10 Questions
Which of the following statements about cells is true?
All cells contain DNA and RNA as genetic material.
What is the fundamental unit of life?
Cells
Which of the following is a characteristic of prokaryotic cells?
They lack a nuclear membrane.
What is the primary function of ribosomes in cells?
Protein synthesis
Which of the following organisms are considered unicellular?
Bacteria
What is the primary function of the cell membrane?
Regulating the flow of substances in and out of the cell
Which of the following is a function of eukaryotic cells?
All of the above
What is the primary function of cytoplasm in cells?
Facilitating chemical reactions
Which of the following statements about viruses is true?
Viruses can only reproduce using the machinery of living cells.
What is the approximate number of cells in the human body?
$10^{12}$ cells
Study Notes
The Cell Theory
- All living organisms are composed of one or more cells
- Each cell is the smallest fundamental living unit
- All cells originate from preexisting cells
Cells: Structural and Functional Units of Life
- Cells are the basic structural units of life
- Cells are also the functional units of life, performing functions such as:
- Taking in nutrients (feeding)
- Respiration
- Removing wastes (excretion)
- Repair, growth, and reproduction
- Sensing and reacting to changes (irritability)
Characteristics of Cells
- All cells have the same basic chemistry, including:
- DNA and RNA (genetic material)
- Cytoplasm
- Protein-building ribosomes
- Cell membranes
- Cells vary greatly in size, shape, growth, chemical requirements, specializations, and functions
Eukaryotic Cells
- Larger and more advanced than prokaryotes
- Have a definite membrane-bound nucleus
- Have linear DNA
- Have membrane-bound organelles
- Examples: protists, plants, fungi, humans
Cell Membranes
- Found in both prokaryotes and eukaryotes
- Acts as a boundary to all living cells
- Composed of lipids (fats) in a double layer (bilayer) and proteins
- Allows movement of necessary nutrient and waste molecules
- Found surrounding organelles (endo-membranes)
Protoplasm
- Refers to the contents of the cell membrane
- Comprised of cytoplasm and nucleus (in eukaryotes)
- Cytoplasm consists of cytosol, organelles, and cytoskeleton
- Cytosol is the fluid inside the cell membrane
- Organelles are specialized subunits with specific functions
Ribosomes
- Found in both prokaryotes and eukaryotes
- Composed of rRNA and proteins
- Not enclosed by a membrane
- Function: to manufacture proteins
- Found free in the cytoplasm and attached to the endoplasmic reticulum (in eukaryotes)
Explore the reasons behind Gram-positive bacteria appearing purple and Gram-negative bacteria appearing pink after Gram staining. Learn about the differences in cell wall structures of both types of bacteria. This quiz is related to the topics covered in Week 4 Lab of BIOL123 course by Santha J at ACU.
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