diploid
Zygotes have a _________ number of chromosomes
haploid
Gametes have a _________ number of chromosomes
Chromatin
While in interphase of mitosis (before division begins), DNA is in its ________ form.
Interphase
All cells spend most of their time in which phase?
To make an exact copy of the nucleus/cell
What is the goal of mitosis?
The make four genetically different copies of the nucleus/cell
What is the goal of meiosis?
Binary fission
How do bacteria divide?
Mitosis and meiosis
In what two ways can eukaryotes divide?
Meiosis
From what type of division are sperm, eggs, spores, etc. produced?
Mitosis
From what type of division are somatic/body cells produced?
pro-meta-ana-tela or “I Poke Monkeys At The Circus”
What are the two mnemonics to learn the phases of cell division?
meiosis – the produce gametes that facilitate sexual reproduction
What occurs in germ cells? Why?
Place where two sister chromatids are joined during prophase and metaphase. Contains the kinetochore
What are centromeres?
One of the two identical halves of a duplicated (X/Y) chromosome, the two chromatids are referred to as sister chromatids.
What are chromatids?
mass of genetic material composed of DNA in and proteins that condenses to form chromosomes.
What are chromatin?
Structures in the cell nucleus containing the genes and composed of chromatin.
Chromosomes
When the cell divides – during Prophase.
When do the chromosomes become condensed into more visible structures?
“matching” chromosome that codes for same gene but a different version – one from mom and one from dad – “chromosome pairs”
Homologues Chromosome
prophase, metaphase, anaphase and telophase
In order, name the phases of Mitosis
prophase I, metaphase I, anaphase I and telophase I – and then repeated using the number II
In order name the phases of Meiosis
G1, S-Phase and G2
What are the subdivisions of interphase?
Time when the cell growing and “living” — when it is not actively dividing
What is the interphase of mitosis?
Chromatids condense into chromosomes, nuclear envelope starts breaking down and centrioles form and move towards opposite ends of cell. Spindle fibers from centriole being to attach to each centromere
What happens during the prophase of mitosis?
each homologous chromosome replicates itself (making it’s sister chromatid)
What is the S-Phase of mitosis?
Stage in which the chromosomes line up on the equatorial plane of the cell. Occurs after prophase and before anaphase.
What happens during metaphase of mitosis?
Where sister chromatids divide at centromere and are pulled apart towards opposite poles – now each can be called chromosomes
What is anaphase of mitosis?
Last phase of mitosis – Beginning of cytokinesis – Nuclear membrane DNA has been pulled to opposite sides. Nuclear membrane (envelope) starts to form around each of the ends. Chromosomes become de-condensed.
What is telophase of mitosis?
During telophase when cleavage furrow forms until the cytoplasm is separated into two different cells.
What is cytokinesis of mitosis?
Division of the cell nucleus, resulting in two daughter nuclei, each with the same number of chromosomes as the parent nucleus. Mitosis consists of four phases: prophase, metaphase, anaphase and telophase
Mitosis
Equitorial/Metaphase plate
What is the area called where the chromosomes line up at the center of the cell during metaphase?
attach to centromeres in center of chromosomes – specifically to the kinetochore
To what do the spindles of the centrosomes attach to during cell division?
organelle from where the microtubules/spindles are organized from.
Centrosome
region of DNA typically found near middle of chromosome where two sister chromatids come in contact
Centromere
G1 subdivision of interphase; gap in time from end of mitosis to beginning of S phase
What is considered the “first gap” and what goes on?
S-phase
What is considered the subdivision in which DNA synthesis occurs in interphase?
G2 subdivision of interphase; hap in time between end of S-phase and beginning of M phase (mitosis)
What is considered the “second gap” and what goes on?
structure consisting of mainly microtubules that assist in the chromosome movement during cell division – extended from centrosome
Spindles
Interphase
During what phase is there no visible chromosome?
Prophase (early)
When does visible chromosomes start to form?
Metaphase
When do spindle fibers start to be seen during cell division (attaching to centromeres)?
Microtubules
What extends from the spindle apparatus?
telophase
When does cytokinesis begin during cell division?
structure that forms during cell division, contraction of which causes the plasma membrane to pinch inward and the cell to divide.
Contractile ring
Contractile ring
During cell division, what is the structure that contracts and pinches the plasma membrane to separate the two cells?
Where cells are increasing in size, but not dividing. (the top portion of the root after root cap and region of cell division
On an onion root tip, what is the region of cell elongation?
where cells are actively dividing but not increasing significantly in size. (right above the bottom root cap)
On an onion root tip, what is the region of cell division?
contains cells that cover and protect the underlying growth region as the root pushed through the soil. (at very bottom)
On an onion root tip, what is the root cap?
Meiosis
Through what are gametes produced?
The condition of having two sets of chromosomes per nucleus (having full number of complement of chromosomes).
Diploid
46
How many chromosomes does a human diploid cell contain?
23
How many chromosomes does a human haploid cell contain?
Meiosis – this reduces diploid number (46) to haploid (23)
In what is reductive chromosomal division found in? What is it?
