B1.2 Fix answers Flashcards
Draw the generalized structure of an amino acid.
H
|
H O
H | /
N - C —-C /
H | \ \
R \ \
O
Alpha carbon
Amino Side. Carboxyl group
Group. Chain
monomers that are used to make proteins.
Label the amine group, carboxyl group, alpha carbon and R group on an amino acid.
H
|
H O
H | /
N - C —-C /
H | \ \
R \ \
O
Alpha carbon
Amino Side. Carboxyl group
Group. Chain
monomers that are used to make proteins.
Define dipeptide, oligopeptide and polypeptide.
Dipeptide: 2 amino acids.
Oligopeptide: 2-20 amino acids.
Polypeptide: More than 20 amino acids.
Amino acids join together through a condensation reaction (Interactive 1). A peptide bond is formed when the carboxyl group (–COOH) of one amino acid reacts with the amino group (–NH2) of another amino acid to form a dipeptide. A molecule of water (H2O) is released as a byproduct. The peptide bond formed is a type of covalent bond and, therefore, is very stable.
The N-terminal (amino-terminal) end of the dipeptide refers to the free amino group that is not involved in the peptide bond, while the C-terminal (carboxyl-terminal) end refers to the unbound carboxyl group. More amino acids can be added to the dipeptide through the formation of a new peptide bond between an incoming amino acid and the C-terminal (carboxyl terminal) of the dipeptide. This process can be repeated multiple times to form longer chains of amino acids, called polypeptides. Every time an amino acid joins the growing polypeptide strand and a new peptide bond is formed, another water molecule is released. Subtopic D1.2 covers the formation of polypeptides.
Draw peptide bond formation in a condensation reaction between two amino acids.
In a condensation reaction, two amino acids form a peptide bond by joining the carboxyl group of one amino acid with the amino group of another, releasing a water molecule.
amino acid + amino acid → dipeptide + 1 water molecule
Condensation reaction between two amino acids. Once the water is removed, the C bonds to the N in a peptide bond.
State where in the cell polypeptide formation occurs.
.
Ribosomes
Compare the source of amino acids by plant and animal cells.
Plant Cells:
Synthesize amino acids from inorganic nitrogen sources (nitrate or ammonium).
Use carbon skeletons from photosynthesis to build amino acids.
Animal Cells:
Obtain amino acids from dietary protein intake.
Break down ingested proteins into amino acids through digestion.
Define “essential” and “non-essential” as related to dietary amino acids.
Essential amino acids are the amino acids that your body cannot produce and therefore you must obtain them from the food that you eat.
Non-essential amino acids can be produced by the body from other amino acids or by the breakdown of proteins. both important
Outline why vegan diets require attention to food combinations to ensure essential amino acids are consumed.
Vegan diets can provide all the essential amino acids necessary for a healthy diet through plant-based protein sources such as beans, lentils, nuts, seeds and tofu (Figure 2). However, if following a vegan diet, it is necessary to ensure that adequate amounts of these protein sources are consumed for optimal health
Outline why there is a limitless diversity of DNA base sequences.
The infinite variety of possible peptide chains arises from the ability to combine the 20 different amino acids in any sequence. This allows for creation of an almost limitless number of unique proteins with different structures and functions. The genetic code, combined with the ability to generate diverse combinations of amino acids, is what makes the complexity and diversity of life possible. The genetic code is composed of codons, which are groups of three nucleotides that specify the type of amino acid or stop signal required. There are 64 different codons in total, but only 20 amino acids
Define denaturation.
Denaturation is a process in which the structure of a protein is altered causing it to lose function, usually permanently
Explain the effect of pH on temperature on protein structure and function.
All proteins have a specific range of temperature and pH for their optimal activity. As all enzymes are proteins, it is essential for them to be exposed to their ideal conditions to maintain efficiency. Extreme changes in pH can affect protein solubility and shape by altering the protein’s charge. This can lead to irreversible changes in protein structure, causing inactivity. For example, the enzyme pepsin requires an acidic environment to function, while an alkaline environment will render it inactive.
Temperature is another critical factor that can cause protein denaturation. High temperatures can break the weak hydrogen bonds holding the protein structure together, causing the protein to unfold and lose function. Most human proteins function optimally at body temperature (~37 °C). Some organisms that live in extreme high-temperature environments have proteins that can only function at higher temperatures. Low temperatures can also affect protein structure, but to a lesser extent than high temperatures
Outline the effect of R-group structure on the properties of an amino acid, with reference to hydrophilic, hydrophobic, polar and charged.
R-groups can be hydrophobic or hydrophilic. Hydrophobic R-groups are non-polar and tend to repel water molecules. Hydrophilic R-groups are polar or charged, acidic or basic, and tend to attract water molecules. Polar R-groups contain partial charges that interact with water molecules, while charged R groups can be either positively charged (basic) or negatively charged (acidic). the R-group is what gives each amino acid its unique characteristics. The R-groups of the amino acids present in a polypeptide determine the properties of the assembled polypeptides
Identify the “backbone” of a polypeptide.
Polypeptide Backbone: The repeating sequence of atoms in a protein chain, consisting of
−
N-C-C
−
−N-C-C− units from the amino and carboxyl groups of amino acids.
Structure: N (amide nitrogen) - C
𝛼
α (alpha carbon) - C (carbonyl carbon).
Function: Provides structural support and determines the overall shape of the protein.
Define “confirmation” as related to protein structure.
Conformation: The three-dimensional shape or arrangement of a protein molecule.
Importance: Determines protein function and interaction with other molecules.
Factors: Influenced by amino acid sequence, environmental conditions, and molecular interactions.
Describe the primary structure of a protein, including the type of bonding involved.
Primary Structure: The linear sequence of amino acids in a polypeptide chain.
Bonding: Peptide bonds link amino acids through condensation reactions.
Significance: Determines higher-level structures and ultimately protein function.
