Biology Cell Theory and Characteristics

Questions and Answers

What is the smallest structural and functional unit of organisms?

Cell (correct)

Organism

Tissue

Organ

Which characteristic is NOT associated with cells?

Senses environmental changes

Capable of self-regulation

Always multicellular (correct)

Can duplicate

What type of cells lack a true nucleus?

Eukaryotic cells

Animal cells

Plant cells

Prokaryotic cells (correct)

Which of the following is true about prokaryotic cells?

They have a circular piece of DNA Signup and view all the answers

The region of the cell that contains the DNA is called the:

Nucleus Signup and view all the answers

Which statement about the cytoplasm is correct?

It contains cytosol and organelles. Signup and view all the answers

Which of the following describes a similarity between eukaryotic and prokaryotic cells?

Both contain DNA. Signup and view all the answers

Which of the following structures is found in eukaryotic cells but not in prokaryotic cells?

Nucleus Signup and view all the answers

What term refers to the area inside of a cell?

Intracellular Signup and view all the answers

What directs proteins to the endoplasmic reticulum (ER)?

An N-terminal signal sequence Signup and view all the answers

What is the primary function of the Golgi apparatus?

Finishing, sorting, and shipping cell products Signup and view all the answers

Which structural feature is unique to the Golgi apparatus?

Flatted membrane vesicles called Golgi saccules Signup and view all the answers

What happens to products as they move through the Golgi apparatus?

They are modified before shipment Signup and view all the answers

What could be a consequence of defects in Golgi function?

Congenital glycosylation disorders Signup and view all the answers

What is the role of transport vesicles in relation to the Golgi apparatus?

To carry products from the ER to the Golgi apparatus Signup and view all the answers

Which of the following describes the structure surrounding the nucleus?

Nuclear membrane with nuclear pores Signup and view all the answers

What is the primary function of the nucleolus?

Ribosome synthesis Signup and view all the answers

What type of chromatin is less compact and frequently expresses genes?

Euchromatin Signup and view all the answers

Which organelle is NOT classified as a membranous organelle?

Ribosomes Signup and view all the answers

Which component of the nucleus is involved in maintaining the shape and structure of DNA?

Histones Signup and view all the answers

During which process do chromatin fibers condense into chromosomes?

Cell division Signup and view all the answers

What is the liquid substance contained within the nucleus called?

Nucleoplasm Signup and view all the answers

Which of the following organelles are involved in the synthesis, storage, and export of molecules?

Nucleus and endoplasmic reticulum Signup and view all the answers

What structure forms the core of DNA wrapped around histone proteins?

Nucleosome Signup and view all the answers

Which of the following organelles is responsible for processing and packaging proteins?

Golgi apparatus Signup and view all the answers

What are anti-nuclear antibodies (ANA) associated with?

Autoimmune diseases Signup and view all the answers

Which of the following is NOT a function of the cytoplasm?

House for the nucleus Signup and view all the answers

What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?

Rough ER synthesizes proteins and contains ribosomes. Signup and view all the answers

Which of the following processes is primarily associated with the smooth endoplasmic reticulum?

Lipid biosynthesis Signup and view all the answers

Which function is NOT performed by the rough endoplasmic reticulum?

Sequestration of calcium ions Signup and view all the answers

What component does the endoplasmic reticulum lack that differentiates smooth ER from rough ER?

Ribosomes on its membrane Signup and view all the answers

What is one of the key roles of the smooth endoplasmic reticulum?

Lipid synthesis and detoxification Signup and view all the answers

What type of chemical substances does the cytoplasm primarily contain?

Enzymes and metabolites Signup and view all the answers

Which organelles are synthesized or directed by the rough endoplasmic reticulum?

Lysosomes and peroxisomes Signup and view all the answers

Which of the following substances is sequestered by the smooth endoplasmic reticulum?

Calcium ions Signup and view all the answers

What is the primary function of the nucleus in a eukaryotic cell?

Storage of DNA and direction of cell activities Signup and view all the answers

Which type of cell is described as having no nucleus and is incapable of division?

Anucleated cells Signup and view all the answers

What is the consequence of polynucleated cells being formed during development in humans?

Formation of skeletal muscle cells (myocytes) Signup and view all the answers

Which of the following is a rare tumor characterized by the presence of multinucleated giant cells?

