Chapter 3: Cell Structure and Function

How are prokaryotic and eukaryotic cells different?

- Eukaryotic cells have a membrane-bound nucleus and a number of other organelles. - Prokaryotic cells have a nucleoid and no true organelles.

What are the mitochondria's two internal compartments called?

- Intermembrane space - Mitochondrial matrix

What does the endomembrane system include?

- Nuclear envelope - Endoplasmic reticulum - Golgi apparatus - Vacuoles - Lysosomes - Plasma membrane

What are membranes composed of?

- Phospholipids - Proteins

What are the four kinds of connections between cells?

- Plasmodesma - Gap junctions - Tight junctions - Desmosomes

What diverse metabolic processes is the smooth er involved in?

- Synthesis of lipids - Metabolism of carbohydrates - Detoxification of drugs and poisons.

Exocytosis

A process of passing material out of a cell.

Isotonic

Describes a solution in which the extracellular fluid has the same osmolarity as the fluid inside the cell.

Phagocytosis

A process that takes up macromolecules that the cell needs from the extracellular fluid; a variation of endocytosis.

Which plasma membrane component can be either found on its surface or embedded in the membrane structure? a. protein b. cholesterol c. carbohydrate d. phospholipid

A

Pinocytosis

A process that takes up solutes that the cell needs from the extracellular fluid; a variation of endocytosis.

Eukaryotic Cell

A cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs.

Ribosome

A cellular structure that carries out protein synthesis.

Gap Junction

A channel between two adjacent animal cells that allows ions, nutrients, and other low-molecular-weight substances to pass between the cells, enabling the cells to communicate.

Plasmodesma

A channel that passes between the cell walls of adjacent plant cells, connects their cytoplasm, and allows material to be transported from cell to cell.

What is chromatin?

A complex of protein and DNA that makes up the cell's chromosomes found inside the nucleus.

Golgi Apparatus

A eukaryotic organelle made up of a series of stacked membranes that sorts, tags, and packages lipids and proteins for distribution.

Tight Junction

A firm seal between two adjacent animal cells created by protein adherence.

Electrochemical Gradient

A gradient produced by the combined forces of the electrical gradient and the chemical gradient.

Central Vacuole

A large plant cell organelle that acts as a storage compartment, water reservoir, and site of macromolecule degradation.

Desmosome

A linkage between adjacent epithelial cells that forms when cadherins in the plasma membrane attach to intermediate filaments.

Organelle

A membrane-bound compartment or sac within a cell.

Vacuole

A membrane-bound sac, somewhat larger than a vesicle, that functions in cellular storage and transport.

Passive Transport

A method of transporting material that does not require energy.

Fluid Mosaic Model

A model of the structure of the plasma membrane as a mosaic of components, including phospholipids, cholesterol, proteins, and glycolipids, resulting in a fluid rather than static character.

Diffusion

A passive process of transport of low-molecular weight material down its concentration gradient.

Plasma Membrane

A phospholipid bilayer with embedded or attached proteins that separates the internal contents of the cell from the surrounding environment.

Chloroplast

A plant cell organelle that carries out photosynthesis.

Facilitated Transport

A process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins.

Cell Wall

A rigid cell covering made of cellulose in plants, peptidoglycan in bacteria, non-peptidoglycan compounds in Archaea, and chitin in fungi that protects the cell, provides structural support, and gives shape to the cell.

Endoplasmic Reticulum

A series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids.

Cilium

A short, hair-like structure that extends from the plasma membrane in large numbers and is used to move an entire cell or move substances along the outer surface of the cell.

Vesicle

A small, membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane and the membranes of the endoplasmic reticulum and Golgi apparatus.

Peroxisome

A small, round organelle that contains hydrogen peroxide, oxidizes fatty acids and amino acids and detoxifies many poisons.

Solute

A substance dissolved in another to form a solution.

Endocytosis

A type of active transport that moves substances, including fluids and particles, into a cell.

Prokaryotic Cell

A unicellular organism that lacks a nucleus or any other membrane-bound organelle.

Receptor-Mediated Endocytosis

A variant of endocytosis involves the use of specific binding proteins in the plasma membrane for specific molecules or particles.

Concentration Gradient

An area of high concentration across from an area of low concentration.

Lysosome

An organelle in an animal cells that functions as the cell's digestive component; it breaks down proteins, polysaccharides, lipids, nucleic acids, and even worn-out organelles.

