Bio Unit 4 Final Exam

Widow’s peaks, short fingers:

WWSS, WWSs, WwSs, WwSS

Widow’s peaks, long fingers:

WWss, Wwss

Straight hairline, short fingers:

wwSS, wwSs

Straight hairline, long fingers

wwss

Autosomal recessive disorder:

Tay-Sachs disease, Cystic Fibrosis (CF), Sickle-cell disease, Phenylketonuria (PKU)

Autosomal dominant disorder:

Huntington’s disease, Marfan syndrome

Although he established many important laws of heredity, Gregor Mendel had no knowledge of the process of ___ 

Meiosis

Despite his lack of knowledge, he observed that all possible combinations of factors can occur in the ___, leading to great variation in the genetic makeup of the eggs and sperm created. 

Gametes

Based upon this observation, he established his second law, the law of ___ ___. 

Independent Assortment 

This law states that each pair of factors separates ___, regardless of how the others move, during the formation of gametes.

Independently 

Even without an understanding of this process, he was able to see that his experimental results were only possible if sperm and eggs were created such that they contained every possible combination of factors or, ___, from the parent organisms.

Alleles

Traits exhibiting simple dominant or recessive inheritance are controlled by the expression of ___ set(s) of alleles.

One

However, variations of these inheritance patterns exist, such as in the case of ___ dominance. 

Incomplete

In this situation, a ___ displays a phenotype that is intermediate between that of the two ___. 

Heterozygote;Homozygotes

For example, the offspring of a homozygous dominant individual displaying ___ hair and a homozygous recessive individual displaying curly hair will be heterozygotes displaying the intermediate phenotype of ___ hair. 

Straight;Wavy

Another example is the case of ___ , where all alleles are equally expressed in a heterozygote.

Codominance 

An example of this type of expression occurs in blood phenotypes, where an individual possessing an A blood type allele and a B blood type allele has a blood phenotype of ___.

 AB

What is the overall purpose of meiosis?

To produce four genetically different haploid cells

When doing dihybrid crosses, it is assumed that the traits assort independently of one another. This is because they are on _____ chromosomes

Different

If an individual within the parental generation was heterozygous for both traits, what combinations of traits could their gametes possess?

WS, Ws, wS, ws

The region of the cell where chromosome pairs line up can be referred to as the spindle equator. T/F? 

Trvke

Random orientation of homologous chromosomes occurs in ________ of meiosis.

Metaphase l

Gregor Mendel investigated genetics at the organism level, using pea plants to establish important laws of ___ 

Heredity

Using information from genetic crosses in these plants, Mendel formulated his first law, the law of ___ 

Segregation

This law states that every individual possesses two factors, now known as ___, for each trait. 

 Alleles

These factors segregate during the formation of ___, such that each receives one factor from each pair of factors. 

Gametes

Thus, ___ of an egg by a sperm creates a new individual that now possesses two factors for each trait, one from each parent.

Fertilization

In diploid organisms such as humans, chromosomes come in pairs called ___

 Homologues

Each member of the pair carries ___ for the same traits arranged in the same order along the length of the chromosome.

Genes

However, each member may possess different ___ of each gene.

Alleles 

These are alternate forms of a gene coding for the same trait, and they are always located at the same ___ on each member of the pair

Locus

In diploid organisms, there are ___ alleles for each trait present in a cell.

Alleles

They are termed dominant and recessive. It is the ___ allele that typically masks the expression of the other allele when they are both located in the same cell. 

Dominant

When a trait is controlled by multiple alleles, the gene exists in several allelic forms. Each individual possesses ___ of the possible alleles. 

Two

For example, ___ alleles for the same gene control the inheritance of ABO blood types.

Three

These alleles determine the presence or absence of ___ on red blood cells.

Antigens

The I^A allele encodes for the production of ___ antigen, the I^B allele encodes for ___ antigen production and the i allele encodes for ___ antigen production.

A;B;no

Both the I^A and I^B alleles are ___ over the i allele; however, both are fully expressed, or codominant, in the presence of each other.

Dominant

This results in ___ possible blood phenotypes from ___ variant genotypes.

