Genetics (3) Flashcards
Advantages and disadvantages of asexual reproduction.
Advantages:
-Produce lots of offspring very quickly (allowing organisms to colonise an area very quickly)
-Only one parent is needed so they can reproduce whenever they want.
Disadvantages:
-No genetic variation means that the population can be affected if the environment changes.
Advantages and disadvantages of sexual reproduction.
Advantages:
-Creates genetic variation meaning that the population has a higher chance of surviving if the environment changes allowing natural selection and evolution to take place.
Disadvantages:
-Takes more time and energy to reproduce so the organism will have less offspring throughout their lifetime.
-Two parents needed which is a problem when individuals are isolated.
What is meiosis?
Meiosis is a type of cell division which produces 4 genetically different haploid cells (gametes). It occurs in reproductive organs.
What is DNA?
DNA is a polymer made of two strands coiled in a double helix shape which are connected by weak hydrogen bonds. Within the strands, there are nucleotides consisting of sugar, a phosphate group with one of the four bases (A, T, C, G) connected to the sugar.
What is the genome and a gene?
Genome - the entire DNA of an organism.
Gene - a section of the DNA molecule that codes for a specific protein.
How can you extract DNA from a fruit?
Mash the fruit and put it in a beaker containing detergent (break down the cell membranes and release the DNA) and salt (make the DNA stick together) solution. Filter the solution to get the froth and larger bits of cell out. Add ice cold ethanol (to create precipitate containing DNA).
What did Mendel do?
He crossed a dwarf pea plant and a tall pea plant which produced a tall pea plant. Then, he bred two tall offspring together which produced three tall pea plants and one dwarf plants. He concluded that characteristics in plants are determined by hereditary units which are passed on from parents and can be dominant or recessive.
What do alleles do?
Alleles are two different variations of a gene - one from each parent. If an organism has two alleles for a gene which are the same, it is said to be homozygous and if the two alleles are different, they are said to be heterozygous. Some alleles are dominant and will be expressed over the recessive allele. A recessive allele will only be expressed if there are two recessive alleles. These alleles form your genotype and determine the characteristics expressed in your phenotype.
