Meioses/Mitosis
Interphase - Mitosis
cells that are about to divide replicate DNA
During mitosis, the chromosomes move because
chromosomes attach to a dynamic, precisely regulated mitotic spindle
What must happen before a cell can begin mitosis?
chromosomes must be duplicated
Cytokinesis
cytoplasm of eukaryotic cell divides to produce two cells
What is Variation?
result of independent assortment & crossing over
Recombination
segments of non sister chromatids trade places
What happens in Meiosis II
sister chromatids are separated
Which of the following is a key difference between meiosis and mitosis?
synapsis occurs during prophase I of meiosis
S phase stands for
synthesis of DNA
Asexual Reproduction
the creation of genetically identical offspring by a single parent, without the participation of sperm and egg
The first step of bacterial replication is?
DNA Replication
Where do sister chromatids come from?
DNA Replication
What is result of crossing over?
Genetic Recombination
Independent Assortment
Independent segregation of genes during the formation of gametes
Stages of Mitosis
Interphase Prophase Metaphase Anaphase Telophase (Cytokinesis)
Variation occurs when chromosomes are shuffled in?
Meiosis
After fertilization, the resulting zygote begins to divide by
Mitosis (gametes divide by Meiosis)
Meiosis 2
Pro - nucleus envelope breaks, new spindles form Meta - spindle fibers bind to both sides of centromeres Ana - spindle fibers contract , sisters move to opposite poles Tele - nucleus envelope reforms around SETS of daughters (4 sets)
Meiosis 1
Pro- recombination, synapsis Metaphase -nucleus membrane disappears, microtubules form, homo chromo lineup Anaphase - chromosomes pull toward poles taking sisters Tele/Cyto- nucleus membrane reforms around daughters
Crossing over occurs during?
Prophase 1 - Meiosis
What is Synapsis and where does it occur?
Prophase 1 of meiosis and it is the pairing of homologous chromosomes
Chromatids form during
S phase - Interphase
Where is DNA synthesized?
S phase of interphase
Production of S phase - Interphase
Single chromosomes enter the synthesis or S phase of interphase. At the end of this phase, after DNA replication, the chromosomes are double, each consisting of TWO SISTER CHROMATIDS.
During which phase of mitosis does the nuclear envelope re-form?
Telophase - Mitosis
Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?
The sequences are identical
What kind of cell does Meiosis start with?
a single diploid cell
What does Meiosis produce?
4 haploid cells
# of chromosomes of human zygote
46
Autosomes
Any chromosome that is not a sex chromosome
What occurs during Mitosis?
Chromatids separate (during anaphase)
Meiosis occurs in
ovaries & testes
Method bacteria divide by?
binary fission
Telophase - Mitosis
- chromosomes arrive at poles -nuclear envelope forms
Prophase 1 - Meiosis
- homologous chromosomes stick together in pairs -recombination
Anaphase - Mitosis
- sister chromatids separate & become chromosomes - move to opposite poles
Homologous Chromosomes
-identical in arrangement of genes -genes may differ between chromosomes
Metaphase - Mitosis
-spindle fully forms - chromosomes line up
Prophase - Mitosis
1) centrosomes move away from each other& nuclear envelope breaks 2) mitotic spindle begins to form
What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?
1) whether DNA is linear or circular 2) the amount of DNA present 3) whether the DNA is housed in a nucleus or not
How many pairs of autosomes & sex chromosomes do humans have?
22 & 1 pair of sex chromosomes
Order of Meiosis
interphase prophase 1 metaphase 1 anaphase 1 telophase 1 cytokinesis -> meiosis 2
All sexual life cycles involve
an alteration of diploid and haploid stages
The function of mitosis is to produce daughter cells that?
are genetically identical to the parent cell (assuming no mutation has occurred)
As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of
density- dependent inhibition
Cell Division involves
distribution of identical DNA to two daughter chromosomes.
Interphase - Meiosis
duplicates chromosomes
What is a feature of plant cell division that distinguishes it from animal cell division?
formation of a cell plate
At the conclusion of meiosis I, the daughter cells are
haploid and the sister chromatids are joined