B1.2 Flashcards
What is in a nucleotide?
Phosphate group, sugar, base
How many possible bases are there in DNA ,what are their names?
4 in mRNA Thymine replaced to Uracil
Adenine
Cytosine
Guanine
Thymine
What are genes, what do they code for
Short section of DNA
-Codes for different proteins
-So different characteristics
Where is DNA found?
In one of the (most likely) 46 (or 47) chromosomes in the nucleus of a cell
Structure of DNA
2 strands joined by complementary base pairing (hydrogen bonds), in a twisted double helix shape
What are the stages of transcription?
-The DNA unzips (separated strands)
-Complementary bases attach to the strand being copied
-The new mRNA leaves the DNA which zips back up
-It escapes the nucleus through pores, ready for translation in the cytoplasm
What mRNA is made from this DNA strand?
GCTATGAC
CGAUACUG
What are the stages of translation?
mRNA attaches to a ribosome
This reads it in triplets (codons)
Each codon codes for an amino acid
They join up to create a protein
How does having a different base to code for haemoglobin cause fatigue?
-Different coded base = different haemoglobin shape
- Meaning that in red blood cells they will carry less oxygen
-Less oxygen getting around the body to cells = Less respiration
- Less ATP (energy) produced, fatigue
What are enzymes and what do they do?
They are made from protein, biological catalysts.
They can build large molecules from small ones,or break large molecules into small ones
Jacques says that if you increase the substrate concentration, the rate of reaction increases. Explain why he is wrong?
Although it does increase at first, soon all the enzyme molecules will be reacting with substrate so no faster reaction can happen
What is the lock and key hypothesis?
The idea that the active site of an enzyme (where the reaction happens) has a certain shape. The molecule that binds to it (substrate) has to fit in that shape or reactions cannot happen
If an enzyme has an O shape, what shape substrate can it bind to
None
How and why do enzymes become denatured?
If the temperature is too high or the pH is too far from optimum,the amino acid chains may start to unravel, causing the active site to change shape and be unable to house any reactions
Jacques says that if you increase the enzyme concentration, the rate of reaction increases. Explain why he is wrong?
Generally the higher enzyme concentation = faster reaction,but soon all reaction will have happened so the reaction will eventually stop
Where does transcription take place?
In the nucleus
Who produced the first ever photograph of DNA, ‘photo 51’ that led to the discover of the DNA’s structure?
Rosalind Franklin
Why is the double helix describe as being ‘anti-parallel’?
The two strands which from DNA are parallel but run in opposite directions.
What is the name of the weak bonds formed between bases of opposing strands of DNA?
Hydrogen bonds
What are the two main stages in protein synthesis?
Transcription and translation
