Bio test 4

crossing over

The exchange of segments between chromatids of homologous chromosomes during synapsis in prophase I of meiosis; also, the exchange of segments between DNA molecules in prokaryotes.

A man who has type B blood marries a woman who has type A blood, Suppose both of their fathers had type O blood. What blood types are possible for their children?

Types A, B, AB, and O

alleles

alternative versions of a gene

metaphase 2

the chromosomes are aligned on the metaphase plate as the are in mitosis, with the kinetochores of the sister chromatids of each chromosome pointing toward opposite poles.

Pleiotropy

the control of more than one phenotypic characteristic by a single gene -occurs when one gene influences many characteristics.

zygote

the diploid fertilized egg, which results from the union of a sperm cell nucleus and an egg cell nucleus

phenotype

the expressed traits of an organism

cleavage furrow

the first sign of cytokinesis during cell division in an animal cell; a shallow groove in the cell surface near the old metaphase plate

mitosis stages

prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis

Genetic recombination during prophase I

produces new combinations of genes due to crossing over.

Meiosis 1

prophase 1, metaphase 1, anaphase 1 -homologous chromosomes separate

cleavage

(1) Cytokinesis in animal cells and in some protists, characterized by pinching in of the plasma membrane. (2) In animal development, the succession of rapid cell divisions without cell growth that converts the animal zygote into a ball of cells.

translocation

(1) During protein synthesis, the movement of a tRNA molecule carrying a growing polypeptide chain from the A site to the P site on a ribosome. (The mRNA travels with it.) (2) A change in a chromosome resulting from a chromosomal fragment attaching to a nonhomologous chromosome; can occur as a result of an error in meiosis or from mutagenesis.

prokaryotes

(bacteria and archaea) reproduce by binary fission ("dividing in half").

Independent orientation at metaphase I

- Each pair of chromosomes independently aligns at the cell equator. - There is an equal probability of the maternal or paternal chromosome facing a given pole. - The number of combinations for chromosomes packaged into gametes is 2n where n = haploid number of chromosomes.

HeLa cells

- have been in culture since 1951 -From Henrietta Lacks- died from cervical cancer at age 31

Cancer cells out of control

-Cancer currently claims the lives of 20% of the people in the United States and other industrialized nations. -Cancer cells escape controls on the cell cycle. -Cancer cells -divide rapidly, often in the absence of growth factors, -spread to other tissues through the circulatory system, -grow without being inhibited by other cells. -Cancer cells have been studied in culture -Never stop dividing; immortal -HeLa cells- have been in culture since 1951 -From Henrietta Lacks- died from cervical cancer at age 31 -Cells have been used in the discovery of polio vaccine, HIV/AIDS research, cloning, gene mapping, in vitro fertilization, disease treatment, drug discovery

compare the events of mitosis and meiosis. Which of the following statements are true?

-During Anaphase 2 and anaphase of mitosis sister chromatids separate and move to opposite poles. -DNA replication occurs during S-phase of the interphase before both mitosis and meiosis

polyploid

-Errors in mitosis or meiosis may produce polyploid species, with more than two chromosome sets. -The formation of polyploid species is • widely observed in many plant species but • less frequently found in animals.

cell division controls

-Essential nutrients -Growth factors -Anchorage dependence -Density-dependent inhibition

chromosome

A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. A chromosome consists of one very long DNA molecule and associated proteins.

Separation of homologous chromosomes during meiosis can lead to genetic differences between gametes

-Homologous chromosomes may have different versions of a gene at the same locus. -One version was inherited from the maternal parent and the other came from the paternal parent. -Since homologues move to opposite poles during anaphase I, gametes will receive either the maternal or paternal version of the gene.

prokaryotic chromosome

-a singular circular DNA molecule, associated with proteins -much smaller than those of eukaryotes

eukaryotic cells

-more complex and larger than prokaryotic cells, -more genes, and -store most of their genes on multiple chromosomes within the nucleus.

cell division is used for

-reproduction of single-celled organisms, -growth of multicellular organisms from a fertilized egg into an adult, -repair and replacement of cells, and -gamete (sperm and egg) production.

meiosis 2

-sister chromatids separate Meiosis Il is essentially the same as mitosis. The important difference is that meiosis II starts with a haploid cell containing a single set of still-duplicated chromosomes. -prophase 2, metaphase 2, anaphase 2, telophase 2 + cytokinesis

cancer cells

-start out as normal body cells, -undergo genetic mutations, -lose the ability to control the tempo of their own division, -reproduce uncontrollably, eventually causing disease.

