AP Biology (Unit 2)

Nucleoid

The region where genetic material is located in a prokaryote

Nuclear envelope

A double membrane enclosing the nucleus; contains small pores

Nucleolus

The location where rRNA is synthesized from genes in the DNA; also helps assemble ribosome subunits

Cytoplasm

The interior of a cell; filled with cytosol and organelles

Rough endoplasmic reticulum

• Has ribosomes attached to its membrane

• Helps package newly synthesized proteins— most secretory proteins are glycoproteins

  • Carbs are attached by enzymes built into the ER membrane

Smooth endoplasmic reticulum

• Helps detoxify molecules

• Synthesizes lipids (oils, steroids, new phospholipids, etc.)

• Metabolizes carbs

• Stores calcium ions

Golgi complex

• A series of flattened membrane-bound sacs (cisternae)

• Helps correctly fold and modify newly made proteins, many of which come from the rough ER

  • Most glycoproteins from the ER have their carbohydrates modified here

• Produces vesicles and adds molecular identification tags to products, helping them be sorted

Vesicles

• Can be incoming or secretory

• Membrane containers that help move molecules

Mitochondria

• Has a double membrane

  • Outer membrane is smooth, while the inner is highly folded (cristae)

• Intermembrane space— the narrow space between the inner and outer membranes

• Mitochondrial matrix— enclosed by the inner membrane

Cristae

The folds within the inner membrane of the mitochondria

Lysosomes

• Contain hydrolytic enzymes that can be used to digest many materials

  • Lysosome enzymes and membrane are made in the ER, and then transferred to the golgi

• Can enact programmed cell death

Phagocytosis

The process of engulfing smaller organisms/food particles

Vacuole

• A large vesicle from the ER and Golgi

• Stores water/other macromolecules, releases waste from cell, etc.

• Plants have large central vacuoles that help maintain turgor pressure

Chloroplasts

• Double outer membrane

• Capture energy from the sun to produce NADPH

• Thylakoids— highly folded membrane compartments, stacked into grana

  • Membranes have chlorophyll pigments that comprise the photosystems

  • Electron transport proteins embedded in thylakoid membrane

• Stroma— fluid between the inner chloroplast membrane and the outside of the thylakoids

Ribosomes

• Not membrane-bound and therefore are not considered organelles

• Free ribosomes— suspended in the cytosol

  • Most proteins made here function within the cytosol

• Bound ribosomes— attached to the rough ER

  • Generally make proteins that are inserted into membranes, sent to other cells, or to be packaged within certain organelles

Peroxisome

• An oxidative organelle with enzymes that convert toxic hydrogen peroxide into water

• May also break down fatty acids

Cytoskeleton

• Provides anchorage for many organelles and even enzymes

• Can quickly disassemble in one part and reassemble in a new location, changing a cell’s shape

• Interacts w/ motor proteins

Microtubules

• Involved during separation of chromosomes during cell division

• Grow out from a centrosome, which has a pair of centrioles, each comprised of nine sets of triplet microtubule

Cell wall

• Protects cells, maintaining their shape, and prevents excessive water uptake

• Found in prokaryotes, some protists, and fungi

Extracellular matrix

• Found in animal cells in place of a cell wall

• Made of glycoproteins and other carb-containing molecules secreted by cells

Endomembrane system

• Consists of the nuclear envelope, the ER, the Golgi, lysosomes, various kinds of vesicles and vacuoles, and the plasma membrane

• Helps synthesize proteins, transport proteins into membranes/organelles/out of the cell, and detoxify poisons

Fluid mosaic model

• The plasma membrane is not static; it is held together by hydrophobic interactions, which are weaker than covalent bonds

  • Weaker interactions allow proteins and lipids to shift and move

• Contains phospholipids, cholesterol, carbohydrates (glycoproteins and glycolipids), and proteins

Peripheral proteins

• Loosely bound to the surface of the membrane

• Hydrophilic with charged and polar r-groups

Integral proteins

• Span the membrane (but some may only extend partway into the hydrophobic interior)

• Hydrophilic with charged and polar r-groups on the ends

• Hydrophobic with nonpolar r-groups inside the bilayer

• May also have hydrophilic channels that allow hydrophilic substances to pass through

Carrier proteins

• Used in active transport

Channel proteins

• Used in facilitated diffusion (passive transport)