Cell Theory and Structure Quiz

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Questions and Answers

What is the primary role of chlorophyll in photosynthesis?

It regulates the inner membrane of mitochondria.

It absorbs carbon dioxide and releases oxygen.

It synthesizes ATP from glucose.

It traps light energy for photosynthesis. (correct)

What is the significance of cristae in the mitochondria?

They directly synthesize glucose.

They prevent the leakage of electrons.

They increase surface area for chemical reactions. (correct)

They store ATP for future use.

What initiates apoptosis in cells?

Activation of chlorophyll.

Interference with energy metabolism. (correct)

Decreased oxygen levels.

Excessive production of glucose.

Which organelle is responsible for converting light energy into ATP?

Chloroplasts Signup and view all the answers

Which of the following is NOT a type of plastid?

Cycloplasts Signup and view all the answers

What role do free radicals play in health?

They contribute to aging and disease. Signup and view all the answers

Which enzyme is activated during apoptosis to help break down cellular components?

Caspases Signup and view all the answers

How do chloroplasts contribute to the production of carbohydrates?

By absorbing sunlight and converting it into chemical energy. Signup and view all the answers

Which statement accurately describes the inner mitochondrial membrane?

It strictly regulates the movement of molecules. Signup and view all the answers

What is the function of thylakoids in chloroplasts?

To absorb light energy for photosynthesis. Signup and view all the answers

What function do integrins serve in relation to the extracellular matrix (ECM)?

They bind to glycoproteins of the ECM. Signup and view all the answers

Which statement accurately describes the primary cell wall of a plant cell?

It is the first layer secreted by a growing plant cell. Signup and view all the answers

What is the composition of the middle lamella that cements adjacent plant cells together?

Pectins Signup and view all the answers

How does the secondary cell wall differ from the primary cell wall?

It has a different chemical composition and is thicker. Signup and view all the answers

Which of the following is NOT a characteristic of plant cell walls?

They can undergo continuous expansion. Signup and view all the answers

What is the primary role of microtubules in eukaryotic cells?

Facilitating intracellular movement Signup and view all the answers

Which of the following proteins are involved in the assembly of microtubules?

Alpha and beta-tubulin Signup and view all the answers

What arrangement characterizes the structural makeup of cilia and flagella in eukaryotic cells?

9 + 2 arrangement of microtubules Signup and view all the answers

What role do motor MAPs like kinesin and dynein play in the cell?

Facilitating movement of organelles Signup and view all the answers

What is a main function of intermediate filaments in cells?

Enhancing mechanical strength and stability Signup and view all the answers

During cell division, where do microtubules anchor in animal cells?

At centrosomes Signup and view all the answers

What is the role of the glycocalyx in cellular function?

Allowing cell recognition and adhesion Signup and view all the answers

Which type of filament is primarily involved in muscle contraction?

Myosin filaments Signup and view all the answers

What best describes the role of fibronectins in the extracellular matrix?

Organizing the matrix for cell attachment Signup and view all the answers

What is the diameter of microfilaments and how do they contribute to cell structure?

7 nm; provide flexibility and support Signup and view all the answers

What pattern structure do centrioles exhibit in animal cells?

9 + 0 structure Signup and view all the answers

What is a function of the cytoskeleton?

Anchoring organelles and maintaining cell shape Signup and view all the answers

Which type of cellular structures help unicellular organisms move through water?

Flagella and cilia Signup and view all the answers

How do microfilaments contribute to the movement of amoebas?

By pushing the plasma membrane outward Signup and view all the answers

What is the primary function of the plasma membrane in a cell?

To act as a selective barrier between cell contents and the environment Signup and view all the answers

What distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells contain a nucleus and membrane-bound organelles Signup and view all the answers

Which cellular structure is responsible for protein synthesis?

Ribosomes Signup and view all the answers

What is the main role of lysosomes in a cell?

To help with the digestion of macromolecules Signup and view all the answers

Which feature is found in both mitochondria and chloroplasts?

Both contain their own DNA and ribosomes Signup and view all the answers

Which organelle is primarily involved in the modification and sorting of proteins?

Golgi complex Signup and view all the answers

How do vacuoles primarily function in plant cells?

To store waste products and maintain turgor pressure Signup and view all the answers

What is the significance of DNA being associated with proteins in chromatin?

It helps in packing the DNA into a compact structure Signup and view all the answers

What role do ribosomes play in the cell?

They manufacture proteins Signup and view all the answers

What is the primary function of the endoplasmic reticulum?

To synthesize and process biomolecules Signup and view all the answers

The function of peroxisomes in a cell is primarily to:

Detoxify hydrogen peroxide and metabolize fatty acids Signup and view all the answers

What is the main role of the Golgi complex's trans face?

It serves as the exit surface for processed proteins Signup and view all the answers

Which type of microscope provides the highest resolving power for studying cellular ultrastructure?

Transmission electron microscope Signup and view all the answers

Why is the concept of homeostasis vital for cell function?

It maintains a stable internal environment for optimal enzyme activity Signup and view all the answers

Study Notes

Cell Theory

Cells are the basic units of organization and function in all organisms.
All cells come from other cells.
All living cells have a common origin, owing to basic similarities in their structures and molecules.