Four;Six

The results are: A blood type (I^AI^A, ___), B blood type ( ___, I^Bi) AB blood type ( ___) and O blood type (ii). 

IA;IB;IAB

In the following pedigree, the inherited condition is due to an autosomal dominant allele. T/F? 

False

Mendel carried out most of his research with

Pea plants

If T = tall and t = short in plants, the genotype of a short plant would be

only tt

In humans, widow's peak (W) is dominant over straight hairline (w). If a heterozygous male and a female with a straight hairline have children, what percent of their children can be expected to have widow's peak?

50%

In which kind of monohybrid cross would you expect to find a phenotypic ratio of 3:1 among the offspring? 

heterozygous × heterozygous

Due to a recessively inherited trait, some plants fail to produce chlorophyll and therefore are white rather than green. If we locate a pea plant that is heterozygous for this trait, self-pollinate it, harvest the seeds, and then plant the seeds, what are the likely phenotypes of the resulting offspring?

approximately 1/4 white and 3/4 green

An individual with a dominant phenotype is crossed with an individual with a recessive phenotype. Five out of nine offspring show the dominant phenotype. What is the genotype of the dominant parent?

heterozygous

A cross that involves two traits is called a 

dihybrid cross

Which of the following crosses will yield only homozygous recessive offspring?

rryy x rryy

In four o'clock flowers, R = red, r = white, and Rr = pink. If two hybrids are crossed, what are the chances that an offspring will have pink flowers? 

50%

Consider skin color is regulated by three genes: A, B, and C. All recessive alleles would be 0 or white on the color scale. All dominant alleles would be 6 or black on the color scale. What color skin would a person have with AAbbCc genotype?

3 or medium brown

You have two true-breeding rose bushes, one with red flowers and one with white flowers. A cross between these two roses yields a bush with pink flowers. The pink flower color is an example of

 incomplete dominance 

What pattern of inheritance is shown in the following pedigree? What is the probability that the affected son in generation III will pass the trait on to his children?

Autosomal dominants, 50%

The alternate forms of a gene for the same trait are known as

Alleles

In peas, the yellow seed color is dominant (YY or Yy) over the green seed color (yy). You have been given a plant that only produces yellow seeds and need to determine if the plant is YY or Yy.  Which of the following crosses would be most effective for determining the genotype of your plant?

your plant × a plant that produces only green seeds

A chromosome contains a long series of ___ in a definite sequence

 Alleles

This sequence is static, as each allele possesses its own particular ___ or location on a chromosome.

 Locus

All alleles residing on a single chromosome form what is called a ___ ___

Linkage Group

Alleles of such a linkage group tend to be inherited ___ due to their proximity.

Together

Because of this, such linked alleles do not exhibit ___ ___ in the results of a genetic cross.

 Independent Assortment

Select the two chromosomal alleles that will cross-over the most frequently.

Alleles a & h, Alleles b & g

In humans, there are two ___ chromosomes: X and Y.

Sex

Traits controlled by genes on these chromosomes are termed ___-___ traits

Sex-Linked

Sex-linked genes are found predominantly on the ___ chromosome, as very few alleles have been found on the smaller ___ chromosome.

X;Y

Transmission of these genes occurs such that a male offspring will always receive an X-linked allele from their ___ ___  through the inheritance of their X chromosome.

Female Parent

Since the Y chromosome from the male parent of a male child does not carry an allele corresponding to this X-linked allele, the male child will express the X-linked trait if the allele from their female parent is ___; if it is normal, the male child will not express the X-linked trait.

Mutated

In order for a female child to express most X-linked traits, they must inherit ________ of the X-linked gene.

Two Mutated Alleles

There are instances, though, where a ___ possesses one normal and one mutated copy of an X-linked gene.

Female

In this case, they are considered a ___ , for a trait, though they do not express the X-linked trait. They do have the ability to silently pass on the mutated form of the X-linked gene.

Carrier

During meiosis I, ___ ___ separate and move towards opposite ends of the poles.

 Homologous Chromosomes

During meiosis II, ___ ___  separate and move towards opposite ends of the poles.

