Bio 150 Exam 3

What are the types of cell division?

mitosis and meiosis

What is the reason for cell division?

to maintain a physiologically appropriate region of surface area to cellular volume

What is a kinase?

An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein.

What is the G1 phase?

The 1st gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.

What is the G2 phase?

The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

What is the S phase?

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

What is semi-conservative replication?

Type of DNA replication in which the replicated double helix consists of one old strand, derived from the parental molecule, and one newly made strand.

What is the difference between a chromatid and a chromosome?

A chromatid is one copy of a duplicated chromosome, which is generally joined to the other copy by a single centromere. A chromosome is a cellular structure carrying genetic material, found in the nucleus of eukaryotic cells.

What are homologous chromosomes?

A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characteristics at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother. Also called homologs, or a homologous pair.

What is the difference between a centromere and a kinetochore?

In a duplicated chromosome, the centromere is the region on each sister chromatid where they are most closely attached to each other.

The kinetochore is a structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle.

What is a telomere?

The repetitive DNA at the end of a eukaryotic chromosome's DNA molecule. Telomeres protect the organism's genes from being eroded during successive rounds of replication.

What is karyokinesis?

the series of active changes that take place in the nucleus of a living cell in the process of division

What is a ploidy?

a set of chromosomes

What is a diploid?

two sets of chromosomes, regular (mitotic, somatic) cells

What is a haploid?

one set, half from 2 different parent cells; gamete (meiotic) cells

What is polyploidy?

A chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division.

What is aneuploidy?

A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.

What is cytokinesis?

The division of the cytoplasm to form two separate daughter cells immediately after mitosis, meiosis I, or meiosis II.

How does cytokinesis differ in plants vs animals?

Because a plant cells are surrounded by the rigid cell wall, it cannot use microfilaments to go through cytokinesis. Instead, it builds a cell plate in the middle of the cell to represent the division. An animal cell does not have this rigid structure, so it forms a cleavage furrow by pinching the cell in the middle with microfilaments. This will successfully divide the cell into two.

What is nondisjunction?

An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.

What is a karyotype?

A display of the chromosome pairs of a cell arranged by size and shape.

What is dosage compensation?

Dosage compensation is a hypothetical genetic regulatory mechanism which operates to equalize the phenotypic expression of characteristics determined by genes on the X chromosome so that they are equally expressed in the human XY male and the XX female.

What is a polygenic trait and give an example?

***Involves the expression from three genes with different loci. With in the population the phenotypes span a gradient of color. EX- skin color

What is an example of epistasis?

Coat color in labrador retrievers (Chin size, chin shape, cleft chin for virtual child, or eye color)

The "s" Phase in the cell cycle can be simply put as the?

Replication of DNA

What are the two parts of the "M" Phase of the cell cycle?

The partitioning of replicated chromosomes (or karyokinesis) to what will become the new daughter cells and...

Partitioning of the cytoplasm contents (cytokinesis). (Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis).

what does G2 do?

Prepares the cell to undergo actual cell division

What does G1 do?

Prepares the cell for the replication of DNA to follow in the S phase

What type of division is it when the partitioning of chromatids is equal?

Mitosis

Explain mitosis?

Cell division type involved in asexual reproduction, and maintenance of cell type and function. DNA is replicated and then distributed equally among the two daughter cells in somatic (body) cells.

What type of cell division it is when the partitioning of chromatids is halved?

Meiosis

Explain meiosis?

cell division type involved in the production of gametes involved in sexual reproduction. The Formation of sex cells is

termed meiosis and produces egg or sperm with half the amount of genetic material.

Genetic Diversity is promoted by what?

crossing over in meiosis 1 (Prophase)

Independent assortment (metaphase 1)

What happens during DNA replication during the S phase?

DNA helices unwind. There is a semi-conservative replication of DNA... with each DNA serving as a template for the synthesis of a new strand of DNA.

Interphase has what parts in it?

G1, S, G2

Explain what happens in Prophase of Mitosis?

Chromatin condenses to form chromosomes.

- Each chromosome is composed of two identical strands of chromatin called sister chromatids, which are joined at a specialized region called the centromere.

- Each chromatid contains one of the DNA molecules replicated during interphase.

