10 Questions
What is the primary difference in cell wall composition between prokaryotic and eukaryotic cells?
Prokaryotic cells have a cell wall composed of peptidoglycan, while eukaryotic cells have a cell wall composed of chitin.
Which of the following is a characteristic unique to prokaryotic cells?
Absence of membrane-bound organelles
What is the primary difference in ribosome size between prokaryotic and eukaryotic cells?
Prokaryotic cells have smaller ribosomes (70S) while eukaryotic cells have larger ribosomes (80S)
What is the primary function of histone proteins in eukaryotic cells?
To associate with DNA and form chromatin
What is the primary difference in DNA organization between prokaryotic and eukaryotic cells?
Prokaryotic cells have a single circular chromosome, while eukaryotic cells have multiple linear chromosomes
Which of the following is a characteristic of eukaryotic cell division?
Mitosis with meiosis
What is the primary function of the glycocalyx in prokaryotic cells?
To serve as a capsule or slime layer
Which of the following is NOT a characteristic of prokaryotic cells?
Ability to undergo meiosis
What is the primary difference in cell size between prokaryotic and eukaryotic cells?
Prokaryotic cells are typically smaller than eukaryotic cells
Which of the following is a characteristic of eukaryotic cells?
Presence of membrane-bound organelles
Study Notes
Historical Overview of Cell Structure
- 1665: Robert Hooke coined the term "cells"
- 1838-1839: Matthias Schleiden and Theodore Schwann concluded that all plant and animal tissues are made up of cells
- 1858: Rudolf Virchow proposed the "Theory of Biogenesis" - Omnis Cellula E Cellula
Types of Cells
- Eukaryotic cells:
- Algae, Protozoa, Fungi, Plants, and Animals
- Have a true nucleus (eu = true, caryo = nut or nucleus)
- Size: 10-30 µm in diameter
- Prokaryotic cells:
- Bacteria and Archaea
- No true nucleus
Cell Structures Common to Most Eukaryotes
- Cell membrane
- Nucleus
- Vacuoles
- Mitochondria
- Endoplasmic Reticulum
- Ribosomes
- Golgi Complex
- Cytoplasm
- Cytoskeleton
- Glycocalyx (outermost boundary of most eukaryotic cells)
Cell Envelope
- The boundary layer of bacteria
- Composed of two or three basic layers:
- Cell wall
- Cell membrane
- In some bacteria, the outer membrane
Prokaryotic Cell Structure
- Cell membrane
- Cytoplasm
- Ribosomes
- One (or a few) chromosomes
- Cell structures found in most bacterial cells:
- Bacterial cell wall
- Glycocalyx
- Cell structures found in some bacterial cells:
- Flagella
- Pili
- Fimbriae
- Capsules
- Slime layers
- Inclusions
- Actin cytoskeleton
- Endospores
External Structures of Bacteria
- Appendages:
- Flagella
- Axial filaments
- Fimbriae/Pili
- Glycocalyx:
- Composed of polysaccharides, polypeptide (protein), or both
- Protects the cell
- Can be a capsule or a slime layer
Gram-Negative Cell Wall
- Thin layer of peptidoglycan (10-20% murein)
- Periplasmic space surrounds peptidoglycan
- Important reaction site for a large and varied pool of substances that enter and leave the cell
Gram-Positive Cell Wall
- Thick layer of peptidoglycan (60-100% murein)
- Contains teichoic and lipoteichoic acids
- Has an acidic charge on the cell surface
Endospores
- Found in gram-positive bacteria
- Produced by Bacillus, Clostridium, and Sporosarcina
- Specialized resting cells
- Capable of sporulation and germination
- Highly durable and desiccated cells with thick walls and additional layers
Comparison of Prokaryotic and Eukaryotic Cells
- Chemically similar
- Use same kinds of chemical reactions to metabolize food, build CHON, and store energy
- Can be distinguished by the structure of cell walls and membranes and the presence or absence of organelles
Summary of Distinguishing Characteristics
- Eukaryotes:
- Have chromosomes
- DNA is associated with chromosomal CHONs, histones, and nonhistones
- Have mitotic apparatus and organelles
- Prokaryotes:
- Genetic material is not enclosed within a membrane
- Lack other membrane-bound organelles
- DNA is not associated with histone proteins
- Cell walls always contain the complex polysaccharide peptidoglycan
- Divide by binary fission
This quiz covers the comparison of prokaryotic and eukaryotic cells, including their chemical similarities and differences in cell structure and organelles. It also touches on binary fission in bacteria and sporulation.
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