If we do a testcross to determine the genotype of a black Lab with normal vision, which of the following results would indicate that it is heterozygous for black coat and homozygous for normal vision?

1 black, normal vision : 1 chocolate, normal vision

In Labradors, black coat color and normal vision are dominant over chocolate coat color and blindness. If we do a testcross to determine the genotype of a black Lab with normal vision, which of the following results would indicate that it is heterozygous for black coat and homozygous for normal vision?

1 black, normal vision: 1 chocolate, normal vision

In fruitflies, red eyes are a sex-linked trait. What would be the phenotypic ratio if we crossed a heterozygous female crossed with a white-eyed male?

1 red-eyed female: 1 white-eyed female: 1 red-eyed male: 1 white-eyed male

plant cell cytokinesis

1. a cell plate forms in the middle, from vesicles containing cell wall material, 2. cell plate grows outward to reach the edges, dividing the contents into two cells, 3. each cell now possesses a plasma membrane and cell wall.

Animal Cell Cytokinesis

1. a cleavage furrow forms from a contracting ring of microfilaments, interacting with myosin, and 2. cleavage furrow deepens to separate the contents into two cells.

Genetic variation in gametes results from

1. genetic recombination during prophase I, 2. independent orientation at metaphase I, and 3. random fertilization.

chromosome theory of inheritance

A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns. ● Genes occur at specific loci (positions) on chromosomes, and ● Chromosomes undergo (I) segregation and (II) independent assortment during meiosis.

inversion

A change in a chromosome resulting from reattachment of a chromosome fragment to the original chromosome, but in a reverse direction. Mutagens and errors during meiosis can cause inversions.

recombinant chromosomes

A chromosome created when crossing over combines the DNA from two parents into a single chromosome.

autosomes

A chromosome not directly involved in determining the sex of an organism; in mammals, for example, any chromosome other than X or Y.

sex chromosomes

A chromosome that determines whether an individual is male or female. Many animals have a pair of sex chromosomes, ● designated X and Y, ● that determine an individual's sex. In mammals, ● males have XY sex chromosomes, ● females have XX sex chromosomes, ● the Y chromosome has genes for the development of testes, ● an absence of the Y allows ovaries to develop.

cell cycle control system

A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle. -a cycling set of molecules in the cell that ● triggers and ● coordinates key events in the cell cycle.

Punnett Square

A diagram used in the study of inheritance to show the results of random fertilization.

cancer

A disease characterized by the presence of malignant tumors (rapidly growing and spreading masses of abnormal body cells) in the body.

karyotype

A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position. -identify chromosomal abnormalities is an ordered display of magnified images of an individual's chromosomes arranged in pairs. • produced from dividing cells arrested at metaphase of mitosis and • allow for the observation of • homologous chromosome pairs, • chromosome number, and • chromosome structure

cell plate

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

pedigree

A family genetic tree representing the occurrence of heritable traits in parents and offspring across a number of generations. A pedigree can be used to determine genotypes of matings that have already occurred.

mitotic spindle

A football-shaped structure formed of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis and meiosis.

sex-linked gene

A gene located on a sex chromosome. In humans, the vast majority of sex-linked genes are located on the X chromosome. -are located on either of the sex chromosomes. The X chromosome carries many genes unrelated to sex. The inheritance of white eye color in the fruit fly illustrates an X-linked recessive trait.

