Biology Chapter: Cell Structure and Function
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Questions and Answers

What is the primary function of the cell membrane?

  • To produce metabolic wastes
  • To provide energy for cellular activities
  • To separate extracellular fluid from intracellular fluid (correct)
  • To facilitate the reproduction of cells

Which of the following statements about the composition of the cell membrane is correct?

  • It consists of 55% proteins, 40% lipids, and 5% carbohydrates. (correct)
  • It is composed of 55% carbohydrates.
  • Proteins make up 40% of the cell membrane.
  • Lipids constitute 5% of the cell membrane.

Which part of the cell contains the genetic material?

  • Extracellular fluid
  • Cytoplasm
  • Cell membrane
  • Nucleus (correct)

Which characteristic is NOT true about cells?

<p>All cells can reproduce. (C)</p> Signup and view all the answers

What is the role of cytoplasm in a cell?

<p>It surrounds the nucleus and provides a medium for metabolic activities. (C)</p> Signup and view all the answers

Which layer of the cell membrane is formed by lipid substances?

<p>Central layer (D)</p> Signup and view all the answers

Which system in the human body is responsible for digestion?

<p>Digestive system (B)</p> Signup and view all the answers

What is NOT a general characteristic of cells?

<p>Cells produce carbon dioxide only. (A)</p> Signup and view all the answers

What is the primary function of the glycocalyx in the cell membrane?

<p>Act as a barrier to negatively charged substances (A)</p> Signup and view all the answers

Which of the following accurately describes the protective function of the cell membrane?

<p>It protects the cytoplasm and organelles from external damage (B)</p> Signup and view all the answers

What is the key characteristic of rough endoplasmic reticulum (RER)?

<p>It has a bumpy or granular appearance due to ribosomes (A)</p> Signup and view all the answers

How does the cell membrane contribute to maintenance of cell shape?

<p>By controlling the structural integrity of the cell (C)</p> Signup and view all the answers

Which of the following substances are NOT expelled through the cell membrane's excretory function?

<p>Nutrients (C)</p> Signup and view all the answers

What is the primary function of the Rough Endoplasmic Reticulum (RER)?

<p>Degradation of worn-out organelles (C)</p> Signup and view all the answers

What role does the endoplasmic reticulum play within the cell?

<p>It connects the cell membrane to the nuclear membrane (D)</p> Signup and view all the answers

Which of the following substances is primarily synthesized by the Smooth Endoplasmic Reticulum (SER)?

<p>Cholesterol (A)</p> Signup and view all the answers

Which type of endoplasmic reticulum is characterized by the presence of ribosomes on its surface?

<p>Rough endoplasmic reticulum (B)</p> Signup and view all the answers

What role does the SER play in muscle tissue?

<p>Storage and release of calcium (A)</p> Signup and view all the answers

Which of the following is a function of carbohydrates in the cell membrane?

<p>They enable tight fixation of neighboring cells (B)</p> Signup and view all the answers

What is the primary function of the Golgi apparatus?

<p>Processing and packing proteins (C)</p> Signup and view all the answers

From which cellular structure are lysosomes formed?

<p>Golgi apparatus (D)</p> Signup and view all the answers

Which of the following best describes the structure of a Golgi apparatus?

<p>5 to 8 flattened membranous sacs (C)</p> Signup and view all the answers

Which face of the Golgi apparatus is associated with receiving vesicles from the endoplasmic reticulum?

<p>Cis face (B)</p> Signup and view all the answers

What type of substances do lysosomes primarily degrade?

<p>Cellular waste (D)</p> Signup and view all the answers

What is the primary characteristic of the lipid bilayer in the cell membrane?

<p>It is a fluid structure. (A)</p> Signup and view all the answers

Which part of the phospholipid molecule is hydrophilic?

<p>Outer part (B)</p> Signup and view all the answers

What role do channel proteins play in the cell membrane?

