Chapter 6

Lysosome

A membrane-enclosed sac of hydrolytic enzymes that a cell uses to digest macromolecules

Stroma

Fluid inside the inner membrane

Pseudopodium

A cellular extension of amoeboid cells used in moving and feeding

Chromatin

A complex of DNA and protein

Dynein

ATP drives the sliding of the microtubules doublets past each other as arm, composed of motor proteins, alternately attach doublets, pull down, release, and reattach.

Describe the function of the extracellular matrix in animal cells.

Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM). The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin. ECM proteins bind to receptor proteins in the plasma membrane called integrins.

Explain the significance of the cis and trans sides of the Golgi apparatus.

Cis and trans help direst the vesicles to the plasma membrane or to other organelles

Chromosomes

DNA (and protein) is organized into units

Mitochondrion

Has an inner membrane with many infoldings

Centrosomes

Microtubules grow out from a region near the nucleus

Explain the roles of peroxisomes in eukaryotic cells.

Perixomes are oxidative organelles filled with enzymes that function in a variety of metabolic pathways, such as breaking down fatty acids for energy or detoxifying alcohol and other poisons.

Desmosomes

Reinforced by intermediate filaments and rivet cells into strong sheets

Rough ER

Ribosomes are attached to the cytoplasmic surface

Vacuole

Sac that buds from the ER, Golgi, or plasma membrane

Microfilament

Solid rods consisting of a twisted double chain of molecules of globular protein actin

Central Vacuole

Surrounded by a vacuolar membrane and enclosing a solution called cell sap. Stores organic compounds and inorganic ions for the cell.

Nucleus

Surrounded by the nuclear envelope

Plasma Membrane

The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell's chemical composition.

Cytoplasm

Thick liquid residing between the cell membrane holding all organelles, except for the nucleus

Granum

a stack of thylakoids in a chloroplast

Gap Junction

Are cytoplasmic connections that allow for the exchange of ions and small molecules between cells through protein-lined pores.

Centriole

Are each composed of nine sets of triplet microtubules arranged in a ring, is associated with the centrosome and replicates before cell division.

Peroxisome

Are oxidative organelles filled with enzymes that function in a variety of metabolic pathways, such as breaking down fatty acids for energy or detoxifying alcohol and other poisons.

Plasmodesma

Channels in plant cell walls through which the plasma membranes of bordering cells connect, thus linking most cells of a plant into a living continuum.

Briefly describe the energy conversions carried out by mitochondria and chloroplasts.

Chemical energy conversion encloses a mitochondrion building enzymes and proteins in the inner membrane. Light Energy stores energy (starch) by absorbing light to the thylakoids.

Explain the structure and role of centrioles.

Centrioles are each composed of nine sets of triplet microtubules arranged in a ring, is associated with the centrosome and replicates before cell division.

Contractile Vacuole

Pump excess water out of freshwater protists.

Glycoprotein

A protein covalently bonded to a carbohydrate.

Cell Wall

Are composed of microfibrils of cellulose embedded in a matrix of polysaccharides and protein.

Eukaryotic cell

Have a true nucleus enclosed in a nuclear envelope and numerous organelles suspended in cytosol.

Explain how the ultrastructure of cilia and flagella relate to their functions (mechanism involving the motor protein).

A core of microtubules sheathed by the plasma membrane, a basal body that anchors the cilium or flagellum and a motor protein called dynein, which drives the bending movements of a cilium or flagellum.

Nucleous

A dense structure visible in the non-diving nucleus, synthesizes ribosomal RNA and combines it with protein to assemble ribosomal RNA and combines it with protein to assemble ribosomal subunits, which then pass through nuclear pores to the cytoplasm

Nuclear Envelope

A double membrane perforated by pores that regulate the movement of materials between the nucleus and the cytoplasm

Phagocytosis

A form of cell eating in which a cell engulfs a smaller organism or food particle

Microtubules

A hollow rod of tubulin protein in the cytoplasm of almost all eukaryotic cells

Transport Vesicle

A membranous compartment used to enclose and transport materials from one part of a cell to another

Cytoskeleton

A network of protein fibers that give mechanical support, function in cell motility (of both internal structures and the cell as a whole), and transmit mechanical signals from the cell's surface to its interior.