Giant-cell tumor of the bone (GCTOB) Signup and view all the answers

What role do RNA polymerases play in the nucleus?

Synthesize the growing RNA molecule Signup and view all the answers

What happens to the nucleus during cell division?

It disassembles Signup and view all the answers

Defective nucleoli have been linked to several neurodegenerative disorders. Which of the following is NOT commonly associated?

Diabetes mellitus Signup and view all the answers

Which of the following macromolecules is actively transported across the nuclear membrane?

Proteins Signup and view all the answers

What characteristic is true of the giant multinucleated cells that sometimes accompany inflammation?

They are a result of monocyte fusion Signup and view all the answers

What is the function of transcription factors within the nucleus?

To regulate gene expression Signup and view all the answers

Study Notes

Cell Theory

Cells serve as the smallest structural and functional unit of all organisms.
Every organism is made up of one or more cells.
Cells arise only from preexisting cells through division.

Characteristics of a Cell

Cells store genetic information and can make and utilize energy.
They possess movement capabilities and can sense changes in their environment.
Cells can reproduce, repair themselves, grow, and develop.
Homoeostasis is maintained through self-regulation.
Cells synthesize various molecules, including proteins, carbohydrates, fats, and nucleic acids.

Types of Cells

Prokaryotic Cells: Simple, smaller (<10 µm), lack a true nucleus and membrane-bound organelles, contain circular DNA, and consist of unicellular organisms.
Eukaryotic Cells: Larger (10-100 µm), have a true membrane-bound nucleus and organelles, contain linear DNA associated with proteins, and can be unicellular or multicellular (includes animal and plant cells).

Prokaryotes vs. Eukaryotes

Prokaryotes: Asexual reproduction via binary fission, small ribosomes, and single circular DNA.
Eukaryotes: Reproduction through mitosis and meiosis, larger ribosomes, multiple linear DNA strands.

Three Important Cell Regions

Cell Membrane: Outermost boundary controlling movement in and out of the cell.
Nucleus: Control center containing DNA, directing cell function.
Cytoplasm: Jelly-like substance where organelles are suspended and biochemical reactions occur.

Cell Organelles

Membranous Organelles: Include endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes.
Non-Membranous Organelles: Include ribosomes and cytoskeletal structures.

Nucleus Structure

Comprised of the nuclear membrane (double-layer with pores), nucleoplasm (liquid similar to cytosol), nucleolus (synthesizes ribosomes), and chromatin (DNA and proteins).
Chromatin condenses into chromosomes during cell division.

Chromosome Structure

Composed of nucleosomes (DNA wrapped around histone proteins), solenoids (coiled nucleosomes), and chromatin fibers.

Anucleated and Polynucleated Cells

Anucleated cells lack a nucleus (e.g., mature red blood cells).
Polynucleated cells contain multiple nuclei (e.g., skeletal muscle cells and giant multinucleated cells associated with inflammation).

Nucleus Functions

Stores DNA and directs cellular activities, including DNA replication and transcription into RNA.
Contains various proteins that mediate transcription and regulate gene expression.
Macromolecules are actively transported across the nuclear membrane via nuclear pore complexes.

Defective nucleoli linked to neurodegenerative disorders, including Alzheimer's and Huntington's.
Autoimmune diseases associated with anti-nuclear antibodies affecting chromatin organization.

Cytoplasm Functions

Medium for biochemical reactions and cellular processes.
Contains enzymes, substrates, and organelles involved in functions like protein synthesis.

Endoplasmic Reticulum (ER)

A network of membranes consisting of rough and smooth ER.
Rough ER is involved in protein synthesis and sending proteins to Golgi apparatus; smooth ER synthesizes lipids, detoxifies substances, and manages calcium ion storage.

Golgi Apparatus

Acts as a "finishing factory" for ER products, consisting of flattened vesicles and transporting materials.
Modifies, sorts, and ships products in vesicles for secretion or storage.
Errors in Golgi function can lead to various disorders, including congenital glycosylation disorders and certain cancers.

Importance of Golgi Apparatus Function

Essential for proper protein localization and cellular functions.
Mistakes in protein sorting can lead to dysfunctional cellular processes.

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Description

Explore the foundational concepts of cell theory, including the characteristics that define cells and their types. Understand the differences between prokaryotic and eukaryotic cells, and how they contribute to the overall functioning of living organisms.