BIL 250 Lecture Notes - Lecture 14: Sister Chromatids, Cell Plate, Separase

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18 Apr 2017

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Sister chromatids of each chromosome, held together only at their centromeric regions, disjoin. Disjunction: pulled to opposite ends of the cell. Cohesin complex holding the centromere region of each sister chromosome is then cleaved by separase. Sister chromatids of each chromosome are pulled toward the opposite poles of the cell. Dependent of the kinetochore spindle fiber attachment for movement. Migration due to activity of a series of specific molecules called motor proteins found at several locations within the dividing cell. Molecular motors: use the energy generated by hydrolysis of atp. Centromeres of each chromosome appear to lead the way during migration, with the chromosome trailing behind. Location of centromere determines the shape of the chromosome during separation. Providing each subsequent daughter cell with an identical set of chromosomes. 2 sets of chromosomes are present in the beginning cytokinesis essential if two new cells are to be produced from one.

Related Questions

Question 3 (5 points)

Match the terms to the definitions provided.

Question 3 options:

	telophase II
	meiosis II
	telophase I
	anaphase I
	anaphase II

1.	Division, beginning without DNA replication, that resembles and produces four haploid cell.s
2.	Phase of meiosis when chiasmata are broken as spindle fibers shorten and homologous pairs are pulled apart.
3.	Phase of meiosis when sister chromatids are pulled to opposite poles of the cells.
4.	Phase of meiosis in which homologues cluster at the poles of the cells and the nuclear envelope reforms.
5.	Phase of meiosis in which four different haploid cells are present.

Question 4 (7 points)

Match the terms to the definitions provided.

Question 4 options:

	G0
	telophase
	G2
	mitosis
	cytokinesis
	cell cycle
	S

1.	The phase in which the cell synthesizes a replica of its genome
2.	The overall process of genome duplication
3.	The phase in the cell cycle during which mitochondria and other organelles replicate.
4.	The phase in mitosis when chromosomes are clustered at opposite poles and the spindle apparatus disappears
5.	A resting state that cells often enter before resuming cell division.
6.	The phase in the cell cycle when the cytoplasm divides creating two daughter cells.
7.	The phase in the cell cycle in which the spindle apparatus assembles and sister chromatids move apart.

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Question 5 (6 points)

Put the events of a MAP kinase cascade in the correct order.

Question 5 options:

	MAPKKK phosphorylates and activates another kinase
	MAPKK phosphorylates and activates MAPK
	Binding of MAPKKK to Ras
	External signal binds to membrane receptor and activates receptor kinase.
	MAPK phosphorylates an inactive response protein and activates it.
	Phosphorylation of receptor kinase and interaction with RAS

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.