1.2 Flashcards
What is DNA?
stands for deoxyribonucleic acid
polymer made from many repeating subunits called nucleotides
contains instructions for growth and development
genetic material that determines characteristics
what are the functions of DNA?
carries set of chemical instructions that make all proteins
determines traits and characteristic of organisms
Where is DNA found?
DNA is contained in structures called chromosomes. In eukaryotic cells, chromosomes are located in the nucleus.
What is a polymer?
molecule made from many repeating subunits called monomers.
What are monomers
Monomers are the small basic units that can make larger complex molecules
What are the individual monomers in DNA called?
nucleotides
How are nucleotides joined together in DNA?
Nucleotides are joined together to form a single long chain or strand, forming the structure of DNA
Is everyone’s DNA unique?
Except for identical twins, every person’s DNA is unique.
What is the role of DNA in protein synthesis?
DNA contains the genetic code for making proteins.
Define gene in the context of DNA.
A gene is a section of DNA that codes for a specific protein.
What are proteins made of?
Proteins are made of chains of molecules called amino acids.
Describe the variability in proteins.
The amount, type, and order of amino acids in a protein chain vary.
How does the shape of a protein relate to its function?
The shape of a protein determines its function.
What is the relationship between genes and proteins
Genes code for proteins through the triplet code in DNA.
- Explain the concept of the triplet code.
The triplet code dictates which amino acids will be used to build a protein.
What is the function of triplet codes in DNA?
Triplet codes in DNA determine the sequence of amino acids in a protein
Describe the process of protein synthesis.
Protein synthesis occurs in two stages: transcription and translation
Differentiate between transcription and translation
Transcription converts DNA into mRNA, while translation synthesizes proteins using mRNA.
Where does transcription occur in eukaryotes?
Transcription takes place in the nucleus
- What is the role of mRNA in protein synthesis?
mRNA carries genetic information from DNA to the ribosomes for protein synthesis.
Why is mRNA necessary for protein synthesis in eukaryotes?
mRNA is necessary because DNA cannot leave the nucleus
Explain how mRNA is produced from DNA.
mRNA is synthesized by copying the DNA sequence during transcription
How does mRNA differ from DNA in structure and function?
mRNA is shorter and single-stranded compared to DNA, and it carries genetic information from the nucleus to the cytoplasm.
. Where does translation occur in eukaryotic cells?
Translation occurs in the cytoplasm
Describe the process of translation.
Translation involves decoding mRNA to determine the sequence of amino acids in a protein.
. How are amino acids joined together during translation?
Amino acids are joined together by ribosomes according to the mRNA sequence.
. What is the end result of translation?
The end result of translation is the synthesis of a protein chain.
Why is transcription necessary before translation in eukaryotes?
Transcription is necessary to produce mRNA, which carries genetic information from the nucleus to the cytoplasm for translation.
Define metabolism in the context of cellular processes
Metabolism is the sum of all the chemical reactions happening in a cell or organism, including the synthesis and breakdown of molecules.
How do enzymes help control cell reactions?
Enzymes act as biological catalysts, speeding up chemical reactions without being changed or used up.
- Why is it beneficial for cells to have enzymes?
Enzymes allow chemical reactions to occur quickly without the need for high temperatures, thus preventing damage to the cell
Give an example of the importance of enzymes in living organisms.
Digestive enzymes enable the breakdown of food within hours, whereas without enzymes, digestion would take weeks.
Describe the structure of enzymes.
Enzymes are made of proteins and have a unique shape that enables them to function.
What is the active site of an enzyme?
The active site is a specially shaped region on an enzyme where the substrate binds, allowing the chemical reaction to occur
Explain the concept of enzyme specificity.
Enzymes usually work with only one type of substrate due to the complementary nature between the shape of the active site and the substrate.
How do enzymes speed up chemical reactions?
Enzymes lower the activation energy required for a reaction to occur, thus increasing the rate of the reaction.
- What happens to enzymes after catalyzing a reaction?
Enzymes remain unchanged and can be reused to catalyze more reactions.
What is the ‘lock and key hypothesis’ used to explain?
enzyme action.
- Describe the analogy used in the ‘lock and key hypothesis.’
In the ‘lock and key hypothesis,’ enzymes are compared to locks, and substrates are compared to keys that fit into the enzyme’s active site.
- What is required for an enzyme to catalyze a reaction according to the lock and key hypothesis?
For an enzyme to catalyze a reaction, the substrate must fit into the enzyme’s active site.
