B1.2: What Happens In Cells? Flashcards
What is DNA?
The genetic material in the nucleus of a cell
DNA is a polymer. What does that mean?
a large molecule made of many monomers
What are the monomers of DNA?
Nucleotides
What are the different nucleotides of DNA?
Adenine, cytosine, thymine, guanine
What is a gene
A section of DNA that contains instructions for making proteins
What is the basic structure of the nucleotides?
Phosphate group
Sugar: deoxyribose
Nitrogenous base (A, C, G, T)
What is transcription?
Copying DNA into mRNA
What is translation?
Cell makes proteins using the genetic information (mRNA)
What is the structure of DNA like?
Double helix structure
Describe the process of transcription
The DNA molecule unzips around the specific RNA polymerase (an enzyme) then reads the DNA sequence and synthesises a complementary strand of mRNA in the nucleus.
Describe the process of translation
Once mRNA is formed, it exits the nucleus and enters the cytoplasm.
Here ribosomes read the nucleotide base sequence in sets of 3 (codons)
tRNA molecules carry specific amino acids, bind to codons. tRNA anticodons pairs with corresponding mRNA codon onto polypeptide chain. This process continues until stop codon is reached.
Newly synthesized protein
How does the structure of DNA affect the proteins made in protein synthesis?
The structure of DNA affects the proteins made in protein synthesis because it determines the sequence of amino acids in a protein.
DNA is made of a sequence of bases (A, T, C, G), which form a genetic code. During transcription, a gene in the DNA is copied into mRNA, which carries the code to the ribosome. In translation, the mRNA is read in triplets (codons), and each codon codes for a specific amino acid. These amino acids are linked together to form a protein. If the DNA sequence changes (mutation), the amino acid sequence may change, affecting the protein’s function.
What are the differences mRNA is from DNA?
Much shorter than DNA
Single stranded, DNA is double stranded
mRNA can leave the nucleus
In mRNA, thymine is replaced by uracil
What are enzymes?
Biological catalysts
What is the structure of enzymes and substrates?
An enzyme contains an active site that fits into a substrate. If not, the molecule cannot bind
What is the lock and key theory?
Enzymes are highly specific. They can only bind to one type of substrate. Like a lock and key
What is the role of enzymes in metabolism?
It significantly speeds up chemical eactions in the body allowing metabolic reactions to occur at a rate necessary for life by lowering the activation energy
What is an example of a pH enzymatic investigation reaction?
Adds a set volume of starch solution to a set volume of amylase solution at a range of different pH values. At each pH, they measure how long it takes for the amylase to break down all of the starch
What are the main 3 factors affecting enzymes
- pH
- temperature
- enzyme or susbtrate concentration
How does temperature affect enzymatic reactions?
The optimum temperature is the temperature that gives the highest enzyme activity. This is around 37 degrees. If the teperature gets too high, enzymes denature, and can no longer bind to the substrate
What does it mean when enzymes denature?
Active site changes shape - can no longer bind to the specific substrate
How does enzyme/substrate concentration effect enzymatic reactions?
The greater substrate concentration, the greater the enzyme activity and the higher the rate of reaction
How does pH affect enzymatic activity?
Different enzymes have different optimum pH conditions. pH changes affect the amino acids interaction
