Biology 11.4
Anaphase 1 splits apart
Tetrads
Telophase 1 & cytokinesis tetrads
Tetrads-0, chromosomes-4 chromatids-8
Mitosis divides once
To form two cells
Crossing over
exchange of genetic info between segments of homologous chromosomes
Advantages of asexual reproduction
It's faster; large numbers of offspring are produced; and the parent doesn't have to find a mate
Anaphase 2
0 terads 2 chromosomes and 4 chromatids
Anaphase 1
Chromosomes move to opposite ends
Purpose of meiosis
Reduce chromosome number of egg and sperm in half
Metaphase 2
0 terads 2 chromosomes and 4 chromatids
Telophase and cytokinesis
0 terads 2 chromosomes and 4 chromatids and ends with 4 cells
How many tetrads in anaphase 1
0 tetrads
In mitosis
1(2N) cell-> 2(2N) cells
How many tetrads are there in metaphase 1
2 tetrads
How many tetrads are there in prophase 1
2 tetrads
Symbol for diploid
2N
Haw many chromosomes are there in prophase 1
4 chromosomes
How many chromosomes are there in metaphase 1
4 chromosomes
How many chromosomes in anaphase 1
4 chromosomes
Meiosis produces
4 haploid cells that are different
How many chromatids in anaphase 1
8 chromatids
How many chromatids in metaphase 1
8 chromatids
How many chromatids in prophase 1
8 chromatids
Zygote
A fertilized egg
Disadvantages of asexual reproduction
All of the offspring look exactly alike and there is no variation; Ability to adapt to a changing environment is greatly reduced
Advantage of sexual reproduction
All offspring are genetically different from each other
Tetrad
Consists of 4 chromosomes
In meiosis each of the four cells
Contains half the number of chromosomes as the parent
In mitosis each new cekk
Contains the same number of chromosomes as the original cell
Meiosis the four haploid cells contain
Different combinations of chromosome ps from each other
Telophase 1 stage
Diploid number of chromosomes is reduced to the haploid number of chromosomes
Meiosis
Division in which the number of chromosomes per cell is cut in half thought separation of homologous chromosomes
In mitosis the homologous cells
Don't come together to form tetrads
Human body
Egg(23) and sperm(23)~~> zygote (46)
Egg and sperm cells have
Half the number of chromosomes so when added together the zygote will have the proper number
Gametes are said to be
Haploid or 1n
Mitosis the new cells contain
Identical information
Type of cell division that results in cells that are different from the mother cell
Meiosis
Mitosis
Occurs in all cells of the body except sex cells
Process of meiosis
Occurs only in sex cells
Asexual reproduction
Offspring are produced by only one parent each parent passes all of its genes to its offspring
Haploid means
Only 1 of each kind of chromosome
Disadvantages of sexual reproduction
Parent must find a mate; fewer offspring will be reduced and it take longer
Sexual reproduction
Requires two parents each parent passes on half its genes to its offspring; must have a male and female
Gamete
Sex cells
Sexual reproduction always involves
Sex cells fertilization and a zygote
Anaphase 2 splits apart
Sister chromatids
Prophase 2
Spindle fibers form 0 terads 2 chromosomes and 4 chromatids
Prophase 1
Spindle fibers form nuclear membrane goes away chromatin turn into chromosomes tetrads form
Metaphase 1
Tetrads are in the middle
Result of sexual reproduction
The organism will have two sets of chromosomes-- one set form mo and one from dad
In meiosis
The pairs do come together to form tetrads this is how crossing over occurs
Homologous chromsomes
The two copies of each chromosome one coming from the mo and one from the dad
Diploid
There are two of each kind of chromosome in each cell
Meiosis divides twice
To produce a total of 4 cells
One 2n cell ----------
Two 2n cells
Diploid cells contain
Two complete sets of chromosomes
Fertilization
Union of sperm and egg