Zoology Lecture 2: Cell Structure

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Questions and Answers

What is the main characteristic that distinguishes eukaryotic cells from prokaryotic cells?

The presence of multiple membranes

The ability to perform photosynthesis

The presence of a cell wall

The presence of a clearly defined nucleus (correct)

Which organelle is responsible for generating energy in eukaryotic cells?

Mitochondria (correct)

Lysosomes

Golgi apparatus

Endoplasmic reticulum

What is the main function of the cell membrane in animal cells?

To synthesize proteins

To store genetic material

To provide structural support

To regulate the movement of molecules into and out of the cell (correct)

Which of the following is a characteristic unique to plant cells?

The presence of a cell wall Signup and view all the answers

What is the function of the phospholipid bilayer in the cell membrane?

To form a stable barrier between two aqueous compartments Signup and view all the answers

Which of the following is NOT a characteristic of prokaryotic cells?

Have multiple chromosomes Signup and view all the answers

What is the function of lysosomes in eukaryotic cells?

To digest and recycle cellular waste Signup and view all the answers

Which of the following is a characteristic of eukaryotic cells?

Have organelles such as mitochondria and Golgi apparatus Signup and view all the answers

What is the primary function of the nucleolus?

Production and assembly of ribosomes Signup and view all the answers

What is the main role of centrosomes in the cell?

Production of microtubules Signup and view all the answers

What is the function of lysosomes in the cell?

Digestion and excretion Signup and view all the answers

What is the composition of cytoplasm?

Water, salts, and various organic molecules Signup and view all the answers

What is the function of the Golgi apparatus in the cell?

Manufacturing, storing, and transporting particles Signup and view all the answers

What is the main function of mitochondria in the cell?

Releasing energy Signup and view all the answers

What is stored in the molecule produced by mitochondria?

Chemical energy Signup and view all the answers

Why do different cells have different amounts of mitochondria?

Because they need different amounts of energy Signup and view all the answers

What is the main function of proteins embedded in the phospholipid bilayer of the plasma membrane?

To regulate the transport of molecules into and out of the cell Signup and view all the answers

What is the term used to describe the cell membrane due to its ability to regulate the transport of materials?

Semi-permeable Signup and view all the answers

What type of proteins are found on the surface of the plasma membrane, allowing for cell-cell interaction?

Glycoproteins and lipoproteins Signup and view all the answers

What is the function of the nuclear membrane?

To regulate the transport of molecules into and out of the nucleus Signup and view all the answers

What is the term used to describe the structure of the nuclear membrane?

Double-membrane structure Signup and view all the answers

What is the function of the nucleus in a cell?

To store genetic information Signup and view all the answers

What is the term used to describe the array of holes in the nuclear membrane?

Pores Signup and view all the answers

What is the function of the nucleolus, a sub-organelle found in the nucleus?

To transcribe RNA Signup and view all the answers

Which organelle is responsible for translating messenger RNA into a string of amino acids?

Ribosome Signup and view all the answers

Which type of Endoplasmic Reticulum is involved in protein synthesis?

Rough Endoplasmic Reticulum Signup and view all the answers

What is the primary function of the organelle with a high concentration of mitochondria in animal cells?

Energy production Signup and view all the answers

Which of the following organelles is composed of a thin, winding network of membranous sacs?

Endoplasmic Reticulum Signup and view all the answers

What is the primary function of the ribosome-studded surface of the Endoplasmic Reticulum?

Protein synthesis Signup and view all the answers

Which organelle is responsible for producing the energy required by the brain?

Mitochondria Signup and view all the answers

Study Notes

Cell Classification

Cells are classified into two main categories: prokaryotic and eukaryotic
Prokaryotes are single-celled microorganisms, include Bacteria and Archaea, and have a single membrane
Eukaryotes have a clearly defined nucleus, nuclear membrane, and organelles such as mitochondria, Golgi apparatus, and lysosomes

Animal Cell Characteristics

Animal cells are generally smaller than plant cells
They have an irregular shape due to the absence of a cell wall
They have only a cell membrane, whereas plant cells have a cell wall and a cell membrane
Animal cells do not have chloroplasts, which are found in plant cells

Cell Organelles

Cell Membrane

A thin, semipermeable membrane layer of lipids and proteins surrounding the cell
Composed of a phospholipid bilayer that forms a stable barrier between two aqueous compartments
Regulates the transport of materials entering and exiting the cell
Provides protection and a fixed environment inside the cell
Has proteins embedded within the phospholipid bilayer that carry out specific functions, including selective transport of molecules

Nucleus

Contains DNA and other genetic materials
Has a double-membrane structure called the nuclear envelope
Has pores that allow for the selective passage of certain molecules into and out of the nucleus
Contains a nucleolus that produces and assembles ribosomes

Centrosome

A small organelle found near the nucleus with a thick center and radiating tubules
Plays an important role in cell division
Produces microtubules

Lysosome

A membrane-bound organelle containing digestive enzymes that help in digestion, excretion, and cell renewal

Cytoplasm

The gelatinous liquid that fills the inside of a cell
Composed of water, salts, and various organic molecules
Contains some intracellular organelles, such as the nucleus and mitochondria, which are enclosed by membranes that separate them from the cytoplasm

Golgi Apparatus

A flat, smooth, layered sac-like organelle near the nucleus
Involved in manufacturing, storing, packing, and transporting particles throughout the cell
Processes and sorts proteins received from the ER for transport to their eventual destinations

Mitochondrion

A spherical or rod-shaped organelle with a double membrane
The powerhouse of a cell, releasing energy through chemical reactions
Generates most of the chemical energy needed to power the cell's biochemical reactions
Produces ATP (adenosine triphosphate) as a source of energy

Ribosome

An intercellular structure made of RNA and protein
The site of protein synthesis in the cell
Translates messenger RNA (mRNA) sequence into a specified string of amino acids that form proteins

Endoplasmic Reticulum (ER)

A cellular organelle composed of a thin, winding network of membranous sacs originating from the nucleus
Has two forms: rough ER with ribosomes and smooth ER without ribosomes

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Description

Learn about the fundamental unit of life, cell structure, and classification into eukaryotic and prokaryotic cells in this zoology lecture for pre-medicine students.