AP Bio Unit 3: Cells Vocab

Diffusion

Movement of particles from an area of higher concentration to one of lower concentration

Facilitated Diffusion

A form of passive transport that uses transport proteins

Active Transport

When energy is required to move materials through a cell membrane (L → H)

Passive Transport

The movement of substances through the cell membrane without the use of cellular energy (H → L)

Contractile Vacuole

The structure inside protists that collect excess water and squeezes it outside through the membrane.

Dynamic Equilibrium

The continuous movement of particles but no overall change in concentration

Equilibrium

When  the molecules of one substance are spread evenly throughout another substance to become balanced

Exocytosis

Release of wastes or cell products from inside to outside a cell by vesicle fusion with the membrane.

Endocytosis

The cell membrane forms around and takes in material from the environment

Osmosis

Diffusion of water molecules through a selectively permeable membrane

Plasmolysis

The loss of water from a cell resulting in a drop in turgor pressure

Cytolysis

When a cell bursts due to excess water diffusing into the cell

Channel Protein

Transport protein that provides a tube-like opening in the plasma membrane through which particles diffuse

Carrier Protein

Transport protein that changes shape when a particle binds with it

Transport Protein

Used to help substances enter or exit the cell membrane

Hypotonic

Lower solute concentration outside the cell, so water moves INTO the cell

Hypertonic

Higher solute concentration outside the cell, so water moves OUT of the cell

Isotonic

Same solute concentration on either side, water moves in and out of the cell at the SAME rate

Turgor Pressure

The internal pressure of a plant cell, when the large, central vacuole exerts outward pressure on the cell wall

Water Potential

The measure of the ability of water molecules to move freely in a solution

Water Potential Equation

Pressure Potential + Solute Potential

Higher solute potential = _______

Less solutes in a solution (makes it less likely water will move to that area)

Higher pressure potential = ______

More pressure in the cell (water will want to leave the cell to relieve the pressure)

Water will move from an area of… (3 things)

• Higher water potential → Lower water potential

• Low solute concentration → High solute concentration

• High pressure → Low pressure

Cell membrane 

Separates the internal environment from external environment, compartmentalizes metabolism, and made up of a phospholipid bilayer

Phospholipids are _______.

Amphipathic

Phospholipid Head

Polar, hydrophillic

Phospholipid Tails

Nonpolar, hydrophobic, and are saturated or unsaturated fatty acids

Saturated Fatty Acid Tails

Straight tails, no double bonds, stack easily, resulting in a more rigid membrane.

Unsaturated Fatty Acid Tails

Bent tails, one or more double bonds, doesn’t stack easily resulting in a more fluid membrane.

Selective Permeability

The ability of a cell membrane to control which substances and how much of them enters or leaves the cell

Fluid Mosaic Model

Describes the organization of cell membranes

• Fluid: phospholipids move fluidly

• Mosaic: made of many proteins, glycoproteins, steroids, & cholesterol molecules embedded in phospholipids

Peripheral Proteins

Temporarily attached to membrane surfaces by interactions with lipids or other proteins. Used in signaling or communication molecules.

Integral Proteins

Permanently attached to membrane

Transmembrane Proteins

Integral proteins that are embedded through the plasma membrane and have ends sticking out and in the cell. Used in transportation or cellular communication.

Cholesterol in the Membrane

Molecules that help maintain membrane fluidity over a range of temperatures

• Higher temps: cholesterol sticks to phospholipids and packs them together into a more rigid and permeable membrane

• Lower temps: cholesterol prevents phospholipids from coming together and crystalizing, keeping it flexible

Carbohydrates in the Membrane

Attached to proteins (glycoprotiens) and lipids (glycolipids), used for cell recognition and communication.

Endosymbiosis Theory

Explains the similarities between prokaryotes and organelles. The theory says cells are engulfed, but not digested. Cells live together in a mutually beneficial relationship (known as symbiosis). Her hypothesis proposed that:

• Mitochondria are the result of the endocytosis of aerobic bacteria

• Chloroplasts are the result of endocytosis of photosynthetic bacteria

• In both cases, by large anaerobic bacteria

• The aerobic and the anaerobic would perform mutually beneficial functions (symbiotic); one would not live without the other

Why is cell size so important?

