Cell and Structures
Cell vs. Viruses
• Cells: Simplest living structures capable of performing all life functions independently.
• Viruses: Non-living entities requiring a host cell to replicate and survive.
Microscopes
• Light Microscope: Uses visible light, magnifies up to 1,000x; resolution limited by wavelength of light.
• SEM (Scanning Electron Microscope): Creates detailed 3D images of surfaces; does not show internal structures.
• TEM (Transmission Electron Microscope): Produces high-resolution images of internal cellular structures.
Magnification and Resolution
• Magnification: Enlarges an object’s appearance.
• Resolution: Measures the clarity of an image by distinguishing two points as separate.
Robert Hooke
• Coined the term "cells" after observing cork under a microscope.
• Published his findings in Micrographia (1665), advancing the study of cells.
Cytology and Biochemistry
• Cytology: The study of cell structure and function.
• Biochemistry: The study of chemical processes and substances within organisms.
Cell Fractionation
• A laboratory technique to break apart cells and isolate organelles for detailed study.
Size Limitations of Cells
• Smaller cells have a higher surface area-to-volume ratio, which is essential for efficient exchange of materials.
Prokaryotes vs. Eukaryotes
• Prokaryotes: No nucleus or membrane-bound organelles; simpler and smaller (e.g., bacteria).
• Eukaryotes: Have a nucleus and membrane-bound organelles; larger and more complex.
Cell Structures and Functions
• Nucleus: Stores genetic material (DNA).
• Plasma Membrane: Protects the cell; regulates material exchange.
• Cytosol: Fluid portion of the cytoplasm where cellular processes occur.
• Microvilli: Increases surface area for absorption in some animal cells.
• Cytoskeleton:
◦ Microfilaments (actin): Provides structural support.
◦ Microtubules: Involved in transport and motility.
• Animal Cell-Specific Structures:
◦ Desmosomes: Anchor cells together.
◦ Gap Junctions: Channels that allow communication between cells.
◦ Tight Junctions: Create a watertight seal between cells.
• Extracellular Matrix (ECM): Nonliving material outside cells, providing structural and biochemical support.
• Plant Cell-Specific Structures:
◦ Plasmodesmata: Channels connecting cytoplasm between plant cells.
Cellular Respiration
Definition
• Process of extracting energy from glucose to produce ATP, the cell's main energy currency.
ATP
• Made by the enzyme ATP synthase, powered by hydrogen ion (H⁺) movement across the inner mitochondrial membrane.
Three Stages of Respiration
1 Glycolysis (Cytoplasm):
◦ Reactants: Glucose.
◦ Products: 2 Pyruvate, 2 ATP (net), and NADH.
2 Krebs Cycle (Mitochondrial Matrix):
◦ Reactant: Acetyl CoA.
◦ Products: CO₂, NADH, FADH₂, and 2 ATP.
3 Electron Transport Chain (ETC) (Inner Mitochondrial Membrane):
◦ Reactants: NADH and FADH₂ (electron carriers).
◦ Products: Water and ~32-34 ATP.
Key Points
• No oxygen = no Krebs cycle or ETC; only 2 ATP are produced via glycolysis.
• Fermentation occurs in anaerobic conditions:
◦ Converts pyruvate into lactic acid (in animals) or ethanol (in yeast).
Photosynthesis
Overview
• Process where plants convert light energy into chemical energy (sugars).
• Formula: CO2+H2O→O2+G3PCO_2 + H_2O \rightarrow O_2 + G3PCO2+H2O→O2+G3P.
Key Concepts
1 Light Reactions (Thylakoid Membranes):
◦ Products: ATP and NADPH (used in the Calvin Cycle).
◦ Oxygen is produced by Photosystem II.
2 Calvin Cycle (Stroma):
◦ Uses ATP and NADPH to fix carbon dioxide into G3P (a sugar precursor).
Photosystems
• Photosystem II: Produces oxygen and ATP.
• Photosystem I: Produces NADPH.
Adaptations
• C4 Pathway: Spatial separation of steps to avoid photorespiration.
• CAM Pathway: Temporal separation, stomata open at night to reduce water loss.
Mitosis and Meiosis
Mitosis
• Division of a eukaryotic somatic (non-reproductive) cell into two identical diploid cells.
• Phases:
1 Prophase: Chromosomes condense; spindle forms.
2 Metaphase: Chromosomes align at the cell's equator.
3 Anaphase: Sister chromatids separate.
4 Telophase: Nuclear envelopes reform.
5 Cytokinesis: Cytoplasm splits into two cells.
Meiosis
• Specialized cell division in germ cells (ovaries/testes) to produce gametes.
• Key Features:
◦ Two divisions produce four genetically unique haploid cells.
◦ Crossing over occurs during Prophase I for genetic diversity.
Binary Fission
• A simple form of cell division in prokaryotes producing two identical cells.
Genetics
• Haploid: Single set of chromosomes (e.g., gametes).
• Diploid: Two sets of chromosomes (e.g., somatic cells).
• Punnett Squares and Pedigrees: Tools to predict genetic inheritance.
