Biology Topic 1: Cell Biology

71 flashcards · Biology · by Marli Williams

  1. Eukaryotic Cells

    Has genetic material in a nucleus

  2. Examples of Eukaryotic Cells

    Animal Cell Plant Cell

  3. Size of Eukaryotic Cells

    10 to 100 μm (micrometers)

  4. Prokaryotic Cells

    Has genetic material in cytoplasm - a single loop of DNA, possibly some additional plasmids

  5. Examples of Prokaryotic Cells

    Bacteria

  6. Size of Prokaryotic Cells

    1 μm

  7. Order of Magnitude

    Order of getting x10 bigger 1 Tm - 1 x 1012 m [Tera] 1 Gm - 1 x 109 m [Giga] 1 Mm - 1 x 106 m [Mega] 1 km - 1 x 103 m [Kilo] 1 dm - 1 x 10-1 m [deci] 1 cm - 1 x 10-2 m [centi] 1 mm - 1 x 10-3 m [milli] 1 μm - 1 x 10-6 m [micro] 1 nm - 1 x 10-9 m [nano] 1 pm - 1 x 10-12 m [pico]

  8. Cell Membrane

    Controls what goes in and out of the cell

  9. Cytoplasm

    Jelly-like substance where chemical reactions occur in the cell

  10. Nucleus

    Contains DNA - which controls activity of the cell

  11. Mitochondria

    Where respiration takes place in the cell

  12. Ribosomes

    Site of protein synthesis

  13. Cell wall

    Supports cell, defines its shape - made of cellulose

  14. Chloroplasts

    Contains chlorophyll which absorbs light energy for photosynthesis

  15. Permanent Vacuole

    Used for storage and supports shape of the cell Made of cell sap - a solution of soluble sugars and salts

  16. Explain how to prepare microscopy slide.

    Place Specimen on the slide Add a stain like iodine Place a cover slip on top - careful not to create air bubbles

  17. Required practical: Observing specimen using a light microscope

    Prepare the slide adding a stain and being careful not to create air bubbles Put slide on the stage and start with the lowest magification Adjust the coarse lens to see the specimen more clearly Then adjust the fine lens to get a clear image Increase the magnification by using a different objective lens

  18. Specialised Cells

    Cell that are adapted to carry out a particular function Cell specialise by undergoing Differentiation

  19. Nerve Cell Functions and Adaptations

    Specialised to transmit electrical signals quickly within the body. Has a cell body where most sub-cellular structures are located Has dendrites to receive signals from other nerve cells, muscles and glands Has a long axon to send signals over a long distance Has Myelin sheath which insulates the electrical signals that travel

  20. Muscle Cell Functions and Adaptations

    Specialised to contract/squeeze to cause movement Has layers of protein filaments which slide over each other causing a muscle contraction Has lots of mitochondria Has stores of glycogen (stores of glucose for respiration)

  21. Sperm Cell Functions and Adaptations

    Specialised to carry the male's DNA to the egg cell for sexual reproduction Has a streamlined head and long tail to aid in swimming Has half the normal number of chromosomes (23) Has digestive enzymes in the acrosome within the head to break down the outer layer of egg cell Has lots of Mitochondria

  22. Root Hair Cell Functions and Adaptations

    Function: absorption of water and mineral ions from soil Has root hairs which increase the surface area - increasing water/mineral intake Has a large and concentrated permanent vacuole which increase water though a high concentration gradient Has thin walls for shorter diffusion distance Has no chloroplasts Has lots of Mitochondria for active transport

  23. Xylem Functions and Adaptations

    Specialised to transport water and mineral ions Dead, empty cells to allow free passage of water Strengthened by Ligin to withstand water pressure

  24. Phloem Functions and Adaptations

    Specialised to transport sugars and amino acids Living cells are joined end to end with sieve plates so nutrients can flow in both directions Has few sub-cellular structures to aid the flow of materials

  25. Importance of Cell differentiation

    For cells to become functional to therefore develop into a functional organism

  26. When do Animal and Plant cells differentiate?

    Animal Cells: At an early stage Mature Animal Cells only differentiate for repair and replacement Plant Cells: At any point through the plant's life

  27. Microscopy Development

    Light microscope was first developed in 17th century Over time the magnification and resolution has increased Electron microscopes were developed in the early 1900s Electron microscopes have higher magnification and resolution that light ones This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures.

  28. Define Resolution

    The shortest distance between two points on a specimen that can still be distinguished by the observer or camera system as separate entities.

  29. Magnification equation

    Magnification = Size of image / Actual size of specimen

  30. Required Practical: Culturing Microorganisms

    Independent Variable: Type of Antiseptic used Dependent Variable: Clear zone of Bacteria Control Variables: Sterile water

  31. Why is Sterile water used as an control for Required practical 2?

    To ensure that any differences in bacterial growth observed can be attributed to the presence of the antiseptic or antibiotic used and not some other factor (such as the paper discs for example)

  32. Binary Fission

    Simple Cell division which bacteria use

  33. How fast do Bacteria reproduce?

    Once every 20 minutes if they have enough nutrients and a suitable temperature.

  34. Where can bacteria be cultured?

    Bacteria can be grown in a nutrient broth solution or as colonies on an agar gel plate.

  35. What are uncontaminated cultures used for

    Investigating the action of disinfectants and antibiotics.

