What Happes In Cells Flashcards
How does the sequence of DNA affect the protein made in protein synthesis?
DNA is a triplet code where 3 bases code for one amino acid and the order of amino acids determine the protein
produced
Enzymes
Enzymes are biological catalysts that speed up the rate of metabolic reactions
Enzyme structure
Enzymes are proteins that contain an active site that fits a specific substrate
Lock and key hypothesis
The idea that only a specific substrate fits the specific active site of the enzyme, and only then a reaction occurs.
Affect enzymes
- Temperature
- рН
- Substrate concentration
- Enzyme concentration
Describe the effect of temperature on the rate of an
enzyme-controlled reaction
As the temperature increases, so does the rate of reaction
- Once the temperature exceeds the optimum, the enzyme denatures and the rate of reaction decreases
What is the function of MRNA and DNA in protein synthesis
- the dna is contains the genetic code that codes for the function of an organism, and this code is needed to code for the correct amino acids during protein synthesis. However, the dna is too large to fir through the nucleus, so mRNA is used to complement the genetic code and then travels to the ribosome where translation can then take place
What is the function of TRNA in protein synthesis
When the mrna reaches the ribosomes, the complemented code is read by the ribosome, and arranged in to groups of three called triplet code or condons. These codons code for the amino acid that needs to be used. The TRNA is what brings the amino acid to the correct codon that codes for it
What are the 4 bases
Adenine, thymine, guanine, cytosine
What bases bond together
Adenine <—> thymine
Guanine <—> cytosine
What is DNA
- DNA is made up of two linked strands that wind around each other to form a double helix it is made up of lots of small units called nucleotides
- DNA is a polymer.
- Nucleotides are made up of sugars, phosphate and a base and are held together by hydrogen bonds between them.
- There are four such found in DNA: adenine, thymine, guanine and cytosine
How to test for proteins
Place two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid. Add about 1 cm3 depth of water to the tube and stir to mix.
Add an equal volume of Benedict’s solution and mix.
If it goes lilac it
Test for proteins
Mash up substance, add it to beaker, add buirets solution and wait for reaction
Colour change from blue to purple indicates proteins
Test for sugars
Mash up item, add sample to boiling tube with a few drops of Benedict’s solution. Heat the mixture in a water bath and observe the reaction.
Test for fats
Mash up substance, mix your substance and water and stir vigorously, add in one to two drops of ethanol and twist for reaction to take place
Order from smallest to largest: allele, chromosome, nucleotide
Smallest : nucleotide
Allele
Largest : chromosome
Drugs can be used to treat type one diabetes
One drug prevents an enzyme from working properly
Suggest how a drug can stop an enzyme from working properly
Changes the shape of the enzymes active site and denatures it
il. The range of the three test readings for the beaker of water and Bunsen burner was 3.4 And for the water bath it was 3.4
Dues the evidence support using an electric water bath instead of a beaker of water and Bunsen
Explain your answer.
- yes
- greater yield of DNA
- less variation in results
Low temperatures protect DNA by slowing down the activity of enzymes that destroy DNA.
High temperatures break down membranes in the cell
some methods use a water bath at 60°C but other methods do not use an increased temperature
Suggest two reasons for the different methods
For using above 60 degrees
- membranes in cell break down meaning more DMA can be extracted
Against using 60 degrees
- could result in DNA breaking down / being damaged due to the high temperatures
Why did scientist incubate erythromycin at 37 degrees instead of lower or higher temperature (2 marks)
- a higher temporiser may mean that the reaction takes place faster as it reaches the bacteria’s optimum temperature
- a lower temperature means that the bacteria won’t reproduce quickly
At 20 degrees the time taken for the milk to be broken down by Lipase is 480 seconds
At 40 degrees the time taken is 240 seconds
Explain the results at 20 degrees and 40 degrees
- reaction at 20 degrees is slower than at 40 degrees
- particles move slower as they have less energy at 20 degrees
- less frequent collisions at 20 degrees
At 40 degrees the time taken for the milk to be broken down by Lipase is 240 seconds
At 80 degrees the time taken is 960 seconds
Explain the results at 80 degrees and 40 degrees
- At 80 degrees the reaction is slower and takes longer
- enzymes have denatures
- shape of active site of enzyme has changed, meaning substrate will no longer bind with it
Is a lipid a polymer
No
Insulin is made of 51 amino acids
How many bases are in the length of DNA coding for insulin
153
What is the name of the monomer in DNA
Phosphate
The rate of gas pordieced in an enzyme catalysed reaction is greater at 30 degrees than at 25 degrees
Use ideas about enzymes to explain why
-> increased kinetic energy of enzyme and substrate molecules causes collisions to happen more frequently (2 marks)
-> higher frequency of collisions means higher chance of successful collisions take place meaning more gas produced as reaction occurs faster
Phenols are chemicals that inhibit enzymes during fermentation.
They bind to amino acids on enzyme molecules.
Suggest how phenols inhibit enzymes.
(2 marks)
-> alters shape of enzymes active site
-> substrate can no longer bind to its active site
-> reactions can’t be catalysed
Describe the role of the tRNA nucleotides and the ribosome in the role of protein production
-> ribosomes are the site of protein synthesis
-> mRNA attaches to ribosome
-> tRNA brings the correct amino acid to the codon that codes for it