<p>They assist in diffusion of water-soluble substances. (A)</p> Signup and view all the answers

What is the function of carrier proteins in the cell membrane?

<p>To transport substances across the cell membrane. (A)</p> Signup and view all the answers

Which substances are able to pass through the lipid layer of the cell membrane?

<p>Oxygen and carbon dioxide (B)</p> Signup and view all the answers

What do glycoproteins and glycolipids have in common?

<p>They are formed by attaching carbohydrates to proteins or lipids. (D)</p> Signup and view all the answers

Which of the following is a function of receptor proteins in the cell membrane?

<p>Binding hormones and neurotransmitters. (C)</p> Signup and view all the answers

How do integral proteins contribute to cell adhesion?

<p>They attach cells to their neighbors or basal lamina. (C)</p> Signup and view all the answers

Which type of lysosome is inactive despite containing hydrolytic enzymes?

<p>Primary lysosome (C)</p> Signup and view all the answers

What is the primary function of lysosomes in the cell?

<p>Degradation of macromolecules (D)</p> Signup and view all the answers

How are secondary lysosomes formed?

<p>By the fusion of a primary lysosome with a phagosome or endosome (C)</p> Signup and view all the answers

Which enzyme group in lysosomes hydrolyzes nucleic acids?

<p>Nucleases (A)</p> Signup and view all the answers

What structure within the mitochondrion is responsible for ATP synthesis?

<p>Cristae (D)</p> Signup and view all the answers

What is the primary role of mitochondria in cellular functions?

<p>Production of energy (B)</p> Signup and view all the answers

What percentage of the total cell volume does the nucleus occupy?

<p>10% (C)</p> Signup and view all the answers

What is the defining characteristic of eukaryotic cells?

<p>They contain a nucleus. (B)</p> Signup and view all the answers

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

<p>Regulating cell metabolism and reproduction (C)</p> Signup and view all the answers

What constitutes the major components of the nucleus?

<p>Nucleoplasm, chromatin, and nucleolus (A)</p> Signup and view all the answers

What is the role of the nucleolus within the nucleus?

<p>It synthesizes RNA and forms ribosome subunits. (A)</p> Signup and view all the answers

How many pairs of chromosomes are typically found in dividing non-reproductive human cells?

<p>23 pairs (A)</p> Signup and view all the answers

What is chromatin primarily composed of?

<p>Coiled DNA and histone proteins (A)</p> Signup and view all the answers

What structure regulates communication between the nucleoplasm and the cytoplasm?

<p>Nuclear membrane (D)</p> Signup and view all the answers

Which function of the nucleus involves the transmission of genetic information?

<p>Sending genetic instructions through mRNA (C)</p> Signup and view all the answers

What is the composition of the nucleoplasm?

<p>Nucleotides and enzymes (B)</p> Signup and view all the answers

Flashcards

Cell

The basic structural and functional unit of all living organisms. It's the smallest unit that can perform all life processes independently.

Tissue

A group of similar cells that work together to perform a specific function. Examples include muscle tissue, nervous tissue, and connective tissue.

Organ

A structure made up of different tissues that work together to perform a complex function. Examples include the heart, lungs, and stomach.

System

A group of organs that work together to carry out major bodily functions. Examples include the digestive system, circulatory system, and nervous system.

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Cell Membrane

A thin, flexible barrier that surrounds every cell, controlling what enters and exits. It separates the cell's internal environment from the external environment.

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Extracellular Fluid (ECF)

The fluid that surrounds cells, providing them with nutrients and removing waste.

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Intracellular Fluid (ICF)

The fluid inside a cell, containing vital components for its function.

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Semipermeable Membrane

A membrane that allows certain substances to pass through while blocking others, based on size, charge, or other factors.

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Lipid Bilayer

The central layer of the cell membrane composed of two layers of lipids, primarily phospholipids and cholesterol.

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Phospholipid

A type of lipid with a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. They arrange themselves in a bilayer with their heads facing the watery environment outside and inside the cell.

