91156 Cells 2.4

DNA Replication

The DNA in the cell makes an exact copy of itself prior to cell division so that their is a full set of genetic information available in each cell after division has occurred.

Aerobic respiration

To convert biochemical energy from nutrients into useable energy (ATP) needed for metabolism, growth and movement.

Diffusion

The spread of particles in fluids through random motion from regions of higher concentration to regions of lower concentration until they are equal.

Osmosis

Movement of water across a partially (semi) permeable membrane from an area of high water potential (low solute concentration) to an area of low water potential (high solute concentration) until they are equal.

Active transport

The movement of molecules or ions across a membrane against a concentration gradient. Active transport requires the use of cell's energy and involves globular proteins which act as pumps.

Enzymes

Biological catalysts that speed up the rate of reaction or allow reactions to take place in conditions where it would not otherwise be possible.

Photosynthesis

Process in which plants and some bacteria convert simple inorganic molecules into organic molecules using light energy.

Denaturation

The loss of the three-dimensional shape of an enzyme, resulting in it's inactivation. This is caused by heats or acids.

Fermentation

Anaerobic process by which pyretic acid is reduced to substances such as lactic acid (in animals) or ethanol (in plants) and a little ATP.

Activation Energy

Minimum amount of energy required to trigger a chemical reaction.

Active site

The site on an enzyme that attaches to a substrate.

ADP

Known as Adenosine Diphosphate, which is the compound that remains when a phosphate group is removed from ATP, releasing energy.

Aerobic

Containing oxygen; referring to an organism, environment, or cellular process that requires oxygen.

Alcohol

Product of anaerobic respiration/fermentation.

Anaerobic

Process that does not require oxygen.

ATP

Known as Adenosine Triphosphate which is the main energy source that cells use for most of their work.

Catalyst

A substance that initiates or accelerates a chemical reaction without itself being affected.

Cell membrane

Thin, flexible barrier around a cell; regulates what enters and leaves the cell.

Cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.

Chloroplast

Organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy.

Co-enzyme

A small molecule (sometimes a vitamin) essential for the activity of some enzymes.

Concentration gradient

A difference in the concentration of a substance across a distance.

Cytoplasm

A jellyllike fluid inside the cell in which the organelles are suspended.

DNA

A double-stranded nucleic acid that contains the genetic information for cell growth, division and function.

Glycolysis

A metabolic process that breaks down carbohydrates and sugars through a series of reactions in the cytoplasm to either pyretic acid or lactic acid and release a little energy for the body in the form of ATP (first step of respiration.)

Flaccid

Low turgor pressure

Grana

A stack of thylakoids within a chloroplast.

Lactic acid

By product of anaerobic respiration in animal cells.

Induced-fit model

Change in the shape of an enzymes active site that enhances the fit between the active site and its substances.

Matrix

Fluid filed interior of the mitochondria where the Krebs cycle occurs.

Mitochondria

Organelle that is the site of ATP production.

Nuclear Membrane

A membrane around the nucleus with pores to allow substances in and out.

Light dependent reaction

Process of chlorophyll molecules absorbing light energy and using it to remove hydrogen atoms from water molecules to give free oxygen atoms and ATP. It is the first step of photosynthesis.

Light independent reaction

Process controlled by enzyme reactions that put together glucose molecules from the carbon dioxide and hydrogen atoms, located in the stroma.

Lock and key theory

This theory states that the enzymes active site is exactly complimentary to the structure of the substrate.

Organelles

Tiny structure in the cell that performs specialized functions.

Passive transport

Transport of a substance across a cell membrane by diffusion, facilitated diffusion or osmosis.

Plasmolysis

When a cell is in a hypertonic environment, the cell will lose water to it's surroundings, shrink and its plasma membrane will pull away from the wall.

Replication fork

A Y-shaped region in a chromosome that serves as a growing site for DNA replication.

Semi-permeable membrane

A cell membrane that allows some molecules to pass through but not others.

Stroma

The fluid filled interior of a chloroplast.

Turgor

A cell's swelling against it's cell wall caused by the pressure of the cells contents.

Vacuole

Cell organelle that stores materials such as water, salts, proteins and carbohydrates.