BLG 143 Study Guide - Final Guide: Sister Chromatids, Spindle Apparatus, Lamin

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11.2 How Mitosis Takes Place

There must be some way of holding sister chromatids together until the signal is given;

achieved with a large number of protein rings called cohesins.

The cell uses microtubules to help move the chromosomes/pieces of DNA to the poles.

The chromosomes must be condensed, which is done with the proteins condensins, they

stabilized loops in the same piece of DNA.

Mitosis is DNA working together with cohesins, microtubules, nuclear lamins and

condensins.

Prophase

➢ Chromosomes condense into compact structures

➢ First become visible in the light microscope

➢ In cytoplasm, marked by the formation of the spindle apparatus  structure that

produces mechanical forces that pull chromosomes to the poles of the cell during

mitosis and push the poles of the cell away from each other

➢ Polar microtubules extend from each spindle and overlap one another in the middle

of the cell

➢ Kinetochore microtubules attach to the chromosomes

Prometaphase

➢ Chromosomes become completely condensed

➢ Nuclear envelope begins to disappear

➢ Kinetochore microtubules from each spindle apparatus attach to one of the 2 sister

chromatids of each chromosome

➢ Attachment between the kinetochore microtubules and each chromatid is made at a

structure called the kinetochore (located at the centromere region of the

chromosome)

Metaphase

➢ Animal centrosomes complete their migration to the opposite poles of the cell

➢ In all eukaryotes, the kinetochore microtubules finish moving the chromosomes to

the middle of the cell

➢ Chromosomes are lined up along an imaginary plane called the metaphase plate

➢ Formation of spindle apparatus is complete

➢ Tug of war is occurring with motor proteins on kinetochore microtubules pulling

each chromosome in opposite directions

Anaphase

➢ Cohesins holding sister chromatids together split

➢ Sister chromatids are pulled apart to create independent chromosomes as soon as

they’re no longer attached

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Document Summary

There must be some way of holding sister chromatids together until the signal is given; achieved with a large number of protein rings called cohesins. The cell uses microtubules to help move the chromosomes/pieces of dna to the poles. The chromosomes must be condensed, which is done with the proteins condensins, they stabilized loops in the same piece of dna. Mitosis is dna working together with cohesins, microtubules, nuclear lamins and condensins. First become visible in the light microscope. In cytoplasm, marked by the formation of the spindle apparatus structure that produces mechanical forces that pull chromosomes to the poles of the cell during mitosis and push the poles of the cell away from each other. Polar microtubules extend from each spindle and overlap one another in the middle of the cell. Kinetochore microtubules from each spindle apparatus attach to one of the 2 sister chromatids of each chromosome.

Related Questions

If an organismâs diploid chromosome number is 18, how many different possible combinations of homologous chromosomes lining up during meiosis exist for the eggs or sperm produced by that organism?

	A.	512
	B.	9
	C.	18
	D.	128
	E.	36

At the end of metaphase I, _______________ separate.

	A.	sister chromatids
	B.	germ cells
	C.	homologous chromosomes
	D.	haploid chromatids
	E.	centrioles

Mendel observed that dominant traits

	A.	are seen in all of the F1 hybrid pea plants in his experiments.
	B.	are expressed in all plants.
	C.	were absent in the F1 generation of pea plants that he used in his experiments.
	D.	were the only traits seen in the F2 generation of pea plants in his experiments.
	E.	are only expressed in hybrids.

Cytokinesis in plant cells differs from cytokinesis in animal cells because

	A.	there is no difference.
	B.	in plant cells, the cell plate must also divide into two parts.
	C.	the contractile protein, actin, is important only in plant cells.
	D.	plant cells have a rigid cell wall.
	E.	a contractile ring forms only in plant cells.

Sickle cell anemia is an example of what type of inheritance?