x-linked genes

A gene located on the X chromosome. X-linked genes display unique patterns of inheritance because males only have one copy whereas females have two.

law of segregation

A general rule in inheritance (originally formulated by Gregor Mendel) that individuals have two alleles for each gene and that when gametes form by meiosis, the two alleles separate, each resulting gamete ending up with only one allele of each gene; also known as Mendel's first law of inheritance. -depends on separation of homologous chromosomes in anaphase I.

law of independent assortment

A general rule in inheritance (originally formulated by Gregor Mendel) that when gametes form during meiosis, each pair of alleles for a particular characteristic segregate independently of other pairs; also known as Mendel's second law of inheritance. -depends on alternative orientations of chromosomes in metaphase I.

sickle cell disease

A genetic condition caused by a mutation in the gene for hemoglobin. The mutation causes the protein to crystallize, which deforms red blood cells into a curved shape. Such blood cells produce a cascade of symptoms that can be life-threatening. -is a human example of pleiotropy. Affects the type of hemoglobin produced and the shape of red blood cells; Sickle-cell and nonsickle alleles are codominant. Carriers of sickle-cell disease are resistant to malaria.

Huntington's disease

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms.

trisomy 21

A human genetic disorder resulting from the presence of an extra chromosome 21; characterized by heart and respiratory defects and varying degrees of mental retardation. -down syndrome produces a characteristic set of symptoms, which include: ● mental retardation, characteristic facial features, short stature, heart defects, susceptibility to respiratory infections, leukemia, and Alzheimer's disease, and shortened life span. ● The incidence increases with the age of the mother.

Cross

A mating of two sexually reproducing individuals; often used to describe a genetics experiment involving a controlled mating. -The cross-fertilization is a hybridization, or genetic

binary fission

A means of asexual reproduction in which a parent organism, often a single cell, divides into two individuals of about equal size.

growth factors

A protein secreted by certain body cells that stimulates other cells to divide

rule of multiplication

A rule stating that the probability of a compound event is the product of the separate probabilities of the independent events.

rule of addition

A rule stating that the probability that an event can occur in two or more alternative ways is the sum of the separate probabilities of the different ways.

gametes

A sex cell; a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zygote.

centrosomes

A structure found in animal cells from which microtubules originate and that is important during cell division. A centrosome has two centrioles.

amniocentesis

A technique for diagnosing genetic defects while a fetus is in the uterus. A sample of amniotic fluid, obtained by a needle inserted into the uterus, is analyzed for telltale chemicals and defective fetal cells.

chorionic villus sampling (CVS)

A technique for diagnosing genetic defects while the fetus is in an early development stage within the uterus. A small sample of the fetal portion of the placenta is removed and analyzed.

incomplete dominance

A type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA and aa). -For some characters, the appearance of F1 hybrids falls between the phenotypes of the two parental varieties. This is called ______ _______, in which neither allele is dominant over the other and expression of both alleles occurs.

complete dominance

A type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable. -Mendel's pea crosses - always looked like one of the parental varieties, called

In rabbits, black hair depends on a dominant allele, B, and brown hair on a recessive allele, b. If a true-breeding black haired male was mated to a brown haired female. a. What are the genotypes of each rabbit in this cross? b. What will be the phenotypes of their offspring? C. What will be the genotypes of their offspring?

A. B. C.

benign tumor

An abnormal mass of cells that remains at its original site in the body.

tumor

An abnormal mass of rapidly growing cells that forms within otherwise normal tissue.

malignant tumor

An abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor.

nondisjunction

An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase. -is the failure of chromosomes or chromatids to separate normally during meiosis.

recessive allele

An allele that has no noticeable effect on the phenotype of a gene when the individual is heterozygous for that gene.

dihybrid cross

An experimental mating of individuals that are each heterozygous for both of two characters (or the self-pollination of a plant that is heterozygous for both characters). is a mating of parental varieties that differ in two characters. Coat color - (black or chocolate) Vision - (normal or blind)

monohybrid cross

An experimental mating of individuals that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant).

carrier

An individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder but who may pass on the recessive allele to offspring.

genetic map

An ordered listing of the relative locations of genes along a chromosome.

cell cycle

An ordered sequence of events (including interphase and the mitotic phase) that extends from the time a eukaryotic cell is first formed from a dividing parent cell until its own division into two cells.

