ch5 Flashcards
distinguish between a monomer and a polymer
- A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds
- The repeating units that serve as the building blocks of a polymer are smaller molecules called monomers
Explain how macromolecules are formed through the condensation of monomers into polymers provide an example
- Process called dehydration= two molecules are covalently bonded to each other with the loss of a water molecule
- When a bond forms between two monomers, each monomer contributes part of the water molecule that is released during the reaction: One monomer provides a hydroxyl group ( -OH), while the other provides a hydrogen ( -H). This reaction is repeated as monomers are added to the chain one by one, making a polymer (also called polymerization).
- example- dehydration of many a-glucose molecules to for starch/ formation of cellulose and more
explain how macromolecules are broken up through the hydrolysis of polymers into monomers
- Process called hydrolysis = water breakage
- The bond between monomers is broken by the addition of a water molecule, with a hydrogen from water attaching to one monomer and the hydroxyl group attaching to the other.
- example- digestion, polymers too large to digest so our digestive system with the help of enzymes breaks down the polymer to monomers
define macromolecules
A macromolecule is a very large molecule, such as a protein. They are composed of thousands of covalently bonded atoms.
Distinguish between monosaccharides, disaccharides and polysaccharides.
simplest carbohydrates are the monosaccharides, or simple sugars; these are the monomers from which more complex carbohydrates are built. A disaccharide consists of two monosaccharides joined by a glycosidic linkage, a covalent bond formed between two monosaccharides by a dehydration reaction. Carbohydrate macromolecules are polymers called polysaccharides, composed of many sugar building blocks.
Compare storage polysaccharides with structural polysaccharides.
- Some polysaccharides serve as storage material, hydrolyzed as needed to provide sugar for cells. Other polysaccharides serve as building material for structures that protect the cell or the whole organism.
- compare starch to cellulose
- The only difference between the structural polysaccharides and storage polysaccharides are the monosaccharides used. By changing the configuration of glucose molecules, instead of a structural polysaccharide, the molecule will branch and store many more bonds in a smaller space.
What is the architecture and function of a polysaccharide determined by?
- its sugar monomers and by the positions of its glycosidic linkages.
describe structure of starch
- amylose= unbranched, 1-4 linkages a-glucose
- amylopectin= branched, 1-4 and 1-6 linkages a-glucose
describe structure of cellulose
- 1-4 glycosidic linkages, b-glucose
- each consecutive monomer is rotated at 180 degrees to form the glycosidic bond
- Cellulose is never branched, and some hydroxyl groups on its glucose monomers are free to hydrogen-bond with the hydroxyls of other cellulose molecules lying parallel to it when held together in this way they are grouped into units called microfibrils
Distinguish among the three types of lipids: triacylglycerols(trigyceride) , phospholipids and steroids; describe the a-composition, b-characteristics (except steroids) and c-biological functions of each.
1) Triacylgycerols
a- unsaturated and saturated, oils and fats
Most animal fats are saturated and most plant and fish fats are unsaturated
b- in Unsaturated fats The kinks where the cis double bonds are located prevent the molecules from packing together closely enough to solidify at room temperature and in saturated fats their flexibility allows the fat molecules to pack together tightly are also solid at room temperature.
c- The major function of fats is energy storage. The hydrocarbon chains of fats are similar to gasoline molecules and just as rich in energy. adipose tissue also cushions such vital organs as the kidneys, and a layer of fat beneath the skin insulates the body.
2)phospholipids
a- only two fatty acids attached to glycerol rather than three. The third hydroxyl group of glycerol is joined to a phosphate group, which has a negative electrical charge
in the cell. Typically, an additional small charged or polar molecule is also linked to the phosphate group.
b- hydrophilic (polar) head and two hydrophobic (nonpolar) tails.
c- The phospholipid bilayer forms a boundary between the cell and its external environment and establishes separate compartments within eukaryotic cells; in fact, the existence of cells depends on the properties of phospholipids.
