BIOL 1000 Lecture Notes - Lecture 9: Mendelian Inheritance, X-Inactivation, Barr Body

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16 May 2016

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Alleles of genes that govern two different characters segregate independently during formation of gametes (principle of independent assortment) This is due to independent assortment during meiosis. More than 3 alleles for a gene. Found among all individuals in a population. Small differences in dna sequences result in multiple alleles. Dominant alleles do not completely mask recessive alleles (recessive is still seen) Allele of one locus inhibits or masks effects of allele at a different locus. Some expected phenotypes do not appear among offspring. Many different genes contribute to the same character (ex. One gene affects more than one character. Recessive allele affects hemoglobin structure and function. Damages many tissues, organs, and functions, and many different symptoms result. In female mammals, inactivation of one x chromosome makes the dosage of x-linked genes the same as males. X is random in each cell of the embryo (ex. Tightly coiled condensed x chromosome copied during mitosis but always remains inactive.

Related Questions

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?

Which of the following is true for alleles that show incomplete dominance?

Heterozygotes have a genotype like the dominant allele.

Homozygotes have a genotype like the recessive allele.

Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.

Homozygotes have the same phenotype as the heterozygotes.

QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?

independent assortment

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?

polygenic inheritance

A single unit of genetic information located on a chromosome defines:

The physical expression (appearance or function) of an organism's genes defines:

genotype

a single characteristic

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?

Which term best describes the effect of a single gene on multiple aspects of the phenotype?

polygenic inheritance

QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?

polygenic inheritance

QUESTION 10

One form of a gene found on a single chromosome defines:

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?

Both the dominant and recessive alleles

Given the parents AABBGgHhrr Ã AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?

___________________ is defined as having two of the same type of allele for a particular trait.

The physical position of an allele on a single chromosome defines:

Which term best describes two or more genes affecting the phenotype in an additive fashion?

codominance

polygenic inheritance

Fill in the blank, each word can be used more than once.

word bank- crossing over, avoid predation, reproduce,independent assortment, phenotypes, frequencies, nucleotides,meiosis, protein, prophase, segregation, gene, allele, amino acids,fertilization, arrangement, chromosome.

A(n) _________ is one of multiple forms of the same gene.

These different forms of genes are in the same locus of a(n)_________, but they have slightly different sequences of________.

During ________ I of meiosis, genes of homologous chromosomesalign side-by-side.

Then in a process called _________, homologous chromosomesrandomly line up double-file at the center of the cell and thenseperate. Since alleles are randomly distributed, this processcreates variation among the gametes. After ________ with a gametefrom the other sex, variation among gametes will create variationamong the offspring.

Some offspring will have a more favorable combination of allelesthan others, and will therefore survive and ________ moresuccessfully, leading to more favorable alleles in the nextgeneration. However, sometimes conditions change, andonce-favorable phenotypes may becomes less favorable.

Scientists hope that they will soon be able to use biotechnologyto track the ________ of alleles over multiple generations, therebywatching evolution as it occurs.

taupewolf882

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.

BIOL 1000 Lecture Notes - Lecture 9: Mendelian Inheritance, X-Inactivation, Barr Body

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