2.1 Cell Structure

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  • Created by: elbungay1
  • Created on: 15-04-19 16:06
What is Magnification?
The number of times larger an image appears, compared with the size of the object
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What is resolution?
Clarity of the image and the ability to distinguish between two separate objects that are very close together
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How would you distinguish an image from a transmission and a scanning electron microscopes
Transmission electron microscopes produce a 2D black and white image and show internal structures of cells. Scanning produces a 3D image with lower magnification
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What are the magnifications of each type of Microscope?
Optical Microscopes: x2000. TEM: x500,000. SEM: x200,000
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What are the resolutions of each type of Microscope?
Optical: 200nm. TEM and SEM: 0.2nm
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Describe the structure and Function of the Nucleus
Surrounded by double membrane (envelope) with pores. Nucleolus contains RNA and genetic material Chromatin. Stores organism's genome, provides instructions for protein synthesis, envelope separates from rest of cell.
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Describe Rough Endoplasmic Reticulum
System of membranes containing Cisternae and is coated with ribosomes. Provides large surface area for ribsomes which site of protein synthesis. Protein pass into Cisternae and then transported
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Describe Smooth Endoplasmic Reticulum
System of membranes containing fluid-filled cavities (cisternae), contains enzymes that catalyse reactions for lipid, cholesterol and steroid hormone synthesis. Involved in absorption, synthesis and transport of lipids
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Describe Golgi Apparatus
Stack of membrane-bound flattened sacs, secretory vesicles bring materials to and from GA. Proteins are modified (e.g. adding sugar, lipids or folding), then packaged into vesicles and pinched off to be stores in cell or released by exocytosis
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Describe Mitochondria
Spherical or rod-shaped surrounded by double membrane, inner membrane highly folded into cristae. Contain fluid filled matrix. Site of ATP production in aerobic respiration. Self-replicating if energy needs increase.
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Describe Chloroplasts
Surrounded by double membrane, inner membrane continuous with flattened sacs called thykaloids which contain chlorophyll. Fluid filled matrix called Stroma. Site of photosynthesis
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Describe Vacuoles
Surrounded by membrane called tonoplast and contains fluid. Filled with water to maintain stability, when full pushes against cell wall maintaining turgidity.
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Describe Lysosomes
Small bags formed by golgi apparatus, contain powerful hydrolytic enzymes and are abundant in phagocytic cells such as neutrophils and macrophages. Lysosomes engulf old cell organelles and foreign matter, digest them and return components for reuse
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Describe Cilia and Undulipodia
Protrusions from cells surrounded by cell membrane, contain microtubules and formed by centrioles. Epithelial cells of airways contain cilia that beat and move mucus. Sperm cells have undulipodium (long cilia).
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Describe Ribosomes
Small organelles (20nm diameter) made of ribosomal RNA. Made in nucleolus and either remain free or bind to RER. Site of protein synthesis.
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Describe Centrioles
Two bundles of microtubules at right angles to each other. Form spindle fibres and bind to histone on chromosomes, motor proteins walk along tubulin threads pulling chromosomes apart. Involved in formation of cilia and undulipodium
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Describe Cytoskeleton
Network of protein structures within cytoskeleton containing microtubules and motor proteins. Give support and mechanical strength, keep cell's shape stable and allow cell movement.
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Describe Cellulose Cell Wall
Outside of plasma membrane of plants. Cell wall is strong an prevent plant cells crenating when turgid. Provide strength and support, maintain the cell's shape, permeable to allow solutions through
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Describe a process in which the organelles function together
Protein synthesis, mRNA copy of instructions made in nucleus. mRNA leaves through nuclear pore and attaches to RNA where protein assembled. Pinched off into vesicles, processed and packages in Golgi, vesicles bind with plasma membrane for exocytosis.
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In what ways are prokaryotic cells similar to eukaryotic cells?
Both have: plasma membrane, cytoplasm, ribosomes for assembling amino acids into proteins, DNA and RNA
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How are prokaryotic cells different to eukaryotic cells?
They are smaller, less well-developed cytoskeleton, no nucleus, no membrane bound organelles, cell wall of peptidoglycan, smaller ribosomes, naked DNA not wound around histone proteins existing as a loop
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What other features of do some Prokaryotic cells have?
Have protective waxy capsule surrounding cell wall, small loops of DNA called plasmids, flagella whip-like projections that enable movement. Pili hair-like projections that enable bacteria to adhere to host cells or to each other.
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How do eukaryotic and prokaryotic cells divide?
Eukaryotic cells divide by mitosis as they have linear chromosomes that can be pulled apart. Prokayotes divide by binary fission as they do not have linear chromosomes or centrioles.
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Card 4

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