Unit 2 - Cell Structure and Function

Prokaryotic cells

cells with no membrane bound organelles

Eukaryotic cells

cells with membrane bound organelles

Nucleoid

where the genetic material in prokaryotic cells are stored.

Plasmids

small circular DNA molecules

Primary cell wall

the outermost layer of a plant cell, thin and flexible layer that provides structural support.

Secondary cell wall

thick and strong layer in a plant cell, ex:- Wood

Middle Lamella

thin layer that acts like a glue between adjacent plant cells.

Plasmodesmata

channels in the cell walls of plants that allow substances to get from one plant cell to the next.

The extracellular matrix (ECM)

a network of proteins and carbohydrates that are outside the animal cell that provide support, adhesion, movement and regulation.

Tight Junctions

holds the plasma membrane of cells tightly together, like a zipper

Desmosomes

structures that connect cells, providing strength by anchoring them together.

Gap Junctions

channels that allows small molecules to pass between cells.

The Endomembrane System

network in eukaryotic cells for making, modifying, and transporting proteins and lipids.

Nucleus

The control center of the cell, contains the DNA and genes

Nucleolus

a structure inside the nucleus that makes rRNA

Nuclear Envelope

a double membrane that has pores that allow RNA and other molecules to pass in and out of the nucleus

Chromatin

the uncoiled form of chromosomes

Ribosomes

cellular structures made up of ribosomal RNA (rRNA) and proteins, and their main job is to carry out protein synthesis

The Endoplasmic Reticulum (ER)

a network connected to the nuclear envelope made of tubes and sacs that help move substances around the cell

Smooth ER

makes lipids and detoxifies. no ribosomes.

Rough ER

makes and folds proteins. covered with ribosomes.

Glycoproteins

proteins attached to carbohydrates

Golgi Apparatus

modifies, sorts, and packages proteins and lipids for transport.

Lysosomes

digestive organelles that break down waste and cellular debris.

Autophagy

process where cells recycle their own components and break down damaged organelles.

Phagocytosis

process where cells engulf and digest large particles or pathogens.

Apoptosis

Cell death

Vacuoles

storage sacs in cells for nutrients, waste, and water.

Food Vacuoles

Stores and digests food particles in cells.

Contractile Vacuoles

Expels excess water from cells to maintain osmotic balance.

Tonoplast

the membrane that surrounds the vacuole

Turgor pressure

pressure from water inside plant cells that maintains their shape and rigidity

Hypertonic

solution with a higher solute concentration than inside the cell, causing the cell to lose water.

Hypotonic

solution with a lower solute concentration than inside the cell, causing the cell to gain water.

Isotonic

solution with equal solute concentration inside and outside the cell, resulting in no net water movement.

Mitochondria

the powerhouse of the cell; produces energy (ATP) through cellular respiration.

Cristae

folds of the inner membrane inside the mitochondria that enhances surface area

Chloroplasts

organelles in plant cells that convert sunlight into energy through photosynthesis.

Plastids

organelles in plant cells for storage and synthesis; include chloroplasts, chromoplasts, and leucoplasts.

Amyloplasts

plastids that store starch in plant cells

Chromoplasts

plastids that contain pigments for color

Peroxisomes

small membrane-bound organelles that break down harmful & poisonous substances in the cell like hydrogen peroxide.

Cytoskeleton

a network of fibers that provides structural support in animal cells

Microtubules

hollow rods that are made of the protein tubulin

Centrosomes

structures located near the nucleus of a cell where microtubules are produced

Centrioles

organelles that assist in organizing the microtubules during cell division

Microfilaments

Solid rods composed of the protein actin

Intermediate filaments

stable and sturdy filaments made of keratins

Stomata

tiny openings located on the surface of leaves that aid in gas exchange.

The plasma membrane

a thin, flexible barrier that surrounds and protects the cell, which control what goes in and out of the cell

Phospholipid molecules

the main building blocks of the plasma membrane, forming a double layer called the phospholipid bilayer

Integral Proteins (Transmembrane Proteins)

proteins embedded in the cell membrane that span its entire width

Peripheral Proteins

proteins located on the surface of the cell membrane

Glycolipids

molecules where carbohydrates attach to lipids.

Aquaporins

special channel proteins that facilitate the rapid movement of water across the membrane

A concentration gradient

the difference in the concentration of a substance between two regions.

Diffusion

molecules move from high to low concentration until equilibrium is reached.

Passive Transport

movement of molecules across the membrane without energy, from high to low concentration.

Active transport

movement of molecules across the membrane with energy (ATP), from low to high concentration.

Facilitated diffusion

diffusion though channels or carrier proteins.

Osmosis

water movement across a membrane from high to low concentration.

Osmoregulation

process of controlling water

Plasmolysis

shrinking of a plant cell’s membrane away from the cell wall due to water loss.

Flaccid

when a plant cell loses water, causing it to become soft and limp.

Exocytosis

moving large molecules out of the cell via vesicles

Endocytosis

taking in large molecules into the cell forming a vesicle

Phagocytosis

engulfing large particles like food or bacteria

Pinocytosis

engulfing extracellular fluid containing dissolved substances

Receptor-Mediated Endocytosis

receptors on the cell membrane that target and bring in specific molecules

Gated Channels

membrane channels that open or close in response to signals, controlling ion flow in and out of cells.

Cystinuria

A genetic disorder that is caused by the absence of a carrier protein that transports cystine.

Cotransport

transport of two substances across a membrane together, using one molecule’s gradient to move the other.

Symporter

a protein that moves two molecules in the same direction across the cell membrane.

Antiporter

a protein that moves two molecules in opposite direction across the cell membrane

The sodium-potassium pump

active transport process that moves sodium (Na⁺) and potassium (K⁺) ions across the cell membrane

Chemical Force

ions naturally want to move from areas of high concentration to low concentration

Electrical Force

ions naturally move towards areas with opposite charges

Electrogenic Pumps

special transport proteins that create a voltage difference across cell membranes.

Voltage gradient

difference in voltage

Proton pump

protein pump that actively transports protons (H⁺ ions) out of the cell, generating a voltage across the membrane. (found in plants, bacteria and fungi)

Osmolarity

The total concentration of all solutes in a solution, regardless if they can cross the membrane or not

Tonicity

The concentration of non-permeable solutes that cannot cross into the membrane

Water Potential

the tendency of water to move from one place to another

Water Potential Formula

Solute Potential Formula

Compartmentalization

the separation of the cell’s interior into distinct areas

Endosymbiosis

theory that mitochondria and chloroplasts originated from engulfed prokaryotes that formed a symbiotic relationship with host cells.