Biological Diversity - Section 3 Flashcards
How is variation achieved in sexual reproduction?
Traits from both parents combine to make a whole set of traits through the parents’ DNA
What is DNA?
Is the inherited material that is responsible for variation.
It acts like a blueprint and is found in every cell
Primarily found in the nucleus
What makes one organism different from another?
The order in which base pairs occur
The chromosomes and genes found in each organism’s DNA
How many chromosomes are in humans?
46 chromosomes in 26 pairs
What are genes?
Specific segments on DNA which contain specific coded instructions to guide the cell are called genes
What are alleles?
Different forms of a certain gene
They give us variation
What are two types of cell division that occur in plants and animals?
Mitosis
Meiosis
What is mitosis?
The cell that is dividing must produce a second chromosome prior to splitting so that 2 new cells will have an exact copy of the organism’s DNA
It occurs in multicellular organisms
What is meiosis?
In meiosis, DNA is replicated and the original chromosome and it’s sister chromatid come together
After the first cell division there are two cells, each with a complete set of chromosomes
After the second cell division, there are four cells, each with half the number of chromosomes as the original parent cell
What is a genotype?
The combination of genes/alleles in the chromosomes of an organisms, inherited from the 2 parents
What is a phenotype?
The observable characteristic/trait that we see exhibited because of the combination of genes/alleles
What is purebred?
An organism with two identical alleles for a specific trait, also called homozygous
What is a hybrid?
An organism with two different alleles for a specific trait, also called heterozygous
What are dominant traits?
Are the result of an organism having at least one copy of the dominant allele for a gene
What are recessive traits?
Can only be exhibited by an organism that is purebred for that recessive trait
