2.4 Vocabulary (Full List)

organelle

Functional units inside a cell that perform specific tasks required by the cell.

cytoplasm

Jelly-like fluid organelle inside the cell in which the organelles are suspended.

mitochondria

Organelle found in both plants and animals that converts the chemical energy stored in glucose into ATP.

nucleus

Semipermeable organelle that contains the genetic material of a cell, and is the site of DNA replication.

cell membrane

Semipermeable barrier surrounding the cytoplasm of a cell.

cell wall

Rigid structural organelle that surrounds the cell membrane and provides support to the plant cell.

phospholipid

Major component of the cell membrane that has a hydrophilic head and hydrophobic tails.

chloroplast

Organelle found only in plants, that is the site of photosynthesis.

vacuole

Fluid-filled organelle in both animal and plant cells that stores water and minerals.

semi-permeable

Ability of cell membranes to allow some substances to pass it but not others.

passive transport

Transport of a substance across a cell membrane by diffusion; Energy is not required.

active transport

Movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

diffusion

Passive movement of molecules down a concentration gradient.

facilitated diffusion

Transport of substances across a membrane from an area of higher concentration to an area of lower concentration by means of a transmembrane protein.

osmosis

Movement of water molecules from an area of high concentration to an area of low concentration through a semipermeable membrane.

channel proteins

Transmembrane protein that is open to both ends.

carrier proteins

Transmembrane protein that is only open to one side of the membrane at a time, and changes shape to transport molecules through the cell membrane.

SA : V ratio

Ratio of the cell's surface area and its volume.

concentration gradient

When a solute is more concentrated in one area compared to another.

tonicity

Difference in relative concentration of solutes of two solutions, which determines the direction of osmosis.

hypotonic

Solution that has a lower concentration of solute than the cell.

isotonic

Solution that has an equal concentration of solute compared with the cell.

hypertonic

Solution that has a higher concentration of solute than the cell.

plasmolysis

Collapse of a plant cell's cytoplasm due to a lack of water.

turgidity

Pressure created by water pushing up against the cell wall

enzyme

Substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction.

substrate

Molecule used in an enzyme-controlled reaction.

product

Molecule made by an enzyme-controlled reaction.

denature

Loss of an enzyme's normal shape so that it no longer functions; caused by a less than optimal pH and temperature.

co-factor

Inorganic molecule that binds to an enzyme's active site, altering its shape to allow substrate to bind more tightly.

co-enzyme

Organic molecule that binds to an enzyme's active site, altering its shape to allow substrate to bind more tightly.

catalyst

Substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.

active site

Region on an enzyme that binds to a protein or other substance during a reaction.

activation energy

Minimum amount of energy needed for a chemical reaction to occur.

lock & key model

Model of enzyme activity that explains how a particular enzyme will only fit with one particular type of substrate.

induced fit model

Model of enzyme activity that explains how a substrate binding to the active site causes a temporary change in the enzyme's shape; perfectly moulds around the substrate.

limiting factor

Environmental factor which is found in low supply, causing a reduction in the reaction rate of a cell process.

inhibitor/poison

Molecule that either binds with the active site OR binds outside of the active site in such a way that the shape of the active site changes so that substrate can no longer bind. A limiting factor of enzyme activity.

temperature

Limiting factor of enzyme activity where very high levels cause denaturation, and very low levels decrease the rate of collisions/reaction.

pH

Limiting factor of enzyme activity where extreme changes (either high or low) cause denaturation.

hydrogen bond

Weak bond between a hydrogen atom of one amino acid and an oxygen atom of another amino acid that contributes to the 3D shape of an enzyme/protein.

disulfide bridge

Strong bond between two sulfur (thiol) groups from different amino acids, that contributes to the 3D shape of an enzyme/protein.

grana

Stack of thylakoids.

thylakoid

Flattened membranes that contain chlorophyll.

stroma

Colourless fluid surrounding grana/thylakoids.

photosynthesis

Enzyme-controlled process occurring in plants that use energy from sunlight to combine carbon dioxide and hydrogen to produce glucose.

light-dependent reaction

Set of reactions in photosynthesis that use energy from light to split water into oxygen and hydrogen atoms. Occurs in the thylakoids/grana.

light-independent reaction

Set of reactions in photosynthesis that combines hydrogen atoms with carbon dioxide to make glucose. Occurs in the stroma.

glucose

Simple sugar that stores chemical energy.

chlorophyll

Green pigment in plants responsible for capturing light energy. This light energy is used to split water molecules during photosynthesis.

