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Questions and Answers
Which of these is NOT primarily a function of the cell membrane?
Which of these is NOT primarily a function of the cell membrane?
Which of the following best describes the movement of molecules in facilitated diffusion?
Which of the following best describes the movement of molecules in facilitated diffusion?
In which cellular structure is the majority of a cell's DNA located?
In which cellular structure is the majority of a cell's DNA located?
During which phase of the cell cycle does DNA replication occur?
During which phase of the cell cycle does DNA replication occur?
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Which of these structural components of the plasma membrane is primarily responsible for its fluidity?
Which of these structural components of the plasma membrane is primarily responsible for its fluidity?
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What is the main function of ribosomes within a cell?
What is the main function of ribosomes within a cell?
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What is the primary function of the proteasome within a cell?
What is the primary function of the proteasome within a cell?
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Which of the following describes the process of transcription in the central dogma?
Which of the following describes the process of transcription in the central dogma?
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Study Notes
Cells
- Fundamental unit of any organism
- Composed of organelles
Main Parts of a Cell
- Cell Membrane (Plasma Membrane): Outer layer, phospholipid bilayer with embedded protein channels
- Cytoplasm: Dense liquid, fills cell, stores carbohydrates, organelles, and enzymes; located between the nucleus and cell membrane; composed of cytosol (liquid part)
- Nucleus: Double-membraned organelle that stores DNA, contains chromosomes and genes, and the nucleolus
- Cytoskeleton: Gives cell shape and protection, made of protein filaments, and involved in cell movement
Cytoskeleton
- Microtubules: 25nm thick, protein tubulin, radiate from centrosome, maintain shape, and facilitate movement of motor proteins
- Intermediate Filaments: 8-10nm thick, keratin protein gives shape and reduces stress
- Microfilaments: 6nm thick, actin protein, forms terminal web, assists in movement
Cell Membrane
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Controls movement (nutrients in, cellular waste out) of the cell
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Selectively permeable
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Ex. Bouncer in a club (picky)
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Fluid Mosaic Model:
- Phospholipid bi-layer (2 layers)
- Hydrophobic tails (non-polar)
- Hydrophilic heads (polar)
- Cholesterol (stabilizes membrane, reduces fluidity, protects from heat)
- Proteins (embedded or peripheral)
- Carbohydrates (for cell-cell communication)
Cell Membrane Transports
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Passive Transport: Movement of substances down a concentration gradient without energy.
- Simple diffusion: Substances move from high to low concentration.
- Facilitated diffusion: Membrane proteins help substances through the membrane.
- Osmosis: Water moves from low to high concentration of solute.
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Active Transport: Movement of substances against a concentration gradient, requiring energy (ATP).
- Types: Sodium-Potassium pump, endocytosis, exocytosis
Tonicity
- Hypertonic: More solute outside the cell, cell shrinks or crenates
- Isotonic: Equal solute inside and outside the cell, no change
- Hypotonic: More solute inside the cell, cell swells or lyses
Cell Organelles
- Organelles: Tiny structures with specific functions in cells.
- Examples: Mitochondria Lysosome Ribosome Smooth Endoplasmic Reticulum Rough Endoplasmic Reticulum Golgi Apparatus Centrosome Nucleus
Protein synthesis
- Ribosomes synthesize proteins by assembling amino acids based on information in mRNA, which is transcribed from DNA.
- Golgi apparatus modifies and packages proteins for transport.
Lysosomes
- "Garbage disposals" of the cell
- Contain digestive enzymes for waste disposal
Peroxisomes
- Similar to lysosomes, containing enzymes to neutralize toxins.
Centrosomes, Centrioles
- Involved in cell division; centrosome contains centrioles
Proteasomes
- Cluster of proteins that degrade damaged proteins
Nucleus
- Houses DNA (genetic material)
- Directs cellular activities
- Contains nucleolus (site of ribosome synthesis)
- Genes are arranged into chromosomes
- Encased in a nuclear envelope with nuclear pores.
Chromatin
- Thread-like strands of DNA, within the nucleus
DNA
- Genetic code for all proteins in an organism
- Consists of nucleotides (bases, sugar, phosphate group)
Transcription
- Process where genetic information in DNA is copied onto a strand of mRNA inside the nucleus to direct protein synthesis.
Translation
- Process where mRNA directs the synthesis of proteins in the cytoplasm.
Cellular Respiration
- Process of using oxygen and nutrients (like glucose) to produce ATP (cellular energy).
- Steps include glycolysis, Krebs Cycle, ETC.
Cell Cycle
- Series of stages in a cell's life, from formation to division.
- Interphase: G1 (growth), S (DNA replication), G2 (preparation for mitosis).
- Mitosis: Cell division (prophase, metaphase, anaphase, telophase, cytokinesis).
- Meiosis: specialized cell division to produce gametes (sex cells)
Membrane Proteins
-
Integral Proteins: Embedded in the phospholipid bilayer, permanently attached, span the bilayer.
- Function: Transport (channels, pumps), cell recognition, enzymes
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Peripheral Proteins: Attached to one side of the membrane, temporarily attached, may not span the bilayer.
- Function: Support, enzyme activity, cell signaling, cell adhesion.
- Types: Channel proteins, carrier proteins, receptor proteins
Types of Endocytosis
- Pinocytosis: Taking in fluids.
- Phagocytosis: Taking in solids.
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Description
Test your knowledge on the fundamental unit of life, the cell. This quiz covers various cell components such as the cell membrane, cytoplasm, nucleus, and cytoskeleton, along with their functions and significance. Explore the intricacies of cellular biology and reinforce your understanding of these essential concepts.
