DNA, Mutation, and Natural Selection Flashcards
1
Q
What are genes?
A
Genes are a length of DNA that code for a specific protein
2
Q
What are alleles?
A
Alleles are alternative forms of the same gene.
For example -
If we take the height gene:
T - tall
t - dwarfism
3
Q
What is DNA?
A
DNA (deoxyribonucleic acid)
1. Nitrogenous based
2. Sugar phosphate backbone
3. Provides instructions for making a protein
4. Shape - double helix
4
Q
Name the four nitrogenous bases which make up a DNA. Also, mention how they bond when DNA undergoes changes.
A
Bases:
A - Adenine
T - Thymine
G - Guamine
C - Cytosine
When DNA undergoes changes:
1. Adenine always bonds with Thymine
2. Guanine always bonds with Cytosine
5
Q
What is mutation?
A
- Mutation refers to a spontaneous change in gene or chromosome which may affect the way the cell works causing disorders/problems
- This may also have no effect or give an advantage to the individual
6
Q
What are some causes to mutation?
A
- Being exposed to harmful chemicals
- Exposed to ionising radiation
7
Q
How does mutation occur?
A
- Mutation occurs due to gene alteration
a. This gene alteration is a result of a base being added or deleted from the gene
b. This results in the formation of new amino acids/proteins
c. Thus the phenotypes change, which we observe as mutation
8
Q
What is natural selection? Explain what happens in it.
A
- Natural selection was proposed by Charles Darwin in the book ‘The origin of species’
- Individuals within species show variation.
- According to the environment, some variation may be better suited to survive than others
- If a variety lives longer it is more likely to leave offspring
- Some of this offspring inherit this variation and may live longer and leave more offspring
- In time, this variety will increase in number and finally replace the original
- This increases biodiversity (as more species are formed) but can also lead to overpopulation