Motor Protein

A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell

Integrin

A receptor protein that span the plasma membrane and bind, via other proteins, to microfilaments of the cytoskeleton.

Vesicle

A sac made of membrane in the cytoplasm

Cytosol

A semifluid medium in a cell in which are located organelles

Thylakoid

A series of flattened sacs within chloroplasts

Cilium

A short hair-like cellular appendage with a microtubule core

Organelle

Any several membrane-enclosed structures with specialized functions, suspended in the cytosol of the eukaryotic cells

Prokaryotic Cell

Are cells with no nucleus or membrane-enclosed organelles

Ribosomes

Composed of protein and ribosomal RNA

Proteoglycan

Consists of a small core protein with many attached carbohydrate chain

Golgi Apparatus

Consists of a stack of flattened sacs

List the components of the endomembrane system, and describe the structure and function of each component.

Consists the nuclear envelope: a double membrane perforated by pores that regulate the movement of materials between the nucleus and the cytoplasm, endoplasmic reticulum: continuous with the nuclear envelope and encloses a network of interconnected tubules or compartments called cisternae, Golgi apparatus consists of a stack of flattened sacs, lysosome are membrane-enclosed sacs of hydrolytic enzymes used by animal cells to digest macromolecules, vacuoles are formed as a result of phagocytosis, and the plasma membrane surrounding every cell must provide sufficient surface area for exchange of oxygen, nutrients, and wastes relative to the volume of the cell.

Mitochondrial Matrix

Contains DNA and ribosomes; enclosed by the inner membrane

Endomembrane reticulum (ER)

Continous with the nuclear envelope and encloses a network of interconnected tubules or compartments called cisternae.

Name two different kinds of vacuoles, giving the function of each kind.

Contractile vacuole pump excess water out of freshwater protists. Central vacuole is found in mature plant cells, surrounded by a vacuolar membrane (tonoplast) and enclosing a solution called cell sap.

Cristae

Folds of the inner membrane create a large surface area and encloses the mitochondrial matrix.

Actin

Form a network just inside the plasma membrane and the core of small cytoplasmic extensions called microvilli.

Food vacuole

Formed as a result of phagocytsis

Collagen

Forms strong fibers that are embedded in a network of proteoglycan complexes

Distinguish between free and bound ribosomes in terms of location and function.

Free ribosomes are used within the cytosol. Bound ribosomes, attached to the endoplasmic reticulum or nuclear envelope, usually make proteins that will be included within membranes, packaged into organelles, or exported from the cell.

Nucleoid

In a prokaryotic cell, the DNA is concentrated in a region that is not membrane-enclosed

Cytoplasmic streaming

In plant cells appears to involve both actin-mysosin interactions and sol-gel conversions

Intermediate Filament

Intermediate in size between microtubules and Microfilaments and are more diverse in their composition.

Smooth ER

Lacks ribosomes

Tight junction

Proteins hold adjacent cell membranes tightly together, creating an impermeable seal across a layer of epithelial

Compare the structure, and functions of microtubules, microfilaments and intermediate filaments.

Microtubules have hollow rods constructed of columns of globular proteins called tubulins. Microtubules change length through the addition or subtraction of tubulin dimers. They also provide the supporting framework of the cell, microtubules serve as tracks along which organelles move with the aid or motor molecules. Microfilaments are solid rods consisting of a twisted double chain of molecules of the globular protein actin. Actin filaments are microfilaments function in support forming a network just inside the plasma membrane and the core of small cytoplasmic extensions called microvilli. Intermediate filaments are intermediate in size between microtubules and Microfilaments are more diverse in their composition. Intermediate fibers appear to be important in maintaining cell shape. The nucleus is securely help in a web of intermediate filaments, and the nuclear lamina lining the inside of the nuclear envelope is composed of intermediate filaments.