Sister Chromatids

During meiosis I, if both members of a homologous pair go into the same daughter cell, ___ is said to occur, and no normal gametes are produced.

Nondisjunction 

During meiosis II, if the sister chromatids fail to separate and both daughter chromosomes go into the same gamete, ___  is said to occur. Half the gametes have 2n+1 chromosomes while the other half have 2n-1 chromosomes.

Nondisjunction 

If an egg that contains 24 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ___ is said to have occurred.

Trisomy

If an egg that contains 22 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ___ is said to have occurred.

Monosomy

Although humans normally possess ___ chromosomes, some individuals are born with too many or too few of these chromosomes, in many cases due to a process called ___

46;Nondisjunction 

Nondisjunction can occur during ___I, when both members of a homologous pair are pulled into the same daughter cell.

 Meiosis

It can also occur during meiosis II if ___ ___ fail to separate, resulting in both daughter chromosomes entering the same gamete.

Sister Chromatids 

In both cases, gametes are created that have either received an extra chromosome resulting in ___ chromosomes present, or have lost a chromosome resulting in ___ chromosomes present.

24;22

If an egg with 24 chromosomes is fertilized by a normal sperm, the result is a ___  due to one chromosome being present in three copies. 

trisomy

On the other hand, if an egg with 22 chromosomes is fertilized by a normal sperm, the result is a ___ because one chromosome is present only in a single copy.

Monosomy

Because too many chromosomes are tolerated more than a deficiency in chromosome number, there are more ___ disorders than monosomy disorders in humans.

Trisomy

An example of nondisjunction in autosomes is ___ ___, also called Down syndrome. 

Trisomy 21

Though there are several ways that this disorder may arise, there is typically a copy of chromosome 21 donated from the egg as a result of ____ during oogenesis. 

Nondisjunction

Down syndrome is associated with characteristics such as short stature, an eyelid fold, short fingers, a fissured tongue, and varying degrees of ___ ___ 

Intellectual Disability 

The chance of having a child with Down syndrome ___ with the age of the female parent. This is likely due to a greater chance of ___ occurring among developing egg cells, although the exact cause remains undetermined. 

Increases; Nondisjunction 

Females with an extra X chromosome have the genotype ___ and are said to have ___ ___ syndrome. This syndrome is associated with characteristics such as being tall and thin. Some individuals may have motor or language difficulties and/or menstrual issues, though more often there is no distinct phenotype.

XXX; poly X

Females with only one X chromosome have the genotype ___ and are said to have ___ syndrome. This syndrome is associated with characteristics such as short stature, a broad chest, and folds of skin on the back of the neck. Individuals with this syndrome have ____ reproductive organs, and do not undergo puberty or menstruate without ___ ___replacement therapy.

XO; Turner; Underdeveloped; Sex Hormone

Males with an extra Y chromosome have the genotype ___ and are said to have ___ syndrome. This syndrome is associated with characteristics such as tall stature, persistent acne, and speech and reading problems.

XYY; Jacobs

Males with an extra X chromosome have the genotype ___ and are said to have ___ syndrome. Individuals who have this syndrome often receive ___ supplements at puberty and would require further treatment in order to parent children biologically.

 XXY; Klinefelter; Testosterone

Inversions:

 Occurs when a piece of a chromosome breaks and reattaches upside down

Duplications:

Occurs when the same piece is repeated within a chromosome

Deletions:

Occurs when pieces of a chromosome are lost, Examples include Williams syndrom & Cri du chat syndrome

Translocations: 

Occurs when pieces of a chromosome are exchanged between non-homologous pairs, Examples include chronic myelogenous leukemia

A Barr body is typically found in the nucleus of 

Female somatic cells only

A cell with three X chromosomes will contain

2 Barr bodies

A linkage group can best be described as

collections of genes on the same chromosome that are inherited together as a group.

Genes C and D are located on opposite ends of a chromosome that is undergoing crossing-over during meiosis. Which of the following outcomes is likely to be true?

Genes C and D have an increased likelihood of undergoing recombination.

All of the genes on a single chromosome form a

a linkage group

The location of a gene on a chromosome is called a 

Locus