Cell Theory and Types

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Questions and Answers

Which of the following statements accurately reflects a tenet of cell theory?

Cells are the basic units of structure and function in all living things. (correct)

All cells arise from spontaneous generation.

Cells cannot arise from pre-existing cells.

All living organisms are composed entirely of multiple types of cells.

What distinguishes prokaryotic cells from eukaryotic cells in terms of structure?

Eukaryotic cells are smaller and simpler than prokaryotic cells.

Eukaryotic cells lack a cell wall.

Prokaryotic cells do not have a true nucleus. (correct)

Prokaryotic cells contain membrane-bound organelles.

Which organelle is primarily responsible for the synthesis of proteins?

Golgi apparatus

Ribosomes (correct)

Vesicles

Endoplasmic reticulum

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

To control the flow of substances in and out of the cell. Signup and view all the answers

During protein synthesis, what is the first step that takes place in the nucleus?

Transcription Signup and view all the answers

What is the primary function of cilia and flagella in cells?

Move the cell through fluid or move fluid past the cell Signup and view all the answers

What distinguishes gap junctions from tight junctions in animal cells?

Gap junctions allow communication while tight junctions prevent fluid passage Signup and view all the answers

Which of the following is a structural feature of the nuclear envelope?

Double-layered membrane encapsulating the nucleus Signup and view all the answers

What roles do chromosomes/chromatin serve in cells?

Contain genetic information for protein synthesis Signup and view all the answers

What component of the cytoplasm helps in transporting substances within the cell?

Cytosol Signup and view all the answers

How do plasmodesmata in plant cells function compared to gap junctions in animal cells?

Both allow for communication and substance exchange Signup and view all the answers

What process is performed by the nucleolus within the nucleus?

rRNA assembly into ribosomal subunits Signup and view all the answers

What characterizes desmosomes in animal cells?

Form mechanically strong connections between adjacent cells Signup and view all the answers

What does the Cell Theory state about the continuity of life?

All cells originate from pre-existing cells. Signup and view all the answers

Which of the following is a key characteristic that distinguishes eukaryotic cells from prokaryotic cells?

Presence of membrane-bound organelles. Signup and view all the answers

What is the primary function of mitochondria in eukaryotic cells?

Energy production through ATP. Signup and view all the answers

Which component of the plasma membrane is primarily responsible for its fluidity?

Cholesterol. Signup and view all the answers

What role do ribosomes play in a eukaryotic cell?

Synthesize proteins. Signup and view all the answers

How do prokaryotic cells differ from eukaryotic cells regarding genetic material?

Eukaryotes have DNA within a nucleus. Signup and view all the answers

In which of the following cellular structures would you NOT find a lysosome?

Bacterial cell. Signup and view all the answers

Which of the following is NOT a function of the plasma membrane?

Providing structural support for the cell. Signup and view all the answers

What distinguishes chloroplasts from other organelles within plant cells?

They contain their own DNA. Signup and view all the answers

Study Notes

Cell Theory

Cells are the fundamental units of life, responsible for structure and function.
The activity of an organism depends on the individual and collective activities of its cells.
The activity of the cell is governed by its subcellular structures.
All cells originate from pre-existing cells.

Cell Types

Prokaryotic Cells:
- Lack a nucleus.
- DNA is located in a region called the nucleoid.
- No membrane-bound organelles.
- Examples: bacteria and archaea.
Eukaryotic Cells:
- DNA is enclosed within a membrane-bound nucleus.
- Contain membrane-bound organelles.
- Generally larger than prokaryotic cells.
- Examples: animal, plant, and fungal cells.

Plasma Membrane

A phospholipid bilayer with embedded proteins, cholesterol, and glycolipids.
Separates the intracellular (inside the cell) environment from the extracellular (outside the cell) environment.
Regulates the passage of substances into and out of the cell.
Plays a role in cell communication.

Cell Wall

Found in plants and fungi.
Provides structural support, protection, and shape to the cell.
Composed of carbohydrate fibers embedded in a carbohydrate or protein matrix.

Cilia and Flagella

Extensions of the plasma membrane, containing a complex of proteins that support and move the structure.
Differences in structure lead to different movement patterns.
Flagella: Usually one or two per cell, responsible for locomotion (moving the cell through fluid).
Cilia: Usually numerous per cell, responsible for movement of fluid past the cell.

Cell Junctions

Tight junctions (animal cells):
- Form an impermeable barrier, preventing extracellular fluids from passing between cells.
Desmosomes (animal cells):
- Act like rivets, forming strong connections between adjacent cells.
Gap junctions (animal cells):
- Channels connecting the cytoplasm of adjacent cells, allowing for communication and exchange of small molecules.
Plasmodesmata (plant cells):
- Similar to gap junctions, connecting the cytoplasm of adjacent cells.

Nuclear Structures

Nuclear envelope:
- Double-layered membrane surrounding the nucleus.
Chromosomes/Chromatin:
- Contain genetic information (DNA) that directs protein synthesis.
Nucleolus:
- Contains structures for assembling rRNA and proteins into ribosomal subunits.

Cytoplasm

Cytosol:
- A watery solution of proteins, salts, sugars, and other solutes.
Cytoplasm:
- The fluid (cytosol) and all the structures within the cell, excluding the nucleus.

Transcription

The process of copying genetic information (DNA) into RNA.
This process takes place in the nucleus.

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Description

Explore the fundamental concepts of cell theory and the different types of cells, including prokaryotic and eukaryotic cells. Understand how cells function as the basic units of life and the roles of their structures. This quiz covers essential knowledge for biology students.