AQA Biology GCSE Topic 1: Cell Biology

Flashcards covering key concepts from AQA Biology GCSE Topic 1: Cell Biology, including cell structures, specializations, microscopy, cell division, and transport mechanisms.

Organelles

Structures in a cell that have different functions.

Nucleus

Contains DNA coding for a particular protein needed to build new cells and is enclosed in a nuclear membrane.

Cytoplasm

Liquid substance in which chemical reactions occur, contains enzymes, and houses organelles.

Cell membrane

Controls what enters and leaves the cell.

Mitochondria

Where aerobic respiration reactions occur, providing energy for the cell.

Ribosomes

Where protein synthesis occurs.

Chloroplasts

Where photosynthesis takes place, providing food for the plant, and contains chlorophyll pigment.

Permanent vacuole

Contains cell sap and improves the cell’s rigidity.

Cell wall

Made from cellulose and provides strength to the cell.

Cell Specialization (Differentiation)

A process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role.

Sperm cells

Specialized to carry the male’s DNA to the egg cell (ovum) for successful reproduction, featuring a streamlined head, long tail, many mitochondria, and an acrosome with digestive enzymes.

Nerve cells

Specialized to transmit electrical signals quickly from one place in the body to another, featuring a long axon, dendrites, and nerve endings with many mitochondria.

Muscle cells

Specialized to contract quickly to move bones (striated muscle) or simply to squeeze (smooth muscle), causing movement, and contains special proteins, lots of mitochondria and can store glycogen.

Root hair cells

Specialized to take up water by osmosis and mineral ions by active transport from the soil, featuring a large surface area, a large permanent vacuole, and mitochondria.

Xylem cells

Specialized to transport water and mineral ions up the plant from the roots to the shoots, forming a continuous tube with lignin deposits.

Phloem cells

Specialized to carry the products of photosynthesis (food) to all parts of the plants, forming sieve plates and supplied with energy by companion cells.

Meristems

Cells that retain the ability to differentiate throughout life and can be used to make clones of the plant.

Resolving Power

The ability to distinguish between two points when using a microscope, where a lower value allows more detail to be seen.

Culturing Microorganisms

The process of growing microorganisms in the lab using nutrients.

Binary Fission

The process where bacteria multiply when they split into two.

Gene

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

Stem Cell

An undifferentiated cell which can undergo division to produce many more similar cells, of which some will differentiate to have different functions.

Embryonic Stem Cells

Form when an egg and sperm cell fuse to form a zygote and can differentiate into any type of cell in the body.

Therapeutic Cloning

Involves an embryo being produced with the same genes as the patient, to avoid rejection when used in transplants.

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.

Osmosis

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

Active Transport

The movement of particles from an area where they are in lower concentration to an area where they are in higher concentration- against their concentration gradient, requiring energy from respiration.

Factors affecting the rate of Diffusion

Increase temperature, increase surface area, increase concentration gradient

Concentration Gradient

The difference in concentration between two areas

Hypertonic Solution

A solution that has a higher concentration of solutes than another.

Hypotonic Solution

A solution that has a lower concentration of solutes than another.

Isotonic Solution

A solution in which the concentration of solutes is the same both inside and outside of the cell.

Partially Permeable Membrane

A partially permeable membrane lets small molecules through but not big ones.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Interphase

A phase in the cell cycle where the cell grows, replicates its DNA, and prepares for mitosis.

Catabolism

The process by which large molecules are broken down into smaller molecules, releasing energy.

Anabolism

The synthesis of complex molecules from simpler ones, requiring energy.

Cell Division Rate

The number of cells that divide in a population over a specific period of time.

Purpose of Mitosis in multicellular organisms

The process of cell division that creates new body cells

Cell Cycle

The replication and division of a cell, resulting in two identical daughter cells each having the same number of chromosomes.

Prophase

DNA condenses into visible chromosomes, the nuclear membrane breaks down, and spindle fibers form.

Metaphase

Chromosomes line up along the metaphase plate (center of the cell).

Anaphase

Sister chromatids separate and move to opposite poles of the cell.

Telophase

Chromosomes decondense, nuclear membranes reform, and the cell starts to divide.

Resolution of Light Microscope

Around 0.2 μm or 200 nm; restricts differentiation of objects closer than this.

Electron Microscope

Microscopes using electron beams instead of light for higher resolution imaging.

Scanning Electron Microscope (SEM)

Examines surface structures with a broad view, typically at lower magnifications.

Transmission Electron Microscope (TEM)

Used for imaging thin slices of cells or tissues to visualize internal structures.

Eukaryotic Cell Size

Typically ranges from 5 μm to 100 μm.

Prokaryotic Cell Size

Typically ranges from 0.2 μm to 2.0 μm.

Eukaryotic Cell Outer Layers

Cell membrane, with a cell wall in plants and fungi.

Prokaryotic Cell Outer Layers

Cell membrane surrounded by a cell wall of peptidylocan and some cases slime capsule

Eukaryotic Cell Contents

Cytoplasm, organelles including mitochondria, chloroplasts (in plants), and ribosomes.

Prokaryotic Cell Differences

lacks mitochondria and chloroplasts.