Biology Lesson 3: Cell Structures and Functions
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Questions and Answers

What is the function of the plasma membrane?

Acts as a gatekeeper, regulating the passage of molecules and ions in and out of the cell.

What are the four common components of all cells?

Plasma membrane, Cytoplasm, DNA, Ribosomes

What is the primary component of cytoplasm?

Water (80-85%)

What does DNA stand for?

<p>Deoxyribonucleic acid</p> Signup and view all the answers

Which of the following structures functions in motility for bacterial cells?

<p>Flagella</p> Signup and view all the answers

What are the two types of glycocalyx?

<p>Slime layer</p> Signup and view all the answers

What is the role of ribosomes in cells?

<p>They form a factory for protein synthesis.</p> Signup and view all the answers

Gram-positive cell walls stain red from safranin counterstain.

<p>False</p> Signup and view all the answers

What are the three parts of flagella?

<p>Filament, hook, basal body</p> Signup and view all the answers

What are the requirements for a city to function?

<p>Requirements include infrastructure, governance, and services.</p> Signup and view all the answers

What are the common components of all cells?

<p>Plasma membrane, cytoplasm, DNA, ribosomes.</p> Signup and view all the answers

What is primarily composed of water and where chemical reactions occur?

<p>Cytoplasm</p> Signup and view all the answers

What is the primary function of the plasma membrane?

<p>Regulating the passage of molecules</p> Signup and view all the answers

What does DNA stand for?

<p>Deoxyribonucleic acid</p> Signup and view all the answers

Ribosomes are responsible for protein synthesis.

<p>True</p> Signup and view all the answers

Which flagellar arrangement has a single flagellum at one end?

<p>Monotrichous</p> Signup and view all the answers

What are fimbriae?

<p>Fine hairlike bristles that function in adhesion.</p> Signup and view all the answers

What is the primary function of pili?

<p>Join bacterial cells for DNA transfer (conjugation) and adhesion.</p> Signup and view all the answers

What is the glyococalyx?

<p>Coating of molecules external to the cell wall</p> Signup and view all the answers

What is the composition of the cytoplasm?

<p>Dense gelatinous solution of sugars, amino acids, and salts.</p> Signup and view all the answers

Match the following cell wall types with their characteristics:

<p>Gram-positive cell wall = Thick peptidoglycan layer Gram-negative cell wall = Thin peptidoglycan layer Peptidoglycan = Framework of glycan chains cross-linked by peptides</p> Signup and view all the answers

What role do chromosomes play in a cell?

<p>They contain tightly coiled DNA around proteins.</p> Signup and view all the answers

Study Notes

Overview of Cell Structures and Functions

  • Cells consist of the plasma membrane, cytoplasm, DNA, and ribosomes.
  • Understanding the structure and function of these components is essential for biology studies.

Plasma Membrane

  • Acts as a barrier regulating substance exchange between the cell and its environment.
  • Composed of a phospholipid bilayer with polar heads outside and nonpolar tails inside.
  • Embedded proteins perform various functions, including transport and signaling.

Cytoplasm

  • A semifluid environment where cellular biochemical reactions occur.
  • Composed of 80-85% water, with proteins (10-15%), lipids (2-4%), polysaccharides (1%), and nucleic acids (1%).

DNA (Deoxyribonucleic Acid)

  • Genetic material in all cellular organisms and most viruses.
  • Comprised of nucleotides with phosphate groups, deoxyribose sugars, and nitrogen bases (A, T, C, G).
  • Carries instructions for protein synthesis and genetic replication.

Ribosomes

  • Complexes made of ribosomal RNA and proteins functioning as sites for protein synthesis.
  • Discovered in 1955 by George E. Palade; found in the cytoplasm and associated with the endoplasmic reticulum.

Prokaryotic Cell Structures

  • Specifically focus on bacterial cell features, including organelles and their functions.

Flagella

  • Motility structures with three parts: filament, hook, and basal body.
  • Capable of 360-degree rotation; can be single, clustered, or distributed over the cell surface.

