♦ ♦ ♦ Mitosis and Meiosis and Fertilization Flashcards
What is the definition of mitosis?
Why do organisms use mitosis?
How does the process of mitosis occur?
One cell produces two genetically identical cells for growth or repair and assorted reproduction (usual method) for unicellular organisms.
Organisms use mitosis for asexual reproduction, growth or repair.
A cell creates a backup DNA copy → the cell doubles from 2n to 4n → the cell then divides into 2n + 2n
What is the definition of meiosis?
What are the features of cells that are created by meiosis?
What must happen for cells to produce genetically different cells?
One cell produces four gametes (sperm or egg) each with different genetic makeup so that all offspring will differ from each other and from the parents.
- each cell has half the normal number of chromosomes
- two parents can contribute to making offspring
- each offspring is genetically different from the parents and from each other - increasing the chances that at least some survive
(create DNA backup) duplicate the DNA 2n to 4n → crossing over pieces of the DNA → independent assortment 4n to n + n + n + n
What is the definition of fertilization?
What happens in fertilization?
What is the expression to represent fertilization?
Sperm and egg combine to form a fertilized egg or zygote so that offspring will have combinations of traits from two different parents.
In fertilization, a gamete from one parent combines wth a gamete from another parent.
n + n → 2n
Explain the chromosome number for mitosis, meiosis, and fertilization
Mitosis = 2n → 4n → 2n + 2n
Meisosis = 2n → 4n → 2n + 2n → n + n + n + n
Fertilization = n + n → 2n
How do meiosis and fertilization cause inheritance of traits?
Offspring of sexual reproduction differ somewhat from parents and from each other.
How do genes cause differentiation?
A fertilized egg undergoes mitosis to become thousands of identical cells that all use the same basic genes to preform metabolism. Specialization of genes is sperate from this process and is usually found in the bone marrow.
Specialized genes are used to become specific tissues (skin, nerve, root or leaf)
Tell 2 ways feedback mechanisms control metabolic pathways?
(Think of also affecting cancer)
- Turn of genes to prevent further reactions
- Turn off proteins already present