• Cells must exchange substances with its environment at a rate that keeps up with its metabolism

• Cell membrane can only handle so many exchanges at a time

• The bigger the cell’s surface area, the more substances can cross the membrane at any given interval

Highest SA:VOL (more SA but smaller volume, compacted) means more ______ transport.

Efficient (the higher the ratio, the better)

A cell that is too large results in…

Matter, such as nutrients or waste, can’t be exchanged fast enough

A cell that is too small results in…

Not enough materials can fit inside. Heat and nutrients could also diffuse out of the cell too fast to keep it alive.

Compartmentalization

The division of a cell into specialized membrane-bound organelles, each responsible for a specific cellular function. Compartmentalization maximizes surface area, improving the efficiency of the cell and allowing more complex cellular processes.

Purpose of Organelles in Eukaryotic Cells

Their folded structure increases surface and specialization

Biomolecules

Nucleic acids, proteins, carbohydrates, & lipids (cells are made up of these)

ALL cells have these:

1. Plasma membrane

2. Cytoplasm

3. Genetic Material (DNA)

4. Ribosomes

→(prokaryotic cells ONLY have these)

Prokaryotic Cells ONLY have these:

1. Plasma membrane

2. Cytoplasm

3. Genetic Material (DNA)

4. Ribosomes

Prokaryotic Cells

Archaea, bacteria (main types)

Eukaryotic Cells has…

Internal membranes

• Compartmentalizes functions & organelles

• Isolates specialized environments

• Increases internal surface area for reactions

Autotrophic Eukaryotic Cells

Plant-like: plant cells, some protist/algae cells

Heterotrophic Eukaryotic Cells

Animal-like: animal cells, fungal cells, some protist/protozoan cells

Plant cells often have…

ONLY plant cells have: Cholorplast, plasmodesmata, large central vacuole

Animal + plant: nucleolus, nucleus, nuclear envelope, ER, golgi, mitochondria, cytoskeleton, vesicles/vacuoles, peroxisomes

Plant + prokaryotes: cell wall

ALL cells: cell membrane, ribosomes, cytoplasm, DNA/RNA

Animal cells often have…

ONLY animal cells have: Centrioles, gap junctions, tight junctions, lysosomes, cilia, microvilli

Animal + plant: nucleolus, nucleus, nuclear envelope, ER, golgi, mitochondria, cytoskeleton, vesicles/vacuoles, peroxisomes

Animal + prokaryotes: flagella

ALL cells: cell membrane, ribosomes, cytoplasm, DNA/RNA

Prokaryotes often have…

ONLY prokaryotic cells have: Nucleoid, pili, capsule, plasmids

Plant + prokaryotes: cell wall

Animal + prokaryotes: flagella

ALL cells: cell membrane, ribosomes, cytoplasm, DNA/RNA

Cell Differentiation

Causes cell structures and functions to vary among tissues and organs of multicellular organisms

Cytoplasm

The entire interior of the cell, containing cytosol and all the molecules and structures within it

Cytosol

The gel-like, water-based fluid that fills the space inside the cell between the plasma membrane and the nucleus. Contains the cell’s organelles and is also the site of many chemical reactions.

Nucleus

Stores genetic information (DNA) that is organized into chromosomes

Nuclear Envelope

Separates nucleus from cytoplasm and regulates transport in and out of the nucleus

Nuclear Pores

Gateways in the nuclear envelope that regulate transport of molecules in and out of the nucleus

Nucleolus

Makes ribosomes

Rough ER

Makes proteins

Smooth ER

Produces lipids and detoxifies

Golgi Apparatus

Modifies & exports proteins

Mitochondria

Produces energy (ATP) for the cell to use, “powerhouses” of the cell, captures energy in cellular respiration, breaks down fuel molecules

Cell Wall

A rigid barrier protecting the cell, provides cell structure

Chloroplast

Performs photosynthesis to convert light energy into chemical energy (sugars)

Vacuole

Stores food, water, & waste

Ribosomes

Builds protein molecules, can be free-floating or attached to RER

Cell Theory

• Every living organism is made of one or more cells.

• The cell is the structural and functional unit of all organisms, it is the smallest unit of life, individually alive even as part of a multicellular organism.

• All living cells arise by division of pre-existing cells.