Biology Unit 1

Describe 3 ways in which a pathogen may damage host cells.

A pathogen may rupture the host cells
It may break down and use nutrients in the host cells, so that the host cells starve A Pathogen may replicate inside host cells and burst them as it leaves

Describe the Function of Anti-Bodies

Describe and explain how a secondary immune responce differs to a primary immune responce

Antibodies coat pathogens, making it wasier for phagocytes to engulf them

Prevent them from entering host cells

Bind Toxins to neutralise them

Secondary immune responce is faster and produces a quicker, stronger responce [2 Marks]

Memory CCells are produced during primary responce, which remember the foreign antigen [2 Marks]

Second infection - B-Cells quicly divide to form plasma cells, which secrete the correct antibody to the antigen, memory T-cells divide quickly into the right type of T-cell, to kill the cell with the antigen.                             

Describe how monoclonal antibodies can be used to target a drug to cancer cells

Monoclonal antibodies are made against antigens specific to cancer cells

An anti-cancer drug is attatched to the anti-bodies

The antibodies bind to tumour markers on the cancer cells because their binding sites have a complementary shape

This delivers the anti-cancer drug to the cells

How does the pancreas aid digestion?

Name one other gland assosciated with the digestive system

Releases pancreatic juice into the intestine, which contains amylase trypsin chymotrypsin and lipase. Amylase breaks down starch into maltose, chymotrypsin and trypsin break down proteins into peptides, lipase breaks down lipids into fatty acids and glycerol. The pancreatic juice also neutralises stomach acid

Salivary Glands

How is a dipeptide formed?

Describe the structures of protein

Two amino acids join together in a condensation re-action. A peptide bond forms between the carboxyl group of one amino acid and the amino group of the other amino acid. A molecule of water is released

Proteins are made from amino acids, these are joined together in a long polypeptide chain. The sequence of amino acid chain foldsin a certain way to form its secondary structure. This is then coiled into a specific shape which is its tertiary structure. Different polypeptide chains can be joined together in the protein moecule. When these chains join it is known as quaternary structure.