NADPH

Carrier molecule that transfers hydrogen from thylakoid (light-dependent reactions) to stroma (light-independent reactions).

ATP

The energy 'currency' of the cell, used to perform many cell processes.

stomata

Small openings on the underside of a leaf through which oxygen and carbon dioxide can diffuse.

palisade layer

Layer of tightly packed cells that have many chloroplasts; part of the leaf where most photosynthesis occurs.

spongy layer

Layer of loosely packed cells that have few chloroplasts. Large amount of space between cells so that carbon dioxide and oxygen easily diffuse.

cristae

Infoldings of the inner mitochondrial membrane that is the site of the electron transport chain.

matrix

Fluid contained within the inner membrane of mitochondria, that is the site of the Krebs cycle.

ATP

Energy 'currency' of the cell, used to perform many cell processes.

NADH

Carrier molecule that transfers hydrogen from glycolysis and the Krebs cycle to the electron transport chain.

FADH2

Carrier molecule that transfers hydrogen from the Krebs cycle to the electron transport chain.

pyruvate

Three-carbon compound that forms as an end product of glycolysis.

aerobic respiration

Enzyme controlled process which requires oxygen to produce 38 ATP from the breakdown of glucose.

anaerobic respiration

Enzyme controlled process which occurs in the absence of oxygen to produce 2 ATP from the breakdown of glucose.

glycolysis

Enzyme controlled process that breaks down glucose into 2 x pyruvate, ATP, and NADH. Occurs in the cytoplasm.

Krebs cycle

Enzyme controlled process that breaks down pyruvate derivative (acetyl CoA) into CO2, NADH, and FADH2. Occurs in the mitochondrial matrix.

lactic acid

Toxic chemical produced during anaerobic respiration.

electron transport chain

Enzyme controlled process that uses a hydrogen ion concentration gradient to produce a large number of ATP. Occurs across the mitochondrial inner membrane/cristae.

polymer

Many monomers bonded together in long chains.

monomer

Single unit of molecule that is able to bond in long chains.

anti-parallel

Term to describe how one DNA strand is in the 3' to 5' orientation, and the other is in the 5' to 3'orientation.

leading strand

DNA daughter strand that is built continuously.

lagging strand

DNA daughter strand that is built in fragments.

parent strand

Term for the original strands of DNA during DNA replication.

daughter strand

Term for the new strands of DNA created during DNA replication.

semiconservative

Term that describes how DNA replication produces DNA consisting of one parent strand and one daughter strand.

DNA replication

Process in which DNA is duplicated.

Okazaki fragment

Small fragments of DNA produced on the lagging strand during DNA replication.

mitosis

Type of cell division that only occurs in somatic cells, resulting in two identical daughter cells.

metaphase plate/equator

Imaginary plane perpendicular to the spindle fibers of a dividing cell, along which chromosomes align during metaphase.

chromatin

DNA in its loose, inconspicuous form. Visible during the interphase of the cell cycle.

chromosome

DNA in its compacted, conspicuous form. Only visible during mitosis.

sister chromatid

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

homologous chromosomes

Pair of chromosomes that are the same size, same appearance/banding, and same genes.

spindle fibres

Protein threads produced by centrioles/centrosomes during mitosis to pull chromatids apart.

nuclear membrane/envelope

Double phospholipid bilayer of the nucleus.

nuclear pore

Passageway through the nuclear membrane/envelope, made of proteins.

centromere

Region of a chromosome where the two sister chromatids attach.