B1 Cells - Paper 1 Revision

Comprehensive vocabulary flashcards covering sub-cellular structures, specialised cells, microscopy formulas and conversions, stem cells, the cell cycle, mitosis, and culturing microorganisms.

Eukaryotic cells

Multicellular organisms like plants, animals, and fungi that contain a nucleus.

Prokaryotic cells

Single-celled organisms like bacteria that do not have a nucleus.

Nucleus

A sub-cellular structure that contains genetic material and controls the activities of the cell.

Cell membrane

A cellular structure that controls the movement of substances in and out of the cell.

Ribosome

The sub-cellular site of protein synthesis.

Cytoplasm

The site within the cell where most of the chemical reactions take place.

Mitochondria

The site of aerobic cellular respiration within the cell.

Cell wall

An outer layer made of cellulose that strengthens plant and algal cells.

Vacuole

A plant organelle filled with cell sap to keep the cell turgid.

Chloroplast

A plant sub-cellular structure containing chlorophyll, which absorbs light for photosynthesis.

Sub-cellular structure

A distinct part or organelle found within a cell.

Plant cell vs animal cell structures

Both animal and plant cells possess a nucleus, cytoplasm, cell membrane, ribosomes, and mitochondria; plant cells uniquely feature a cell wall, a permanent vacuole, and chloroplasts.

Plasmid

A small ring of DNA found in bacterial cells that carries genes providing advantages such as antibiotic resistance.

Flagellum

A tail-like structure that enables bacterial movement.

Bacterial cell structure

A prokaryotic cell containing cytoplasm, ribosomes, a cell membrane, a cell wall (which may be surrounded by a capsule), a single loop of DNA not enclosed in a nucleus, plasmids, and sometimes flagella.

Magnification

A measure of how many times bigger the observed image of a specimen is in comparison to its actual size.

Resolution

The ability to distinguish between two separate points.

Cell differentiation

The process by which unspecialised cells acquire different sub-cellular structures to become specialised and carry out specific functions.

Stem cells

Unspecialised cells capable of differentiating into many different types of specialised cells.

Therapeutic cloning

A technique where an embryo is produced with the exact same genes as the patient, ensuring derived stem cells will not be rejected by the patient's immune system.

Meristems

Plant tissues containing stem cells capable of differentiating throughout life to produce plant clones quickly and cheaply.

Adult stem cells

Partially specialised stem cells obtained from bone marrow that can treat specific diseases; donor consent is given and no embryos are killed, but painful surgery with risk of infection is required.

Embryonic stem cells

Fully unspecialised stem cells obtained from leftover IVF embryos that can treat a wide range of diseases without surgery; however, the embryo cannot give consent, the process destroys embryos, and long-term effects remain unknown.

Red blood cell

A specialised animal cell that carries oxygen; adapted with a large surface area, haemoglobin, and no nucleus to maximise available space.

Nerve cell

A specialised cell that carries electrical impulses throughout the body; adapted by being long, having branched connections at each end, and possessing an insulating myelin sheath.

Root hair cell

A specialised plant epidermal cell adapted to absorb water and minerals from soil via an extended large surface area.

Muscle cell

A specialised animal cell that contracts to move the body; adapted with contracting protein fibres and large numbers of mitochondria.

Sperm cell

A specialised male reproductive cell that carries paternal DNA to fertilise an egg cell; adapted with a long flagellum for swimming, head enzymes to penetrate the egg, and large numbers of mitochondria.

Electron microscope

A microscope that offers much higher magnification and resolution than a light microscope, allowing cells and internal organelles to be observed in fine detail.

Magnification equation

$$\text{Magnification} = \frac{\text{Image size}}{\text{Actual Size}}$$

Total magnification equation

$$\text{Total magnification} = \text{magnification of eyepiece} \times \text{magnification of objective lens}$$

Microscopy unit conversions

Converting units from larger to smaller: multiply centimetres by $10$ to get millimetres, millimetres by $1000$ to get micrometres ($\mu\text{m}$), and micrometres by $1000$ to get nanometres ($\text{nm}$); divide by these factors to convert upwards.

Methylene blue

A biological stain added to animal cheek cells on a glass slide to make sub-cellular structures clearly visible under a light microscope.

Iodine stain

A chemical stain applied to thin plant tissue specimens (such as onion cells) on a microscope slide to highlight internal cell features.

The cell cycle

The repeating series of stages governing cellular lifespan and replication, consisting of cell growth, organelle multiplication, DNA replication, mitosis, and cytoplasmic division.

Mitosis

The nuclear division stage in the cell cycle where duplicated chromosomes move apart and form two identical nuclei for growth or repairing tissues.

Chromosomes

Thread-like structures made of DNA located in the nucleus, arranged in pairs in body cells and carrying large numbers of genes.

Binary fission

A method of simple asexual cell division by which bacteria multiply, occurring as rapidly as once every $20\,\text{minutes}$ under optimal temperature and nutrient conditions.

Nutrient broth solution

A liquid culture medium providing essential nutrients used to cultivate bacteria in suspension.

Agar gel plate

A solid growth medium poured into a Petri dish used to cultivate individual colonies of microorganisms.

Aseptic technique

A collection of sterile laboratory procedures employed to prevent contamination when culturing and investigating microorganisms.

Zone of inhibition

The circular clear region around an antiseptic, disinfectant, or antibiotic disc on an agar plate where bacterial growth is prevented, evaluated by measuring its diameter in $\text{mm}$.