Cell and Structures
Cell vs. Viruses
• Cells: Simplest living structures capable of performing all life functions independently.
• Viruses: Non-living entities requiring a host cell to replicate and survive.
Microscopes
• Light Microscope: Uses visible light, magnifies up to 1,000x; resolution limited by wavelength of light.
• SEM (Scanning Electron Microscope): Creates detailed 3D images of surfaces; does not show internal structures.
• TEM (Transmission Electron Microscope): Produces high-resolution images of internal cellular structures.
Magnification and Resolution
• Magnification: Enlarges an object’s appearance.
• Resolution: Measures the clarity of an image by distinguishing two points as separate.
Robert Hooke
• Coined the term "cells" after observing cork under a microscope.
• Published his findings in Micrographia (1665), advancing the study of cells.
Cytology and Biochemistry
• Cytology: The study of cell structure and function.
• Biochemistry: The study of chemical processes and substances within organisms.
Cell Fractionation
• A laboratory technique to break apart cells and isolate organelles for detailed study.
Size Limitations of Cells
• Smaller cells have a higher surface area-to-volume ratio, which is essential for efficient exchange of materials.
Prokaryotes vs. Eukaryotes
• Prokaryotes: No nucleus or membrane-bound organelles; simpler and smaller (e.g., bacteria).
• Eukaryotes: Have a nucleus and membrane-bound organelles; larger and more complex.
Cell Structures and Functions
• Nucleus: Stores genetic material (DNA).
• Plasma Membrane: Protects the cell; regulates material exchange.
• Cytosol: Fluid portion of the cytoplasm where cellular processes occur.
• Microvilli: Increases surface area for absorption in some animal cells.
• Cytoskeleton:
◦ Microfilaments (actin): Provides structural support.
◦ Microtubules: Involved in transport and motility.
• Animal Cell-Specific Structures:
◦ Desmosomes: Anchor cells together.
◦ Gap Junctions: Channels that allow communication between cells.
◦ Tight Junctions: Create a watertight seal between cells.
• Extracellular Matrix (ECM): Nonliving material outside cells, providing structural and biochemical support.
• Plant Cell-Specific Structures:
◦ Plasmodesmata: Channels connecting cytoplasm between plant cells.
Cellular Respiration
Definition
• Process of extracting energy from glucose to produce ATP, the cell's main energy currency.
ATP
• Made by the enzyme ATP synthase, powered by hydrogen ion (H⁺) movement across the inner mitochondrial membrane.
Three Stages of Respiration
1 Glycolysis (Cytoplasm):
◦ Reactants: Glucose.
◦ Products: 2 Pyruvate, 2 ATP (net), and NADH.
2 Krebs Cycle (Mitochondrial Matrix):
◦ Reactant: Acetyl CoA.
◦ Products: CO₂, NADH, FADH₂, and 2 ATP.
3 Electron Transport Chain (ETC) (Inner Mitochondrial Membrane):
◦ Reactants: NADH and FADH₂ (electron carriers).
◦ Products: Water and ~32-34 ATP.
Key Points
• No oxygen = no Krebs cycle or ETC; only 2 ATP are produced via glycolysis.
• Fermentation occurs in anaerobic conditions:
◦ Converts pyruvate into lactic acid (in animals) or ethanol (in yeast).
Photosynthesis
Overview
• Process where plants convert light energy into chemical energy (sugars).
• Formula: CO2+H2O→O2+G3PCO_2 + H_2O \rightarrow O_2 + G3PCO2+H2O→O2+G3P.
Key Concepts
1 Light Reactions (Thylakoid Membranes):
◦ Products: ATP and NADPH (used in the Calvin Cycle).
◦ Oxygen is produced by Photosystem II.
2 Calvin Cycle (Stroma):
◦ Uses ATP and NADPH to fix carbon dioxide into G3P (a sugar precursor).
Photosystems
• Photosystem II: Produces oxygen and ATP.
• Photosystem I: Produces NADPH.
Adaptations
• C4 Pathway: Spatial separation of steps to avoid photorespiration.
• CAM Pathway: Temporal separation, stomata open at night to reduce water loss.
Mitosis and Meiosis
Mitosis
• Division of a eukaryotic somatic (non-reproductive) cell into two identical diploid cells.
• Phases:
1 Prophase: Chromosomes condense; spindle forms.
2 Metaphase: Chromosomes align at the cell's equator.
3 Anaphase: Sister chromatids separate.
4 Telophase: Nuclear envelopes reform.
5 Cytokinesis: Cytoplasm splits into two cells.
Meiosis
• Specialized cell division in germ cells (ovaries/testes) to produce gametes.
• Key Features:
◦ Two divisions produce four genetically unique haploid cells.
◦ Crossing over occurs during Prophase I for genetic diversity.
Binary Fission
• A simple form of cell division in prokaryotes producing two identical cells.
Genetics
• Haploid: Single set of chromosomes (e.g., gametes).
• Diploid: Two sets of chromosomes (e.g., somatic cells).
• Punnett Squares and Pedigrees: Tools to predict genetic inheritance.
Updated 247d ago
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