Anaphase 1

Anaphase of meiosis is marked by the migration of Chromosomes toward the two poles or the cell. In contrast to mitosis, however, the sister chromatids making up each doubled chromosome remain attached. Only the tetrads (pairs of homologous chromosomes) split up. Thus, in the drawing you see three still-doubled chromosomes moving toward each pole.

somatic cells

Any cell in a multicellular organism except a sperm or egg cell or a cell that develops into a sperm or egg

clone

As a verb, to produce genetically identical copies of a cell, organism, or DNA molecule. As a noun, the collection of cells, organisms, or molecules resulting from cloning; also (colloquially), a single organism that is genetically identical to another because it arose from the cloning of a somatic cell.

metaphase 1

At metaphase I the chromosome tetrads (consisting of a pair of homologous chromosomes, each with two sister chromatids) are aligned on the metaphase plate, midway between the two poles of the spindle. Spindle microtubules are attached to kinetochores at the centromeres. In each tetrad, the homologous chromosomes are held together at sites or crossing over. Notice that, for each tetrad, the spindle micro- Tubules attached to one or the homologous chromosomes come from one pole of the cell, and the microtubules attached to the other homologous chromosome come from the opposite pole. With this arrangement, the homologous chromosomes of each tetrad are poised to move toward opposite poles of the cell.

Observe the cells shown on the screen. Which of the cells are diploid with replicated chromosomes?

B (2 chromosomes in one circle)

Observe the cells shown on the screen. Which of the cells are diploid?

B and A (2 chromosomes in one circle + 2 sister chromatids separated in 1 circle)

Which of the following is a heterozygous genotype?

Bb

In rabbits, black hair depends on a dominant allele, B, and brown hair on a recessive allele, b. If a true-breeding black haired male was mated to a brown haired female, what would be the phenotypes and genotypes of their offspring?

Black, Bb

Mitosis and meiosis

Both cell types have pairs of homologous chromosomes In humans - 23 pairs: 1 pair of sex chromosomes (X, Y) 22 pairs of autosomes (1, 2, 3...22) One member of each homologous pair is from each parent.

Observe the cells shown on the screen. Which of the cells are haploid?

C and D (1 chromosome in 2 diff circles + 4 diff circles with 1 sister chromatid each)

If a version of a gene is dominant, then

C. A single copy of it will produce its trait.

Which of the following is NOT one of the processes that increases genetic diversity in the offspring of sexually reproducing organisms?

Centromeres splitting so sister chromatids can move to separate poles

Prophase 1 (crossing over)

During this time, nonsister chromatids of each homologous pair of chromosomes exchange segments in a process called crossing over. Because the versions of some genes on a chromosome differ from those on the other member or the homologous pair, crossing over rearranges genetic information.

Trait

Each variant for a character within a population is a ______, e.g., purple or white flowers

prophase 1

Early in this phase, homologous chromosomes, composed of two sister chromatids, come together as pairs. The new structure, consisting of four chromatids aligned gene by gene, is called a tetrad. During this time, nonsister chromatids of each homologous pair of chromosomes exchange segments in a process called crossing over. Because the versions of some genes on a chromosome differ from those on the other member or the homologous pair, crossing over rearranges genetic information. As prophase I continues, the chromosomes coil tightly and a spindle forms. The nuclear envelope breaks into fragments, and the chromosome tetrads, captured by spindle microtubules, are moved toward the center or the cell.

Accidents during meiosis

Fertilization after nondisjunction yields zygotes with altered numbers of chromosomes.

linked genes

Genes located near each other on the same chromosome that tend to be inherited together. Bateson and Punnett studied different characters in sweet pea plants that did not show a 9:3:3:1 ratio in the F2 generation. This is an example of linked genes, which ● are located close together on the same chromosome ● tend to be inherited together.

