A2.2 Cell Structure [SL&HL] Key Terms

Nutrition Movement Growth Response to stimuli Reproduction Aseptate Cell wall Microvilli Sap vacuole

Cell

The smallest basic unit of living organisms. All living organisms are made of cells.

Cell Theory

All living things are made of individual units, cells, which are the basic units of life, and that all cells arise from other cells.

Microscope

A tool used to examine an object with greater detail that uses lenses or electron beams to increase its magnification.

Magnification

The comparison of the size of an image compared to the actual size of an object.

Scale bar

A graphic that represents the actual size of the object prior to magnification.

Resolution

The shortest distance between two separate points in a microscope’s field of view that can still be distinguished as separate objects.

Electron microscope

Instrument using a beam of electrons to obtain a magnified image of a very small object such as a sub

DNA

Deoxyribonucleic acid, contained in the cell’s nucleus, the molecule that carries genetic information for development and functioning of an organism.

Cytoplasm

Gel

Plasma membrane

A thin, selectively permeable layer of phospholipid and protein molecules that surrounds the cell, acting as a boundary and regulating the passage of molecules and ions in and out of the cell.

Nucleoid region

An irregularly shaped region within the prokaryotic cell that contains all or most of the genetic material.

Prokaryote

Organisms that do not have a proper nucleus enclosing their genetic material.

Eukaryote

An organism whose cells have a true nucleus enclosing their genetic material.

Metabolism

The enzyme

Ribosome

Subcellular structures in which protein synthesis takes place.

Nucleus

A double membrane

Chromosome

A long molecule of DNA containing part of the genetic material of an organism.

Sister chromatids

Two identical copies of a chromosome, formed by DNA replication and attached to each other at the centromere.

Histone protein

Proteins around which eukaryotic DNA is wrapped, forming structures called nucleosomes. This organisation helps to regulate gene expression and protect the structural integrity of DNA.

Organelle

Specialised structures inside cells with specific functions.

Mitochondria

Double

Rough endoplasmic reticulum

A network of membranes within the cell that is studded with ribosomes, which are responsible for synthesising proteins.

Smooth endoplasmic reticulum

Meshwork of fine disk

Golgi apparatus

A membrane

Vacuole

Membrane

Lysosome

Compartmentalised spaces within cells that are responsible for breaking down and recycling waste materials.

Cytoskeleton

A network of protein fibres that provides shape and allows for the movement of molecules around the cell.

Unicellular

An organism composed of only one cell.

Multicellular

An organism composed of more than one cell.

Homeostasis

The ability of the body to seek and maintain equilibrium and maintain conditions optimal for survival.

Plastids

Small organelles responsible for manufacturing and storing chemical energy. (Like chloroplasts

Chloroplasts

Chloroplasts are organelles found in some plant cells. They contain chlorophyll and carry out the process of photosynthesis.

Centrioles

Cylindrical organelles that help to establish and organise the microtubules, playing an important role in cell division.

Fungal hyphae

Thread

Flagellum

A hair

Cilia

Hair

Cellulose

A type of polysaccharide that is a major structural component of plant cell walls.

Peptidoglycan

An important component of bacterial cell walls.

Pilus

Protein filaments on the cell wall that help with cell adhesion and transferring of DNA between two cells.