B1.2 What happens in cells Flashcards
State the role of DNA in the body
DNA is the substance that contains all the instructions that determine your characteristics
Place in size order: gene, chromosome, genome, DNA, nucleus, cell, nucleotide
Nucleotide (smallest)
Gene
DNA
Chromosome
Genome
Nucleus
Cell (largest)
What is DNA?
DNA is deoxyribose nucleic acid, the genetic material found within the nucleus of every one of your cells.
Each long molecule (polymer) of DNA is a…
Chromosome
The units that make up the polymer DNA are called
nucleotides
Each nucleotides are composed of:
1 phosphate 1 deoxyribose 1 organic base
There are four organic bases
Adenine Thymine Cytosine Guanine
A gene is
A short section of DNA found upon a chromosome which codes for a specific protein
Name the protein that DNA coils around in the formation of a chromosome
Histone
What it complementary base pairing?
Adenine always pairs with thymine Cytosine always pairs with guanine
What is the name of the structure formed by DNA, as discovered by Watson and Crick in the 1950s
Double Helix
Why is the double helix described as being ‘anti-parallel’?
The two strands which form DNA are parallel but run in opposite directions
The phosphate and deoxyribose molecules in a DNA polymer are joined to form the…
sugar-phosphate backbone
What is the name of the weak bonds formed between bases of opposing strands of DNA?
Hydrogen bonds
Name the two main stages of protein synthesis
Transcription Translation
Where does protein synthesis take place
Transcription - starts in the nucleus, and ends when the mRNA strand leaves through the nuclear pore to towards the ribosomes Translation - In the cytoplasm with the assistance of ribosomes
Define transcription
The process by which DNA unzips to allow mRNA to use it as a template to make a copy of a section which codes for a specific protein. Once copied the mRNA detaches and leaves the nucleus and the DNA zips back up.
Define translation.
The process by which mRNA is read by the nucleus in groups of three ‘codons’, to produce a protein. During translation tRNA molecules are attracted to their complementary bases upon the mRNA bringing specific amino acids with them that join together into a chain to form a protein.
What are the key differences between DNA and RNA?
DNA
- Deoxyribonucleotides
- Bases: A, T, C, G
- Sugar: deoxyribose
- Double helix
- Can not leave the nucleus
- Long polynucleotide chain
- DNA is completely protected by the body from degradation.
- Self-replicating
RNA
RNA
- Ribonucleotides
- Bases: A, U, C, G
- Sugar: ribose
- Single strand
- RNA can move in and out of the nucleus.
- Short polynucleotide chain
- Strands are continually made, broken down and reused
- Synthesized from DNA on an as-needed basis.
What are enzymes?
Proteins which act as biological catalysts - meaning they speed up reactions without being used up in the process.
What is the name of the molecule that an enzyme binds to?
Substrate
What is an ‘active site’?
An active site is part of an enzyme that binds to the substrate. It has a specific shape which is formed by the way its amino acids are folded togther within the protein.
This hypothesis states that only one substrate will fit one enzyme, and that they must be an exact fit.
Lock and key hypothesis
What is formed when a substrate binds to an enzyme
Enzyme-substrate complex