Water moves via osmosis _________. a. throughout the cytoplasm b. from an area with a high concentration of other solutes to a lower one c. from an area with a low concentration of solutes to an area with a higher one d. from an area with a low concentration of water to one of higher concentration

C

When viewing a specimen through a light microscope, scientists use _________ to distinguish the individual components of cells. a. a beam of electrons b. radioactive isotopes c. special stains d. high temperatures

C

__________________ involves conversion of chemical energy in foods to chemical energy in ATP (adenosine triphosphate).

Cellular respiration

Which of the following is found both in eukaryotic and prokaryotic cells? a. nucleus b. mitochondrion c. vacuole d. ribosome

D

Which of these do all prokaryotes and eukaryotes share? a. nuclear envelope b. cell walls c. organelles d. plasma membrane

D

Hypotonic

Describes a solution in which extracellular fluid had lower osmolarity than the fluid inside the cell.

Hypertonic

Describes a solution in which extracellular fluid has higher osmolarity than the fluid inside the cell.

The membranes within a eukaryotic cell are physically connected and composed the ___________________________________.

Endomembrane system

What are integrins?

Give the membrane a stronger framework.

Cellular respiration is accomplished in the __________________ of eukaryotic cells.

Mitochondria

What are the advantages and disadvantages of light, transmission, and scanning electron microscopes?

The advantages of light microscopes are that they are easily obtained, and the light beam does not kill the cells. However, typical light microscopes are somewhat limited in the amount of detail that they can reveal. Electron microscopes are ideal because you can view intricate details, but they are bulky and costly, and preparation for the microscopic examination kills the specimen. Transmission electron microscopes are designed to examine the internal structures of a cell, whereas a scanning electron microscope only allows visualization of the surface of a structure.

Tonicity

The amount of solute in a solution.

Unified Cell Theory

The biological concept that states that all organisms are composed of one or more cells, the basic unit of life, and new cells arise from existing cells.

Nucleus

The cell organelle that houses the cell's DNA and directs the synthesis of ribosomes and proteins.

Mitochondria

The cellular organelles are responsible for carrying out cellular respiration, resulting in the production of ATP, the cell's main energy-carrying molecule.

Selectively Permeable

The characteristic of a membrane that allows some substances through but not others.

What is photosynthesis?

The conversion of light energy to chemical energy of sugar molecules.

Nucleolus

The darkly staining body within the nucleus is responsible for assembling ribosomal subunits.

Nuclear Envelope

The double-membrane structure constitutes the outermost portion of the nucleus.

Cytoplasm

The entire region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in the gel-like cytosol, the cytoskeleton, and the various chemicals.

Cytosol

The gel-like material of the cytoplasm in which cell structures are suspended.

Endomembrane System

The group of organelles and membranes in eukaryotic cells that work together to modify, package, and transport lipids and proteins.

Microscope

The instrument that magnifies an object.

Flagellum

The long, hair-like structure extends from the plasma membrane and is used to move the cell.

Extracellular Matrix

The material, primarily collagen, glycoproteins, and proteoglycans, secreted from animal cells that holds cells together as a tissue, allows cells to communicate with each other, and provides mechanical protection and anchoring for cells in the tissue.

Active Transport

The method of transporting material that requires energy.

Cytoskeleton

The network of protein fibers that collectively maintains the shape of the cell, secures some organelles in specific positions, allows cytoplasm and vesicles to move within the cell, and enables unicellular organisms to move.

Rough Endoplasmic Reticulum

The region of the endoplasmic reticulum is studded with ribosomes and engages in protein modification.

Smooth Endoplasmic Reticulum

The region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates, lipids, and steroid hormones; detoxifies chemicals like pesticides, preservatives, medications, and environmental pollutants, and stores calcium ions.

Osmolarity

The total amount of substances dissolved in a specific amount of solution.

Osmosis

The transport of water through a semipermeable membrane from an area of high water concentration to an area of low water concentration across a membrane.

What do prokaryotic and eukaryotic cells have in common?

They both have a plasma membrane and one or more chromosomes and ribosomes.

What are glycoproteins?

They serve as identification tags that are specifically recognized by membrane proteins of other cells.

Why does osmosis occur?

Water moves through a semipermeable membrane in osmosis because there is a concentration gradient across the membrane of solute and solvent. The solute cannot effectively move to balance the concentration on both sides of the membrane, so water moves to achieve this balance.