3)steroids
a- carbon skeleton consisting of four fused rings. Different steroids are distinguished by the particular chemical groups attached to this ensemble of rings.
c- component of cell membranes and signalling molecules such as hormones
Why can’t lipids form polymers?
They aren’t polymers because they are made up of smaller units of different kinds (like glycerol and fatty acids) rather than monomers that repeat themselves.
Describe lipids affinity for water
Little to no affinity as they are hydrophobic.
State the difference between unsaturated and saturated
-saturated is when the carbon skeleton is bonded to as many hydrogens as possible, said
to be saturated with hydrogen
-unsaturated fatty acid has one or more double bonds, with one fewer hydrogen atom on each double-bonded carbon.
State the difference between cis and trans bonds
- cis is on the same side
- trans is across
State the difference between cis and trans fatty acid
Cis fats are the typical form of unsaturated fat found in nature, while trans fats are made through hydrogenation. Trans fats are linear and have a similar shape to saturated fats (however they are still unsaturated), so many of the physical properties are the same. Cis fats have a different shape, so the physical properties are different.
explain the process of hydrogenation
unsaturated fats have been synthetically converted to saturated fats by adding hydrogen, allowing them to solidify.
which stores more energy fat or polysaccharide?
fat because
fat vs polysaccharide
9cal/g > 4cal/g
Provide function and example for Enzymatic protein
Function: Selective acceleration of chemical reactions
Example: Digestive enzymes catalyse the hydrolysis of bonds in food molecules.
Provide function and example for storage protein
Function: Storage of amino acids
Examples: Casein, the protein of milk, is the major source of amino acids for baby mammals. Plants have storage proteins in their seeds. Ovalbumin is the protein of egg white, used as an amino acid source for the developing embryo.
Provide function and example for hormonal protein
Function: Coordination of an organism‘s activities
Example: Insulin, a hormone secreted by the pancreas, causes other tissues to take up glucose, thus regulating blood sugar concentration.
Provide function and example for defensive protein
Function: Protection against disease
Example: Antibodies inactivate and help destroy viruses and bacteria.
Provide function and example for transport protein
Function: Transport of substances
Examples: Haemoglobin, the iron-containing protein of vertebrate blood, transports oxygen from the lungs to other parts of the body. Other proteins transport molecules across membranes, as shown here.
Provide function and example for receptor protein
Function: Response of cell to chemical stimuli
Example: Receptors built into the membrane of a nerve cell detect signalling molecules released by other nerve cells.
Provide function and example for structural protein
Function: Support
Examples: Keratin is the protein of hair, horns, feathers, and other skin appendages. Insects and spiders use silk fibers to make their cocoons and webs, respectively. Collagen and elastin proteins provide a fibrous framework in animal connective tissues.
Provide function and example for Contractile and motor protein
Function: Movement
Examples: Motor proteins are responsible for the undulations of cilia and flagella. Actin and myosin proteins are responsible for the contraction of muscles.
state the 8 protein functions
Contractile and motor, structural, receptor, transport, defensive, hormonal, storage, enzymatic
describe the structure of an amino acid
At the center of the amino acid is an asymmetric
carbon atom called the alpha (α) carbon, around it is an amino group, a carboxyl group, a hydrogen atom, and a variable group symbolized by R. The R group, also called the side chain, differs with each amino acid.
how are peptide bonds formed
When two amino acids are positioned so that the carboxyl group of one is adjacent
to the amino group of the other, they can become joined by a dehydration reaction, with the removal of a water molecule. The resulting covalent bond is called a peptide bond
from where to where do we read a polypeptide chain
N-terminus to C-terminus
Distinguish the 4 levels of protein structure by the different shapes and the various chemical bonds that stabilize each structural level.
