Biochemistry Fundamentals Quiz

Biochemistry & Cell Medical Biochemistry Course Information

• Course instructor: Dr. Lina Yousif Mohammed
• Email: [email protected]
• University: University of Zakho
• College: College of Medicine
• Semester: First
• Academic Year: 2024-2025

Session One: Introduction to Biochemistry Aims

• The course provides a fundamental understanding of biochemistry's core principles and experimental underpinnings.
• The course enables students to gain specialized knowledge and comprehension of selected aspects through focused lecture series.

Learning Outcomes

• Students will demonstrate advanced knowledge and understanding of the following core topics:
  • Structures and functions of prokaryotic and eukaryotic cells' basic components, particularly macromolecules, membranes, and organelles.
  • Cellular mechanisms used for energy generation and utilization in cells.
  • Cellular components involved in mitotic cell division.

What is Biochemistry?

• Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and concerning living organisms. These processes generate the complexity of life.
• Biochemistry is divided into three major fields: Molecular genetics, Protein science, and Metabolism.

What Molecules Do Biochemists Study?

• Biochemists investigate biological macromolecules (proteins, nucleic acids, carbohydrates, and lipids). These molecules form the structure of cells and facilitate life's functions.

Introduction to Cells

• The term "cell" originated from the Latin word cellula, meaning "small room."
• Cytology is the study of cells.
• Robert Hooke was the first scientist to use the term "cell."
• Robert Brown discovered the nucleus in 1833.
• Theodor Schwann discovered that animals are composed of cells in 1838.

Cell Theory

• All living things are made up of cells.
• Cells are the fundamental functional units of living organisms.
• All cells originate from pre-existing cells through cell division.

Types of Cells

• The biological world is composed of two types of cells:
  • Prokaryotic Cells: These cells have a single, enclosed compartment, lack a defined nucleus, and possess a relatively simple internal organization. Examples include bacteria and blue-green algae.
  • Eukaryotic Cells: These cells contain a defined membrane-bound nucleus and complex internal membranes enclosing various compartments. Examples include plant and animal cells, fungi (which can be both multicellular and single-celled).

Biological Membranes

• Membranes are the outer boundaries of individual cells and organelles.
• Plasma membranes are selectively permeable, controlling the passage of molecules into and out of the cell.

Components of Biological Membranes: Lipids

• Lipids are the primary components of cell membranes (40-80% by weight).
  • Phospholipids: These are the most abundant type of membrane lipid. They are polar, ionic compounds, amphipathic (having both hydrophilic and hydrophobic regions). The hydrophilic "head" group contains phosphate and an alcohol. The hydrophobic "tail" consists of a hydrocarbon fatty acid chain.
  • Cholesterol: An amphipathic molecule featuring a polar hydroxyl group and a hydrophobic steroid ring. Cholesterol is interspersed between phospholipids and stiffens the cell membrane.
  • Glycolipids: Carbohydrate-attached lipids, present in lower concentrations than phospholipids and cholesterol. They are oriented toward the cell's exterior, facilitating cell-cell interactions.

Components of Biological Membranes: Proteins

• Proteins are essential for the biological functions of the membrane, not just its structure.
• Proteins associate with the membrane in one of three ways:
  • Transmembrane proteins: Embedded within the lipid bilayer; their hydrophilic regions interact with the aqueous environment, while their hydrophobic regions interact with the fatty acid tails.
  • Lipid-anchored proteins: Attached to a lipid molecule within the bilayer without penetrating the core.
  • Peripheral proteins: Located on the cytosolic face of the membrane and associate indirectly with membrane lipids through interactions with other membrane proteins.

Cell Wall

• The cell wall is the outermost layer in plant and bacterial cells, located outside the plasma membrane.
• It's a non-living structure secreted by the cell itself.
• In plants, it's primarily composed of cellulose, with additional substances like pectin and lignin.

Transport Across Membranes

• Transport of small molecules (e.g., glucose) across plasma membranes occurs through:
  • Diffusion: Movement from high to low concentration, requiring no energy expenditure.
  • Osmosis: Movement of water from high to low concentration across a semipermeable membrane.
  • Active Transport: Movement against a concentration gradient requiring energy expenditure (e.g. ATP).

