Lab 8 Set
Meiosis I begins with one cell. How many cells are produced by the end of telophase II?
4
What is the diploid number for humans?
46
Give two processes in meiosis that contribute to genetic variation
1. Crossing over 2. Random chromatid assortment
How many gametes are required to form a diploid (2n) offspring?
2
What is the haploid number for humans?
23
How many chromosomes are in each cell of your model following telophase 1? Each chromosome has how many chromatids?
3 , 2
When do sister chromatids become independent chromosomes? What occurs to allow this change?
Anaphase
S
DNA is **replicated** during this phase
When during the cell cycle do chromosomes duplicate?
S phase of Interphase
Does each new cell formed by mitosis have the same or different chromosomal material as each other?
Same
Is the chromosomal material the same or different from the original cell?
Same
Telophase I
complete haploid set of chromosomes, cleavage furrow appears
By the end of telophase II, is each chromosome within each gamete duplicated or unduplicated?
duplicated
Mitosis
eukaryotic cell undergoes carefully coordinated nuclear division into 2 identical daughter cells
What is the effect of crossing over?
formation of recombinant chromosomes
By the end of telophase II, is each gamete haploid or diploid?
haploid
Why is genetic variation important in populations?
it allows natural selection to increase or decrease frequency of alleles in population
Spindle fibers are composed of what type of cellular material?
microtubules
Prophase II
nuclear envelope breaks down and spindle apparatus forms
Telophase II
nuclear envelope forms around each set of chromosomes, cytokinesis occurs
what occurs during Interphase?
resting phase between first and second divisions of meiosis
Cytokinesis
separation into two daughter cells
By the end of telophase II, are the gametes alike or varied from each other?
varied
Anaphase
chromosomes move away from one another to opposite poles of the spindle
Anaphase I
chromosomes start moving towards opposite pole
G2
Cell will continue to **grow** and produce new proteins
Describe how cytokinesis is accomplished in animals
Cleavage furrow
How do the chromosomes in anaphase I in meiosis differ from those of anaphase in mitosis?
anapahse in mitosis = 4 chromosomes anaphase 1 = 2 chromsomes
Why are autosomal trisomies or monosomies rare in humans?
because there is an extra chromosome with autosome pair 21
When does crossing over occur?
between prophase I and metaphase I
G1
cell **synthesizes mRNA and proteins** in preparation for subsequent steps leading to mitosis
Describe how cytokinesis is accomplished in plants
cell plate
Metaphase I
centrioles are at opposite poles of the cell
Anaphase II
centromeses seperate and sister chromatids move toward opposite end
Telophase
chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed
Metaphase II
chromosomes arrange on metaphase plate
Metaphase
chromosomes become attached to spindle fibers
Prophase
chromosomes become visible as paired chromatids and nuclear envelope disappears.
Prophase I
chromosomes become visible, crossing over occurs