1) Primary Linear chain of amino acids Primary structure is determined by inherited genetic information dictates secondary and tertiary structure, due to the chemical nature of the backbone and the side chains (R groups) of the amino acids along the polypeptide.
2) Secondary
Regions stabilized by hydrogen bonds between atoms of the polypeptide backbone
coils and folds result of hydrogen bonds between the repeating constituents of the polypeptide backbone
Within the backbone, the oxygen atoms have a partial negative charge, and the hydrogen atoms attached to the nitrogens have a partial positive charge.
-α helix, a delicate coil held together by hydrogen bonding between every fourth amino acid,
-β pleated sheet, in this structure two or more segments
of the polypeptide chain lying side by side (called β strands) are connected by hydrogen bonds between parts of the two parallel segments of polypeptide backbone
3) Tertiary
Three-dimensional shape stabilized by interactions between side chains
hydrophobic interaction, h-bonds, disulfide bridges, ionic bonds
4) Quaternary
Association of two or more polypeptides (some proteins only)
example 1- is collagen, which is a fibrous protein that has three identical helical polypeptides intertwined into a larger triple helix, giving the long fibers great strength.
example 2- haemoglobin, has 2 a-globin and 2 b-globin, contains a non-polypeptide component called heme with an iron atom that binds oxygen.
Describe protein denaturation, and state why it causes a loss of normal function of a protein.
pH, salt concentration, temperature, or other aspects of its environment are altered, the weak chemical bonds and interactions within a protein may be destroyed, causing the protein to unravel and lose its native shape, a change called denaturation
Because it is misshapen, the denatured protein is biologically inactive.
Most proteins become denatured if they are transferred from an aqueous environment to a nonpolar solvent, such as ether or chloroform; the polypeptide chain refolds so that its hydrophobic regions face outward toward the solvent. Other denaturation agents include chemicals that disrupt the hydrogen bonds, ionic bonds, and disulfide bridges that maintain a protein’s shape. Denaturation can also result from excessive heat, which agitates the polypeptide chain enough to overpower the weak interactions that stabilize the structure.
What are nucleic acids responsible for?
storing genetic information and transferring that
information for protein synthesis
what are the monomers and polymers of nucleic acids called?
nucleotides
polynucleotides
what is gene expression?
DNA also directs RNA synthesis and, through RNA, controls protein synthesis; this entire process is called gene expression
describe the 3 step process of gene expression
1- Synthesis of
mRNA in the
nucleus
2-Movement of
mRNA into cytoplasm via nuclear pore
3-Synthesis of protein (site of synthesis is ribosomes) using information carried on mRNA
describe the structure of a nucleotide
a five-carbon sugar (a pentose), a nitrogen-containing (nitrogenous) base, and one to three phosphate groups
Provide 2 types of nucleic acid and their functions
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), enable living organ- isms to reproduce their complex components from one gen- eration to the next.
DNA= provides directions for its own replication. RNA= to convert the information stored in DNA into proteins. (eg mRNA conveys genetic info to ribosomes)
what are nucleoside?
The portion of a nucleotide without any phosphate groups eg nitrogenous bases
which nitrogenous bases fall under pyrimidines and which are purines and how many rings do each group have
Pyrimidines: C,T,U 1 ring
Purine: A,G 2 rings
describe formation of polynucleotide
- via dehydration reaction
- dehydration occurs on carbon 3 and 5 causing the formation of a phosphodiester bond
- This bonding results in a repeating pattern of sugar-phosphate units called the sugar-phosphate backbone
in what order do we read the bases?
5’ to 3’ end
what are the differences and similarities in DNA and RNA
-Similarities
both have phosphate groups
have pentose sugar
have nitrogenous base
-differences
DNA has one less oxygen on carbon 2’
DNA strands form a double helix whereas RNA is more variable in shape
RNA has U, DNA has T
what are antiparallel strands
are antiparallel if they run parallel to each other but with opposite directionality
5’ to 3’ and 3’ to 5’