ABO blood groups

Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The ABO blood group phenotypes, also called blood types, are A, B, AB, and O. Many genes have more than two alleles. Human ABO blood group phenotypes are controlled by three alleles (IA , IB , i ) that produce a total of four phenotypes (Types A, B, AB, and O) . The IA and IB alleles are codominant: Both alleles are expressed in heterozygous individuals (IAIB), who have type AB blood. The i allele is recessive to both IA and IB alleles.

homozygous

Having two identical alleles for a given gene

meiosis

In a sexually reproducing organism, the division of a single diploid nucleus into four haploid daughter nuclei. Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parents.

diploid

In an organism that reproduces sexually, a cell containing two homologous sets of chromosomes, one set inherited from each parent; a 2n cell.

mitosis and meiosis

In sexually reproducing organisms, eggs and sperm result from

telophase 1 and cytokinesis (meiosis)

In telophase I, the chromosomes arrive at the poles of the cell. When the chromosomes finish their journey, each pole of the cell has a haploid chromosome set, although each chromosome is still in duplicate form (with two sister chromatids) at this point. Usually, cytokinesis (division of the cytoplasm) occurs simultaneously along with telophase I, and two haploid daughter cells are formed. -Following telophase I in some organisms, there is an interphase between telophase I and meiosis Il. In other species, meiosis I immediately leads to meiosis Il. In either case, no chromosome duplication occurs between telophase and the onset of meiosis II

haploid

In the life cycle of an organism that reproduces sexually, a cell containing a single set of chromosomes; an n cell.

codominant

Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles.

Environmental effects on many characteristics

Many characters result from a combination of heredity and the environment. For example, ● skin color is affected by exposure to sunlight, ● susceptibility to diseases, such as cancer, has hereditary and environmental components, and ● identical twins show some differences. Only genetic influences are inherited.

Separation - with TWO cross-over events

Meiosis 1: Homologous chromosomes are paired all along their lengths Nonsister chromatids form chiasma. Homologous segments cross over, producing hybrid chromosomes Homologous pairs separate into recombinant chromosomes. When the homologous chromosomes separate in anaphase I, half contain a new segment originating from the other member of the homologous pair. Meiosis 2: Sister chromatids separate, each going to a different gamete. Result: two parental chromosomes that match the originals, and two recombinant chromosomes with new gene combinations.

Mitosis vs. Meiosis

Mitosis: one division of the nucleus and cytoplasm forming 2 identical diploid cells (clones); used for growth, tissue repair, asexual reproduction Meiosis: two divisions of nucleus and cytoplasm forming 4 genetically different haploid cells; used for sexual reproduction

Human sex-linked disorders affect mostly males

Most sex-linked human disorders ● due to recessive alleles ● seen mostly in males. ● Examples: Hemophilia, Red-green color blindness, Duchenne muscular dystrophy A male receiving a single X-linked recessive allele from his mother will have the disorder. A female must receive the allele from both parents to be affected.

Hybrids

Offspring that results from the mating of individuals from two different species or from two true-breeding varieties of the same species; an offspring of two parents that differ in one or more heritable traits; an individual that is heterozygous for one or more pair of genes -The offspring of two different varieties

sister chromatids

One of the two identical parts of a duplicated chromosome in a eukaryotic cell. prior to mitosis, sister chromatids remain attached to each another at the centromere

If you cross two pink snapdragon plants and see that the offspring are 25% red : 50% pink : 25% white, what does that tell you about the genes controlling flower color?

