Hydrogen bonds are found between water molecules which allows for strong
cohesion between water molecules. This then means that columns of water can
move up the xylem of plants. Xylem vessels are hollow tubes impregnated with lignin
to help the dead cells not collapse under pressure. When water molecules evaporate
from the leaf by transpiration, the water potential in the leaf cells decreases. This
creates tension, which pulls more water into the leaf. The water molecules are
cohesive and stick together so when some are pulled into the leaf others follow. This
means the whole column of water in the xylem, from the leaves down to the roots,
moves upwards. Hydrogen bonds are important in water because without the
hydrogen bonds moving the water, plants would not be able to photosynthesise and
survive.
Hydrogen bonds are also important in cellulose. Cellulose is a polysaccharide found
in plant cell walls, which consists of long, unbranched beta glucose chains. Individual
cellulose chains are bound to each other by hydrogen bonds so that microfibrils can
be formed. The bonds are formed between these chains due to hydrogen atoms and
hydroxyl groups which firmly hold the chains together. Microfibrils are strong fibres
that provide structural support for cells in plants. The Hydrogen bonds are essential
because without them, the cell wall in plant cells would be weak and give no
structural support.
They are also useful in proteins. The hydrogen bonds in between amino acids create
the secondary structure of proteins. The two types of secondary structures are alpha
helix and beta pleated sheet. These structures are held together by hydrogen bonds
between CO and NH groups. Additionally, in tertiary structures, the proteins are 3D.
The bonds included are polypeptide bonds, ionic bonds, disulfide bridges and
hydrogen bonds. The quaternary structure is formed from several different
polypeptide chains held together by bonds. An example of a protein with a
quaternary structure is haemoglobin.
Finally, hydrogen bonds are essential in DNA replication.
Hydrogen bonds exist between bases on the opposite strands of DNA; Adenine to
Thymine and Cytosine to Guanine. The hydrogen bonds hold the two strands
together. In transcription, the first stage of protein synthesis, the hydrogen bonds
between the two strands of a gene are broken. One of the DNA strands acts as a
template-free-floating RNA nucleotide to form hydrogen bonds with their
complementary exposed bases on the DNA template strand through complementary
base pairing. These hydrogen bonds hold the complementary RNA nucleotides in a
specific order and position. This allows RNA polymerase to join the RNA nucleotides
together in condensation reactions, forming phosphodiester bonds. This pre-mRNA
is then spliced and introns are removed in eukaryotic cells. This mRNA will code for
a specific protein produced in translation such as antibodies produced by plasma
cohesion between water molecules. This then means that columns of water can
move up the xylem of plants. Xylem vessels are hollow tubes impregnated with lignin
to help the dead cells not collapse under pressure. When water molecules evaporate
from the leaf by transpiration, the water potential in the leaf cells decreases. This
creates tension, which pulls more water into the leaf. The water molecules are
cohesive and stick together so when some are pulled into the leaf others follow. This
means the whole column of water in the xylem, from the leaves down to the roots,
moves upwards. Hydrogen bonds are important in water because without the
hydrogen bonds moving the water, plants would not be able to photosynthesise and
survive.
Hydrogen bonds are also important in cellulose. Cellulose is a polysaccharide found
in plant cell walls, which consists of long, unbranched beta glucose chains. Individual
cellulose chains are bound to each other by hydrogen bonds so that microfibrils can
be formed. The bonds are formed between these chains due to hydrogen atoms and
hydroxyl groups which firmly hold the chains together. Microfibrils are strong fibres
that provide structural support for cells in plants. The Hydrogen bonds are essential
because without them, the cell wall in plant cells would be weak and give no
structural support.
They are also useful in proteins. The hydrogen bonds in between amino acids create
the secondary structure of proteins. The two types of secondary structures are alpha
helix and beta pleated sheet. These structures are held together by hydrogen bonds
between CO and NH groups. Additionally, in tertiary structures, the proteins are 3D.
The bonds included are polypeptide bonds, ionic bonds, disulfide bridges and
hydrogen bonds. The quaternary structure is formed from several different
polypeptide chains held together by bonds. An example of a protein with a
quaternary structure is haemoglobin.
Finally, hydrogen bonds are essential in DNA replication.
Hydrogen bonds exist between bases on the opposite strands of DNA; Adenine to
Thymine and Cytosine to Guanine. The hydrogen bonds hold the two strands
together. In transcription, the first stage of protein synthesis, the hydrogen bonds
between the two strands of a gene are broken. One of the DNA strands acts as a
template-free-floating RNA nucleotide to form hydrogen bonds with their
complementary exposed bases on the DNA template strand through complementary
base pairing. These hydrogen bonds hold the complementary RNA nucleotides in a
specific order and position. This allows RNA polymerase to join the RNA nucleotides
together in condensation reactions, forming phosphodiester bonds. This pre-mRNA
is then spliced and introns are removed in eukaryotic cells. This mRNA will code for
a specific protein produced in translation such as antibodies produced by plasma
