Cell Biology Quiz

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Questions and Answers

What is the primary function of the nucleolus within a cell?

Protein synthesis

Ribosome production (correct)

Energy production

Waste breakdown

Which structure is responsible for the production of ATP?

Lysosome

Mitochondrion (correct)

Granular Endoplasmic Reticulum

Smooth Endoplasmic Reticulum

What distinguishes the granular endoplasmic reticulum from the smooth endoplasmic reticulum?

Presence of ribosomes (correct)

Location in the nucleus

Involvement in lipid synthesis

Function in waste breakdown

The primary function of lysosomes is to:

Break down waste materials Signup and view all the answers

What is the primary composition of the cell membrane?

Proteins and lipids Signup and view all the answers

What is the primary function of the cell membrane?

Act as a barrier to water and water-soluble substances Signup and view all the answers

Which component of the cell membrane provides specificity?

Proteins Signup and view all the answers

What role does cholesterol play in the cell membrane?

Decreases fluidity and permeability, while increasing stability Signup and view all the answers

Which organelle is responsible for modifying, packaging, and transporting proteins and lipids?

Golgi apparatus Signup and view all the answers

What primarily makes up the cytoplasm of a cell?

Dissolved proteins, electrolytes, and glucose Signup and view all the answers

Which structure is involved in the formation of microtubules?

Centrioles Signup and view all the answers

Which component of the cell membrane contributes approximately 10% to its structure?

Glycolipids Signup and view all the answers

What defines integral proteins in the cell membrane?

They are fully embedded in the lipid bilayer Signup and view all the answers

What is the primary function of cilia in single-celled organisms like paramecium?

To assist in fluid movement and locomotion Signup and view all the answers

Which statement correctly describes the composition of a cilium?

Composed of 11 microtubules with a specific structure Signup and view all the answers

How does ciliary movement occur?

Through sliding of cilia's edges facilitated by protein arms Signup and view all the answers

What is the primary function of mitochondria?

Extraction of energy from nutrients Signup and view all the answers

Which of the following correctly describes the composition of microtubules?

Heterodimers of alpha and beta tubulin Signup and view all the answers

What characterizes primary cilia in human cells?

They are non-motile and generally occur as a single cilium Signup and view all the answers

What is a common function associated with primary cilia?

Acting as cellular sensory antennae Signup and view all the answers

What structural feature allows the nuclear membrane to be selectively permeable?

Nuclear pores Signup and view all the answers

Which statement accurately describes the function of the nucleolus?

It forms the granular subunits of ribosomes. Signup and view all the answers

What initiates the process of receptor-mediated endocytosis?

Molecules attaching to surface receptors Signup and view all the answers

Which of the following processes involves the engulfing of large particles by a phagocyte?

Phagocytosis Signup and view all the answers

What is a key role of lysosomes in cellular digestion?

They fuse with vesicles to digest substances. Signup and view all the answers

What triggers the formation of a vesicle during pinocytosis?

Collection of extracellular fluid in a pit Signup and view all the answers

What is the primary function of the Rough Endoplasmic Reticulum?

Protein synthesis and processing Signup and view all the answers

What distinguishes Smooth Endoplasmic Reticulum from Rough Endoplasmic Reticulum?

Site of lipid synthesis Signup and view all the answers

What is the role of the Golgi Apparatus in the cell?

Sorting and packaging substances for secretion Signup and view all the answers

Which of the following is NOT a characteristic of lysosomes?

Formed by self-replication Signup and view all the answers

What is the function of hydrolytic enzymes found in lysosomes?

Break down nucleic acids Signup and view all the answers

What distinguishes peroxisomes from lysosomes?

They contain oxidases and are formed by self-replication Signup and view all the answers

What type of secretion involves a specific trigger?

Stimulated secretion Signup and view all the answers

Lysosomal storage diseases are the result of which of the following?

Absence of one or more hydrolases Signup and view all the answers

What happens to the engulfed particles once the phagosome fuses with a lysosome?

Digestive enzymes break them down into smaller molecules. Signup and view all the answers

What is the role of clathrin in receptor-mediated endocytosis?

It helps to coat and stabilize clathrin-coated pits. Signup and view all the answers

Which of the following is NOT a function of lysosomes?

