Topic 6a- DNA Flashcards
What does DNA stand for?
deoxyribonucleic acid
Where is DNA found in the cell?
nucleus
What is the shape of DNA
a double helix
What is a gene
a gene is a small secion of DNA found on a chromosome
What does each gene do?
Each gene codes fofr a particular sequence of amino acids which are put together to make a specific protein
How many different types amino acids are used by genes to make proteins?
20
Define a genome
A genome is the entire set of genetic material in an organism
What are chromosomes made up of?
Coils of DNA
Why are DNA molecules described as double helixes?
They are shaped in a double stranded spiral
What is within one nucleotide of DNA
a phosphate, a sugar and a base
How many types of bases are there (in DNA)
4
What are the repeating units in DNA called?
Nucleotides
What is the base in DNA bound to?
The sugar
What two chemicals form the ‘backbone’ of DNA?
The sugar and phosphate
How many bases in a gene code for an amino acid?
3
Which bases pair together (which are complimentary)
A-T
C-G
What are non-coding parts of DNA?
Parts of DNA that don’t code for proteins. Some og these non-coding parts switch genes on and off and control whether a gene is expressed (used to make a protein).
Where are proteins synthesised in the cell?
The ribosomes
Why can’t the DNA simply go directly from the nucleus to the ribosome so that it can synthesise the protein? What is used instead?
- The DNA is too big to and cannot move in and out of the nucleus.
- mRNA can however as it copies the code from the DNA and acts as a messenger between the DNA and the ribosome
Explain the process of protein synthesis
- The DNA in the nucleus of the cell is too large to exit and go to the ribosome
- Instead, the molcule mRNA copies the DNA and carries the code to the ribosome
- The correct amino acids are brought to the ribosome in the correct order by carrier molecules
- From this, the ribosome assembles the chain of amino acids that fold into a unique shape which allows the protein to perform the task it’s meant to do
What is a mutation?
A mutation is a random change in an organism’s DNA .
What do mutations do to the sequence of DNA bases in a gene? What is the effect of this?
- Mutations change the sequence on the DNA bases in a gene which produces a genetic variant (a different form of the gene).
- Most mutations will have very little effect or no effect on the protein, while others could code for an altered protein and affect its ability to perform its function.
What are the types of mutation?
- Insertion- when a new base is inserted into the DNA base sequence where it shouldn’t be (knock on effect on the sequence)
- Deletion- when a random base is from the sequence (knock on effect on the sequence)
- Substitution- when a random base in the DNA base sequence is changed to a different base (only affects that one )
