BIOL113 M2 L2-L3

• Compare and contrast the physical structures of prokaryotic and eukaryotic cells

  Prokayotic cells are simple in structure, they lack membrane bound organelles and a distinct nucleus, and have a rigid cell wall. In contrast, eukaryotic cells are larger and more complex, with membrane bound organelles, a distinct nucleus, and a variable presence of a cell wall. These structural differences reflect the diverse evolutionary adaptations and cellular functions of prokaryotes and eukaryotes.
• What are the three pathways by which horizontal gene transfer take place ?

  Transformation, transduction and conjugation
• What is transformation

  Transformation refers to the process where a bacterium takes up genetic material from its environment. This genetic material can come from the breakdown of other bacterial cells or from the release of DNA into the environment. The recipient bacterium then incorporates this foreign DNA into its own genome, potentially acquiring new traits or characteristics.
• What is conjugation?

  Conjugation occurs when two bacterial cells physically connect and transfer genetic material through a tube-like structure called a pilus. This allows for the exchange of DNA, often in the form of plasmids, between the two cells, potentially leading to the recipient cell acquiring new traits.
• What is transduction ?

  Transduction in horizontal gene transfer happens when a virus infects bacteria and accidentally carries some bacterial DNA with it. When the virus infects other bacteria, it transfers this bacterial DNA to them, possibly giving them new traits.
• Describe a bacterium and a way that it or a product it makes is used by humans

  Lactococcus bacteria are used to make cheese by fermenting lactose in milk, which helps to coagulate milk proteins and form curds. These bacteria also add flavor and texture to the cheese while preserving it by creating an acidic environment that prevents harmful bacteria growth.
• what do bacteroidetes do?

  In addition to carbohydrate metabolism, they are also involved in energy production and conversion as well as amino acid transport and metabolism.
• what do fermicutes do?

  Ferment carbohydrates
• Phototrophs

  Obtain energy from light
• Chemotrophs

  obtain energy from chemicals
• troph

  to eat
• auto

  self
• hetero

  other
• autotrophs

  require CO2 as a carbon source
• heterotrophs

  Require organic nutrients as a carbon source
• Diazotroph

  Organinisms that can fix N2
• Explain why nitrogen fixation is an important process

  Nitrogen fixation is vital because it converts atmospheric nitrogen into ammonia which plants can use to grow. This process is crucial for the production of proteins and nucleic acids, which are essential for all living organisms. Without nitrogen fixation, many ecosystems would lack the nitrogen necessary for plant growth, which would disrupt entire food chains and ecosystems.
• What is reduction ?

  The addition of electrons from an atom or molecule
• What is oxidation?

  The removal of electrons from an atom or molecule
• O - oxidation

  I - is

  L - loss

  R - reduction

  I - is

  G - gain
• NADH purpose

  it traps hydrogen and stops it from escaping cells. NADH carries electrons from metabolic reactions to the electron transport chain, ultimately contributing to the production of ATP, the cells primary energy source.
• what is anaerobic respiration ?

  respiration without oxygen. A compound other than O2 serves as a terminal electron acceptor
• photons

  light energy
• how does photosynthesis create energy?

  Photons are used to split water into O2, H + and electrons. The Electrons are used to power enzymes that increase the concentration of H+ withiing the mebrane until H+ is finally accepted by NADP. The H+ gradient is used to turn the ATP synthase, generating ATP.
• evolution of photosynthesis occurred before the great oxygenation event.
• products for aerobic respiration:

  CO2 and H2O
• How do Cyanobacteria do photosynthesis ?

  Cyanobacteria contain chlorophyll and accessory pigments, allowing them to conduct photosynthesis in specialized structures called thylakoids. Within these structures, they fix carbon dioxide (CO2) in compartments known as carboxysomes, producing oxygen as a byproduct. Additionally, cyanobacteria have gas vesicles that help them maintain buoyancy, facilitating their widespread distribution and colonisation of diverse environments.
• where do some Cyanobacteria fix N2

  in specialised cells called heterocysts
• what did fixing N2 allow cynobacteria to do ?

  to thrive in various habitats and significantly contribute to the nitrogen cycle
• what did oxygenation of the environment lay the basis for ?

  the development of aerobic respiration, ultimately leading to the diversification and expansion of aerobic life forms.
• early cynobacteria possessed primitive light-sensitive pigments that allowed them to harness light energy for metabolic processes. Over time, through genetic mutations and selective pressures, these organisms developed more sophisticated photosynthetic machinery, including chlorophyll and accessory pigments, which enabled them to capture light energy more efficiently.
• oxygen is the electron acceptor for aerobic respiration
• macronutrients 


  Carbon, Hydrogen, oxygen, nitrogen, phosphorus and sulfur (CHNOPS)
• What are the specialized nitrogen fixing cells  in cyanobacteria called ?

  Heterocysts
• Where do cyanobacteria fix O2?

  in carboxysomes
• Where are carboxysomes located ?

  In the thylakoids
• Where do cyanobacteria conduct photosynthesis ?

  Thylakoid membranes
• What do cyanobacteria contain?

  chlorophyll and accessory pigments
• Before cyanobacteria, the process of photosynthesis in bacteria was ...

  anoxygenic
• In a bacterial system, H2S mostly acts as the electron donor for photosynthesis making the process anoxygenic, whereas in cyanobacteria and plants, H2O is used as the electron donor which produces oxygen as a byproduct.