Production of ATP. Signup and view all the answers

Which chemical compound has the largest change in free energy (ΔG) under standard conditions?

ADP Signup and view all the answers

What initiates the process of ATP production in cells?

Conversion of carbohydrates into glucose. Signup and view all the answers

What is the maximum amount of ATP that can be generated from one molecule of glucose?

38 molecules Signup and view all the answers

In amoeboid locomotion, what process occurs at the leading edge of the pseudopodium?

Exocytosis Signup and view all the answers

Which agent contained in lysosomes is responsible for dissolving the bacterial cell wall?

Lysozyme Signup and view all the answers

Study Notes

Cell Organization

Protoplasm: collective name for all substances within a cell
Cell membrane encloses the cell
Cytoplasm surrounds the nucleus
Nucleoplasm is inside the nucleus
Nucleus contains the nucleolus
Nuclear membrane surrounds the nucleolus

Cell Composition

Protoplasm (of cells)
Water/Ions: 70-85% of cell mass

Cell Membrane: Bilayer of Phospholipids with Proteins

Bilayer of phospholipids with proteins
Extracellular fluid surrounds the cell
Cytoplasm (the interior of the cell)
Integral proteins traverse the bilayer
Peripheral proteins are associated with the surface

Membrane Components: Lipids

Barrier to water and water-soluble substances
Organized in a phospholipid bilayer
Molecules like CO₂, O₂, glucose, urea, and halothane pass through.
Hydrophilic heads face outward, hydrophobic tails inward

Membrane Components: Proteins

Provide specificity to the membrane
Defined by association with the lipid bilayer
Integral proteins: channels, pores, carriers, enzymes
Peripheral proteins: inside the cell, help with signal mediation and enzymes

Membrane Components: Carbohydrates

Glycolipids (approx. 10%)
Glycoproteins (majority of integral proteins)
Proteoglycans
Glycocalyx: Negative charge repels other negative charges, involved in cell-cell interactions
Acts as receptors for hormones like insulin, plays a role in immune responses

Cholesterol

Present in membranes in varying amounts
Generally decreases membrane fluidity and permeability (except in plasma membrane)
Increases membrane flexibility and stability

Cell Organelles

Centrioles,
Secretory granules,
Microtubules,
Nuclear membrane,
Chromosomes and DNA
Golgi apparatus,
Cell membrane,
Nucleolus,
Glycogen,
Ribosomes,
Lysosomes
Mitochondrion,
Granular endoplasmic reticulum
Smooth endoplasmic reticulum
Microfilaments

Membranous Structures of the Cell

Cell membrane
Nuclear membrane
Endoplasmic reticulum membrane
Mitochondria membrane
Lysosomes
Golgi apparatus

Cell Membrane

Thin, pliable, elastic structure
About 7.5-10 nanometers thick
Composed mostly of proteins and lipids
Approximate composition: 55% protein, 25% phospholipids, 13% cholesterol, 4% other lipids, and carbohydrates

Cytoplasm and its Organelles

Cytosol: jelly-like fluid portion in the cytoplasm
Contains dissolved proteins, electrolytes
Various dispersed structures: neutral fat globules, glycogen granules, ribosomes, secretory vesicles
Important organelles: endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, peroxisomes

The Endoplasmic Reticulum

Network of tubular and flat vesicular structures
Membrane similar to the plasma membrane
Space inside tubules is the endoplasmic matrix

Rough or Granular ER

Outer membrane surface covered with ribosomes
Newly synthesized proteins extruded into the ER matrix
Proteins are processed, crosslinked, folded, glycosylated (N-linked), cleaved inside the matrix

Smooth ER

Site of lipid synthesis: phospholipids, cholesterol
Growing ER membrane buds continually forming transport vesicles which migrate to the Golgi apparatus

The Golgi Apparatus

Membrane composition similar to smooth ER and plasma membrane
Composed of 4-or more stacked layers of flat vesicular structures
Receives transport vesicles from smooth ER
Substances formed in the ER are processed, phosphorylated, or glycosylated
Substances concentrated, sorted, and packaged for secretion

Exocytosis

Secretory vesicles diffuse through cytosol and fuse with the plasma membrane
Lysosomes fuse with internal endocytotic vesicles