  36. Why petri dishes and culture media must be sterilised before use?

    The culture could be contaminated and have to compete with other organisms for space and food

  37. Why must inoculating loops be sterilised by passing them through a flame?

    To make sure any organism on them are killed to prevent contaminating the culture

  38. Why must the lid of the Petri dish should be secured with adhesive tape and stored upside down?

    To stop airborne microorganisms from contaminating the culture To prevent condensation from lid to land on the agar surface

  39. Why must (in school laboratories) cultures should generally be incubated at 25°C.

    Optimum temperature is 37℃ (body temperature) This makes the bacteria more dangerous as it could infect students.

  40. Chromosomes

    Contained within the nucleus and contains DNA 46 Chromosomes (23 pairs) in a human body cell

  41. Mitosis

    One set of chromosomes is pulled to each end of the cell and the nucleus divides.

  42. The Cell Cycle

    Cell increases in size and number of subcellular structures (like ribosomes and mitochondria) DNA replicates to form two copies of each chromosome Mitosis (One set of chromosomes is pulled to each end of the cell and the nucleus divides) The cytoplasm and cell membrane divide to form two identical daughter cells

  43. Why is cell division by Mitosis important?

    For the growth and development of multicellular organisms.

  44. Stem Cell

    A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

  45. Embryonic Stem Cells

    Stem cells found in the early stages of organism development - are not found in mature organisms Function: To form all different cells to create a functional organism. (healthy baby)

  46. Adult bone marrow

    Unspecialised cells which can differentiate into certain cells throughout the life of the organism like blood cells Function: To replace cells lost via damage For growth

  47. Plant meristem tissue

    Unspecialised cells which can differentiate throughout the life of the plant Function: For growth and repair

  48. What can Embryonic Stem Cells be used for?

    They can be cloned and made to differentiate into most different types of human cells.

  49. Treatment with stem cells could help with what diseases?

    Diabetes - insulin resistance / little insulin production Paralysis - damaged nerve cells

  50. Therapeutic Cloning

    An embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment.

  51. Cons of Stem Cells

    Risk of transfer of viral infections Ethical objections

  52. Stem cells from meristems in plants can be used to produce clones of plants quickly and economically. This means: Rare species can be cloned to protect from extinction. Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.

    Why is the fact plants can be cloned useful?

  53. Diffusion

    The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

  54. Factors of Diffusion Rate

    The difference in concentrations (concentration gradient) The temperature The surface area of the membrane.

  55. How does the difference in concentrations (concentration gradient) effect the rate of diffusion?

    The greater the difference on concentration between two regions - faster the overall rate of diffusion

  56. How does the temperature effect the rate of diffusion?

    Higher temperature equals higher net movement of particles due to move energy

  57. How does surface area of the membrane effect the rate of diffusion?

    More space for the substances to diffuse through

  58. Why do single-celled organisms have a relatively high surface area to volume ratio?

    To allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.

  59. Why do multicellular organisms need exchange surfaces and transport systems?

    Multicellular organisms need exchange surfaces and a transport system to gain sufficient diffusion / active transport / osmosis rates due to their relatively small SA to volume ratio. This is to allow for the sufficient transport of molecules into and out of the cells to meet the needs of the multicellular organism.

  60. In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organism’s needs. The effectiveness of an exchange surface is increased by: having a large surface area a membrane that is thin, to provide a short diffusion path (in animals) having an efficient blood supply (in animals, for gaseous exchange) being ventilated.

    Why do multicellular organisms need exchange surfaces and transport systems?

  61. Small Intestine

    Function: To absorb soluble food molecules into the blood Adaptations: Has a large SA via Villi Each villius has a good blood supply - maintaining a stable concentration gradient One cell thick - decreases diffusion distance

  62. Lungs

    Function: To exchange oxygen and carbon dioxide Adaptations: Millions of Alveoli - large SA Good ventilation Alveoli are one cell thick Alveoli have a good blood supply

  63. Gills

    Function: To exchange oxygen and carbon dioxide Adaptations: Each gill is made of filaments with projections called lamellae increasing SA Good blood supply that flows in the opposite direction of water - maintains a concentration gradient

  64. Roots

    Function: Absorption of Water and mineral ions Adaptations: Root hair cells with root hair projections increasing SA Lots of Mitochondria for active transport Concentrated via cell sap - maintaining a water concentration gradient

  65. Leaves

    Function: Gas Exchange Adaptations: Stomata allows airs to circulate in the leaf - Good ventilation Air gaps within the leaf - decreasing diffusion distance

  66. Osmosis

    The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

  67. Required Practical: Effects of Solutions on Plant Tissue

    Independent Variable: Concentration of salt or sucrose within the solution Dependent Variable: Percentage Change in Mass Control Variables: Type and volume of solute in solution, temperature, and time

  68. Why is percentage change in mass used as a dependent variable?

    To make fair comparisons of the change of mass.

  69. The change in mass when the tissue is more concentrated in water is decrease - water is lost. The change in mass when the tissue is less concentrated in water is increase - water is taken in. The change in mass when the tissue has the same concentration of water is no change.

  70. Active Transport

    Movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.

  71. Examples of Active Transport

    Root hair cells - mineral ions from soil Gut - sugar molecules into the blood