Enzymes and Their Activity

Enzymes 1.7.25

• Enzymes are globular proteins that act as biological catalysts
• Catalysts speed up chemical reactions by lowering the activation energy needed for the reaction to occur.
• A molecule that interacts with an enzyme is likely a substrate
• Enzymes have a specific role in the human body. Examples include lactase breaking down lactose.
• High fever (105°F) can denature enzymes, reducing their activity

Effects of Temperature, pH, and Substrate Concentration on Enzyme Activity

• Each enzyme has an optimum temperature at which it functions most effectively
• Increasing temperature above the optimum causes enzyme denaturation
• Decreasing the temperature reduces the collisions between enzyme and substrate molecules, thus decreasing the reaction rate.
• Each enzyme has an optimum pH range
• Deviations from the optimum pH leads to enzyme denaturation
• Initially increases in substrate concentration will increase enzyme activity, but once the substrates are saturated, additional substrate concentrations do not increase the reaction rate further.

Harmless Skin Virus Fights Acne

• Acne occurs when hair follicles become blocked with sebum
• Bacteria, such as Propionibacterium acnes, can contaminate and infect the plugged follicles.
• Phage viruses appear to help reduce acne by targeting and destroying specific bacteria using endolysin.
• A protein called endolysin destroys bacteria by breaking down their cell walls.
• Phages are programmed to target only specific bacteria, unlike antibiotics that kill many types of bacteria.

Proteins

• Proteins are chains of amino acids
• The structure of proteins determines their function
• Enzymes are proteins that catalyze biochemical reactions
• The active site is the location on an enzyme where a substrate binds
• Enzyme-substrate specificity means the active site of each enzyme has a shape that matches the shape(s) of a specific substrate(s).

Denaturation

• Denaturation is a structural change in a protein that causes a loss of its biological properties.
• Changes in temperature and pH are some causes of protein denaturation

Outline the Range of Functions of Proteins

• Proteins act as enzymes, biological catalysts

• Examples include lactase, which breaks down lactose into galactose and glucose

• Proteins act as hormones: Chemical Messengers

• Example Insulin signals the uptake of sugar from the blood stream into the liver cells

• Proteins act as cell receptors

• Example Insulin Receptors in liver cells

• Proteins assist the immune system

• Example antibodies recognizes pathogens

• Proteins form structural components in tissues

• Example Collagen is the main structural protein in connective tissues between bones.

Outline the Organization of Human DNA

• Coding DNA contains instructions to build proteins
• Non-coding DNA regulates the transcription of genes
• 'Junk DNA' has no known function.

Outline the Evidence for Evolution

• Fossils are the preserved remains of ancient organisms
• Fossils evidence changes in organisms over time
• Fossil evidence includes bone structures, impressions in rock, remains in amber, and ancient pollen grains
• Domesticated plants and animals demonstrate selective breeding to produce specific traits
• Homologous structures have similar underlying structures, but different functions, suggesting a common ancestor
• DNA sequence comparisons can determine evolutionary relationships based on shared nucleotides or differences in their sequences and lengths

Describe the genetic code

• The Genetic Code is a system allowing cells to translate information from nucleic acids (DNA and RNA) into proteins.
• Three RNA Nucleotides form a codon—each codon codes for one amino acid.
• Amino acid sequences form proteins.

Outline the Process of Translation Leading to Protein Formation

• mRNA molecules carry information stored in DNA.
• mRNA leaves the nucleus and travels to ribosomes in the cytoplasm.
• Each tRNA molecule carries a specific amino acid.
• Anticodons on the tRNA bind with complementary codons on the mRNA.
• Enzymes bond amino acids together to form a protein structure
• Translation stops at a STOP codon

Define Mutation

• A gene mutation is any change in the DNA base sequence of a gene

Nucleotides, DNA Replication, and Complementary Bases

• Nucleotides are the building blocks of DNA.
• Describes DNA Replication, using terms like template, enzyme and nucleotides.
• Complementary base pairs in DNA are: Adenine pairs with Thymine (A-T) and Guanine pairs with Cytosine (G-C)

Genetic Code and Codons

• A codon is three RNA bases that together code for one amino acid
• Translation of codons from a genetic code chart provides amino acid sequences (codon table provided)

Describe a gene

• A gene is a segment of DNA that contains the genetic information needed to produce a protein.
• It consists of a series of bases, A, C, T, G.
• The sequence of bases determines the sequence of amino acids in the protein they encode, and the shape and function of the resulting protein(enzymes, structural components etc.).

Define Trait, Heredity, Chromosome and Gene

• Traits are characteristics determined by genes
• Heredity is the transmission of genetic information from one generation to the next.
• Chromosomes are thread-like structures composed of DNA and proteins.
• Genes are segments of DNA that contain instructions for building proteins

Define DNA

• DNA, deoxyribonucleic acid, stores genetic information needed for heredity.
• It is composed of subunits called nucleotides

Explain how a DNA double helix is formed

• Two single strands of DNA form Hydrogen bonds between bases.
• Bases A & T and, G & C pair together.
• Once formed, it twist into a double helix shape.

This quiz covers the fundamental principles of enzyme function, including their roles as biological catalysts and the factors affecting their activity. Key topics include temperature, pH levels, and substrate concentration influences on enzymes. Test your understanding of enzyme dynamics and their importance in the human body.