Secretion

Secretory vesicles release synthesized proteins from Golgi apparatus to fuse with the plasma membrane
Constitutive secretion occurs randomly
Stimulated secretion requires a trigger

Lysosomal Storage Diseases

Absence of one or more hydrolases: not synthesized, inactive, not properly sorted and packaged
Result: Lysosomes engorged with undigested substrate
Examples: Acid lipase A deficiency, I-cell disease, Tay-Sachs disease

Lysosomes

Vesicular organelles formed from Golgi buds
Contain hydrolytic enzymes (acid hydrolases): phosphatases, nucleases, proteases, lipid-degrading enzymes, lysozymes (bacteria digesting enzymes)
Responsible for digestion.

Peroxisomes

Similar physically to lysosomes
Two major differences: formed by self-replication, contain oxidases
Function: Oxidize substances (e.g., alcohol)

Secretory Granules

These are secretory vesicles.
Function in cells which release substances.

Mitochondria

Primary function: extraction of energy from nutrients
Has an outer membrane which encloses an inner membrane (crests) and an outer chamber.
The matrix contains oxidative phosphorylation enzymes which produce energy.

The Cytoskeleton

Intermediate filaments: comprised of cell-specific fibrillar proteins
Microtubules: heterodimers (of alpha and beta tubulin), part of the spindle fibers/axoneme structure
Thin filaments: F-actin, part of "stress fibers"
Thick filaments: myosin

The Nuclear Membrane

Permeated by thousands of nuclear pores
100nm in diameter, with functional diameter of 9nm
Selectively permeable to molecules up to 44,000 MW

Nucleolus

One or more per nucleus
Contains RNA and proteins
Not membrane delimited
Functions to form granular subunits of ribosomes

Comparison of Animal Cells with Precellular Forms of Life

Comparison of sizes

Receptor-mediated Endocytosis

Molecules attach to cell surface receptors; receptors concentrated in clathrin-coated pits
Receptor binding causes invagination
ATP-dependent recruitment of actin and myosin

Digestion of Substances in Pinocytotic or Phagocytic Vesicles

Process by which lysosomes digest substances in vesicles
The substances are broken down by enzymes after fusing with a lysosome.

Pinocytosis

Vesicle that engulfs extracellular fluid

Endocytosis

Active movement of substances into a cell inside membrane-bound vesicles

Phagocytosis

Specific form of endocytosis in specialized cells (phagocytes)
Occurs in response to microbes, dead cells, and cellular debris
Receptors on phagocyte surface bind to particles
Plasma membrane extensions (pseudopods) surround the particles
Vesicle forms (phagosome)
The phagosome fuses with a lysosome to digest enzymes

ATP Production

Carbohydrates, Glucose, proteins and fats are converted to produce ATP (energy).
Acetyl CoA is used in step 3 to generate ATP.

The Use of ATP for Cellular Function

ATP is crucial for cell processes
It fuels membrane transport, chemical compound synthesis, and mechanical work

Ameboid Locomotion

Continual endocytosis at the "tail" and exocytosis at the leading edge of the pseudopodium
Movement facilitated by receptor proteins and actin/myosin interactions (ATP-dependent)

Chemotaxis

Cell movement influenced by chemical substances
Movement toward high concentrations
Movement away from low concentrations

Cilia and Ciliary Movements

Occurs in airway and fallopian tubes
Each cilium is made of microtubules: 9 double tubules, 2 single tubules; an outgrowth of basal bodies and covered by membrane; movement is ATP dependent

Mechanism of Ciliary Movement

Four stages involved in producing ciliary movement.
Fifth, there are multiple protein arms which are activated by adenosine triphosphate (ATP).
The double tubule moves in a specific direction to generate movement.

Non-motile Primary Cilia

Found on nearly every cell type (except red blood cells)
Non-motile cilia act as antenna
Involved in chemical and mechanical sensations to coordinate cellular signaling, cell growth, and signal transduction

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Description

Test your knowledge on key cell structures and their functions with this engaging quiz. From the role of the nucleolus to the differences between types of endoplasmic reticulum, challenge yourself with questions that dig deep into cell biology.