Cell Structure

Flashcards by , created over 4 years ago

A Levels Biology (F211) Flashcards on Cell Structure, created by megan.radcliffe16 on 11/23/2014.

Created by megan.radcliffe16 over 4 years ago
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Question Answer
What are the characteristics of a Transmission Electron Microscope? 2D images - dead material Beam of electrons = black and white images- can be enhanced with colour.
What are the characteristics of a Scanning Electron Microscope? Uses moving beam of electrons = 3D images shows surface detail excellent depth of field.
why are stains used with light microscopes? 1. make structures more visible 2. enable small structures to be seen.
what are the different stains that can be used? Light microscopes: 1. Methylene blue 2. Iodine Solution 3. Acetic Orcein TEMs: salts of heavy metals SEMs: layer of heavy metal
why are salts of heavy metals used in TEMs. To deflect the beam of electrons
why is a layer of heavy metal used in SEMs? To reflect the electrons
what does Methylene blue do to the cells? Stains the nucleus dark blue and the cytoplasm pale blue
what does Iodine solution do to the cells? Stains the plant cell walls orange/brown and starch grains purple.
what does Acetic Orcein do to the cells? Stains the chromosomes red.
what does the modern cell theory state? 1. All living organisms are composed of cells. 2. All new cells are derived form pre-existing cells. 3. Cells contain heredity information 4.metabolic reactions take place in cells
what is Metabolism? The total of all chemical changes that take place in an cell/organism
What is Anabolism? the metabolic process that builds up larger molecules from smaller ones.
what is catabolism? the metabolic breakdown of complex molecules into simpler ones - resulting in the release of energy.
what is muticellular? many cells working together
what is magniifcation? the factor by which the image size is enlarged compared to the original object.
what is the calculation of magnification? magnification= image size/ actual size
what is the calculation of magnification when using scale bars? magnification= length of scale bar in micrometers/ length scale bar represents in micrometers
what is resolution? 1. the degree of detail that can be seen 2. the ability to distinguish separately two small objects.
what are the two measurements that two points can be resolved? 0.2 µm apart -light microscope 0,5 µm apart- electron microscope
why are light microscopes used more widely? 1. cheaper 2. allows colour 3. required less expertise 4. can observe living matter
what is the ultra structure? the detailed structure that is revealed with an electron microscope
what structures are seen in both animals and plants by a light microscope? 1. nucleus 2. mitochondria 3. cytoplasm 4. cell surface memebrane
what structures are only seen in animal cells? Vesicles
what structures are only seen in plant cells? 1. cell wall 2. vacuole 3. chloroplast
what structures of the cells can only be seen by an electron microscope? 1. rough ER 2. Smooth ER 3. Golgi 4. Cytoskeleton 5. Ribosomes 6. Plasmodesmata
what is the plasma membrane? A partially permeable membrane that acts as a barrier between the inside and outside of the cell. It helps regulate the cells internal composition bu controlling the substances between the cell and its environment.
what is the nucleus? contains the genetic information and controls all cellular activities. It is surrounded by the nuclear envelope - contains nuclear pores
why are the nuclear pore present on the nuclear envelope? Allows movement of molecules into and out of the nucleus.
what is the cytoplasm? It is a fluid where the chemical reactions of the metabolism take place. Where the enzymes, proteins and other substances produced and manufacture.
what are the three components that the cytoplasm is made up of? 1. fluid 2. membrane systems 3. organelles
what is compartmentation? It is the basis of cell organisation The division of labour.- allows cells to be split into compartments.
what does compartmentation do? It ensures that different biochemical activities can take place in different places in ideal conditions.
what are the four advantages to compartmentation? 1. potentially harmful substances/enzymes can be isolated- not able to damage the rest of the cell. 2. products of one reaction can bein close proximity- speed up rate of reactions. 3. surface area of membranes and number of enzymes is increased. 4. membranes can provide ion gradients.
what is the function of the nucleolus? Synthesis of ribosomes.
what is chromatin? Threadlike structures int eh cell nucleus. represent extended form of chromosomes during interphase.
what is the Endoplasmic Reticulum (ER)? network of sac-like and tubular cavities formed from membrane.
what is the difference between Rough ER and Smooth ER? Rough ER has ribosomes on the outer surface. Smooth ER has no ribosomes on outer surface.
what are the functions of Rough ER? !. Protein synthesis 2. Transports proteins to other parts of cell. 3. Makes Golgi Apparatus
what are the functions of Smooth ER? 1. Site of Lipid synthesis 2. Synthesises steriods
what is the Golgi Apparatus? Stack of flattened membrane sacs
what are the functions of the Golgi? 1. Forms lysosomes 2. Transports and modifies materials 3. Enzymes made in the rough ER are concentrated and packaged into vesicles
what are the characteristics of Mitochondria? 1. outer membrane contains a folded inner membrane 2. important enzymes are attached to the inner membrane(large surface area) 3. Matrix present inside inner membrane 4. Contains DNA 5. Self- replicating
what are the functions of the Mitochondria? 1. Aerobic respiration 2. ATP systhesis
what is the functions of ribosomes? Site of protein synthesis
what are the sizes of ribosomes? In Eukaryotic cells - 22nm In prokaryotic, mitochondria cells and chloroplasts -18nm
what are Lysosomes? Simple spherical sacs bound by a single membrane containing hydrolytic enzymes.
what are the functions of Lysosomes? 1. Autophagy ( digestion of worn out cells) 2. Digestions of material ingested by phagocytoysis 3. Secretion of Lysosomal enzymes 4. Autolysis- release of enzymes to destroy and break down cells.
what are the functions of chloroplasts? Photosynthesis in plants - Grana- light reactions -Stroma- dark reactions
what are the characteristics of chloroplasts? Contain DNA and are self replication contain own ribosomes- to carry out protein synthesis
what are Cillia and Flagella? Hair like extensions. Long= Flagella Short= Cillia
What are the characteristics of the Cillia and Flagella? 1. 3-4 µm long 2. covered with an extension of the plasma membrane. 3. Contains microtubules
what is the cytoskelaton made up of? Actin microfilaments and microtubules
what are the functions of the cytoskeleton? 1. provide mechanical strength to cells and holds them in shape. 2. Aids transport 3/ Enables cell movement
what is the difference between Eukaryotic cells and Prokaryotic cells? Eukaryotic- larger and possess a nucleus and other membrane bound organelles in their cytoplasm. Prokaryotic- first forms of life. DNA not enclosed by nuclear membrane. Do not possess any membrane bound organelles.
what do Eukaryotic and Prokaryotic cells have in common? 1. Both are single celled 2. Have cytoplasmic structure 3. Use flagella for cell movement 4. Have Ribosomes 5. Have cell wall and cytoplasm