Lecture 1 & 2 Chemical components of the cell Flashcards
Polymers of Nucleotides:
DNA, RNA
Polymer of Amimo acids:
Proteins
Polymer of Fatty Acids:
Lipids
Polymer of Sugars:
Polyssacharides
Nucleotides are the building bloks for what?
DNA
What are nucleotides composed of?
phosphate group, deoxyribose (5 carbon sugar), Nitrogen-containing base (adenine, thymine, guanine, cytosine)
Deoxyribose sugar has what element missing?
Oxygen missing from the 2’ of sugar
How are nucleotides bonded together?
covalently linked via a sugar phosphate backbone to form nucleotides (phosphodiester bonds), following from the 5’ phosphate to 3’ hydroxyl end
How is DNA formed to make it double stranded?
antiparallel chains, stuctured by the sugar-phosphate backbone and held together by hydrogen bonding between complimentary base pairs
Number of H bonds between A and T?
2
Number of H bonds between G and C?
3
What is the relation of the two antiparallel strands to one another? What does this allow?
Reverse compliments of eachother, which allows for DNA replication with one strand acting as a template to another
What does DNA code for?
RNA
Replication -> ………….. -> …………..
Replication -> Transcription -> Translation
3 differences of RNA from DNA:
ribose replaces deoxyribose
uracil replaces thymine
RNA is single stranded
4 types of RNA and functions:
mRNA - translated into proteins in rER
rRNA - structural rna which is important for making proteins from rna molecules
tRNA - delivers aa for translation
microRNA - regulates expression of other mRNA (targets mRNA to degrate or blok translation)
mRNA is translated into proteins by what?
ribosomes
In translation, how are the codes read?
In triples: codons
What is the number of possible combinations for aa?
64
only 24 aa present - mulitiple codons code for same aa, stop codons, regulatory codons
AA are the building bloks for what?
Proteins
AA are composed of what?
H group
Carbonyl group
R group
Amino group
How are aa bonded together?
condensation reactions in the ribosome (release of H2O)
Peptide bond formed by the carbonyl and amino group
How do AA vary from one another?
R groups
side chains affect the behaviour of the protein
Non-polar side chains in AA - properties:
unreactive side chains (no H bonding)
hyrdrophobic side chains
Non-polar side chains in AA - alphabet:
Gly, Ala, Val, Leu, Ile, Met, Phe, Trp, Pro
Polar side chains in AA - properties
reactive side chains
hydrophillic side chains
accept/donate H bonds
Polar side chains in AA - alphabet:
Ser, Thr, Cys, Tyr, Asn, Gln
Charged side chains in AA - properties:
(theres postive and basic)
Salt bridges
H bonding
Hydrophillic
Charged side chains in AA - alphabet:
Negative/acidic: Asp, Glu
Positive/basic: Lys, Arg, His
1°protein stucture:
the sequence of aa in a protein
Mutation: sickle cell anemia (Glu6Val Hb), change in aa of the sequence E6V
2°protein stucture:
the local fold of a protein dependent on H bonds (stability)
- alpha helix
- beta sheet
3°protein stucture:
3D shape of a protein with the interactions between different domains/ side chains
Interactions:
- van der waals interactions
- disulfide bridges
- salt bridges
- H bonding
4°protein stucture:
interations between two or more polypeptide chains to form a protein complex
- collagen
- haemoglobin
What type of bonds are present in fully saturated fatty acids?
single bonds
- palmitic acid
- stearic acid
What is the enzyme which transforms Stearic acid (saturated) to Oleic acid (unsaturated)?
desaturase - binds to one of the long ends of the fatty acid and removes H bonds from carbon to form double bond
What is a monounsaturated acid?
one double bond
(oleic acid)
What does cis mean?
H on the same side
What does trans mean?
H on oppostie sides
What is a polyunsaturated acid?
many double bonds
(linoleic acid - 2 double bonds = omega6)
(alpha-linoleic acid - 3 double bonds = omega3)
What is the effect on the fact that saturated and unsaturated fatty acids pack differently in membranes?
they change the fluidity and premeability
Creation of mediators of inflammation, pain, fever, etc. with Omega6:
membrane phospholipids –(phospholipidase)–> omega6
–(elongases desaturases)–> archidonic acid
–(cyclo-oxygenase 2, cox-2)–> paracrines, leukotrienes, prostaglandins
–> mediators of inflammation, pain, fever, etc
What are fatty acids primarily stored as?
Triglycerides
What are triglycerides composed of?
3 glycerols bonded to fatty acids through ester bonds
Comparison of energy storage in fat and glycogen:
more energy stored in fat
takes longer to produce ATP from fat
What type of molecule is glycogen?
Storing molecule for sugar and fatty acids
Glycine
Gly, G
Alanine
Ala, A
Valine
Val, V
Leucine
Leu, L
Isoleucine
Ile, I
Methionine
Met, M
Trytophone
Trp, T
Proline
Pro, P
Serine
Ser, S
Threonine
Thr, T
Cysteine
Cys, C
Tryosine
Tyr, Y
Asparagine
Asn, N
Glutamine
Gln, Q
Aspartic
Asp, D
Glutamic acid
Glu, E
Lysine
Lys, K
Arginine
Arg, R
Histidine
His, H