- What happens if the substrate does not fit into the enzyme’s active site according to the lock and key hypothesis?
If the substrate is not the correct shape to fit into the enzyme’s active site, the reaction will not be catalyzed.
What are the factors that affect enzyme reactions?
Factors such as temperature, pH, and concentration can affect how well enzymes work
- How does temperature affect enzyme reactions?
Initially, higher temperatures increase the rate of an enzyme-controlled reaction because both the enzyme and substrate molecules have more kinetic energy, leading to more collisions and faster reaction rates. However, heating to very high temperatures can denature enzymes, causing them to lose their shape and become unable to catalyze reactions.
What happens if an enzyme is denatured due to high temperature
If an enzyme is denatured due to high temperature, its active site loses its shape, making it unable to bind to the substrate. This results in the enzyme becoming irreversibly inactive and unable to catalyze reactions.
At what temperature do enzymes work fastest in the human body?
Enzymes work fastest at their optimum temperature, which is around 37°C, the normal body temperature for humans
Can you explain why enzymes stop working at very high temperatures?
At very high temperatures, enzymes become denatured, meaning their active sites lose their shape. As a result, the substrate molecules can no longer bind to the active site, rendering the enzyme unable to catalyze reactions.
How does pH affect enzyme reactions?
pH can affect enzymes by interfering with their activity. If the pH is too high or too low, it can disrupt or break the bonds that hold the enzyme’s amino acid chain together, altering the shape of the active site and reducing the enzyme’s ability to catalyze reactions
What is the optimum pH for most human enzymes?
The optimum pH for most human enzymes is pH 7, which is neutral.
How do enzymes produced in acidic conditions differ in terms of optimum pH?
Enzymes produced in acidic conditions, such as those in the stomach, have a lower optimum pH, typically pH 2.
How do enzymes produced in alkaline conditions differ in terms of optimum pH?
Enzymes produced in alkaline conditions, such as those in the duodenum, have a higher optimum pH, typically pH 8 or 9.
- What happens if the pH deviates too far from the enzyme’s optimum pH?
Deviating too far from the optimum pH can disrupt the bonds in the enzyme’s amino acid chain, changing the shape of the active site and reducing enzyme activity. Extreme pH levels can cause denaturation of the enzyme, leading to the cessation of the catalyzed reaction.
How does substrate concentration affect enzyme activity?
Increasing substrate concentration generally leads to higher enzyme activity and a faster rate of reaction.
What happens as the substrate concentration increases?
As the number of substrate molecules increases, the likelihood of enzyme-substrate complex formation increases.
- What happens if the enzyme concentration remains fixed but the substrate concentration is increased past a certain point?
If the enzyme concentration remains fixed but the substrate concentration is increased beyond a certain point, all available active sites eventually become saturated, and further increases in substrate concentration do not increase the reaction rate
- What occurs when the active sites of enzymes are all full?
When all active sites of enzymes are full, any additional substrate molecules added have nowhere to bind, leading to the plateauing of the reaction rate.
- What is the significance of the saturation point in enzyme-substrate interactions?
At the saturation point, all active sites of the enzyme are occupied, and substrate molecules “queue up” for an available active site, resulting in a constant reaction rate despite increasing substrate concentration
What is the purpose of investigating the effect of pH on the rate of reaction of amylase?
The purpose is to understand how pH levels affect enzyme activity, specifically focusing on the breakdown of starch by amylase.
- Describe the method used to investigate the effect of pH on amylase activity.
The method involves adding iodine solution to wells of a spotting tile, then adding amylase and buffer solution to a test tube followed by starch solution. The reaction is monitored by transferring droplets of the solution to iodine solution every 10 seconds until starch digestion is complete.
How are the results analyzed in the investigation?
At the optimum pH, starch disappearance occurs fastest, indicated by the shortest time for iodine to remain orange-brown. At pH levels above or below the optimum, the time for starch disappearance increases due to enzyme denaturation.
What is the significance of the time taken for starch disappearance in relation to the rate of reaction
The time taken for starch disappearance provides an indication of the rate of reaction. A shorter time indicates a higher rate of reaction.
How can the rate of reaction be calculated in this investigation?
The rate of reaction can be calculated using the formula: Rate = 1 ÷ Time, where ‘Time’ refers to the time taken for starch disappearance.
- What formula is used for rate calculations in enzyme activity experiments?
The formula used for rate calculations is: Rate = Change ÷ Time, where ‘Change’ refers to the change in substrate or product concentration, and ‘Time’ is the time taken for that change to occur.