Red is incompletely dominant over white

True breeding

Referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents; the organisms are homozygous for the characteristics under consideration. -varieties result when self-fertilization produces offspring all identical to the parent.

duplication

Repetition of part of a chromosome resulting from fusion with a fragment from a homologous chromosome; can result from an error in meiosis or from mutagenesis.

sarcomas

Squamous cell carcinoma; basal cell carcinoma• Sarcomas arise in supportive and connective tissue. • Soft tissue sarcoma; osteosarcoma

New technologies can provide insight into one's genetic legacy

Techniques for detecting genetic conditions in a fetus: karyotyping and biochemical tests on cultured fetal cells to detect other conditions, such as Tay-Sachs disease.

The Y chromosome provides clues about human male evolution

The Y chromosome is passed intact from father to son, so ● mutations in Y chromosomes can reveal data about recent shared ancestry.

dominant allele

The allele that determines the phenotype of a gene when the individual is heterozygous for that gene.

density-dependent inhibition

The ceasing of cell division that occurs when cells touch one another. -formed a complete layer

random fertilization

The combination of each unique sperm with each unique egg increases genetic variability.

chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope

asexual reproduction

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg. -produces offspring that are identical to the original cell or organism and -involves inheritance of all genes from one parent.

sexual reproduction

The creation of genetically unique offspring by the fusion of two haploid sex cells (gametes), forming a diploid zygote. -produces offspring that are similar to the parents, but show variations in traits and!involves inheritance of unique sets of genes from two parents.

mitosis

The division of a single nucleus into two genetically identical daughter nuclei.

life cycle

The entire sequence of stages in the life of an organism, from the adults of one generation to the adults of the next.

telophase

The fifth and final stage of mitosis, during which daughter nuclei form at the two poles of a cell. Telophase usually occurs together with cytokinesis. -Cell continues to elongate -Nuclear envelope forms around chromosomes at each pole, establishing daughter nuclei -Chromatin uncoils and nucleoli reappear -Spindle disappears

anaphase

The fourth stage of mitosis, beginning when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell. -Sister chromatids separate at centromeres -Daughter chromosomes are moved to opposite poles of cell as motor proteins move chromosomes along spindle microtubules and kinetochore microtubules shorten -Cell elongates due to lengthening of nonkinetochore microtubules

deletion

The loss of one or more nucleotides from a gene by mutation; the loss of a fragment of a chromosome.

chiasma

The microscopically visible site where crossing over has occurred between chromatids of homologous chromosomes during prophase I of meiosis.

tetrad

The new structure, consisting of four chromatids aligned gene by gene

F2 generation

The offspring of the F1 generation; F2 stands for second filial.

F1 generation

The offspring of two parental (P generation) individuals; F1 stands for first filial.

p generation

The parent individuals from which offspring are derived in studies of inheritance; P stands for parental.

mitotic phase (M phase)

The part of the cell cycle when the nucleus divides (via mitosis), its chromosomes are distributed to the daughter nuclei, and the cytoplasm divides (via cytokinesis), producing two daughter cells. -mitosis + cytokinesis

locus

The particular site where a gene is found on a chromosome. Homologous chromosomes have corresponding gene loci.

centromere

The region of a duplicated chromosome where two sister chromatids are joined and where spindle microtubules attach during mitosis and meiosis.

anchorage dependence

The requirement that to divide, a cell must be attached to a solid surface.

prometaphase

The second stage of mitosis, during which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids. -Spindle microtubules reach chromosomes, where they attach at kinetochores on the centromeres of sister chromatids and move chromosomes to the center of the cell through associated protein "motors" -Other microtubules meet those from the opposite poles -Nuclear envelope disappears

metastasis

The spread of cancer cells beyond their original site

metaphase

The third stage of mitosis, during which all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle. -Mitotic spindle fully formed -Chromosomes align at cell equator (metaphase plate) -Kinetochores of sister chromatids are facing the opposite poles of the spindle

fertilization

The union of the nucleus of a sperm cell with the nucleus of an egg cell, producing a zygote.

mutant

The version of a character that occurs less frequently in nature than the wild-type.

recombination frequency

With respect to two given genes, the number of recombinant progeny from a mating divided by the total number of progeny. Recombinant progeny carry combinations of alleles different from those in either of the parents as a result of independent assortment of chromosomes or crossing over.

