chapter 2- nucleic acids and proteins Flashcards
whats a protein
A biomacromolecule made of amino acid chains folded into a 3D shape.
whats a polypeptide
A long chain of amino acids joined through a condensation reaction.
whats the proteome
All the proteins that are expressed by a cell or organism at a given time.
whats a peptide hormone
A protein signalling molecule that regulates physiology or behaviour
whats a carboxyl group
the functional group on amino acid molecules that contains a hydroxyl (-OH) and an oxygen double-bonded to a carbon atom.
whats an amino group
the functional group on amino acid molecules that is made up of one nitrogen and two hydrogens (NH2).
whats the R-group
the variable portion of an amino acid molecule. It can be one of twenty variations and determines the identity of the amino acid.
whats a condensation reaction
a reaction where two monomers join to form a larger molecule, producing water as a by-product.
whats a biomacromolecule
a large organic molecule found in organisms.
whats an RNA polymerase
Function: Enzyme
Explanation: Organic catalysts that speed up chemical reactions
Whats a chloride channel embedded within the plasma membrane
Function: transport
Explanation: embedded in membranes controls the entry and exit of substances from a cell
whats the elongated structure of keratin
Function: structural
Explanation: support cell and tissue shape
whats an antibody
Function: defence
Explanation: involved in the immune system by recognising and destroying pathogens
what are amino acids made up of
Each amino acid is made up of a central carbon, an amino group (NH2), a carboxyl group (COOH), and an R-group.
how many types of amino acids are there and what causes the differences
There are 20 amino acids, all with different R-groups. This difference makes each amino acid unique from one another, and also determines their identity.
what are the four levels of protein structures
There are four levels of protein structures:
Primary level – The sequence of amino acids
Secondary level – Their arrangement into alpha-helices, beta-sheets, or random coils
Tertiary level – The functional 3D shape of the protein
Quaternary level – The bonding of multiple polypeptide bonds together
For the protein to function correctly, it must carefully fold into the correct functional structure. As we go down the levels, the structure gets more and more complex.
Therefore, the protein’s folding at the tertiary and quaternary level relies heavily on it’s primary level, in particular, the bonding between the different R-groups of the amino acid.
what are nucleic acids and what are the two types of nucleic acid structures
Nucleic acids are large polymers of nucleotides monomers that store genetic information and help with the synthesis of proteins in organisms.
There are two types:
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
dna and rna similarities and differences
They both have the same basic structure:
A phosphate group
A five-carbon (pentose) sugar ring
A nitrogen containing base (nitrogenous base)
Their main difference is the presence or absence of an oxygen atom at the 2’ position (2-prime position) of the five-carbon sugar ring.
what are nucleotides connected by
Nucleotides are connected via a phosphodiester bond (a strong covalent bond – sharing of electrons between two atoms) formed from a condensation reaction. The linkage of the sugar and phosphate is called a sugar-phosphate backbone of nucleotides.
what is the protein secretory pathway
The protein secretory pathway involves various different organelles that produce, fold, modify, and package proteins, eventually exporting them from the cell via exocytosis.
whats exocytosis and the steps involved in it
A process by which contents of a vesicle are released from a cell. It is a form of bulk transport and is a form od active transport (requiring energy).
A vesicle is a small fluid-filled organelle enclosed in a phospholipid membrane that transports substances around the cell. The fluidity of a phospholipid bi-layer allows exocytosis to occur.
Process:
A vesicle containing secretory products is transported to the plasma membrane
The membrane of the vesicle fuses with the plasma membrane
The secretory products are released from the cell into the extracellular environment
steps of the protein secretory pathway
Proteins are assembled at the ribosomes.
If the protein is to be secreted, it is usually at the rough ER for correct folding.
It is then passed onto the Golgi Body through a transport vesicle.
The protein could have chemical groups added at the Golgi, then it is packaged into secretory vesicles for export.
Secretory vesicles bud off the Golgi body and fuses with the plasma membrane, releasing the proteins from within into the extracellular environment
