Cell Biology Chapter: Organelles and Nucleus

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Questions and Answers

What is the primary function of the Golgi apparatus?

To produce energy for the cell

To break down waste materials in the cell

To sort, modify, and ship products from the rough ER (correct)

To synthesize proteins for cellular functions

What characteristic structure does the Golgi apparatus resemble?

Spherical vesicles

Pancakes stacked in a stack (correct)

A network of filaments

Long tubular structures

What happens to products received by the Golgi apparatus?

They are sorted and packaged into new vesicles. (correct)

They are exported directly without modification.

They are synthesized into new proteins.

They are destroyed for recycling.

Which organelle is responsible for breaking down unneeded cellular components?

Lysosome Signup and view all the answers

What is the process by which a cell digests its own structures called?

Autophagy Signup and view all the answers

Which of the following is a primary function of peroxisomes?

Lipid metabolism Signup and view all the answers

Where does the vesicle go after packaging if the product is to be exported from the cell?

To the cell surface to fuse with the cell membrane. Signup and view all the answers

What type of membrane-bound organelle contains enzymes for various functions, including lipid metabolism?

Peroxisomes Signup and view all the answers

What is the primary function of the G1 phase in the cell cycle?

Cell growth Signup and view all the answers

During which phase does a cell replicate its DNA?

S phase Signup and view all the answers

What is the significance of checkpoints in the cell cycle?

They allow the cycle to continue or stop Signup and view all the answers

Which phase is characterized by cells that have temporarily stopped dividing?

G0 phase Signup and view all the answers

What role do cyclins play in the cell cycle?

They are control molecules that regulate cell cycle progression Signup and view all the answers

How long does the S phase typically last during the cell cycle?

Approximately 8-10 hours Signup and view all the answers

Which phase follows the S phase in the cell cycle sequence?

G2 phase Signup and view all the answers

What is primarily evaluated at a cell cycle checkpoint?

Cell size and DNA damage Signup and view all the answers

What is the primary function of cilia in the female fallopian tubes?

To assist in the movement of egg cells towards the uterus Signup and view all the answers

Which of the following statements is true about the nucleus?

It serves as the control center of the cell. Signup and view all the answers

What role do intermediate filaments play in a cell?

They help maintain cell shape and resist tension. Signup and view all the answers

What is unique about the only flagellated cell in humans?

It propels itself towards female egg cells. Signup and view all the answers

Which protein is primarily associated with microfilaments in muscle tissue?

Actin Signup and view all the answers

What happens to red blood cells (RBCs) as they mature?

They eject their nuclei. Signup and view all the answers

What is the function of the nuclear envelope?

To protect the nucleus and separate it from the cytoplasm Signup and view all the answers

During cell division, what role does actin play?

It aids in the physical splitting of the cell. Signup and view all the answers

Which type of cytoskeletal filament is intermediate in thickness between microtubules and microfilaments?

Intermediate filaments Signup and view all the answers

What is the significance of the nuclear pore?

It allows for communication between the nucleus and the cytoplasm. Signup and view all the answers

What is the primary source of Platelet-Derived Growth Factor (PDGF)?

Macrophages Signup and view all the answers

Which mediator has the strongest effect on vascular permeability during acute inflammation?

Bradykinin Signup and view all the answers

Which phase is NOT part of the inflammatory response?

Exacerbation phase Signup and view all the answers

What is the primary effect of interleukins in chronic inflammation?

Lymphocyte activation Signup and view all the answers

Which layer of skin serves as the waterproof barrier?

Epidermis Signup and view all the answers

Which of the following is NOT a characteristic of chronic inflammation?

Immediate vascular response Signup and view all the answers

What is the primary role of melanocytes in the skin?

Produce melanin Signup and view all the answers

Which mediators are primarily produced by macrophages and T lymphocytes during chronic inflammation?

Interleukins Signup and view all the answers

What is the primary function of connective tissues?

Connecting cells and organs Signup and view all the answers

Which of the following statements correctly describes epithelial tissues?

Epithelial tissues are avascular. Signup and view all the answers

What type of epithelial tissue consists of a single layer of irregularly shaped cells?

Pseudostratified epithelium Signup and view all the answers

Which muscle type is categorized as voluntary?

Skeletal muscle Signup and view all the answers

What is a key feature of nervous tissue?

Propagates electrochemical signals Signup and view all the answers

Endocrine glands are characterized by which of the following?

Releasing products directly into the bloodstream Signup and view all the answers

Which type of epithelial tissue acts as a barrier and controls permeability?

Epithelial tissue Signup and view all the answers

Which of the following best describes cuboidal epithelial cells?

Boxy, as wide as they are tall Signup and view all the answers

What type of secretion do eccrine sweat glands provide?

Dilute salt solution Signup and view all the answers

Which gland is responsible for secreting oily sebum into hair follicles?

