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What significant structure did Ramachandran discover in 1954?
Which influential figure did Ramachandran meet during his time at Cambridge?
What educational achievement did Ramachandran complete first?
What is one of Ramachandran's notable contributions to structural biology?
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In which year did Ramachandran receive his Ph.D.?
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Which academic institution had a significant influence on Ramachandran's education due to his father's role?
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What distinguishes unicellular organisms from non-cellular structures?
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Where was Ramachandran born?
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At what age did Ramachandran pass away?
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What was the significant contribution of Rudolf Virchow to cell theory?
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Which part of the cell is unique to plant cells as noted by Theodore Schwann?
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Who first described live cells using a microscope?
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What did Matthias Schleiden's observations lead him to conclude about plants?
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Which statement accurately reflects the cell theory as formulated by Schleiden and Schwann?
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Which of the following advancements allowed for better observation of cell structures?
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What is the primary role of the plasma membrane in cells?
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What type of transport allows molecules to move across the membrane without energy?
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In which process does water move from higher to lower concentration?
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Which type of molecules require a carrier protein to facilitate their transport across the plasma membrane?
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What type of transport moves ions against their concentration gradient?
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What is the composition of the primary cell wall in plants?
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What layer mainly holds neighboring plant cells together?
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Which of the following is NOT a function of the cell wall?
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What is the purpose of plasmodesmata in plant cells?
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What do amyloplasts primarily store?
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Which structure in chloroplasts is responsible for carrying out photosynthesis?
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What is the primary function of leucooplasts?
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How many chloroplasts can typically be found in the mesophyll cells?
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What is the space limited by the inner membrane of the chloroplast called?
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Which type of leucoplast stores oils and fats?
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What connects the thylakoids of different grana?
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Which of the following statements about chloroplasts is incorrect?
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What distinguishes cilia from flagella in terms of structure and function?
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What is the term used to describe the arrangement of microtubules in the axoneme of cilia and flagella?
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What connects the central microtubules in the axoneme?
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Which of the following statements is true regarding the structural differences between prokaryotic and eukaryotic flagella?
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What role do linkers serve in the structure of cilia and flagella?
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What is the composition of the axoneme in cilia and flagella?
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From where do cilia and flagella emerge?
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What characteristic of cilia allows them to create movement in the surrounding fluid?
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Study Notes
G.N. Ramachandran
- Renowned for contributions to protein structure and conformational analysis of biopolymers.
- Founded the ‘Madras school’ of structural biology.
- Discovered the triple helical structure of collagen; published in Nature in 1954.
- Developed the 'Ramachandran plot' for analyzing protein conformations.
- Born on October 8, 1922, near Cochin, India; influenced by a mathematically inclined father.
- Graduated in 1942 as top student in B.Sc. (Honors) Physics from the University of Madras.
- Earned a Ph.D. from Cambridge University in 1949.
- Influenced by Linus Pauling's work on α-helices and β-sheets during his time at Cambridge.
- Passed away on April 7, 2001, at age 78.
Understanding Cells
- Cells are the basic structural and functional units of all living organisms.
- Organisms can be unicellular (single cell) or multicellular (many cells).
- Independent living is dependent on the complete structure of a cell; incomplete structures do not suffice.
Cell Theory
- Developed by Matthias Schleiden (1838) and Theodore Schwann (1839), who observed that all plants and animals are composed of cells.
- Schwann noted the presence of a thin outer membrane (plasma membrane) in cells.
- Rudolf Virchow (1855) contributed to cell theory by stating that all cells arise from pre-existing cells (Omnis cellula-e cellula).
- Modern cell theory encompasses two main principles:
- All living organisms are composed of cells and products of cells.
- All cells arise from pre-existing cells.
Structure of Plant Cells
- Plant cells, like those in onions, have distinct structures including a cell wall and plasma membrane.
- Cell membrane is selectively permeable, facilitating passive and active transport of molecules.
Transport Mechanisms
- Passive transport allows molecules to move across the membrane without energy, following concentration gradients.
- Osmosis refers specifically to water movement across the membrane.
- Active transport requires ATP and moves substances against their concentration gradient (e.g., Na+/K+ Pump).
Cell Wall
- A rigid structure surrounding the plasma membrane in plants and fungi.
- Provides shape, protection, and facilitates intercellular interactions.
- Composed of cellulose and other materials that vary by organism (e.g., algae have walls made of calcium carbonate).
Leucoplasts and Chloroplasts
- Leucoplasts are colorless plastids that store nutrients; amyloplasts store starch, elaioplasts store oils, and aleuroplasts store proteins.
- Chloroplasts are found in mesophyll cells of leaves, essential for photosynthesis and possessing chlorophyll.
- Chloroplast structure includes:
- Double membranes with less permeable inner membranes.
- Stroma containing enzymes, DNA, and ribosomes.
- Thylakoids arranged in stacks (grana) where carbohydrate synthesis occurs.
Cilia and Flagella
- Hair-like structures that facilitate movement; cilia are shorter and help move fluids, while flagella are longer and propel cells.
- Both structures have a core called axoneme, structured in a 9+2 microtubule array.
- Emerges from a centriole-like structure (basal body) that anchors them in the cell.
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Description
Explore the groundbreaking contributions of G.N. Ramachandran to protein structure and the fundamental understanding of cells as the building blocks of life. This quiz covers his discoveries, including the Ramachandran plot and the nature of unicellular and multicellular organisms. Test your knowledge on these critical topics in biology and biochemistry.
