body.

Catalyst

A substance that speeds up a chemical reaction by reducing the energy required to begin the reaction.

Degradation

An enzyme-controlled reaction where large insoluble molecules are broken down into smaller soluble molecules. These release energy.

Denature

A permanent and irreversible change in shape of proteins, such as enzymes, when exposed to high temperatures. In enzymes, this will affect the rate of reaction.

Enzyme

A protein that acts as a biological catalyst. They speed up cellular reactions and are unchanged in the process.

Hormone

A protein that is released into the blood and acts as a chemical messenger.

Optimum

Used to describe conditions such as temperature or PH at which an enzyme's rate of activity is highest.

Product

The substance produced by a chemical reaction.

Receptor

A protein found on cell surfaces that allow cells to recognise certain substances

Specific

The term which describes the fact that each enzyme only binds with one substrate.

Structural protein

A protein found in membranes and in muscle, bone, hair, skin cells.

Substrate

The substance with which an enzyme binds.

Synthesis

An enzyme-controlled reaction where small molecules are built up into larger molecules. These require energy.

Donor

The organism from which genetic material is taken.

Genetic engineering

The artificial transfer of genetic information from one donor cell or organism to another.

Genetically Modified Organism (GMO)

Organism which has been produced or altered by genetic engineering techniques.

Plasmid

Circular genetic material (DNA) present in bacterial cells and used in genetic engineering.

Recipient

The cell or organism that receives genetic information from a donor.

ATP

Adenosine Triphosphate; a substance that stores chemical energy in cells.

Ethanol

An alcohol produced as a result of fermentation in plant and yeast cells.

Fermentation

A type of respiration when oxygen is not present.

Lactate

A substance produced during fermentation in animal cells. It is also responsible for muscle fatigue.

Mitochondria

The site of aerobic respiration and ATP (energy) production in cells.

Pyruvate

A substance produced by the breakdown of glucose in the cytoplasm during respiration.

Respiration

A series of enzyme controlled reactions resulting in the production of ATP from the chemical energy in glucose.

Yeast

A unicellular fungus used in the brewing and baking industry.