Transport of Large Molecules (Bulk Transport)

• Endocytosis: Taking large molecules into the cell (e.g., phagocytosis, pinocytosis).
• Exocytosis: Removing large molecules from the cell.

Organelles

• Organelles are membrane-bound compartments in eukaryotic cells that carry out specific functions.
• Their membranes and components are similar to those of the plasma membrane.
• They're interconnected and part of the cytosol (liquid portion of the cytoplasm).

Nucleus

• The nucleus is the control center of the eukaryotic cell (except for mature human red blood cells). It houses the cell's genetic material (DNA).
• The nuclear envelope surrounds the nucleus (consisting of a double-layered phospholipid membrane containing nuclear pores).
• The nucleolus is responsible for ribosome production.

Ribosomes

• Ribosomes are the protein synthesis machinery in cells.
• Ribosomes are composed of proteins and rRNA (ribosomal RNA).
• They can be free in the cell's cytosol or bound to the endoplasmic reticulum (ER).

Endoplasmic Reticulum (ER)

• The ER is a network of interconnected membranes surrounding the nucleus.
  • Rough ER: Contains ribosomes and is involved in protein production and modification.
  • Smooth ER: Lacks ribosomes and is involved in lipid synthesis and protein glycosylation.

Golgi Complex

• The Golgi complex is a collection of flattened sacs (cisternae) involved in protein modification.

Mitochondria and Chloroplasts

• These are double-membrane-bound organelles crucial for energy conversion.
• Mitochondria: Involved in ATP (adenosine triphosphate) production via cellular respiration (breaking down carbohydrates, fats). Their folded inner membrane is called cristae.
• Chloroplasts: Found in plant cells and are involved in photosynthesis.

Plastids

• Plastids are plant cell organelles.
• Chloroplasts: Green plastids found in plant cells that capture energy in photosynthesis, contain DNA and thylakoids, etc.
• Chromoplasts: Coloured plastids involved in pigment synthesis (e.g., blue, red, yellow etc)
• Leucoplast: White or colorless plastids involved in storage (starch)

Microbodies (Lysosomes, Peroxisomes, Glyoxysomes)

• Small organelles involved in various metabolic processes.
  • Lysosomes: Contain enzymes for breaking down macromolecules.
  • Peroxisomes: Involved in detoxification (hydrogen peroxide), lipid metabolism, and cholesterol synthesis.
  • Glyoxysomes: Found in plant cells and involved in lipid to carbohydrate conversion. (e.g., germination)

Cilia and Flagella

• These organelles are involved in cell movement. Cilia are short, hair-like structures, while flagella are longer, whip-like appendages.
• Microtubules: The structural components of cilia and flagella.

Centrioles

• Involved in cell division, organizing the mitotic spindle.

Vacuoles

• Membrane-bound sacs involved in storage, digestion, and waste disposal.
• Important in maintaining plant cell shape. Usually quite large in plant cells.

Cytoskeleton

• The cytoskeleton provides structural support and enables movement within the cell.
• The cytoskeleton is composed of protein filaments. They include actin and intermediate filaments and microtubules. Each type plays different roles.

Molecules of the Cell

• Water: Essential for many metabolic and cellular reactions. A major component of protoplasm and a universal solvent.
• Elements: Elements like Hydrogen, Oxygen, Nitrogen, Calcium, Potassium, Sodium, etc. are required to form inorganic and organic compounds of the body's fluids

Carbohydrates

• Simple carbohydrates (e.g., glucose) are monosaccharides; larger chains are disaccharides/polysaccharides (e.g., Sucrose, starch, and cellulose.) These are used for energy storage.

Proteins

• Proteins are macromolecules formed from amino acids. They have diverse structures (primary, secondary, tertiary, and quaternary) and play important roles in cellular structure and function including enzyme activity and metabolic reactions

Nucleic Acids

• Nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA carries genetic information, while RNA plays a vital role in protein synthesis and other processes.

Lipids

• Lipids are composed of C, H, and O; relatively low oxygen levels. They are used in energy storage and form important component of cell membranes (for example as phospholipids).

Test your knowledge on the essential concepts of biochemistry, including cell theory, biomolecules, and important scientific discoveries. This quiz covers key topics that define the study of life's chemical processes. Perfect for students wanting to reinforce their understanding of biochemistry.