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Cholesterol

A type of lipid found within the cell membrane, distributed among phospholipid molecules. It helps maintain membrane fluidity and stability.

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What does the lipid layer allow to pass through?

The lipid layer of the cell membrane is semipermeable, allowing only fat-soluble substances like oxygen, carbon dioxide, and alcohol to pass through.

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Integral Protein

Proteins embedded within the cell membrane that provide structural integrity and contribute to various functions.

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Channel Protein

Integral proteins that form channels across the cell membrane, allowing the passage of water-soluble substances like glucose and electrolytes.

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Carrier Protein

Integral proteins that bind to specific molecules and facilitate their transport across the cell membrane, either actively or passively.

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Receptor Protein

Integral proteins that bind to specific molecules like hormones and neurotransmitters, triggering a cellular response.

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RER's Role in Protein Synthesis

The rough endoplasmic reticulum (RER) is responsible for creating proteins within the cell.

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RER's Role in Organelle Degradation

The RER helps break down old cellular components, like mitochondria.

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SER's Role in Non-Protein Synthesis

The smooth endoplasmic reticulum (SER) produces substances like cholesterol and steroids.

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SER's Role in Metabolism

The SER contains enzymes that participate in various metabolic processes within the cell.

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SER's Role in Calcium Storage

The SER acts as a storage and regulation center for calcium, especially important for muscle contraction.

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SER's Role in Detoxification

The SER helps break down harmful substances like drugs and toxins in the liver.

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Golgi Apparatus: What it is

A membrane-bound organelle in cells (except red blood cells) that processes proteins.

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What does the Golgi Apparatus do?

The Golgi apparatus processes, packages, labels, and delivers proteins and other molecules to different parts of the cell.

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Lysosomes

Membrane-bound organelles containing hydrolytic enzymes responsible for breaking down cellular waste and worn-out components.

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Primary lysosome

An inactive lysosome formed by the Golgi apparatus.

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Secondary lysosome

An active lysosome formed by the fusion of a primary lysosome with a phagosome or endosome.

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Mitochondria

Membrane-bound organelles responsible for producing energy (ATP) for cellular functions.

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Cristae

Inward foldings of the inner membrane of mitochondria that increase surface area for ATP production.

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Nucleus

The largest and most prominent organelle in eukaryotic cells, containing genetic material (DNA) and controlling cellular activities.

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Eukaryotes

Cells that have a nucleus and other membrane-bound organelles.

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Prokaryotes

Cells that lack a nucleus and other membrane-bound organelles.

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Glycocalyx

A thin, loose layer of carbohydrate molecules covering the cell membrane.

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Glycocalyx Function: Barrier

The negatively charged glycocalyx prevents negatively charged substances from easily entering the cell.

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Glycocalyx Function: Cell Adhesion

Glycocalyx from neighboring cells helps them stick tightly to each other.

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Cell Membrane Function: Protection

The cell membrane shields the cytoplasm and organelles within the cell.

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Cell Membrane Function: Selectivity

The cell membrane acts as a semipermeable barrier, allowing some substances to pass through while restricting others.

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Cytoplasm

The jelly-like substance inside the cell, containing water, proteins, carbohydrates, lipids, and electrolytes.

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Endoplasmic Reticulum (ER)

A network of interconnected tubules and sacs that transports materials within the cell.

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Rough ER (RER)

ER with ribosomes attached to its surface, giving it a bumpy appearance. It's involved in protein synthesis.

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What does the nucleus control?

The nucleus controls all cell activities, including metabolism, protein synthesis, growth, and reproduction (cell division).

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What is the nuclear membrane?

The nuclear membrane is a double-layered and porous membrane that surrounds the nucleus. It allows communication between the nucleoplasm and cytoplasm.

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What is nucleoplasm?

Nucleoplasm is a viscous fluid that fills the nucleus, similar to cytoplasm. It contains the chromatin and nucleolus.

