DNA basics Flashcards
Parts/ structure of the nucleus
- Nuclear envelope (double membrane) with pores
- Nucleolus
- Chromatin network (DNA and proteins)
The general structure of DNA
- A very long molecule
- Double strand resembling a ladder
- Twisted into a helix (I.e. a double helix)
what is a polymer?
A molecule that contains monomers which are similar units or building blocks
The monomer of DNA?
nucleotides
Nucleotides are made up of?
- A phosphate
- A deoxyribose sugar
- A nitrogenous base
The different nitrogenous bases of DNA.
- A adenine
- T thymine
- C cytosine
- G guanine
Purine bases
- Larger
- A and G
Pyramidines
- smaller
- C and T
The pairing of nitrogenous bases of DNA and how many bonds for each?
- A with T (2 H-bonds)
- G with C (3 H-bonds)
The name of the bonds between nitrogenous bases in DNA?
Hydrogen bonds
Mutation
Change in the sequence of nucleotides in DNA
True or false: mutations are always harmful
False
Types of mutations
- Point: single nucleotide change
- Substitution: replacing one (or more) nucleotide(s) with another
- Deletion: deleting one (or more) nucleotide(s) from the DNA
- Insertion: adding one (or more) nucleotide(s) into the DNA
Frame shift
A change in the way codons are read because nucleotide triplets shift as a result of a deletion or insertion
Causes of mutations
- exposure to radiation,
- viruses,
- faulty copying during transcription
Mutation (definition)
Change in the sequence of nucleotides in DNA
The effect of a mutation could be…
- beneficial - the change results in a new adaptation that makes the organism better suited to its environment (natural selection will favour this mutation)
- neutral - no change as the same amino acid is coded for
- harmful - the change results in a different protein, or no protein, being produced, which is harmful to the organism lethal - the change results in a non-viable cell/ zygote/ organism, which therefore dies.
A change in the sequence of nucleotides in DNA
Mutation
Where is DNA found?
- Nuclear DNA in the nucleus
- Extranuclear DNA in mitochondria