Honors Biology: Chapter 4 Review

Give the two points of the cell theory.

All living things are composed of cells; Cells come from other cells.

Contrast light and electron microscopes.

Light microscopes use beams of light through lenses to magnify an image, and electron microscopes use a beam of electrons and computers to produce a much more magnified image.

List the two types of electron microscopes and describe what is able to be seen with each type.

SEM: scanning electron microscope; shows the surface structures in detail; TEM: transmission electron microscope; shows the interior structures in detail

Why must the surface area to volume ratio be large (why must cells divide if they grow too large)?

There must be sufficient surface area to handle materials moving into and out of the cell through the plasma membrane. If the cytoplasm (volume) gets too large, processes inside the cell will take too long, so the cell must divide.

Contrast prokaryotic and eukaryotic cells.

Prokaryotic: no nucleus or other membrane-bound structures (no organelles); Eukaryotic: possess a nucleus and membrane-bound organelles

What four features are found in all cells?

DNA (chromosomes/chromatin); cytoplasm (region between the nucleus and the plasma membrane), cytosol (fluid within the cytoplasm); plasma membrane; Ribosomes

What are organelles?

Small structures with specific functions found in cells

What is cellular metabolism?

All the reactions that occur in a cell

What is the Nucleus?

The control center of a cell that houses DNA; directs all cellular activities through a genetic code (DNA)

What is Chromatin?

Strand-like material composed of DNA and proteins; present when the cell is NOT dividing

What are Chromosomes?

Dense structures composed of coiled DNA and proteins that are present during cellular division

What is the Nuclear envelope?

The membrane covering that surrounds the nucleus; contains several pores to allow passage of substances (nuclear pores)

What is the Nucleolus?

A dark structure present in the nucleus; produces rRNA (ribosomal RNA), which composes ribosomes

What are Ribosomes?

Composed of rRNA and protein; ribosomes are the sites of protein synthesis (protein factories); smallest organelles; don't have a membrane; some float freely in the cytoplasm, others are attached to the rough endoplasmic reticulum (rough ER)

What is the Endomembrane system

A collection of membranous organelles (many are connected or in very close contact) that are involved in the manufacture, modification, and transport of different cellular products (factory parts of the cell)

What are Vesicles?

Small, membrane-bound organelles used for transport of materials

What is the Rough endoplasmic reticulum (Rough ER)?

A collection of tubules studded with ribosomes; site of protein synthesis

What is the Smooth endoplasmic reticulum (Smooth ER)?

A collection of tubules that is not studded with ribosomes; more tubular in appearance; located near the rough ER; involved in lipid synthesis and detoxification

What is Glycoprotein?

A protein with an attached sugar chain (used as ID tags for the cell)

What is the Golgi apparatus (Golgi complex)?

A structure composed of flattened sacs called cisternae that is involved in the modification and transportation of proteins and other products (the FedEx of the cell)

What is a Lysosome?

A membrane-bound structure that contains digestive enzymes that break down nutrients, foreign invaders, or worn-out cell parts

What are Vacuoles?

Membrane-bound structures used for storage of various substances; animal cells contain several small vacuoles, while plant cells contain a large, central vacuole

What are Peroxisomes?

Small, membrane-bound structures that are involved in the metabolism of fatty acids; peroxisomes produce the toxic compound hydrogen peroxide, which enzymes convert into water

What is the Mitochondria?

The powerhouse of the cell; Produces ATP (stands for adenosine triphosphate and acts as cellular energy) by breaking down glucose (sugar); The process of making ATP is called cellular respiration; Mitochondria (plural), Mitochondrion (singular)

What is the Mitochondrial matrix?

The space contained within the inner membrane of the mitochondria; aqueous environment with dissolved substances

What are Cristae?

Folds present in the inner membrane of the mitochondria; increases the surface area to give space for cellular respiration (to make ATP); Cristae (plural), crista (singular)

What metabolic process occurs in the mitochondria?

Cellular respiration--the process of converting food into ATP (cellular energy)

What is the Chloroplast?

A double-membrane organelle present in plants, algae, and some bacteria; site of photosynthesis

What is the Stroma?

The fluid-filled space that surrounds the grana of the chloroplast

What are Thylakoids?

Disk-like, membranous structures present in chloroplasts; contain chlorophyll (location of first stage of photosynthesis)

What is the Granum?

A stack of thylakoids present in chloroplasts (plural: grana)

What metabolic process occurs in the chloroplast?

Photosynthesis--process of using solar energy to produce food

Explain the endosymbiont theory.

The endosymbiont theory states that mitochondria and chloroplasts were once prokaryote-like, free-living cells that were engulfed by a larger cell and used for energy processing. (Because mitochondria and chloroplasts have their own DNA)

What is the Cytoskeleton?

Fibers present in the cytoplasm which provide structure to the cell and assist in transport or movement

What are Microtubules?

A type of cytoskeleton fiber; hollow tubes composed of the globular protein tubulin; grow out of a region near the nucleus called the centrosome; shape and support the cell and act as tracks along which some organelles move; largest of cytoskeleton fibers (25 nm)

What are Intermediate filaments?

A type of cytoskeleton fiber; More permanent structures composed of coiled proteins that make cable-like structures; reinforce cell shape and anchor some organelles; present in the outer layer of skin; smaller than microtubules/larger than microfilaments (10 nm)

What are Microfilaments?

A type of cytoskeleton fiber; Also called actin filaments; arranged in a twisted double chain; form a network just inside the plasma membrane; supports the cells shape; also involved in cell movements; cause muscle contraction; smallest cytoskeleton filaments (7 nm)

What are Centrioles?

Tube-shaped paired structures composed of microtubules; located in animal cells (NOT in plant cells) in an area near the nucleus known as the centrosome; these structures direct the movement of chromosomes during cell division, produce the mitotic spindle

What is the Centrosome?

A region near the nucleus that contains centrioles and organizes microtubules; organizes the mitotic spindle during cell division (only found in ANIMAL CELLS)

What are Cilia (singular: cilium)?

Short, numerous cellular extensions (composed of nine pairs of microtubules arranged concentrically around a central pair); cilia assist in movement of a cell or movement of material past a cellular surface (the word cilia means eyelash); Found in paramecia for movement; Found in the trachea to move dust particles out of the respiratory tract

What are Flagella (singular: flagellum)?

Long, whiplike cellular extensions that assist in mobility;

What is the Extracellular matrix (ECM)?

A layer of proteins, especially glycoproteins, found outside of the cell; holds cells together in tissues and protects the plasma membrane; found in animal cells

What are Tight junctions?

Tightly knit animal cells together to prevent leakage of fluids (example: digestive system)

What are Anchoring junctions?

Fasten animal cells together into strong sheets (act as rivets)

What are Gap junctions?

Channels in animal cells that allow molecules to flow from cell to cell; found in heart tissue to coordinate contraction and embryos to allow communication during development

What are Plasmodesmata?

Channels in plant cell walls that allow water and other small molecules to pass from cell to cell

What are the four groups in which all organelles are organized?

Genetic control (nucleus/ribosomes); Manufacturing, distribution, and breakdown (endomembrane system); Energy processing (chloroplast and mitochondrion); Structural support, movement, and communication between cells (cytoskeleton, cell junctions, etc.)