Module 1 - Cells as the Basis of Life

Active transport

Movement of molecules across a membrane requiring an input of energy (often ATP)

ADP

Adenosine diphosphate helps store energy. It waits for extra energy that needs to be stored. When storage is needed, a phosphate group will be added to turn ADP into ATP

Aerobic respiration

Glucose + oxygen → carbon dioxide + water + energy

Anaerobic respiration

Glucose + enzymes → lactic acid + carbon dioxide

ATP

Adenosine triphosphate; a molecule that releases chemical energy to the cell; it breaks down into adenosine diphosphate, a phosphate group and energy

Autotrophs

Organisms which are able to produce their own food from their surroundings, using either photosynthesis or chemosynthesis

Concentration gradient

Variation in the concentration of a substance in a mixture from high to low

Denature

Permanent change to the structure, enzyme is changed so it no longer functions

Diffusion

Movement of molecules from area of high concentration to area of low concentration, until equilibrium reached. No energy input is required

Endocytosis

Process of taking substance into a cell by surround it with the cell membrane

Enzymes

Specific biological catalysts which release the rate of metabolic reactions by lowering the activation energy

Exocytosis

Process where the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane

Heterotrophs

Organisms which are not able to synthesise their own food, so must rely on consumption of other organisms or external carbon molecules for their nutritional carbon source

Light dependent

Use light energy to make two molecules needed for the next stage of photosynthesis: the energy storage molecule ATP and the reduced electron carrier NADPH

Light independent

The light independent reactions use the chemical energy derived from light dependent reactions to form organic molecules. Occur in the fluid-filled space of the chloroplast called the stroma (calvin cycle)

Metabolism

The sum of all chemical processes which take place within an organism

Osmosis

Passive movement of water across a membrane, to equalise concentration of a solute on both sides

Passive transport

Spontaneous movement of materials across the cell membrane without the expenditure of energy and from places of high to low concentrations

Phagocytosis

"cellular eating". Intake of solid particles with the formation of vesicles called phagosomes

Photosynthesis

6CO2 + 6H2O + light → C6H12O6 + 6O2

Pinocytosis

"cellular drinking". Intake of liquid particles with the formation of vesicles called pinosomes

Substrates

Specific substance that an enzyme combines with to form an enzyme-substrate complex and so facilitate its chemical reaction

Surface Area to Volume Ratio

Comparison of the size of the outside of an object and the amount it can

hold inside. Small object/cell has a large surface area to volume ratio. Large objects/ cells have a small surface area to volume ratio. The surface area to the volume ratio gets smaller as the cell gets larger.

Amoeba

Single celled eukaryotic organism that has no definite shape

Archaea

Unicellular organisms without cell nucleus and any other membrane bound organelles. Found in harsh conditions (e.g. bottom of sea) - can easily survive.

Binary fission

Process that bacteria use to carry out cell division - form of asexual reproduction.

Cellulose

Main substance found in plant cell walls - helps plants to remain stiff and strong. Humans cannot digest.

Cytosol

Semi transparent fluid that suspends other elements. Dissolved in cytosol is mainly water, nutrients and a variety of solutes (fluid present in cell membrane)

Endoplasmic reticulum

Network of membrane-enclosed sacs involved in protein and lipid synthesis. Present in both rough and rough form in eukaryotic cells

Eukaryotic cells (Eukaryote)

Eukaryotic organisms like plants, animals, fungi (multicellular) and protists (unicellular). Reproduce by mitosis and have cellular membrane and cytoplasm, a nucleus containing DNA on linear chromosomes, ribosomes, membrane bound organelle.

Genome

An organism's complete set of DNA - all its genes. Each genome contains information needed to build and maintain that organism

Golgi apparatus

Responsible for packaging proteins for transport around the cell - eukaryotic cells only

Mitochondria

Organelles are responsible for energy (ATP) production in cells. Only in eukaryotic cell

Nucleoid

Space within prokaryotic cell where genetic information. Has no membrane around it - attached to cell membrane and in immediate contact with the cytoplasm. Doesn't take a uniform shape and has no specific size.

Organelles

Structures within cells that perform specific functions like controlling cell growth and producing energy. Embedded within cytoplasm of eukaryotic and prokaryotic. Wide range of responsibilities - anything from generating energy to controlling cell's growth

Paramecium

Single-celled protists naturally found in aquatic habitats. Slipper-shaped and covered with short hairy structures (cilia).

Phospholipid

Hydrophilic head - attracted to water. Two hydrophobic tails made of fatty acids - repel water. Line up and arrange themselves into two parallel layers - phospholipid bilayer makes up cell membrane and critical to cell's ability to function

Prokaryotic cells (Prokaryote)

Simplest form of organisms. Unicellular organisms which do not have membrane bound nucleus, mitochondria or membrane bound organelle. Two types - archaea and bacteria. Contain cellular membrane and cytoplasm, ribosomes and circular DNA/chromosome called nucleoid.

Protozoa

Single celled organisms - different shapes and sizes. Live in a wide variety of moist habitats including freshwater, marine environments and soil. Some are parasitic - live in plants and animals causing disease.

Ribosome

Composed of RNA, a molecular structure that is the site of protein synthesis. Found in both eukaryotic (bound to rough ER, larger) and prokaryotic (free floating in cytoplasm, smaller) cells