Unit 2 AP Bio

Cell

Basic functional unit of all living things

Cytoplasm

Consists of specialized bodies (organelles) suspended in a fluid matrix (cytosol)

Cell

Basic functional unit of all living things

Cytoplasm

Consists of specialized bodies (organelles) suspended in a fluid matrix (cytosol)

Plasma Membrane

Separates internal metabolic events from the external environment; controls the movement of materials into and out of the cell (selective permeability); lipid bilayer with hydrophilic heads and hydrophobic tails, proteins, cholesterol to provide some rigidity, and a glycocalyx of glycolipids (lipids + oligosaccharides) and glycoproteins (proteins + oligosaccharides)

Peripheral Proteins

Proteins that attach to the inner or outer surface of the membrane

Integral Proteins

Proteins that extend into the membrane

Transmembrane Proteins

Integral proteins that span completely through the membrane; held in place by hydrophilic/hydrophobic regions

Fluid Mosaic Model

Describes structure of the plasma membrane; scattered proteins within a flexible matrix of phospholipids

Channel Proteins

Provide open passageways through the membrane

Ion Channels

Allow the passage of ions across the membranes; gated channels open and close in response to specific stimuli i.e. Na+ and K+

Porins

Allow the passage of certain ions and small polar molecules; aquaporins increase the passage rate of water molecules

Carrier Proteins

Bind to specific molecules, undergo a change in shape, and then transfer the molecules across the membrane; i.e. the passage of glucose

Transport Proteins

Use ATP to transport materials through active transport; i.e. sodium-potassium pump maintaining higher sodium and potassium concentrations on opposite sides of the membrane

Recognition Proteins

Give each cell type a unique identification so it can distinguish between "self" and "foreign" cells

Receptor Proteins

Provide sites that hormones or other trigger molecules can bind to in order to activate a cell response

Nucleus

Bounded by the nuclear envelope (consisting of two phospholipid bilayers); contains DNA in chromatin form; serves as the site of chromosome separation during cell division

Chromatin

Threadlike form of DNA

Chromosomes

Chromatin condenses during cell division into rod-shaped bodies

Nucleolus

Concentrations of DNA within the nucleus that are in the process of manufacturing components of ribosomes

Ribosomes

Consist of RNA molecules and proteins; the two subunits move across the nuclear envelope into the cytoplasm to be assembled; ribosomes assist in the assembly of amino acids into proteins

Rough Endoplasmic Reticulum

Stacks of flattened sacs with ribosomes; as ribosomes assemble polypeptides, polysaccharides are attached to them to create glycoproteins

Smooth Endoplasmic Reticulum

Without ribosomes; synthesizes lipids and hormones

Golgi Apparatus

Flattened sacs arranged like a stack of bowls; modify and package proteins and lipids into vesicles; these vesicles bud out from the Golgi apparatus, migrate to the surface, and merge with the plasma membrane to release contents

Lysosomes

Vesicles from the Golgi apparatus that contain digestive enzymes; break down food, debris, and foreign invaders; they DO NOT occur in plant cells

Peroxisomes

Break down substances (i.e. hydrogen peroxide, fatty acids, and amino acids)

Mitochondria

Carry out aerobic respiration to obtain ATP from carbohydrates

Chloroplasts

Carry out photosynthesis to convert energy from sunlight into carbohydrates

Microtubules

Made of tubulin; provide support and motility for cellular activities; found in spindle apparatus of mitosis, and in cilia and flagella

Microfilaments

Made of actin; involved in motility of cell

Flagella and Cilia

Structures that protrude from the cell membrane and make wavelike movements; flagella are long, few and move in snakelike motion; cilia are short, numerous, and move with back-and-forth movement; "9 +2" array of microtubules

Centrioles and Basal Bodies

Act as microtubule organizing centers (MTOCs); a centrosome outside the nuclear envelope gives rise to microtubules making the spindle apparatus in cell division; basal bodies are at the base of cilia and flagella and are made of nine triplets of microtubules

Transport Vesicles

Move materials between organelles or between organelles and the plasma membrane

Food Vacuoles

Store nutrients temporarily; may merge with lysosomes which digest food with their enzymes

Storage Vacuoles

In plants; store starch, pigments, toxic substances (i.e. nicotine)

Central Vacuole

Large bodies in plant cells; exert turgor pressure on cell walls when full and maintain rigidity this way

Contractile Vacuole

Collect and pump excess water out of cell

Cell Wall

Provide support outside the plasma membrane; made of cellulose in plants; made of chitin in fungi

Solute

Substance being dissolved

Solvent

Substance that the solute is being dissolved in; i.e. water

Hypertonic Solution

The solution that has a higher concentration of solutes than the other solution

Hypotonic Solution

The solution that has the lower concentration of solutes than the other solution

Isotonic Solution

The solution has the same concentration of solutes as the other solution

Passive Transport

Movement of substances from higher to lower concentration; does not require energy

Simple Diffusion

Random movement from high to low concentration

Osmosis

Diffusion of WATER molecules across a selectively permeable membrane

Plasmolysis

Movement of water out of a cell resulting in the cell's collapse

Facilitated Diffusion

Diffusion of solutes or water through channel proteins

Active Transport

Movement of solutes against a gradient, requiring the expenditure of energy

Exocytosis

Vesicles fuse with the plasma membrane and release their contents to the outside

Endocytosis

The plasma membrane engulfs a substance and enters the cytoplasm in a vesicle; phagocytosis (undissolved, solid material) and pinocytosis (dissolved, liquid material), receptor-mediated (specific molecules bind to receptors)

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

Pinocytosis

process by which a cell takes in liquid from the surrounding environment