Biology: Cell Structure and Function

Comprehensive vocabulary flashcards covering cell organelles, photosynthesis, cellular transport, enzymes, and cellular respiration.

Nucleus

The control centre of the cell that contains the genetic code in the form of DNA and is surrounded by a nuclear envelope.

Nucleolus

A structure within the nucleus that produces ribosomal RNA, which is where ribosomes come from.

Plasma membrane

A thin, selectively permeable outer layer of the cell that controls what substances enter and leave to maintain a stable internal environment.

Mitochondria

Known as the powerhouse of the cell, it is the site of respiration where glucose is broken down to release energy in the form of ATP.

Chloroplast

The site of photosynthesis in plant cells where light energy is absorbed by chlorophyll to convert carbon dioxide and water into glucose.

Cell wall

A rigid outer layer that provides structural support, maintains cell shape, and prevents the cell from bursting when water enters by osmosis.

Vacuole

An organelle that stores water and maintains turgor pressure against the cell wall to keep the plant upright (turgid).

Lysosomes

Organelles containing digestive enzymes that break down waste materials and worn-out organelles for recycling.

Rough Endoplasmic Reticulum (ER)

A network of membranes studded with ribosomes that functions in making and transporting proteins.

Smooth Endoplasmic Reticulum (ER)

A network of membranes without ribosomes that makes lipids (fats) and helps store calcium.

Ribosomes

The site of protein synthesis where proteins are made using instructions from DNA.

Golgi apparatus

An organelle that modifies, sorts, and packages proteins into vesicles for transport to specific locations inside or outside the cell.

Centrioles

Organelles that help organise spindle fibers during mitosis to ensure chromosomes are separated correctly into two new cells.

Cytoplasm

A jelly-like substance holding organelles in place; it consists of organelles and cytosol (cellular fluid).

Autotrophs

Organisms, such as plants, that have the ability to produce their own food through photosynthesis using light energy, carbon dioxide, and water.

Heterotrophs

Organisms, such as animals, that cannot make their own food and must obtain glucose by consuming other organisms.

Photosynthesis Word Equation

$$\text{carbon dioxide} + \text{water} + \text{light energy} \rightarrow \text{glucose} + \text{oxygen}$$

Thylakoid

Flat disk-shaped structures within the chloroplast; a single stack is called a granum, and multiple stacks are called grana.

Stroma

The transparent fluid that fills the inside of the chloroplast and is the site of the light-independent phase of photosynthesis.

Light-dependent phase (Photolysis)

The first phase of photosynthesis occurring in the grana where chlorophyll absorbs light energy to split water molecules, releasing oxygen and producing energy carriers (ATP and NADPH).

Light-independent phase (Carbon fixation)

Also called the Calvin cycle, this occurs in the stroma and uses carbon dioxide along with ATP and NADPH to produce glucose.

Diffusion

The passive movement of particles from a region of high concentration to a region of low concentration without the use of energy.

Osmosis

The passive movement of water through a partially permeable membrane from a high water concentration to a low water concentration.

Concentration gradient

The difference in the concentration of particles between two areas.

Facilitated Diffusion

A form of passive transport that requires a protein in the plasma membrane to shuttle larger or polar particles across, requiring no energy.

Hypertonic Solution

A solution with a higher solute concentration than another; cells in this solution will lose water and shrink.

Hypotonic Solution

A solution with a lower solute concentration than another; cells in this solution will gain water, swell, and potentially burst.

Isotonic Solution

A solution where the solute concentration is the same as another, resulting in no net movement of water.

Active transport

The movement of substances against a concentration gradient requiring ATP energy, such as ion pumps and bulk transport (endocytosis and exocytosis).

Enzymes

Proteins that act as biological catalysts, speeding up chemical reactions by lowering the activation energy required.

Active site

A specific pocket or groove in an enzyme's structure where the substrate binds according to the lock and key model.

Anabolic enzymes

Enzymes that use energy to synthesise larger molecules from smaller ones, such as Calvin cycle enzymes.

Catabolic enzymes

Enzymes that generate energy by breaking down large molecules into smaller ones, such as amylase breaking down starch.

Cellular Respiration

A chemical reaction occurring in the mitochondria where glucose is broken down to release energy in the form of ATP.

ATP (adenosine triphosphate)

The main source of usable energy in cells, produced during cellular respiration.

Glycolysis

The first stage of respiration occurring in the cytoplasm, where glucose is split into two 3-carbon pyruvic acid molecules with a net gain of $2$ ATP.

Krebs Cycle

The second stage of respiration occurring in the mitochondrial matrix where pyruvate is broken down, producing carbon dioxide as waste and $2$ net ATP.

Electron transport chain

The final stage of respiration occurring in the cristae of the mitochondria, using oxygen as the final acceptor to produce a large amount of ATP and water.

Cristae

The highly folded structures of the inner mitochondrial membrane that increase surface area for the electron transport chain.

Matrix

The liquid medium inside the mitochondria that provides the environment for the Krebs cycle to occur.