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What is chromatin?

Chromatin is a thread-like material made up of DNA molecules. It carries the genetic instructions for the cell.

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What is a chromosome?

A chromosome is a rod-shaped structure in the nucleus, formed by tightly coiled DNA around histone molecules. It carries a complete set of genetic information.

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What is the nucleolus?

The nucleolus is a small, round structure in the nucleus where RNA is synthesized and stored. It's important for ribosome subunit formation.

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How do ribosome subunits form?

The nucleolus synthesizes RNA and combines it with proteins to form ribosome subunits. These subunits are then transported to the cytoplasm through the nuclear membrane pores.

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What is the role of mRNA?

Messenger RNA (mRNA) carries genetic instructions from the nucleus to the cytoplasm, where proteins are synthesized.

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Study Notes

Introduction

  • Cells are the fundamental structural and functional units of living organisms.
  • Cells group together to form tissues, which then combine to form organs and systems.
  • The body's systems work together to maintain homeostasis and overall health.
  • Cells need nutrients, oxygen, and energy for survival and growth.
  • Cells produce energy, eliminate waste products, and respond to internal and external stimuli.
  • Reproduction, through cell division, ensures continuation of life.

General Cell Characteristics

  • All cells require nutrients and oxygen.
  • Each cell produces energy for its functions.
  • Cells eliminate metabolic waste products.
  • Cells maintain a stable internal environment to support processes.
  • Cells respond to invaders.
  • Cells multiply through division (except some like neurons).

Cell Structure

  • A cell comprises a cell body and a surrounding cell membrane.
  • The cell body contains a nucleus and cytoplasm.
  • Three main components are studied: cell membrane, cytoplasm, and nucleus.

Cell Membrane

  • A protective layer, also known as the plasma or plasmalemma.
  • Separates intracellular fluid (inside the cell) from extracellular fluid (outside the cell).
  • A semipermeable membrane.
  • Consists of lipids (phospholipids and cholesterol) and proteins.

Cytoplasm

  • Gel-like material filling the cell body.
  • Contains various organelles with specific functions.
  • Cytoplasm includes cytosol, organelles, and various other particles.

Nucleus

  • The control center of the cell.
  • Contains the cell's genetic material (DNA).
  • A membrane-bound organelle.
  • Contains nucleoplasm and nucleoli.
  • Important for cell division and protein synthesis.

Other Organelles (Page 4-5)

  • Endoplasmic Reticulum (ER): A network of tubules; rough ER is studded with ribosomes (involved in protein synthesis), while smooth ER lacks ribosomes (involved in lipid synthesis and detoxification).
  • Golgi Apparatus: Processes and packages proteins and other molecules.
  • Lysosomes: Contain enzymes for breaking down cellular waste and debris.
  • Mitochondria: "Powerhouses" where energy is produced (ATP).
  • Ribosomes: Involved in protein synthesis.
  • Vacuoles/Vesicles: Membrane-bound sacs for storage and transport.

Membrane Carbohydrates

  • Some membrane carbohydrates are attached to proteins (glycoproteins) or lipids (glycolipids).
  • Carbohydrate molecules form a layer called glycocalyx.

Functions of Cell Membrane

  • Protective barrier
  • Selective permeability (controlling what enters and exits)
  • Absorption and excretion
  • Gas exchange
  • Maintaining cell shape and size

Functions of Nucleus

  • Controlling all cell activities.
  • Synthesizing RNA.
  • Forming ribosome subunits.
  • Directing protein synthesis.
  • Controlling cell division.
  • Storing genetic information.

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UNIT 1. Cell - Structure and Function PDF

Description

Test your knowledge on cell membranes, organelles, and their functions with this comprehensive quiz. From the role of the cell membrane to the importance of the rough endoplasmic reticulum, each question delves into the essential characteristics of cells and their components. Challenge yourself and enhance your understanding of cellular biology!

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