Sebaceous gland Signup and view all the answers

Study Notes

Endomembrane System Organelles

Golgi Apparatus:
- Modifies, packages, and ships off products from the rough ER
- Produces lysosomes
- Resembles stacked flattened discs
- Has two distinct sides:
  - One side receives products in vesicles
  - The other side releases repackaged products in new vesicles
- Vesicles carrying exported products fuse with cell membrane for secretion

Lysosomes

Contain enzymes for breaking down and digesting cellular components
Autophagy: process of a cell digesting its own structures

Peroxisomes

Membrane-bound organelles containing enzymes
Functions:
- Lipid metabolism

The Nucleus and DNA Replication

The Nucleus
- Largest and most prominent organelle in a cell
- Considered the control center of the cell because it stores genetic instructions for protein manufacture
- Multinucleated cells have more than one nucleus (e.g., muscle cells)
- Mammalian red blood cells lack nuclei
- Red blood cells eject nuclei during maturation, making space for hemoglobin
- Without nuclei, red blood cells have a short lifespan
- Sends "commands" to the cell via molecular messengers

Organization of Nucleus and Its DNA

Nuclear Envelope
- Membrane surrounding the nucleus
- Consists of two adjacent lipid bilayers with a thin fluid space
Nuclear Pores
- Tiny passageways for proteins, RNA, and solutes

Cell Cycle

The sequence of events in a cell's life from its creation to its division
Consists of two main phases:

Interphase

Period during which the cell is not dividing
Most cells spend most of their time in interphase
Divided into:
- G1 phase: first growth phase
- S phase: DNA replication occurs
- G2 phase: second gap phase, preparation for mitosis
- G0 phase: resting phase, cells temporarily stopped dividing

Mitosis

The process of cell division that results in two identical daughter cells

Connective Tissues

Bind and support the cells and organs of the body
Includes:
- Connective tissue proper
- Cartilage
- Bone
- Blood

Muscle Tissues

Specialized for contraction
Types:
- Skeletal (voluntary)
- Cardiac
- Smooth

Nervous Tissues

Composed of:
- Nerve cells (neurons)
- Glia cells (neuroglial)
Allow propagation of electrochemical signals (nerve impulses)

Epithelial Tissues

Line the body’s surfaces and cavities
Form a barrier between the internal and external environments
Avascular: don't contain blood vessels
Functions:
- Protection from physical, chemical, and biological wear and tear
- Gatekeeping: control permeability and selective transfer of materials
- Secretion of mucous and chemical compounds

Classification of Epithelial Tissues

Shape:
- Squamous: flattened and thin
- Cuboidal: boxy, as wide as it is tall
- Columnar: rectangular, taller than it is wide
Number of Layers:
- Simple: one layer
- Stratified: more than one layer
- Pseudostratified: appears to be multiple layers, but is actually one layer with irregularly shaped cells

Endocrine and Exocrine Glands

Consist of groups of epithelial cells
Exocrine glands:
- Secrete their products outside the epithelial membranes through ducts (e.g., lacrimal glands, sebaceous glands, eccrine sweat glands, apocrine sweat glands)

The Inflammatory Response

A protective response to injury or infection
Three phases:
- Acute inflammation: initial response, characterized by redness, swelling, heat, and pain
- Immune response: delayed phase, involves antibody production and activation of immune cells
- Chronic inflammation: prolonged inflammation, can lead to tissue damage and scarring

Platelet Derived Growth Factor (PDGF)

Source: macrophages, endothelial cells, fibroblasts, platelets
Primary effects: fibroblast chemotaxis and proliferation

Rheumatoid Arthritis

Chronic inflammation
Causes pain and destruction of bone and cartilage
Can lead to severe disability and shortening of life
Autoimmune disease: T-cell activation triggers production of IL-1 and TNF-alpha

Mediators of Acute Inflammation

Vasodilation
Increased permeability
Chemotaxis
Pain
Histamine:
- Causes significant vasodilation and increased permeability
Serotonin:
- Mild vasodilation and increased permeability
Bradykinin:
- Strong vasodilation and increased permeability
- Causes pain
Prostaglandins:
- Vasodilation and increased permeability
- Pain and chemotaxis
Leukotriene:
- Increased permeability and chemotaxis

Mediators of Chronic Inflammation

Interleukins 1, 2, 3
- Source: macrophages, T lymphocytes
- Primary effects: lymphocyte activation and prostaglandin production

The Skin

Largest organ of the body
Total area: 20 square feet
Three layers:

Epidermis

Outermost layer
Provides a waterproof barrier
Determines skin tone
Contains 8-10 layers of keratinocytes

Dermis

Beneath the epidermis
Composed of tough connective tissue

Hypodermis

Subcutaneous layer
Contains fat and connective tissue
Melanocytes: produce melanin (pigment)

Stratum Spinosum

Layer of the epidermis
Keratinocytes begin synthesizing keratin

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Test your knowledge on the endomembrane system and organelles such as the Golgi apparatus, lysosomes, and peroxisomes. Explore the functions of the nucleus and the process of DNA replication. This quiz will deepen your understanding of cellular structures and their roles.