Character

a heritable feature that varies among individuals within a population In 1866, Mendel described "heritable factors" (= genes) - A heritable feature that varies among individuals is called a _______, e.g., flower color

prophase 2

a spindle forms and moves the chromosomes toward the middle of the cell.

ultrasound image

a technique for examining a fetus in the uterus. high-frequency sound waves echoing off the fetus are used to produce an image of the fetus.

linkage map

an ordered listing of the relative locations of genes along a chromosome, as determined by recombination frequencies

leukemias and lymphomas

arise from blood-forming tissues

carcinomas

arise in external or internal body coverings.

Gregor mandel

began the field of genetics in the 1860s, deduced the principles of genetics by breeding garden peas

Crossing over occurs

between 2 non sister chromatids during Prophase 1 of meiosis

healthy body

cell division allows for -growth, -the replacement of damaged cells, and -development from an embryo into an adult.

interphase (meiosis)

chromosomes duplicate -Like mitosis, meiosis is preceded by an interphase, during which the chromosomes duplicate. At the end of interphase, each chromosome consists or two genetically identical sister chromatids attached together. The cell's centrosome has also duplicated by the end of this interphase

Eukaryotic Chromosomes

composed of chromatin consisting of -one long DNA molecule and -proteins that help maintain the chromosome structure and control the activity of its genes. -Before a eukaryotic cell begins to divide, it duplicates all of its chromosomes, resulting in -two copies called sister chromatids -joined together by a narrowed "waist" called the centromere.

A micrograph of a dividing cell from a mouse showed 19 chromosomes, each consisting of 2 sister chromatids. During which of the following stages of cell division could such a picture have been taken?

prophase 2 of meiosis

Meiosis

converts diploid nuclei to haploid nuclei.

cytokinesis

division of the cytoplasm to form two separate daughter cells -telophase

S

duplication of chromosomes

binary fission of prokaryotes

duplication of the chromosomes and separation of the copies, continued elongation of the cell and movement of the copies, division into two daughter cells

self-fertilization

fertilization in which both egg and pollen come from the same plant

prophase

first stage of mitosis, during which the cell's chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact -In the cytoplasm: microtubules begin to emerge from centrosomes, forming the mitotic spindle -In the nucleus: chromosomes coil and become compact, nucleoli disappear

genotype

genetic makeup of an organism

G1

growth, increase in cytoplasm

G2

growth, preparation for division

heterozygous

having two different alleles for a particular gene

checkpoints

in the cell cycle can ● stop an event or ● signal an event to proceed. 1. G1 checkpoint: allows entry into the S phase or causes the cell to leave the cycle, entering a nondividing G0 phase. 2. G2 checkpoint, and 3. M checkpoint. -Research on the control of the cell cycle is one of the hottest areas in biology today.

Dominant Inheritance

in which ● one dominant allele is needed to show disease and ● dominant lethal alleles are usually eliminated from the population.

Recessive Inheritance

in which ● two recessive alleles are needed to show disease, ● heterozygous parents are carriers of the disease-causing allele, and ● the probability of inheritance increases with inbreeding, mating between close relatives.

When observing a sample of dividing cells from an onion root tip, most cells would appear to be in

interphase

2 stages of cell cycle

interphase and mitotic phase

chemotherapy

is used for metastatic tumors.

Inbreeding

mating between close relatives.

Two types of cell division

mitosis (asexual) and meiosis (sexual)

telophase 2 and cytokinesis

nuclei form at the cell poles, and cytokinesis occurs at the same time. There are now four daughter cells, each with the haploid number of (single) chromosomes.

