Lecture 1 Cells Flashcards
(27 cards)
Prokaryotic cells
Bacteria
Archaea
• Small cells, smaller than 2 micrometers
• Aerobic/anaerobic metabolism
• NO membrane-bound organelles
• 1 single molecule of circular DNA, not complexed with proteins
• No cytoskeleton
• Division: Fusion/Budding
Eukaryotic cells
Unicellular
Plants, animals
• Large cells 10-100 micrometers
• Aerobic metabolism (Mitochondria)
• Compartimentalization due to membranes
• Liner DNA molecules, complexed with proteins
• Complex network of mictotubules, microfilaments and intermediate filaments.
• Division: Meiosis, Mitosis
Elemental composition of biomolecules
Carbon
Oxygen
Hydrogen
Nitrogen
Subunits of biomolecules that assemble into a larger structure
Fatty acids > Glycerides
Nucleotides > Nucleic acids
Monosaccharides > polysaccharides
Amino acids > Proteins
What are chemical bonds influenced by?
Chemical bonds are influenced by the arrangement of electrons in the outermost shell of each atom
they are most stable when this layer is full.
What are the 2 main types of chemical bonds?
Ionic bonds where e- are transferred
Covalent bonds where e- are shared
What are the types of non-covalent chemical bonds?
Hydrogen bonds
Electrostatic interactions
Van Der Waals forces
Hydrogen bonds
• occur when a hydrogen atom, bonded to an electronegative atom like oxygen or nitrogen, interacts with another electronegative atom.
• strongest non-covalent bonds
• ensure the stability of bio molecules
What role do electrostatic interactions play in enzyme-substrate interactions, and how can the presence of charged ions affect these interactions?
• Can explain the interactions between enzymes and their substrate.
• The presence of charged ions can weaken these interactions through a competitive mechanism.
What are van der Waals forces, and what causes them to occur between neighboring atoms?
• When neighbouring atoms are close enough that their outer electron shells almost touch
• This results from temporary imbalances in electric charge distribution within molecules, leading to an attraction between neighboring molecules.
• Weakest non-covalent bonds
Amino acids
• they can be precursors for other molecules
• Cannot be stored or disposed, but can be decomposed:
From
Glucogenic amino acids > Glucose
Ketogenic amino acids > acetyl-coenzyme A
What are the three steps involved in nitrogen (N) removal
- Transamination
- Conversion to NH3
- NH3 enters the urea cycle
Polar amino acids
Have an asymmetrical charge distribution which allows their carboxyl and amide groups to form hydrogen bonds with each other
These amino acids are hydrophilic
Found on the surface of water-soluble proteins
Non polar amino acids
have a side chain with evenly distributed electrons, so they do not form hydrogen bonds, as a result they are found in the hydrophobic core of proteins.
What makes proteins highly diverse in terms of structure and function, and how are they composed?
•Proteins are highly diverse biomolecules both structurally and functionally
• They are essentially polymers of amino acids linked by peptide bonds formed between the carboxyl and amino groups of specific amino acids arranged in a precise sequence, determined by the genetic code contained in messenger RNA.
What is the nature of peptide bonds in proteins, and how does their ability to rotate affect protein structure?
Peptide bonds are rigid with the atoms in the same plane, but they can rotate around this bond. The rotation ability has consequences for the overall protein structure
How does water influence the shape of proteins?
Hydrophobic residues are packed Inside
Hydrophilic are positioned outside
Proteins structure
Primary structure - linear sequence of amino acids
Secondary structure - grouping of primary structure into sheets or spirals
Tertiary structure - 3D secondary structure packing
Quaternary structure - arrangement in space of individual polypeptide subunits
Post translation modification
Glycosylation - addition of carbohydrates
Phosphorylation - Addition of a phosphate group to Ser/Tyr/Thr
DNA
double chain of nucleotides, strung on a backbone of phosphate groups
The sequence of nucleotides determines which proteins are produced, in which cells they are produced, what the function of those cells is.
DNA alphabet
A - Adenine
C- Cytosine
G- guanine
T- Thymine
RNA
• similarly organized, except that instead of T (thymine) we have U (uracil)
• Single stranded, but can fold into various structures
How is the sequence in RNA obtained?
Obtained by Transcribing the information from DNA
Carbohydrates
Monosaccharides form oligosaccharides or polysaccharides through glycosidic bonds between them.