Cell Size

Most cell components are measured in nanometers (nm).
Everything entering or leaving a cell passes through the plasma membrane.
The ratio of surface area to volume is critical for cell size.
Some variations in cell shape increase the surface area to volume ratio (e.g., microvilli).

Cell Movement and Structure

Amoebas and white blood cells change shape as they move.
Sperm cells have long, whip-like tails (flagella) for locomotion.
Nerve cells have long, thin extensions to transmit messages over great distances.
Rectangular epithelial cells stack to form sheet-like tissues.

Cell Study Methods

Robert Hooke first described cells in 1665 using a microscope he made.
Antonie van Leeuwenhoek discovered bacteria, protists, blood cells, and sperm cells using small lenses.
Microscopes in the late 19th century allowed biologists to study cells in more detail.

Light Microscopes

Light microscopes use a tube with glass lenses to magnify images.
Magnification is the ratio of the size of the magnified image to the actual size of the object.
Light microscopes have magnification up to a maximum of 2000x, dependent on lens quality and wavelength.
Resolving power refers to the smallest distance between two points that can be distinguished as separate.
Different types of light microscopes, with different optical systems, help study living cells: bright-field, dark-field, phase contrast, differential-interference-contrast, fluorescence, and confocal.

Electron Microscopes

Electron microscopes study the ultrastructure of cells.
Some electron microscopes have resolving powers less than 1 nm.
An electron beam, focused by electromagnets, is used to create images.
Two types: transmission electron microscope and scanning electron microscope.

Cell Fractionation

Cell fractionation separates cell parts to study them in detail.
Cells are broken apart and spun in a centrifuge, separating the extract into a pellet and a supernatant.
The supernatant can be centrifuged multiple times (differential centrifugation) to separate further components.
Pellets of separated parts can be resuspended or further purified by density gradient centrifugation.

Prokaryotic Cells

Bacteria and Archaea are prokaryotic cells.
Prokaryotic cells lack membrane-bound organelles.
Prokaryotic DNA is located in a nucleoid region.
Most have cell walls outside the plasma membrane.
Many have prokaryotic flagella for movement.
The interior contains ribosomes and storage granules.

Eukaryotic Cells

Eukaryotic cells have membrane-bound organelles.
DNA is located in the nucleus.
Cytoplasm is the area outside the nucleus.
The cytoskeleton provides structure and facilitates movement.
Some organelles (e.g., ribosomes) are present in all types of cells, while others are specific to particular cell types.

Organelles (membranous)

Endoplasmic reticulum (ER): A network of membranes; smooth ER synthesizes lipids and breaks down toxins; rough ER synthesizes proteins.
Golgi complex: Processes, sorts, and modifies proteins.
Lysosomes: Small sacs of digestive enzymes that break down wastes, bacteria, and damaged organelles.
Vacuoles: Large, membrane-enclosed sacs that store water, nutrients, or wastes. Plant vacuoles play a significant role in growth and development.
Peroxisomes: Contain enzymes that transfer hydrogen from other compounds to oxygen, break down fatty acids, produce cholesterol and phospholipids, and help detoxify some substances.

Organelles (energy converting)

Mitochondria: Convert chemical energy in some foods to ATP through aerobic respiration. Have a double membrane with folds (cristae) that increase surface area for reactions. Mitochondrial DNA contributes to genetic diseases.
Chloroplasts: Convert light energy to chemical energy through photosynthesis, enclosed in membranes. Important in plants and some algae. Store starch in cells of plants.

Cytoskeleton

The cytoskeleton gives eukaryotic cells their shape and allows for movement.
It's a network of fibers: microtubules (hollow rods), microfilaments (flexible, solid fibers), and intermediate filaments (tough, flexible fibers).
Microtubules are involved in cell division, intracellular transport, and form cilia/flagella.
Microfilaments generate movement and are important in muscle cells.
Intermediate filaments are important for cell shape.

Cell Coverings

Many animal cells secrete an extracellular matrix composed of carbohydrates and fibrous proteins.
Collagen is a main fibrous protein in the ECM, organized by fibronectins.
Integrins in the cell plasma membrane attach to fibronectins.
Many cells have a glycocalyx (surface coating), aiding cellular recognition and interactions.
Bacterial, archaeal, fungal, and plant cells are often enclosed by cell walls; animal cells do not usually have a cell wall. Plant cell walls contain cellulose.

Nucleus

The nucleus is the control center of the cell.
It has a double membrane (nuclear envelope).
Pores regulate material movement.
The nuclear lamina helps organize nuclear contents and regulates the cell cycle.
Chromatin is DNA and associated proteins.
The nucleolus is a region within the nucleus where ribosomal RNA (rRNA) is produced, part of ribosome assembly.
DNA replication occurs during cell division, copying DNA and passing it on to daughter cells.

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Description

Test your knowledge on cell theory, size, movement, and study methods. This quiz covers essential concepts such as the origin of cells, the importance of surface area to volume ratio, and the discovery of cells by early scientists. Perfect for biology students looking to reinforce their understanding of cellular biology.