Cell Structure and Function

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Questions and Answers

Which of the following statements is TRUE about the relationship between cell biology and cytology?

Cytology encompasses cell biology, focusing on the structure and function of cells, while cell biology primarily studies the structure of cells.

Cell biology and cytology are synonymous, both studying the structure and function of cells.

Cell biology and cytology are distinct fields, with cell biology focusing on the structure of cells and cytology focusing on the function of cells.

Cell biology encompasses cytology, focusing on the structure and function of cells, while cytology primarily studies the structure of cells. (correct)

The statement "Cells divide, and cells + their products = organism" best describes which aspect of the cell doctrine?

Organisms arise from pre-existing cells through cell division.

Cells are the fundamental units of structure and function in all living organisms.

Cells are capable of independent existence and are the building blocks of all organisms.

The continuity of life is maintained through the process of cell division and subsequent production of new cells. (correct)

Which of the following statements best reflects the concept of "double-life" as it relates to the cell doctrine?

A cell can function independently and also contribute to the overall function of the organism.

Cell division allows for the creation of new cells, which can then specialize and perform specific tasks.

A cell's lifespan is dependent on the lifespan of the organism to which it belongs.

The cell is capable of both independent existence and contributing to the organism's function. (correct)

Which of the following elements is NOT among the most abundant elements found in cells?

Sodium (Na) (B) Signup and view all the answers

Which of the following molecules is NOT considered a biomolecule?

Water (H2O) (A) Signup and view all the answers

What makes water an exceptional solvent?

Its polar structure allows it to form hydrogen bonds with both charged and polar molecules, enabling their dissolution. (A) Signup and view all the answers

Which of these is NOT a DIRECT consequence of water's high polarity?

Water's tendency to form complex structures, such as the double helix of DNA. (C) Signup and view all the answers

Which statement BEST represents the role of water in the cell?

Water serves as a solvent, facilitating chemical reactions within the cell and maintaining cell structure. (C) Signup and view all the answers

Why are proteins not considered energetic molecules?

Their primary function is to facilitate and regulate cellular processes, rather than directly supplying energy. (B) Signup and view all the answers

What is the key factor determining the diversity in protein function?

The specific combination of amino acids found in each type of protein. (A) Signup and view all the answers

Which statement about amino acids is NOT true?

All amino acids are essential for human metabolism. (D) Signup and view all the answers

Which of the following BEST describes the role of metal ions in protein function?

They act as co-factors, enhancing the activity of certain proteins. (D) Signup and view all the answers

What is the MAIN reason for the difference in concentration of mineral salts between the intracellular and interstitial fluids?

All of the above factors contribute to the difference in mineral salt concentrations between the intracellular and interstitial fluids. (D) Signup and view all the answers

What is the PRIMARY reason why proteins are considered the most abundant organic molecules in living organisms?

They have the most diverse range of structures and functions, enabling them to perform essential tasks in every biological process. (A) Signup and view all the answers

What is unique about the structure of a zwitterion?

It has both a positive and a negative charge, but an overall neutral charge. (D) Signup and view all the answers

Which of the following statements about essential amino acids is TRUE?

They must be obtained from the diet as the body cannot synthesize them. (B) Signup and view all the answers

Study Notes

Cell Structure and Function - Cell Biology

Reem Dakhil, M1 Biochemistry (Lebanese University), M2 Physiology, Epigenetics, Differentiation, and Cancer (Université Grenoble Alpes) is presenting this material.

Chapter 1: Cell Biology Birth

The presentation is about the Cell Doctrine, and definitions

Cell Biology vs Cytology

Cell Biology: Study of cells and their components structurally and functionally
Cytology: Study of cells and their components, specifically focusing on their structure.

The Cell Doctrine

Unit: The cell is the fundamental unit of structure and function in living organisms.
Division: Cells divide to produce new cells via mitosis and meiosis for continuity and growth.
Organism: Cells and their products (e.g., tissues, organs) work together to form an organism.
Life: Cells are the basis of life continuity, from one generation to the next through fertilization and mitosis/meiosis.
Double-life: Each cell has a life for itself and contributes to the life of the whole organism.

Chapter 2: Molecular Components of Cells

The presentation focuses on Inorganic and Organic compounds in cells

What atoms and molecules are found in our cells?

The presentation discusses the atomic level components of cells

Atomic Level

Most abundant atoms: 96% are Carbon (C), Hydrogen (H), Nitrogen (N), and Oxygen (O).
4% are Sodium (Na), Potassium (K), Chlorine (Cl), and Phosphorus (P).
Very low, trace elements (e.g., Boron (B), Fluorine (F), Manganese (Mn) and others) are also present in small quantities.

Molecular Level

Organic molecules ("Biomolecules"): Proteins, Carbohydrates, Lipids, and Nucleic acids
Inorganic molecules: Water, Mineral salts

Water:

Basis of life
Most abundant
Electrically neutral
Extremely polar (partially negative oxygen and partially positive hydrogen)
Forms hydrogen bonds with other molecules
Solubilizes salts via ionic bonds.

Mineral Salts:
- Dissolved and ionized in water.
- Internal/external balance plays a crucial role in membrane permeability, nerve impulses, muscle contraction, and cell division.
- Metal ions are essential for certain proteins' activity (e.g., muscle contraction, oxygen transfer, intercellular signaling)
Organic Compounds:

Molecules: amino acids, fatty acids, monosaccharides, nucleotides.
Macromolecules: proteins, polysaccharides, lipids, DNA, and RNA
Vitamins: needed at low concentrations; some are part of carbohydrates or lipids.

1. Proteins

Introduction: Most abundant organic molecules with diverse functions determined by their genes and amino acids. Unbranched chain polymers of amino acids.
Function: Essential for various cellular processes (e.g., morphology, DNA replication, storage, transport, communication, immunity, senses, cell cycle, muscle contraction), but are not energy sources.
Diverse Chemical Composition: Chemically homogeneous (unbranched chain of amino acids), differing by the number and sequence, resulting in varied 3D structures and functions.
Amino Acids: Composed of C, H, N, O, and S. Different groups (non-polar, polar uncharged, polar positive, polar negative) with 20 types: 9 are essential (require diet). Only L-stereoisomers form polypeptides.
- All amino acids are soluble due to amino and carboxyl groups, although the solubility of proteins/peptides is affected by factors like pH and R-group characteristics (zwitterions).

5. Polypeptide

Peptide Bond Formation: Covalent bonds forming a linear, and unbranched chain of amino acids. The bond is created by ribosomes. Digested through proteases. Made through a nucleophilic attack of NH2 (amino group) of amino acid (n) and COOH (carboxyl group) of amino acid (n-1). Forming an "amide bond" and eliminating water (H2O).
Backbone: repeating N - Cα - C - units. Polarized by N-terminus (NH2) and C-terminus (COOH).

6. Polypeptide Flexibility

Extended groups (R, H, =O) outside the peptide backbone plane allow rotation in relation to one another.
This confers flexibility, enabling 3D conformation and thus, functionality.

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Description

This quiz covers the foundational concepts of cell biology, including the Cell Doctrine and the distinction between cell biology and cytology. Understand the fundamental unit of life and how cells contribute to the structure and function of living organisms. Test your knowledge on the characteristics and significance of cells.