B6-Inheritance, variation and evolution Flashcards
What are the 2 different types of reproduction?
Sexual and Asexual
What does sexual reproduction involve?
2 parents with seperate gametes-the fusion of male and female gametes
What does asexual reproduction involve?
Reproduction with 1 parent
What process occurs in sexual reproduction?
Meiosis to form the gametes
What process occurs in asexual reproduction?
Mitosis
What are the characteristics of asexual reproduction?
- It involves 1 parent only
- Gametes are not produced
- Offspring are genetically identical to the parent
- The cell division are only mitotic
- Fast reproduction
What are the characteristics of sexual reproduction?
- Involves 2 organisms
- Gametes are produced by the organisms
- Offspring show genetic variation
- Gametes are produced by meiotic divisions and zygote develops by mitotic division
- Comparatively the number produced is low
What is the process of meiosis?
The genetic material is copied and then the cell divides twice to form four gametes, each with a single, unique set of chromosomes
What are the characteristics of Mitosis?
- Copies of chromosomes are made
- Adult cells are made
- Cells produced are genetically identical
- Cells divide once
- Cells contain the same number of chromosomes as the original cell
- Used in Asexual reproduction
What are the characteristics of Meiosis?
- Copies of Chromosomes are made
- Sperm and egg cells are made
- Cells produced have variation
- Cells divide twice
- Cells contain half the number of chromosomes as the original cell
- Used in sexual reproduction
How do malaria parasites reproduce?
- Sexually in mosquitos and Asexually in their human host
How do fungi reproduce?
Mostly asexually by spores but can also reproduce sexually for variation
How do plants reproduce?
Mostly sexually with pollen and plant eggs however can also reproduce asexually e.g. by runners or bulb division
What is the structure of DNA?
A phosphate connected to a pentose sugar connected to an organic base (either A, T, C or G)
What is a base in DNA also called?
A nucleotide
What are the combimations of bases?
A&T or C&G
What is the code for a single amino acid?
A sequence of 3 bases
What do amino acids do?
Code for a particular protein
How is protein synthesis carried out?
1) A template strand of the DNA is made in the nucleus
2) The template strand leaves the nucleus and binds to a ribosome
3) The cytoplasm contains carrier molecules, each attached to a specific amino acid
4) The carrier molecules attach themselves to the template strand using complementary codes
5) The amino acids on the carrier molecules are joined together to form a specific protein
6) Carrier molecules keep bringing specific amino acids to add to the growing protein in the correct order until the template is complete
7) Once complete the protein detaches from the carrier molecules and folds to form a unique shape that will enable it to carry out its functions in the cell
What is it called when a gene codes for a protein that is synthesised in a cell?
The gene is expressed
How are mutations caused?
By the active site of proteins changing
What are different forms of the same gene called?
Alleles
What does Homozygous mean?
2 copies of the same alleles e.g. aa, AA
What does Heterozygous mean?
2 different alleles for the same characteristics e.g. Aa, aA
What does Genotype mean?
The alleles present or genetic makeup of an individual regarding a particular characteristic
What does Phenotype mean?
The physical appearance of an individual regarding a particular characteristic-genotype + environment
When is a dominant allele expressed?
When one or both alleles are dominant