cell theory

• Why are the cell wall, cytoplasm, and cytoskeleton not considered organelles?

  CELL WALL: "extracellular" or external to actual cell

  CYTOPLASM: no specialized function

  CYTOSKELETON: composed of different filaments and tubleles, not a discrete structure

  ALL: Does not follow cell theory
• Why is testing hypothesizes on the origin of cells difficult?

  Conditions of early earth are (1) very different from what we have now and (2) impossible to replicate perfectly in lab conditions. Additionally, (3) well-preserved fossils are very hard to find and (4) methods used to estimate dates of the first living cells (to determine exact state of early earth's condition) include wide ranges of uncertainty
• Why was RNA thought to be come first?


  Ribose (RNA) is readily produced in labs that closely mimic early earth conditions, while deoxyribose (DNA) needs to be catalyzed by a protein enzyme- something early earth's atmosphere lacked.
• Why is DNA preferred to RNA?

  DNA is more stable as it contains thymine, which is less prone to mutation than the uracil in RNA
• 3 components of cell theory?

  all 1) living things are composed of cells as they are the 2) smallest/basic unit of life. 3) All cells come from pre-existing cells.
• Outliers to cell structure?

  1 - red blood cells/phloem sieve tube element: upon maturing, loses nucleus and mitochondria

  2 - aseptate fungal hyphea: no clear cell division with multiple nuclei

  3 - skeletal muscle: fusion of multiple prokaryotes resulting in a large eukaryotic cell with multiple nuclei
• 3 Implications of cells being formed from pre-existing cells?

  1 - Origin can be traced back to the original zygote produced by the fertilization of an egg

  2 - All cells can be traced back to LUCA

  3 - The first cell arose from non-living material and can be found going back (most likely from membrane covered RNA)
• What are the 8 processes of living?

  (1) Homeostasis, (2) Movement, (3) Metabolism, (4) Excretion, (5) Nutrition, (6) Reproduction, (7) Growth and Development, (8) Response to stimuli
• homeostasis: the tendency towards a relatively stable equilibrium between interdependent elements (ex. concentration of water and minerals)- keeping its internal conditions stable despite external factors
• excretion: the removal of metabolic waste from an organism/cell
• metabolism: the sum of all the chemical reactions in a cell or organism
• Nutrition: The process of obtaining the energy and nutrients needed for growth and development.
• Response to stimuli: The body's response to a stimulus, such as a painful stimulus.
• Movement: change of position or size of cell
• Reproduction: Can be asexual or sexual- cell division to create new cells or a new organism (asexual= identical, sexual= fusion of egg + sperm genes)
• Examples of the functions of Life (Paramecium):

  Metabolism: Cytoplasm produces enzymes for reactions

  Reproduce: Nuclear division for mitosis and meiosis

  RT stimuli: cilia detects when cell hits block and changes direction

  Homeostasis: Contractile vacuole keeps internal compositions stable

  Excretion: Plasma membrane excretes waste

  Nutrition: The food vacuole connects to what makes products out of the cell

  Growth: Moves in call directions with cilia

  
• Examples of the functions of Life (Chlamydomonas):

  Metabolism: Cytoplasm site of all reactions

  Reproduce: Asexual and sexual reproduction to form spores

  RT stimuli: Senses light changes with eye spot and moves accordingly

  Homeostasis: Contractile vacuole keeps water balance as it collects water

  Excretion: surface of plasma membrane excretes waste

  Nutrition: Photosynthesis used to produce its own food

  Growth: Consumes organic molecules to increase in size

  
• Evidence of eukaryotic cells originating from large prokaryotes engulfing smaller, free-living prokayotes is found in their chloroplasts
• Concentrations of cyclins correspond to stages of mitosis and interphase
• As a cell increases in size, the surface area of to volume ratio decrease linearly (IN CORROLATION) which reduces the speed at which substances can enter or exit the cell which reduces the rate of metabolism and energy and heat transfers which restricts how big the cell can get
• Emergent properties are properties that arise from the interactions of the parts of a system and are not visible at a cellular level
• Embryonic stem cells are pluripotent but not always fully compatible with grown adult
• cord blood stem cells and bone marrow stem cells are only multi-potent but fully compatible with adult
• Stargardt's disease - stem cells injected into to encourage its development into healthy retina cells
• Leukaemia - stem cells are extracted from person's bone marrow and then chemotherapy is made to kill rest of abnormal blood cells. Stem cells are put back in bone marrow to form healthy WBCs, this time
• Paramecium and chlahydohonas metabolize through enzymatic reactions, reproduce through binary fission, grow with an increase in size, maintain their conditions in the cytoplasm, and expels waste for excretion
• Paramecium reacts to solids for its response, and generates nutrition through endocytosis
• Chlamydomonas responds to light for its response, and photosynthesizes to create food
• Resolution is defined as the ability to distinguish two close-by objects. Light has a long wavelenght and low resolution while electron beams have short wavelengths and high resolution
• Osmosis can control the uptake of water by the cell in the wall of the intestines, or the loss of water from a plant cell in a hypertonic environment- not just the loss of water like in sweating
• Condensation of two carbs form a disaccharide
• Natural selection includes development of resistance
• Francesco Redi found that maggots formed from flies not meat/matter
• John Needham heated meat broth which "formed" bacteria- pro spontaneous generation
• Lazaro Spallanza sealed flask of boiled meat broth and concluded that germs were carried by the air, not the broth
• Theodore Schmann let air pass through a thin, hot tube but saw no germ generation
• George Friedrich Schrode and Theodor Von Dusch used sterile cotton to seal the flask and found it to keep contaminations (ex. bacteria) out as microbes are filtered
• Louis Pasteur disproved spontaneous generation theories for the last time by using swan neck flasks to heat borth then cooling them to prove that microbes could not arise spontaneously. He then broke the head of the flask and waited and solution did collect bacteria as the neck curve that trapped bacteria before was no longer present