B1.2 Flashcards
What is a chromosome?
Long strands of DNA in the nucleus
What are genes?
Sequence of bases that codes for a sequence of amino acids that produce a protein
Determine characteristics
What is the structure of DNA?
Made of 2 strands
Joined together by bases
Forms a double helix
What is DNA made of?
Nucleotides which make up the polymer DNA
What are nucleotides made of?
Sugar (deoxyribose)(pentagon)
Phosphate group (circle)
4 different bases (rectangle) (C,G,A,T)
How do the bases bond?
Complementary base pairings are formed
C - G
A - T
What is DNA?
Genetic material, that determines the characteristics of all living organisms
Contained in chromosomes
What is protein synthesis?
How proteins are made
Proteins are made of amino acids
What is transcription?
DNA cannot leave the nucleus as it’s too big so a copy of DNA is made called mRNA which a single strand of DNA
How is mRNA made?
1) DNA unzips and one strand acts as a template
2) Complementary bases attach to the template to form mRNA
3) Uracil (U) replaces thymine (T)
4) When the mRNA is complete it detaches from the DNA template and the DNA zips back up
What is the process of translation?
Where proteins are made
1) mRNA attaches to a ribosome which ‘read’ the nucleotides on the mRNA in groups of 3 (codons)
2) each codon codes for a different amino acid
3) as the amino acids are read they join together in a chain which is a protein
How are proteins differentiated?
Sequence of amino acids determines how the protein folds
Each protein has a specific shape
What are enzymes?
Made of proteins
Biological catalysts (speed up reactions without being used up)
How do enzymes bind?
Substrate binds to the active site of the enzyme to form an enzyme-substrate complex
Only one type of substrate can bind to one type of enzyme
What is the lock and key hypothesis?
Enzyme is a lock and substrate is the key
Only one key works
What are some roles of enzymes?
Build larger molecules from smaller ones
Break down larger molecules into smaller ones
What factors affect enzymes?
Temperature
pH
Concentration of enzymes and substrates
How does temperature affect enzyme-controlled reactions?
At lower temperatures the enzymes work slower
Rate of reaction increases with increase in temperature
Optimum temperature is when the reaction works as fast as possible
Temperatures above the optimum mean the enzyme denatures (shape of active sit changes) and the reaction stops (substrate can’t bind to active site)
How does pH affect enzyme-controlled reactions?
Change in pH affects the interactions between the amino acids in a chain
Enzyme may unfold or shape of active site may change (enzyme denatures)
How does substrate concentration affect enzyme-controlled reactions?
Higher substrate concentration = faster rate initially
When all the substrate are bound to the enzymes that is the maximum rate
At the point of saturation the graph plateaus
How does enzyme concentration affect enzyme-controlled reactions?
Higher enzyme concentration = faster rate of reaction
But substrate concentration becomes a limiting factor