Fimbriae

  • Hairlike bristles on the cell surface that assist in adhesion to other cells and surfaces.

Pili

  • Rigid tubes made of pilin protein, unique to Gram-negative bacteria.
  • Serve roles in bacterial conjugation (DNA transfer) and adhesion.

Glycocalyx

  • Coating of sugar and/or protein molecules outside the cell wall.
  • Two types: capsule (organized and tightly bound) and slime layer (loosely bound).
  • Functions include adhesion, protection from white blood cell attacks, and receptor capabilities.

Cell Wall

  • Composed of peptidoglycan, providing structural support and preventing lysis due to osmotic pressure changes.
  • Differences between Gram-positive and Gram-negative bacteria:
    • Gram-positive: Thick peptidoglycan layer, retains crystal violet, stains purple.
    • Gram-negative: Thin peptidoglycan layer, loses crystal violet, stains red with safranin.

Cytoplasm (Prokaryotic)

  • Dense, gelatinous solution with a high water content (70-80%).
  • Serves as a solvent for materials involved in cellular functions.

Chromosome

  • DNA found tightly coiled around proteins, essential for genetic information storage and transmission.
  • Key element in cell replication and protein coding.

Overview of Cell Structures and Functions

  • Cells consist of the plasma membrane, cytoplasm, DNA, and ribosomes.
  • Understanding the structure and function of these components is essential for biology studies.

Plasma Membrane

  • Acts as a barrier regulating substance exchange between the cell and its environment.
  • Composed of a phospholipid bilayer with polar heads outside and nonpolar tails inside.
  • Embedded proteins perform various functions, including transport and signaling.

Cytoplasm

  • A semifluid environment where cellular biochemical reactions occur.
  • Composed of 80-85% water, with proteins (10-15%), lipids (2-4%), polysaccharides (1%), and nucleic acids (1%).

DNA (Deoxyribonucleic Acid)

  • Genetic material in all cellular organisms and most viruses.
  • Comprised of nucleotides with phosphate groups, deoxyribose sugars, and nitrogen bases (A, T, C, G).
  • Carries instructions for protein synthesis and genetic replication.

Ribosomes

  • Complexes made of ribosomal RNA and proteins functioning as sites for protein synthesis.
  • Discovered in 1955 by George E. Palade; found in the cytoplasm and associated with the endoplasmic reticulum.

Prokaryotic Cell Structures

  • Specifically focus on bacterial cell features, including organelles and their functions.

Flagella

  • Motility structures with three parts: filament, hook, and basal body.
  • Capable of 360-degree rotation; can be single, clustered, or distributed over the cell surface.

Fimbriae

  • Hairlike bristles on the cell surface that assist in adhesion to other cells and surfaces.

Pili

  • Rigid tubes made of pilin protein, unique to Gram-negative bacteria.
  • Serve roles in bacterial conjugation (DNA transfer) and adhesion.

Glycocalyx

  • Coating of sugar and/or protein molecules outside the cell wall.
  • Two types: capsule (organized and tightly bound) and slime layer (loosely bound).
  • Functions include adhesion, protection from white blood cell attacks, and receptor capabilities.

Cell Wall

  • Composed of peptidoglycan, providing structural support and preventing lysis due to osmotic pressure changes.
  • Differences between Gram-positive and Gram-negative bacteria:
    • Gram-positive: Thick peptidoglycan layer, retains crystal violet, stains purple.
    • Gram-negative: Thin peptidoglycan layer, loses crystal violet, stains red with safranin.

Cytoplasm (Prokaryotic)

  • Dense, gelatinous solution with a high water content (70-80%).
  • Serves as a solvent for materials involved in cellular functions.

Chromosome

  • DNA found tightly coiled around proteins, essential for genetic information storage and transmission.
  • Key element in cell replication and protein coding.

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Explore the essential components of cell structures and their functions in this insightful quiz. Understand the biological significance of cells and how they contribute to life. Perfect for students looking to enhance their knowledge of foundational biology concepts.

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