Chapter 2- Proteins Flashcards
Draw a condensation reaction of two amino acids
Do it
What does the condensation reaction involve and what does it eliminate?
1) amine group (NH2) of one amino acid and the carboxyl group (COOH) of another
2) water is eliminated
What bond is formed?
Peptide bond
What is a dipeptide?
Is a molecule consisting of two amino acids linked by a peptide bond
Because of the different R groups; the twenty amino acids are what?
Chemically diverse
The ribosome can make peptide bonds between any pair of amino acids so it makes polypeptides what?
Diverse- as they can be linked together in any sequence giving a huge range of possible polypeptides
The amino acid sequence of each polypeptide is stored in a codes form in what?
In the base sequence of a gene
How do base sequence of genes store amino acids?
Use genetic code
How many bases at needed to code for each amino acid?
3 codons (bases)
A protein may consist of what?
A single polypeptide or more than one polypeptide linked together
Give an example of polypeptides with 1, 2,3 and 4 polypeptides linked together
1) lysozyme - enzyme in secretion
2) integrin- membrane protein
3) collagen- structural protein in tendons, ligaments , skin etc
4) haemoglobin- transports protein in RBC
The amino acid sequence determines what?
The three- dimensional conformation of a protein
How is the three dimensional conformation of proteins stabilised?
By bonds between R groups of amino acids within the molecule
When disrupted or broken the protein becomes what?
Denatured
How does heat cause desaturation ?
Causes vibrations within the molecule which can break intermolecular bonds
How does pH cause denaturation?
Changes the charge on the R group, breaking ionic bonds within the protein or causing New Ionic bonds to form
Living organisms synthesise many different proteins with what?
A wide range of functions
What 3 examples of the use of proteins?
1) Blood clotting- plasma proteins act as clotting factors that cause blood to turn from liquid to gel in wounds
2) transport of nutrients and gas - proteins in blood help transport oxygen, carbon dioxide, iron and lipids
3) cell adhesion- membrane proteins cause adjacent animal cells to stick to each other within tissues
Name 6 examples of proteins
1) rubisco
2) insulin
3) immunoglobulin
4) rhodopsin
5) collagen
6) spider silk
Outline function of rubisco
Shape and chemical properties of its active site allow it to catalyse the reaction that fixed carbon dioxide from the atmosphere, which provides the source of carbon from which all carbon compounds needed by living organisms can be produced
Outline function of insulin
This hormone is produced as a signal to many cells in the body to absorb glucose and help reduce the glucose concentration of the blood
Outline the function of immunoglobulin
Known as antibodies. They bind to antigens on bacteria or pathogens. Also causes a response such as actin as a marker to phagocytes that can engulf the pathogens
Outline the function of rhodopsin
A membrane protein of rod cells of the retina
Outline the function of collagen
Forms a mesh of fibres in the skin and in the blood vessel walls that resists tearing - gives ligaments and blood vessels their immense strength
Outline function of spider silk
Used to make the webs that spiders live on - when first made it contains regions where the polypeptides forms parallel arrays
What is a proteome ?
Is all the proteins produced by a cell; a tissue or an organism
To find out how many different proteins are being produced what do scientists do?
Mixtures of proteins are removed and then separated by gel electrophoresis
What is a genome?
Is all the different genes of a cell, tissue or organism
Genomes of an organism are fixed m, why are proteomes variable?
Because different cells in an organism make different proteins
The proteome of each organism is what?
Individual - because of small differences in the amino acid sequence of a protein
What are amino acids linked together by and to form what?
By condensation reaction to form polypeptides
