Inheritance, Variation and Evolution Flashcards
What organisms reproduce asexually?
Bacteria, fungi, small plants and animals
What are the advantages of sexual reproduction?
- Variation
- If there’s a change in environment, natural selection can happen
- Natural selection can be sped up by humans in breeding to increase food production
What are the advantages of asexual reproduction?
- Only one parent needed
- Quicker
- A mate doesn’t need to be found
- Many identical offspring can be produced
What are the functions of mitosis?
Growth, repair and asexual reproduction
What is the process of meiosis?
1) The chromosomes duplicate
2) The cell divides into two
3) Each cell divides again
Each cell will have 23 chromosomes
What is the purpose of meiosis?
To produce gametes
What is a diploid?
A cell that has 46 chromosomes
What is a haploid?
A cell that has 23 chromosomes
What does a nucleotide consist of?
A base, phosphate group and sugar
What is a triplet / codon?
A three base sequence that codes for a specific amino acid
What is the process of protein synthesis?
1) The base sequence of the gene is copied into the mRNA in the nucleus
2) The mRNA passes into the cytoplasm and then attaches onto a ribosome
3) Amino acids are brought to the ribosomes on carrier proteins
4) The ribosome reads the triplets of bases in the mRNA and uses this code to put together the amino acids in the correct order
5) When the protein chain is complete, it’s folded into a specific shape to carry out a specific function
What is a mutation?
A random change to the base sequence of a gene
What are the chances of mutation increased by?
Smoking and radiation
What is an insertion mutation?
When a new base is inserted into the DNA sequence which has a knock on effect in the chain and changes the amino acid
What is a deletion mutation?
When a random base is deleted from the DNA sequence, having a knock on effect in the chain and changing the amino acid
What is a substitution mutation?
When a random base in a DNA sequence is changed to a different base- this doesn’t have a knock on effect
What does coding DNA do?
Determines the structure of the proteins coded for
What does non coding DNA do?
Switches genes on and off to control whether the protein is made or not
What did Gregor Mendel do?
He discovered the existence of dominant and recessive alleles
What is Darwin’s theory of natural selection?
Due to mutations, there’s variation in a population and some individuals are better suited to their environment. They are therefore more likely to survive and pass on their advantageous genes
What was Lamark’s theory of evolution?
The changes an organism aquires during its lifetime would be passed onto it’s offspring
e.g. a giraffe that stretched its neck often to reach food would have offspring with longer necks