Lecture 1 Cells

Question 1

Prokaryotic cells
Bacteria
Archaea

Answer 1

• 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

Question 2

Eukaryotic cells
Unicellular
Plants, animals

Answer 2

• 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

Question 3

Elemental composition of biomolecules

Answer 3

Carbon
Oxygen
Hydrogen
Nitrogen

Question 4

Subunits of biomolecules that assemble into a larger structure

Answer 4

Fatty acids > Glycerides

Nucleotides > Nucleic acids

Monosaccharides > polysaccharides

Amino acids > Proteins

Question 5

What are chemical bonds influenced by?

Answer 5

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.

Question 6

What are the 2 main types of chemical bonds?

Answer 6

Ionic bonds where e- are transferred

Covalent bonds where e- are shared

Question 7

What are the types of non-covalent chemical bonds?

Answer 7

Hydrogen bonds

Electrostatic interactions

Van Der Waals forces

Question 8

Hydrogen bonds

Answer 8

• 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

Question 9

What role do electrostatic interactions play in enzyme-substrate interactions, and how can the presence of charged ions affect these interactions?

Answer 9

• Can explain the interactions between enzymes and their substrate.

• The presence of charged ions can weaken these interactions through a competitive mechanism.

Question 10

What are van der Waals forces, and what causes them to occur between neighboring atoms?

Answer 10

• 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

Question 11

Amino acids

Answer 11

• 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

Question 12

What are the three steps involved in nitrogen (N) removal

Answer 12

1. Transamination
2. Conversion to NH3
3. NH3 enters the urea cycle

Question 13

Polar amino acids

Answer 13

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

Question 14

Non polar amino acids

Answer 14

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.

Question 15

What makes proteins highly diverse in terms of structure and function, and how are they composed?

Answer 15

•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.

Question 16

What is the nature of peptide bonds in proteins, and how does their ability to rotate affect protein structure?

Answer 16

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

Question 17

How does water influence the shape of proteins?

Answer 17

Hydrophobic residues are packed Inside

Hydrophilic are positioned outside

Question 18

Proteins structure

Answer 18

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

Question 19

Post translation modification

Answer 19

Glycosylation - addition of carbohydrates

Phosphorylation - Addition of a phosphate group to Ser/Tyr/Thr

Question 20

DNA

Answer 20

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.

Question 21

DNA alphabet

Answer 21

A - Adenine
C- Cytosine
G- guanine
T- Thymine

Question 22

RNA

Answer 22

• similarly organized, except that instead of T (thymine) we have U (uracil)

• Single stranded, but can fold into various structures

Question 23

How is the sequence in RNA obtained?

Answer 23

Obtained by Transcribing the information from DNA

Question 24

Carbohydrates

Answer 24

Monosaccharides form oligosaccharides or polysaccharides through glycosidic bonds between them.

Question 25

What is another form of carbohydrate organization?

Answer 25

glycosaminoglycans

Question 26

Lipids

Answer 26

• are insoluble in water = Hyrophobic

Question 27

How are phospholipids formed?

Answer 27

If fatty acids bind to glycerol and with a phosphate group, then phospholipids are formed