Biology Key Terms - Ch. 7: Cell Structure

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1. Light Microscopy

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uses light to view a sample through two set of magnifying lenses (ocular and objective). Allows for a resolution up to 1000x.

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2. Fluorescent Microscopy

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most uses require antibodies (proteins that are produced by plasma cells) but may use antigens. Limits are of a 1000x magnification and a 0.2 micrometer resolution.

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3. Transmission Electron microscopy

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used a sectioned, stained sample and electrons to produce 2-D images.

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4. Scanning Electron microscopy

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shadows a coat of heavy metal on specimen where electrons are directed on the sample to produce 3-D images.

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5. Magnification

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makes an object appear larger; has a unit (fold or “x”) and has indefinite limits; can allow for large magnifications but still object may appear blurry due to lack of resolution.

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6. Resolution

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ability to see magnified object clearly; resolution of light is limited due to the light’s wavelength and interference rings.

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7. Nucleoid

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found in prokaryotes, but not eukaryotes since prokaryotes have no membrane bound organelles. The DNA contained in the nucleoid is naked and circular.

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8. Cell Wall

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unique to plant cells, the cell wall surrounds the cell’s membrane for added structural support.

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9. Nucleus

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found in eukaryotes; contains a double membrane and DNA is in the form of chromosomes (chromatin in plural).

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10. Nuclear Pores

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complex structure that allows for the passage of large macromolecules and particles into and out of the nucleus; is found between two edges of nuclear membrane and is composed of 60-100 different proteins.

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11. Nuclear lamina

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a system of protein filaments that lines the inner nuclear membrane and gives the nucleus its shape.

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12. Chromosome

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contain the cell’s genes; consists of DNA and proteins; DNA compresses into dense chromosomes during replication but chromosomes are usually threadlike strands.

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13. Chromatin

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non-condensed, threadlike strands of chromosomes (plural form).

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14. Nucleolus

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where ribosomal DNA is being made by the process of transcription ; found in the nucleus.

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15. Ribosome

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makes proteins in the cells by the process of translation; attach to the mRNA which tell the ribosomes which amino acids to bring and in which order. Forms peptide bonds between the amino acids.

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16. Endomembrane system

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series of organelles within the membrane that work together to make proteins, add sugars to these proteins and send these proteins to their appropriate destinations. Organelles include the outer membrane of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and lysosomes with the plasma membrane as the proteins destinations.

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17. Smooth endoplasmic reticulum

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an organelle that is made up of a network of tubules and sac that is connected to the outer membrane of the nucleus; function is determined by the fact it contains no ribosomes; basic function: has enzymes that are involved with lipid and carbohydrate synthesis.

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18. Cisternae

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tubes and sacs that make up the endoplasmic reticulum.

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19. Lumen

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the interior of the endoplasmic reticulum which contains the cisternae (tubes and sacs).

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20. Rough endoplasmic reticulum

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an organelle that is made up of a network of tubules and sac that is connected to the outer membrane of the nucleus; function is determined by the fact it contains ribosomes; first organelle involved in the secretion of proteins… proteins that are produced by surface ribosomes are threaded through a protein pore.

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21. Protein glycosylation

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the addition of sugars to the proteins occurring the in the ER lumen; short carbohydrate chains are added to specific amino acids in the proteins (most made are glycoproteins); disulfide bonds are formed in the proteins.

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22. Golgi Apparatus

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glycosylation of the protein gets modified here when the protein enters the structure through the Cis face and exits through the Trans face. Different areas contain unique enzymes that modify protein specifically. The sacs that make up this structure are called cisternae and the interior region is the lumen.

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23. Secretion

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the exiting of the modified protein from the plasma membrane.

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24. Vesicle

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holders of the proteins; they are sorted into these at the Trans face of the Golgi in order for the proteins to flow to their destination.

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25. Lysosome

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a membrane-bound sac that consists of a single lipid bilayer; function is to receive and digest materials from endocytosed material and parts of itself; created in the rough ER; contain 40 types of hydrolases (enzyme type proteins) that can digest all organic macromolecules.

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26. Vacuole

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found in only plants, these are single-membrane bound sacs that can store food, pump excess water out of a cell (contractile vacuole), store organic compounds and ions, contain pigments or poisons, absorb water or help to maintain plants strength.

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27. Peroxisome

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membranous sac composed of a single membrane that contains oxidative enzymes that transfer hydrogen from substrates; receive proteins from free ribosomes, which are imported after their production.

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28. Mitochondria

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double membrane (inner – “cristae” very impermeable & outer – very permeable). Matrix is found inside the inner membrane while the intermembrane space is found in between both membranes. Inside mitochondria, mitochondrial ribosomes (produce mitochondrial proteins) and mitochondrial DNA (slightly different that nuclear DNA) are found. Function: “cellular respiration”, extracts energy from macromolecules and stores the energy in ATP.

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29. Endosymbiotic theory

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primitive, ancestral anaerobic (doesn’t require oxygen) eukaryote endocytosed bacteria that was capable of oxidative phosphorylation; mitochondria are now remnants of part of the cell.

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30. Plastid

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organelles that are specific and found in only plants (i.e.: amyloplasts that store starch, chromoplasts that contain pigment for color, and chloroplasts which mark the site of photosynthesis).

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31. Chloroplast

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site of photosynthesis (production of sugar (sucrose, glucose and starch from CO2 gas). 3 membranes: outer, inner, and thylakoid (location of pigment that absorbs light for photosynthesis). 3 spaces: thylakoid space contained in the stroma (inside inner membrane, location of reactions in photosynthesis and location of chloroplast genomes), and intermembrane space (found between inner and outer membranes).

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32. Photosynthesis

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production of sugar to be turned into energy.

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33. Thylakoid

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disks inside the chloroplasts; multiple thylakoids = granum.

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34. Stroma

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liquid component inside chloroplast’s inner membrane.

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35. Amyloplast

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organelles that contain starch; i.e., potato tubers.

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36. Chromoplast

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contain pigments that give fruit and flowers their color.