Chapter 9.3 Flashcards
HAPLOID CELLS
abbreviated (n)
They contain on one full set of genetic information ( 23)
Haploid cells are called
gametes= sex cells
FERTILIZATION
merges the gametes from two parents to form zygote.
ZYGOTE
the first cell of a new organism ( union of gamete)
How many sets of chromosomes does a zygote have
a one- celled zygote is diploid cell with 2 sets of chromosomes one from each parent
How soon does mitosis begin in a new organisim
mitosis begins shortly after fertilization
sexually reproducing, multicellular organisms require 2 ways to package DNA
- MITOSIS
2. MEIOSIS
MITOSIS
divides a eukaryotic cell’s chromosomes into identical daughter cells
purpose of Mitosis
- produces cell for growth and development
and tissue repair
MEIOSIS
forms genetically variable gametes that each contain half of the organism’s diploid cells
GERM CELLS
Occur only in the ovaries and testes. they are the only cells ( specialized diploid cells)
that undergo meiosis
SOMATIC CELLS
the rest of the body’s diploid cells that have 2 full sets of chromosomes and do not participate directly in reproduction.
. The divide by mitosis but do not divide by meiosis.
The only haploid cells in human life cycle
gametes
What does meiosis do
halves the chromosome number and scrambles alleles
What are the 2 main outcomes of MEIOSIS
- the resulting gamete has half the number of chromosomes as the the rest of the body’s cell’s ( ensuring that the chromosome number does not double with every generation
- Scramble genetic information ( so that 2 parents can generate offspring that are genetically different from both the parents and from one another
2 differences between mitosis and meiosis
Meiosis has 2 unique outcomes:
- it has 2 divisions which create 4 haploid cells from one diploid germ cell
- It shuffles genetic information, setting the stage for each haploid nucleus to receive a unique mixture of alleles
What is the difference between somatic and germ cells?
Germ cells can undergo meiosis and produce haploid gametes; somatic cells are body cells that reproduce by mitosis.
How do haploid and diploid nuclei differ
A diploid cell (2n) has two full sets of chromosomes, with one set coming from each parent. A haploid cell (n) has only one set of chromosomes.
. What are the roles of meiosis, gamete formation, and fertilization in a sexual life cycle?
In meiosis, a diploid cell divides twice to produce four haploid nuclei, reducing the chromosome number by half. Meiosis also creates new allele combinations in the haploid nuclei. Gamete formation packages the haploid chromosomes into reproductive cells. Fertilization merges haploid gametes from two parents, producing a new diploid cell with half its chromosomes coming from each parent.
What is a zygote?
A zygote is a fertilized egg cell that is the start of a new diploid organism.
