A Tour of the Cell & Membrane Structure and Function

Flashcards covering Chapter 4: A Tour of the Cell, including cell theory, cell types, organelles, and cell structures in eukaryotic cells.

What are the three main tenets of Cell Theory?

All organisms are made of cells, the cell is the most basic unit of life, and all cells descend from earlier cells.

What is the typical size range of most cells?

Between 1 and 100 um in diameter.

What is the maximum magnification power of a light microscope?

Up to about 1000x.

Which type of microscope provides much higher resolution and is used to study internal cell structures?

Electron microscope.

Why do cells need a high surface area to volume ratio?

To maximize available membrane for material absorption and waste release, and to efficiently manage all internal cell activity.

What four common features do ALL cells contain?

Plasma membrane, cytoplasm (containing cytosol), chromosomes (DNA), and ribosomes.

What are the key characteristics of prokaryotic cells?

Unicellular, no membrane-enclosed organelles or nucleus, DNA in a nucleoid region, often have a cell wall, smaller, and simpler.

What are the key characteristics of eukaryotic cells?

Some unicellular, some multicellular, membrane-enclosed organelles with specialized functions, DNA in the nucleus, larger, and more complex.

What is the most prominent internal structure and defining feature of eukaryotic cells?

The nucleus, which contains the chromosomes.

What is the function of the nuclear envelope?

A double phospholipid bilayer that covers the surface of the nucleus, regulating entry and exit of RNA, proteins, and macromolecules through nuclear pores.

What are ribosomes responsible for?

Protein synthesis.

Where are free ribosomes suspended and what types of proteins do they primarily assemble?

Suspended in the cytosol, primarily used for assembling proteins destined to remain in the cell.

What are the two types of endoplasmic reticulum (ER)?

Smooth ER and Rough ER.

What are some functions of the smooth ER?

Synthesis of lipids (including sex hormones), metabolism of carbohydrates, and detoxification of poisons.

What is the primary function of the rough ER?

Protein synthesis by ribosomes on its surface, for proteins destined to leave the cell or be secreted.

What is the function of the Golgi apparatus?

Modifies, stores, and tags proteins and lipids received from the ER before sending them to other destinations (receiving and shipping).

What are lysosomes and what is their primary role?

Membrane sacs of digestive enzymes with an acidic interior, responsible for recycling and digestion within the cell.

What is phagocytosis?

Intracellular digestion where a cell engulfs a smaller organism or food to form a food vacuole, which then fuses with a lysosome for digestion.

What are the functions of the central vacuole in plant cells?

Stores water and ions, and maintains cell shape through water pressure.

What are mitochondria responsible for?

Cellular respiration, using oxygen to generate ATP by extracting energy from organic molecules (the power source for the cell).

What are chloroplasts responsible for?

Photosynthesis, converting light energy into chemical energy through the synthesis of organic compounds.

What are peroxisomes and what do they do?

Organelles that break down toxins (like alcohol) and fatty acids, producing H2O2 as a byproduct, which they then convert to water and oxygen using enzymes like catalase.

What are the three main types of fibers that make up the cytoskeleton?

Microtubules (thickest), microfilaments (thinnest), and intermediate filaments.

What are microtubules made of and what are their functions?

Hollow tubes of tubulin protein, involved in cell division, cell structure/shape, and movement (flagella, cilia).

What is the 9+2 arrangement characteristic of cilia and flagella?

Nine pairs of microtubules in a ring around a central pair, which enables their bending movement.

What are microfilaments made of and what are their functions?

Solid rods of actin protein, involved in structure/shape, movement (like pseudopods), and muscle contraction (with myosin).

What are intermediate filaments and what is their function?

More permanent, sturdy fixtures in cells made of various proteins (like keratin), providing structure/shape and fixing organelle position.

What is the extracellular matrix in animal cells?

A combination of proteins (like collagen) and carbohydrates secreted by cells, which aids in the regulation of cell behavior.

What are the three main types of cell junctions in animal cells?

Tight junctions, desmosomes, and gap junctions.

What is the function of tight junctions?

Form continuous seals around cells to prevent leakage, as seen in skin, kidney, and intestinal cells.

What are plasmodesmata?

Junctions in plant cells that perforate the cell walls, allowing passage of small molecules between cells, similar to gap junctions.

Which of the following is present in a prokaryotic cell?

Ribosomes

Which of the following frequently imposes a limit on cell size?

ratios of surface area to volume

Which organelle is the primary site of ATP synthesis in eukaryotic cells?

Mitochondria

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and, therefore, abundant in liver cells?

smooth endoplasmic reticulum

Cilia and flagella bend because of

a motor protein called dynein

Which of the following are found in prokaryotic and eukaryotic cells?

Ribosomes

Which structure is common to plant and animal cells?

mitochondrion

Which of the following is a major difference between prokaryotic cells and eukaryotic cells?

Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not.

Which organelle often takes up much of the volume of a plant cell?

central vacuole

Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely malfunctioning in this disease?

mitochondria

Amoebae move by crawling over a surface (cell crawling), which involves

growth of actin filaments to form bulges in the plasma membrane

Tay-Sachs disease is a human genetic abnormality that results in brain cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle is most likely defective in this condition?

the lysosome

A cell with a predominance of smooth endoplasmic reticulum is likely specialized to

synthesize large quantities of lipids

Cyanide binds to at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the

mitochondria

In bacteria, DNA will be found in

the nucleoid region

Examination of a cell by transmission electron microscopy reveals a high density of ribosomes in the cytoplasm. This observation suggests that this cell is actively producing large amounts of which of the following molecules?

proteins

Thylakoids, DNA, and ribosomes are all components found in

chloroplasts

Which of the following structures form cytoplasmic channels that connect adjacent plant cells through the cell walls?

Plasmodesmata

Which structure is not part of the endomembrane system?

chloroplast

Name the organelle

A: Flagellum

B: Chromatin

C: Smooth ER

D: Mitochondria

E: Rough ER

AB: Centrosome

CD: Golgi Apparatus