	A.	complete dominance
	B.	incomplete dominance
	C.	codominance
	D.	multiple alleles
	E.	recessive dominance

Which of the following statements is true:

	A.	The dominant allele is masked in homozygous dominant individuals.
	B.	With recessive genetic disorders, if both parents are carriers, the offspring will all be affected.
	C.	In carriers, the recessive allele causes an intermediate phenotype.
	D.	In recessive genetic disorders, the mother and/or father of an affected individual must also be affected.
	E.	With dominant genetic disorders, the mother and/or father of an affected individual must also be affected.

Skin cancers typically develop in the

	A.	upper layers of the epidermis.
	B.	lower layers of the dermis.
	C.	subcutaneous layer.
	D.	lower layers of the epidermis.
	E.	upper layers of the dermis.

Duchenne muscular dystrophy (MD) is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

	A.	1/2
	B.	0
	C.	1/16
	D.	1/4
	E.	1/8

The genetic makeup of a particular trait in an individual is its

	A.	genotype.
	B.	heterozygosity.
	C.	phenotype.
	D.	filial.
	E.	dominance.

What structure holds the sister chromatids to the spindle fibers?

	A.	chromatin
	B.	kinetochore
	C.	MPF
	D.	centromere
	E.	cyclin

If you view a cell in which the genetic material is beginning to be visible as separate bodies, and the nucleus has disappeared from view, you may surmise that the cells is in

	A.	telophase.
	B.	anaphase.
	C.	interphase.
	D.	metaphase.
	E.	prophase.

Gregor Mendel was successful in his analysis of the genetics of pea plants because

	A.	he examined and analyzed both the F1 and F2 generations.
	B.	he studied the parental plants to determine their differences.
	C.	he decided to only look at his results in an objective manner.
	D.	he studied a trait that had a strange inheritance pattern.
	E.	pea plants have genetics different from other organisms.

Tall corn plants (T) are dominant to dwarf plants (tt). Solid green leaves (G) are dominant to leaves with a white tip (gg). A cross between two corn plants yielded the following phenotypes: 51 tall plants with a white tip on their leaves; 43 dwarf plants with solid leaves; 48 dwarf plants with white tips on their leaves; 45 tall plants with solid leaves. What are the genotypes of the parents that produced these plants?

	A.	None of the above
	B.	TtGg x Ttgg
	C.	ttGG x TTgg
	D.	TtGg x TtGg
	E.	TtGg x ttgg

In humans, a gene that has been identified as causing a type of skin cancer is the

	A.	superwoman echidna.
	B.	mutant superman.
	C.	sonic hedgehog.
	D.	mutant mole rat.
	E.	superhero aardvark.

The segregation principle states that in sexually reproducing diploid organisms the two copies of each gene

	A.	segregate from each other during meiosis.
	B.	must always be the same allele.
	C.	separate from each other during mitosis.
	D.	will both wind up in either the sperm or egg.
	E.	move together as a unit during meiosis.

In what phases is the genetic material in the cell correctly referred to as chromatids?

	A.	metaphase and telophase
	B.	anaphase and metaphase
	C.	interphase and telophase
	D.	interphase and prophase
	E.	metaphase and prophase

Consider two traits for an organism, determined by two genes, each of which is governed by at least two alleles. In the case of a dihybrid individual, the gametes formed will be of either the parental type or the recombinant type. Recombinant type gametes are formed because of

	A.	the principle of dihybrids.
	B.	multiple alleles.
	C.	heterozygosity.
	D.	incomplete dominance.
	E.	independent assortment.

An allele is

	A.	an alternate form of a gene.
	B.	always recessive.
	C.	the main factor determining a trait.
	D.	always one of a pair.
	E.	the dominant form of a gene.

After the DNA is replicated, and it condenses in prophase, two identical rods of DNA are seen. These are

	A.	spindle fibers.
	B.	kinetochores.
	C.	chromatids.
	D.	chromatin.
	E.	centromeres.

Special cells found in the gonads that give rise to gametes upon division are called

	A.	egg cells.
	B.	somatic cells.
	C.	germ cells.
	D.	stem cells.
	E.	basal cells.