23
How many chromosomes does an egg and sperm each have?
cell that results from the union of gametes in sexual reproduction
Zygote
Zygote
What is a cell called that results from the union of gametes in sexual reproduction?
A sex cell (an egg or sperm). In sexual reproduction, the union of gametes results in the formation of a zygote. The chromosome number of a gamete is half of a full complement of chromosomes.
Gamete
gamete
What is considered a “sex cell”?
A diploid zygote
Fertilization (egg+sperm) produces what?
The condition of having half the number of full complement of chromosomes.
Haploid
cells in the body, not in the germline (which produce gametes)
Somatic cells
Diploid (zygote, somatic, etc.)
Which cells have ‘2n’ number of chromosomes?
Haploid (egg, sperm)
Which cells have ‘n’ number of chromosomes?
When the cell is growing and replicates its chromosomes to now have two sister chromatids
What happens in Interphase before Meiosis?
when chromosomes gather together in center, the homologous chromosomes come together side by side instead of end to end. When doing this, the chromosomes side by side can cross over on each other at homologous points. This leads to genetic variation
What are the notable differences in the prophase I of Meiosis I?
During Prophase in Meiosis I, the homologous chromosomes come together side by side and can cross over on each other at homologous points – this is the formation of tetrads
What is the main reason for genetic variation?
During Meiosis at prophase
When are tetrads formed?
4 chromatids
What do tetrad’s contain?
instead of sister chromatids separating from each other, the homologous pairs separate from each other – sister chromatids stay together
What are the notable differences in anaphase I of Meiosis I?
each cell produced at this point ends up with two chromosomes (one pair of each homologous pairs) – stage set to start meiosis II
What are the notable differences in telophase I of Meiosis I?
Sister chromatids are separated
What are the notable differences in anaphase I of Meiosis II?
Anaphase II
Where is the only notable change seen in Meiosis II?
Prophase I, Anaphase I and Telophase I
Where are the only notable changes seen in Meiosis I?
Went from a diploid germ cell, split the homologous pairs in first phase. Second phase separated sister chromatids. Ended up with 4 haploid cells that are called gametes.
Give short overview of what Meiosis does…
1st – circular chromosomes replicate 2nd copies attach to different parts of cell membrane (mesosome) 3rd cell pulls apart 4th cytokinesis
What is the process of binary fission?
one parent cell and one daughter cell (an exact replica)
What does binary fission produce during prokaryotic cell division?
Binary fission happens in prokaryotic cells in which there is no nucleus to separate – they are a simple organism.
What is a main difference between binary fission and other cellular reproduction?
Process in which a 2n cell undergoes two successive nuclear divisions (meiosis I and meiosis II), potentially producing four n nuclei; leads to the formation of gametes in animals and spores in plants.
Definition of Meiosis
Binary fission
Why type of cell division does prokaryotic cells go through?
the breaking and rejoining of homologous (non-sister) chromatids during early meiotic prophase I – resulting in exchange of genetic material
Crossing over
crossing over or recombination
Synapsis is necessary for what?
Synapsis
Pairing of homologous chromosomes is also know as what?
paring of two homologous chromosomes that occurs during meiosis
Synapsis
Synapsis and independent assortment of chromosomes – “shuffling the genetic deck of cards”
What are two main areas involved in the genetic implications of meiosis?
Synapsis – a tetrad
The pairing process in meiosis of the homologous pairs of chromosomes lining up next to each other in Meiosis? And the four sister chromatids involved are called what?
allele pairs separate independently during the formation of gametes in meiosis
Independent assortment
Independent assortment
Homologs are free to go different directions in different gametes refers to what?
8
Given the fusion of gametes from a mother and a father (two total), how many potential gametes are there for a given division?
two gametes (one maternal and one paternal), they form a diploid offspring (with homologous pairs), and then there are 8 potential gametes to be formed
Name the “hierarchy” of independent assortment
From random fertilization in man, about how many possible gametes can be produced? 2^23 x 2^23 = (about) 70 trillion
From random fertilization in man, about how many possible gametes can be produced?
There is a lack of diversity
What is the problem with production of hybrid corn?
no crossing over and lining at the ends in prophase — synapsis and crossing over in prophase I
What is the difference between prophase and prophase I?
Anaphase = sister chromatids separate — anaphase I = homologous chromosomes separate — anaphase II = sister chromatids separate
What is the difference between anaphase, anaphase I and anaphase II?
Mitosis
What produces diploid daughter cells?
Animals have centriols where the spindles form from, plants have the spindle but no centriols. During cytokinesis, animal cells split by cleavage furrow (pinched); in plants, it happens by the formation of cell plates gather and become a rigid cell wall separating the two cells(made new wall). Shape of plant cell does not change during mitosis like animal cell does (due to it’s rigid shape)
What are the differences in mitosis between animal and plant cells?
series of repeating events that occur during growth and division of cells
Cell cycle
24 hours
Typical mammalian tissue culture cell has a cell cycle that lasts how long?
G0
Many cells in adult organisms no longer divide and enter a resting state called what?
Mitosis
What is the method of asexual reproduction found in single-celled eukaryotic organisms?
Just above the root cap
The center of cell division in an onion is found where?
mitosis
Homologous chromosomes do not pair up during ________.
