IV. Gymnosperm

non-flowering plants

Naked seeds (fruits are not produced)

Heterosporous- life cycle

Better adaptation for land habitat

TLS Online TPP Program

#Id: 8758

#XL - T Zoology

The combined hydrophobic and hydrophilic tendencies of individual amino acid residues in proteins can be expressed as hydropathies. The greater a side chain’s hydropathy, the more likely it is to occupy the interior of a protein.

TLS Online TPP Program

#Id: 8759

#XL - T Zoology

Hydrogen bonds, which are central features of protein structures, make only minor contributions to protein stability.

TLS Online TPP Program

#Id: 8760

#XL - T Zoology

This is because hydrogen-bonding groups in an unfolded protein form hydrogen bonds with water molecules. Thus the contribution of a hydrogen bond to the stability of a native protein is the small difference in hydrogen bonding free energies between the native and unfolded states (−2 to 8 kJ ∙ mol−1)

TLS Online TPP Program

#Id: 8761

#XL - T Zoology

The Hydrophobic Effect Has the Greatest Influence on Protein Stability. The hydrophobic effect, which causes nonpolar substances to minimize their contacts with water, is the major determinant of native protein structure.

TLS Online TPP Program

#Id: 8762

#XL - T Zoology

Thermostable proteins have such a high incidence of salt bridges.

TLS Online TPP Program

#Id: 8763

#XL - T Zoology

Thermophilic proteins have increased amounts of Arg, increased occurrence of Ala in helices, and Gly/Ala substitutions (which affect the entropy of the denatured state, and thus its free energy) and increased number of salt bridges.