Meiosis

occurs in germ cells

Mitosis

occurs in somatic cells

Haploid cells

one set of chromosomes

Sex chromosome abnormalities

tend to be less severe, perhaps because of• small size of the Y chromosome or• X-chromosome inactivation. -In general - a single Y chromosome is enough to produce "maleness," even in combination with several X chromosomes • the absence of a Y chromosome yields "femaleness"

polygenic inheritance

the additive effects of two or more genes on a single phenotypic character -when a single phenotypic character results from the additive effects of two or more genes. • Human skin color is an example of polygenic inheritance. Other examples of polygenic inheritance in humans? • Hair color, eye color, weight, height, intelligence, many forms of behavior

anaphase 2

the centromeres of sister chromatids separate, and the sister chromatids of each pair, now individual chromosomes, move toward opposite poles of the cell.

testcross

the mating between an individual of unknown genotype for a particular characteristic and an individual that is homozygous recessive for that same characteristic -the mating between an individual of unknown genotype and a homozygous recessive individual. • Can show whether the unknown genotype includes a recessive allele. • Can be used to verify true-breeding genotypes.

interphase

the period in the eukaryotic cell cycle when the cell is not actually dividing. majority of time spent in cell cycle -duplication of cell contents -G1—growth, increase in cytoplasm -S—duplication of chromosomes -G2—growth, preparation for division -cytoplasmic contents double -two centrosomes form -chromosomes duplicate in the nucleus during S phase -nucleoli (sites of ribosome assembly) are visible

cell division

the reproduction of a cell through duplication of the genome and division of the cytoplasm -plays many important roles in the lives of organisms. -Organisms reproduce their own kind, a key characteristic of life. -is reproduction at the cellular level, -requires the duplication of chromosomes, and -sorts new sets of chromosomes into the resulting pair of daughter cells.

Genetics

the scientific study of heredity. -began with gregor mandel

Heredity

the transmission of traits from one generation to the next.

homologous chromosomes

the two chromosomes that make up a matched pair in a diploid cell. homologous chromosomes are of the same length, centromere position, and staining pattern and possess genes for the same characters at corresponding loci. one homologous chromosome is inherited from the organism's father, and the other from the mother. -are matched in length centromere position gene locations

wild-type

the version of a character that most commonly occurs in nature most common in population; not necessarily dominant alleles

Diploid cells

two homologous sets of chromosomes

Cancers are named according to the organ or tissue in which they originate

• Liver cancer starts in the liver, may spread to other organs. • Carcinomas arise in external or internal body coverings. • Squamous cell carcinoma; basal cell carcinoma• Sarcomas arise in supportive and connective tissue. • Soft tissue sarcoma; osteosarcoma • Leukemias and lymphomas arise from blood-forming tissues.

radiation/surgery

• Localized tumors can be • removed surgically and/or • treated with concentrated beams of high-energy radiation. • Personalizing cancer treatments • Depends on characteristics of individual cancers; • Look for mutations in specific genes

Mendels character traits

• Mendel studied seven different characters. - Each character has only two possible variations (traits).

Chronic myelogenous leukemia (CML)

• is one of the most common leukemias, • affects cells that give rise to white blood cells (leukocytes), and • results from part of chromosome 22 switching places with a small fragment from a tip of chromosome 9.

dominant human disorders

● Achondroplasia, resulting in dwarfism ● Huntington's disease, a degenerative disorder of the nervous system.

recessive human disorder

● Cystic fibrosis (CF) - most common fatal genetic disease in the U.S. ● results in excessive thick mucus secretions ● carried by about 1 in 31 Americans.

Fragile X Syndrome

● Individuals exhibit a range of developmental problems including delayed speech and language development, some degree of intellectual disability, and various features from the autism spectrum. ● Mutations in the Fragile X Mental Retardation-1 (FMR1) gene on the X chromosome result from an excessive number of "CGG" repeats (duplication). ▬ FMR1 gene produces a protein involved in normal brain development.

Cri-du-chat Syndrome (Cat's Cry Syndrome)

● Infant's cry is high-pitched, like that of a cat, due to incomplete development of larynx. ● Disorder characterized by intellectual disability, delayed development, smaller head size, low birth weight, weak muscle tone. ● Results from a deletion of part of chromosome 5.