A-Level biology module 2 summary

Compact, water soluble, roughly spherical protein

Long, strong insoluble proteins which do not form complex 3D shapes like globular proteins

Globular proteins that contain a non protein compartment called a prosthetic group

Insulin

Keratin, elastin, collagen

Haemaglobin

Smaller bases which contain single carbon ring

Larger bases which contain double carbon ring

Thymine and cytosine

Adenine and guanine

When two new molecules of DNA are made, each one consists of one old strand of DNA and one new strand

Strand of DNA that contains the code for the protein to be synthesised

5’ to 3’

Lock and key hypothesis states that enzyme active site is complementary to substrate, induced fit hypothesis states that the enzyme active item changes shape slightly to better fit the substrate.

Enzymes that work inside a cell as are used to synthesis polymers from monomers (polysaccharides from glucose)

Catalase, breaks down H2O2 which is toxic to oxygen and water inside plant and animal tissue

Enzymes that work outside the cell and can move substrates from outside the cell to inside to be used for survival

Trypsin which acts as a protease and breaks down proteins to amino acids so that they can be absorbed by the cell

Temperature change against enzyme activity

pH change against enzyme activity

Maximum rate of reaction

A molecule with a similar shape to a complementary substrate to an enzyme will bind to the enzyme active site to prevent ES complexes from forming, the inhibitors action is reversible because the only temporarily bind to the active site

Inhibitor binds to allosteric site, this causes the tertiary structure of the enzyme to change which causes the active site shape to change, resulting in substrates no longer being able to bind to the active site to form ES complexes

Absence of inhibitor

Fixed quantity of competitive inhibitor

Fixed quantity of non-competitive inhibitor

Cofactors are usually non organic molecules such as metal ions whereas coenzymes are usually organic molecules such as vitamins

Ca2+, Fe2+, Cl-

Vitamin b5, vitamin b3

Cofactors bind loosely to proteins in order to activate them, prosthetic groups are tightly bond and form a permanent feature of the protein

Long periods of growth and normal working separate divisions

G1, S, G2

Proteins from which organelles are synthesised are produced and organelles replicate, cell increases in size

Synthesis phase, DNA is replicated in the nucleus

Cell continues to increase in size, energy stores are increased and duplicated DNA is checked for errors

The phase when the cell leaves the cycle, either temporarily or permanently

• Differentiation- cell is no longer able to divide

• DNA may be damaged so no longer viable

• cell size

• Nutrients

• Growth factors

• DNA damage

• cell size

• DNA replication

• DNA damage

Centromere

• chromosomes condense to become visible under a light microscope

• Protein microtubules form spindle fibres

• Centrioles move to oposite poles of the cells

• Nuclear envelope disappears

Chromosomes are moved by spindle fibres to form a plane at the equator of the cell, called the metaphase plate

• centromeres holding together the chromatids divide

• Chromatids are separated and pulled to opposite sides of the cell by the spindle fibres

• chromatids reach the poles and are now called chromosomes

• The two new sets of chromosomes assemble at each pole

• Nuclear envelope reforms

They form a cleavage furrow which causes cell surface membrane to be pulled inward by cytoskeleton until it fuses around the middle, forming two new cells

Vesicles from the Golgi assemble where the metaphase plate was, the vesicles fuse with each other and the cell surface membrane, forming two new cells

Stem cells which can differentiate into any type of cell

Stem cells which can form any type of tissue but not whole organismw

Stem cells that an only form a range of cells within a certain type of tissue

• embryonic stem cells (totipotent)

• Tissue stem cells (multipotent)

Meristems (wherever growth is occurring in plants such as tips of roots and shoots)

• resolution of 3-10nm

• Magnification of 500,000x

• resolution of 0.5nm

• Magnification of 1,000,000x

SEM produces 3D images while TEM produces 2D images