Describe two examples of intracellular digestion by lysosome.

Phagocytosis in intracellular digestion by lysosomes fuse with food vacuoles to digest material ingested. Macrophages are also in intracellular digestion by lysosomes that is a type of white blood cells that is made to destroy ingested bacteria.

Describe the basic structure of a plant cell wall.

Plant cell walls are composed of microfibrils of cellulose embedded in a matrix of polysaccharides and protein.

Name the intercellular junctions found in plant and animal cells and list the function of each type of junction.

Plasodesmata are channels in plant cell walls through which the plasma membranes of bordering cells connect, thus linking most cells of a plant into a living continuum. Three intercellular junctions between animal cells are tight junction where proteins hold adjacent cell membranes tightly together, creating an impermeable seal across a layer of epithelial cells, Demosomes (anchoring junctions) are reinforced by intermediate filaments and rivet cells into strong sheets, Gap junctions (communicating junctions) are cytoplasmic connections that allow for the exchange of ions and small molecules between cells through protein-lined pores.

Distinguish between prokaryotic and eukaryotic cells.

Prokaryotes are cells with no nucleus or membrane-enclosed organelles. Eukaryotic cells have a true nucleus enclosed in a nuclear envelope and numerous organelles suspended in cytosol.

Flagellum

Tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells

Describe the functions of the cytoskeleton.

The cytoskeleton is a network of protein fibers that give mechanical support, function in cell motility (of both internal structures and the cell as a whole), and transmit mechanical signals from the cell's surface to its interior. It also interacts with special proteins called motor proteins to produce cellular movements.

Ribosomal RNA (rRNA)

The most abundant type of RNA, which together with protein makes up ribosomes

Explain the role of the nucleolus in protein synthesis.

The nucleolus, a dense structure visible in the non-dividng nucleus, synthesizes ribosomal RNA and combines it with protein to assemble ribosomal subunits, which then pass through nuclear pores to the cytoplasm.

Briefly explain how the nucleus controls protein synthesis in the cytoplasm.

The nucleus directs protein synthesis by synthesizing messenger RNA (mRNA) according to instructions provided by the DNA. The mRNA is then transported to the cytoplasm via the nuclear pores. Once an mRNA molecule reaches the cytoplasm, ribosomes translate the mRNA's genetic message into the primary structure of a specific polypeptide.

Chloroplast

The site of photosynthesis in plants and algae

Compare the structure and functions of smooth and rough ER.

The smooth ER serves diverse functions in different cells: Its enzymes are involved in phospholipids and steroid (including sex hormone) synthesis, carbohydrate metabolism, and detoxification of drugs and poisons. The smooth ER is also in storage and release of calcium ions during muscle contraction. The rough ER manufactures membranes from the cell. Enzymes built into the membrane assemble phospholipids, and membrane proteins formed by bound ribosomes are inserted into the ER membrane.

Identify thee three functional compartments of a chloroplast. Explain the importance of compartmentalization in chloroplast function.

The stroma is in the inner membrane that is a fluid surrounding a membraneous system of flattened sac called thylakoids, inside of which is the thylakoid space. Photosynthetic enzymes are embedded in the thylakoids, which may be stacked together to form structures called grana.

Extracellular matrix (ECM)

The substance in which animal tissue cells are embedded

Describe the structure of a mitochondrion and explain the importance of compartmentalization in mitochondrial function.

Two membranes, each a phospholipid bilayer with unique embedded proteins, encloses the mitochondrion. A narrow intermembrane space exists between the smooth outer membrane and the convoluted inner membrane, called cristae, create a large surface area and encloses the mitochondrial matrix. Many respiratory enzymes, mitochondrial DNA, and ribosomes are housed in this matrix. Other respiratory enzymes and proteins are built into the inner membrane.