Unit 2 Study Guide Cells Name ____________________

1. I can identify the function of each of the following organelles: cell wall, cell membrane, cytoplasm, nucleus,

ribosome, rough ER, smooth ER, Golgi apparatus, lysosome, mitochondria, vacuole, chloroplast, cytoskeleton, and

centrioles Cell Wall = support & protection of the cell (not found in animal cells)

Cell Membrane = regulates/monitors what materials enter and leave the cell; helps maintain homeostasis

Cytoplasm = fluid within the cell that provides a place for chemical reactions to occur

Nucleus = contains the genetic information (DNA) that controls the production of proteins (proteins do EVERYTHING);

the nuclear envelope is a double layered membrane with pores that allows the nucleus to send & receive messages; the

nucleolus is a dense region inside the nuclear lamina (fluid) that produces ribosomes

Ribosome = makes proteins (protein synthesis)

Rough Endoplasmic Reticulum = modifies & folds proteins that will be sent to the Golgi and then exported (has

ribosomes attached)

Smooth Endoplasmic Reticulum = production of lipids for the cell membrane and detoxification of poisonous materials

(does not have ribosomes attached)

Golgi apparatus = sort and package proteins prior to export from the cell

Lysosome = digestion (break down) of large molecules or damaged organelles

Mitochondria = breaks down food (glucose) in the presence of oxygen in order to produce energy (ATP)

Vacuole = storage of water, minerals, and other materials

Chloroplast = production of food (glucose) through photosynthesis

Cytoskeleton = a network of microtubules and microfilaments that provides support, allows movement of the cell &

organelles within the cell, and helps maintain the shape of the cell

Centrioles = part of the cytoskeleton that helps form the spindle in animal cells (not in plant cells)

2. I can explain the similarities and differences between plant and animal cells. I can label a diagram of a plant

cell and an animal cell. Eukaryotes include protists, fungi, plants, & animals. The genetic material (DNA) is found in the nucleus of a eukaryote.

The DNA is arranged in chromosome pairs. Eukaryotes can reproduce asexually through mitosis or sexually through

meiosis. Animal cells do NOT have: a cell wall, a large central vacuole, or chloroplasts (Plants do have these structures)

Plant cells do NOT have: centrioles or lysosomes (Animals do have these structures)

Plant cells are larger than animal cells and are usually cube-shaped. Plants have a rigid cell wall made of cellulose.

Animal cells are usually round but can easily change shape because they do not have a cell wall.

Unit 2 Study Guide Cells Name ____________________

3. I can identify the structures that form the cell membrane and how they help maintain homeostasis. Homeostasis is keeping an internal balance. The cell membrane is a selectively-permeable barrier between the inside of

the cell and the outside of the cell; this means that it only allows certain substances to cross the membrane. The cell

membrane maintains homeostasis by controlling what materials enter or leave the cell. This allows the cell to keep

stable concentration levels of water and solutes within the cytoplasm.

4. I can tell the difference between the types of cell transport. This means that I can identify and explain diffusion,

osmosis, facilitated diffusion, active transport, endocytosis and exocytosis.

Particles must be able to pass through the cell membrane in order for cells to function. Particle transport can be

categorized as Active Transport, which requires energy, and Passive Transport, which does not require energy.

There are 3 basic types of passive transport: diffusion, osmosis, and facilitated diffusion.

Carbohydrates = allow cell identification Phospholipids = form majority of cell membrane, the semi-permeable barrier around the cell; phospholipids are turned so that the tails point to the middle of the membrane. Cholesterol = adds stability and strength to the membrane Proteins = adds structure to the membrane and provides transport channels for facilitated diffusion or transport pumps for active transport

Phospholipids have a phosphate head that is hydrophilic. These are always oriented to the outside of the membrane because the cytoplasm and extracellular fluid are both primarily made of water. Phospholipids have 2 hydrophobic fatty acid tails; one is an unsaturated fatty acid which allows mobility for the phospholipids. The membrane is referred to as fluid-mosaic because the phospholipids are not fixed and are able to move fluidly. The membrane is also composed of many different parts which gives it a mosaic quality.

Cytoplasm

Unit 2 Study Guide Cells Name ____________________

Diffusion is the simplest form of transport and can happen with or without a membrane. Diffusion is where molecules

naturally move from areas of higher concentrations (high density or “crowded”) to areas of lower concentration (low

density or “uncrowded”). Small uncharged and nonpolar molecules such as (CO2 & O2) diffuse easily across the cell

membrane. Diffusion does not require the cell to use energy because the molecules move with/down the concentration

gradient. Molecules will stay in motion even after equilibrium has been reached, but the motion will be equal (there will

be no net movement of substances in one direction).

Osmosis is the diffusion of water (H2O) across a semi-permeable membrane. Water molecules can pass through the

lipid bilayer of the cell membrane even though it is polar because they are very small. Through osmosis, water

molecules from areas of higher water concentration to areas of lower water concentration with/down the

concentration gradient. This does not require the input of energy. The area with less water will have a higher

concentration of solutes; this type of solution is called hypertonic. When placed in a hypertonic solution, water will

move out of the cell causing it to lose mass and shrivel. If a solution is hypotonic, it will have a higher concentration of

water and lower concentration of solutes. A hypotonic solution will cause a cell to swell and possibly burst (ex: blood

cell in pure water). An isotonic solution is one that has the same concentration as the cytoplasm of the cell.

Facilitated Diffusion is a type of passive transport where molecules that cannot pass through the lipid bilayer diffuse

through specialized passages called Protein Channels or Carrier Proteins. These proteins “facilitate,” or help, diffusion

occur because they allow large or polar molecules to move across the membrane from areas of higher concentration

to areas of lower concentration. This does not require the cell to use energy because the molecules are moving

with/down the concentration gradient.

High Concentration

Low Concentration

Equilibrium

Hypertonic Solution Hypotonic Solution

Isotonic Solution

Unit 2 Study Guide Cells Name ____________________

Active Transport is where molecules move against/up the concentration gradient. This means that it requires energy to

move the molecules from an area of lower concentration to an area of higher concentration. This requires the use of

specialized proteins in the cell membrane called Protein Pumps. The cell must release energy from ATP in order to move

these molecules. An example of this is the Sodium-Potassium (Na+/K+) Pump which is essential for neuron

communication.

Exocytosis occurs when the cell prepares to export a substance, such as proteins or waste. The material is packaged in

a lipid membrane by the Golgi apparatus. The membrane then carries the substance to the cell/plasma membrane. This

smaller membrane is called a vesicle. The vesicle then fuses with the cell membrane in order to release the substances

into the extracellular environment (outside the cell).

Endocytosis occurs when the cell ingests (imports) a substance from outside the cell. The cell membrane folds around

the substance, such as food, liquid, or specific molecules, and forms a vesicle. The vesicle then transports the substance

into the cytoplasm, often to the lysosome for digestion. There are 3 types of endocytosis: Phagocytosis (importing large

solid particles), Pinocytosis (importing fluid and dissolved particles), or Receptor-mediated Endocytosis (receptor

proteins bind to specific molecules for import).

Exocytosis = Export

Endocytosis = Import