AQA Biology GCSE Topic 1: Cell Biology Flashcards

A comprehensive vocabulary flashcard set covering cell structure, cell specialisation, cell division, culturing microorganisms, microscopy, and transport mechanisms from AQA Biology GCSE Topic 1.

Eukaryotic cells

Cells that make up animals and plants; they contain a cell membrane, cytoplasm, and a nucleus containing DNA.

Prokaryotic cells

Much smaller bacterial cells that contain a cell wall, cell membrane, cytoplasm, a single circular strand of DNA, and plasmids.

Plasmids

Small rings of DNA found floating in the cytoplasm of bacterial cells.

Organelles

Sub-cellular structures in a cell that have different specific functions.

Nucleus

A sub-cellular structure enclosed in a nuclear membrane that contains DNA coding for a particular protein needed to build new cells.

Cytoplasm

A liquid substance in which chemical reactions occur, containing enzymes and other organelles.

Enzymes

Biological catalysts, i.e. proteins that speed up the rate of chemical reactions.

Cell membrane

A structure that controls what enters and leaves the cell.

Mitochondria

Sub-cellular structures where aerobic respiration reactions occur, providing energy for the cell.

Ribosomes

Structures found on the rough endoplasmic reticulum where protein synthesis occurs.

Chloroplasts

Plant cell structures where photosynthesis takes place, containing chlorophyll pigment which harvests light to provide food.

Permanent vacuole

A structure found within plant cell cytoplasm that contains cell sap and improves the cell's rigidity.

Cell wall

A outer layer made from cellulose in plant and algal cells that provides strength to the cell.

Peptidoglycan

The specific compound that forms the cell wall in bacterial cells.

Differentiation

A process that involves a cell gaining new sub-cellular structures in order to become suited to its specific role.

Stem cells

Undifferentiated cells that have the ability to differentiate throughout life and undergo division to produce many more similar cells.

Acrosome

The region at the top of a sperm cell's head containing digestive enzymes that break down the outer layers of the egg cell membrane.

Dendrites

Branched extensions from a nerve cell body that enable connections to form with other nerve cells.

Neurotransmitters

Special transmitter chemicals synthesized using energy in nerve endings that allow electrical impulses to pass from one cell to another.

Lignin

A chemical deposited in xylem cells upon formation causing them to die, form continuous tubes, and withstand pressure from the movement of water.

Sieve plates

Structures formed when the cell walls of phloem cells break down, allowing the movement of substances from cell to cell.

Mitosis

The stage in the cell cycle that involves a cell dividing to produce $2$ identical cells.

Resolving power

A property affecting resolution, defined as the ability to distinguish between two distinct points.

Scanning electron microscope (SEM)

A type of electron microscope that creates 3D images at a resolving power of $10\,\text{nm}$.

Transmission electron microscope (TEM)

A type of electron microscope that creates 2D images detailing organelles at a resolving power of $0.2\,\text{nm}$.

Culture medium

A nutrient-rich preparation containing carbohydrates, minerals, proteins, and vitamins used to grow microorganisms in a laboratory.

Inoculating loops

Wire loops used to spread microorganisms evenly over agar jelly, sterilised by passing them through a flame.

Autoclave

An oven used to sterilise Petri dishes and culture media before use to prevent contamination.

Binary fission

The process of cell division in bacteria where one cell splits into two, occurring as fast as every $20$ minutes under suitable conditions.

Inhibition zone

The clear area left on an agar plate where bacteria have died around an antibiotic or disinfectant disc.

Chromosomes

Structures in the nucleus containing coils of DNA, each carrying many genes.

Gene

A short section of DNA that codes for a protein and controls a characteristic.

Interphase

Stage 1 of the cell cycle where the cell grows, DNA is replicated, organelles increase in number, and protein synthesis occurs.

Cytokinesis

Stage 3 of the cell cycle where two identical daughter cells form when the cytoplasm and cell membranes divide.

Embryonic stem cells

Stem cells formed when an egg and sperm fuse into a zygote that have the ability to differentiate into any cell type in the body.

Meristems

Tissues found in plant root and shoot tips that retain the ability to differentiate into any type of plant cell throughout the life of the plant.

Therapeutic cloning

A technique where an embryo is produced with the same genes as the patient to harvest compatible embryonic stem cells.

Diffusion

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Alveoli

Millions of tiny, spherical air sacs in the lungs providing a surface area of approximately $75\,\text{m}^2$ for gas exchange.

Villi

Projections on the surface cells of the small intestine that increase surface area for faster absorption of digested food into the blood.

Stomata

Pores in plant leaves through which carbon dioxide enters for photosynthesis, and oxygen and water vapour exit.

Guard cells

Cells that control the size of stomata by swelling with water to facilitate gas exchange.

Osmosis

The movement of water from a less concentrated solution to a more concentrated one through a partially permeable membrane.

Isotonic solution

A solution where the sugar concentration outside matches the internal cell concentration, resulting in no net movement of water.

Hypertonic solution

A solution where the concentration of sugar in the external solution is higher than the internal cell concentration, causing water to move out of the cell.

Hypotonic solution

A solution where the external sugar concentration is lower than the internal cell concentration, causing water to move into the cell.

Turgor

Pressure inside a plant cell created when water enters the vacuole, causing it to swell and keeping the stems and leaves rigid.

Plasmolysis

The process where the cell membrane pulls away from the cell wall after excess water leaves a plant cell placed in a concentrated solution.

Active transport

The movement of particles from an area of lower concentration to an area of higher concentration against a concentration gradient, requiring energy from respiration.