Cell Biology, Microscopy, Enzymes, and Transport Flashcards

Vocabulary flashcards covering cellular structures, specialized cells, microscopy, enzyme kinetics, food tests, and transport mechanisms based on core biology practicals.

Eukaryotic cells

Cells, such as animal and plant cells, that contain a cell membrane, cytoplasm, and a nucleus containing DNA.

Prokaryotic cells

Small cells, such as bacterial cells, that have a cell wall, cell membrane, cytoplasm, and a single circular strand of DNA and plasmids.

Organelles

Structures within a cell that have specific functions, such as the nucleus, mitochondria, and ribosomes.

Nucleus

The organelle enclosed in a nuclear membrane that contains DNA coding for proteins needed to build new cells.

Cytoplasm

A search liquid substance containing enzymes where chemical reactions occur and organelles are found.

Cell membrane

The structure that controls what enters and leaves the cell.

Mitochondria

The site of aerobic respiration reactions which provide energy for the cell.

Ribosomes

Found on the rough endoplasmic reticulum, these are the sites where protein synthesis occurs.

Chloroplasts

Organelles in plant cells where photosynthesis takes place; they contain chlorophyll pigment to harvest light.

Permanent vacuole

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

Cell wall (plants)

A structure made from cellulose that provides strength to plant and algal cells.

Plasmids

Small rings of DNA found in bacterial cells that code for extra genes.

Flagella

Long, thin 'whip-like' tails attached to bacteria that allow them to move.

Haploid nucleus

A nucleus containing $23$ chromosomes, characteristic of sperm and egg cells, instead of the $46$ found in most body cells.

Acrosome

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

Ciliated epithelial cells

Specialised cells with hair-like cilia that waft bacteria-trapping mucus to the stomach to be killed by acid.

Lignin

A chemical deposited in xylem cells that causes them to die and form hollow tubes for water transport while providing structural support.

Sieve plates

Structures formed in phloem cell walls when they break down, allowing the movement of photosynthesis products between cells.

Resolution

The ability to distinguish between two points; for a light microscope, this is approximately $200\text{nm}$.

Magnification equation

$$\text{Magnification} = \frac{\text{measured size}}{\text{actual size}}$$

Total magnification formula

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

Enzymes

Biological catalysts, typically protein molecules, that increase the rate of reaction without being used up.

Active site

The uniquely shaped part of an enzyme where the substrate binds to form an enzyme-substrate complex.

Lock and Key Hypothesis

A model where the substrate shape is complementary to the enzyme's active site, ensuring enzyme specificity.

Denatured

The state of an enzyme when its shape is altered by extreme pH or temperature, preventing it from functioning.

Saturation point

The specific substrate concentration beyond which the rate of reaction no longer increases.

Amylase

A carbohydrase produced in the salivary glands, pancreas, and small intestine that breaks down starch into maltose.

Proteases

Enzymes, such as pepsin, that convert proteins into amino acids.

Lipases

Enzymes produced in the pancreas and small intestine that convert lipids into fatty acids and glycerol.

Rate of reaction formula

$$\text{Rate} = \frac{\text{Change}}{\text{Time}}$$

Benedict's Solution

A reagent used to test for reducing sugars that changes from blue to reddish-brown if heated in a boiling water bath.

Biuret Test

A food test for protein using potassium hydroxide and copper sulfate; a positive result turns the solution from blue to violet.

Emulsion Test

A test for lipids involving ethanol and deionised water; a positive result is indicated by a white emulsion.

Diffusion

A form of passive transport involving the net movement of molecules from an area of high concentration to an area of low concentration.

Osmosis

The passive transport of water from a dilute solution to a more concentrated solution across a selectively permeable membrane.

Active Transport

An energy-requiring process that moves molecules against a concentration gradient using $ATP$ from respiration.

Percentage change equation

$$\frac{\text{change in mass}}{\text{start mass}} \times 100$$

Independent variable

The variable being changed in an experiment, such as the concentration of sucrose solution in the potato practical.

Dependent variable

The variable being measured, such as the change in mass of potato disks.

Control variable

A factor kept constant to ensure a fair test, such as the diameter of potato disks ($2\text{cm}$) or temperature.