- Centrioles begin to migrate to opposite poles as spindle apparatus is formed.

- At the end of prophase, the nuclear envelope and nucleoli disappear.

Explain what happens in Metaphase of Mitosis?

Chromosomes, attached to microtubules through the kinetochore, line up along the equator (metaphase plate)

Explain what happens in Anaphase of Mitosis?

Centromeric DNA replicates to begin the process of separating the two identical sets of chromosomes.

- The two sets of chromosomes are pulled by the spindle fibers toward opposite poles.

Explain what happens in Telophase of Mitosis?

Chromosomes have reached the opposite poles (marked by the MTOC)

- In animals, a cleavage furrow is evident; In plants, the formation of the primary cell wall is evident

- Nuclear envelope and nucleolus begin to reappear

What is Cytokinesis?

Division of cytoplasm/partitioning of cellular content to produce 2 identical daughter cells

What three phases is the cell cycle organized into?

Interphase, Mitosis, Cytokinesis

A cell must increase its surface area relative to???

Its volume

What is a Genotype?

The description of the genes that produce the phenotype

What is the Phenotype?

Measurable trait or characteristic

What are both of Mendel's Laws?

Law of Segregation- during gamete production, alleles seperate

Law of Independent Assortment- each pair of alleles segregate into gametes independently-sometimes

Each genetic trait, such as flower color, is regulated by?

A pair of genes called alleles

What are the Genetic Loci?

alleles are found at particular places on the chromosomes

What is Epistasis?

Genes at one locus influencing how the genes at another locus are expressed.

Incomplete dominance prohibits?

the full expression of either allele, thereby giving the appearance of blending.

What are Sex-limited genes?

their expression is limited to one sex or the other

What does homoallelic or homozygous mean?

Having two identical alleles for a given gene.

What does heteroallelic or heterozygous mean?

Having two different alleles for a given gene.

What is a recessive allele?

An allele whose phenotypic effect is not observed in a heterozygote.

What is a dominant allele?

An allele that is fully expressed in the phenotype of a heterozygote.

What is Mendel's law of Segregation?

Mendel's first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation.

What is Mendel's law of assortment?

Mendel's second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes.

What is Mendelian inheritance?

Simple inheritance, one of two potential phenotypes (dominant or recessive) displayed; genotypes are homozygous dominant, homozygous recessive, and heterozygous dominant.

What is incomplete dominance?

The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.

What is codominance?

The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways.

What is polygenic inheritance?

An additive effect of two or more genes on a single phenotypic character.

What is epistasis?

A type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene.

What is the difference between sex limited and sex linked inheritance?

Sex-limited inheritance is where an allele on an autosomal gene cannot be expressed because the individual is the wrong sex. For example, a gene governing breast size is only expressed in females, whereas a gene for beard growth is only expressed in males. Sex-linked inheritance is where the pre-existing dominance relationships between alleles are altered according to the sex of the individual. For example, baldness is dominant in men but recessive in women.

What is prophase?

The first stage of mitosis, in which the chromatin condenses into discrete chromosomes visible with a light microscope, the mitotic spindle begins to form, and the nucleolus disappears but the nucleus remains intact.

What is metaphase?

The second stage of mitosis, in which the nuclear envelope fragments, the spindle microtubules attach to the kinetochores of the chromosomes, and then are all aligned at the metaphase plate.

What is anaphase?

The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.

What is telophase?

The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.

What is the difference between Prophase (mitosis) and Prophase I (meiosis)?

In Prophase I, homologous chromosomes pair (forming a tetrad), and chiasmata forms as the chromosome pairs overlap, exchanging genetic information

What is the difference between Metaphase (mitosis) and Metaphase I (meiosis)?

In Metaphase I, the homologous chromosomes attached to fused kinetochore shared by sister chromatids align at the plane of division.

What is the difference between Anaphase (mitosis) and Anaphase I (meiosis)?

In Anaphase I, the homologous chromosomes separate and move to the poles of the cell as sister chromatids

What is the difference between Telophase (mitosis) and Telophase I (meiosis)?

In Telophase I, the sister chromatids arrive at poles of cell, nuclear membrane forms again, and 2 nuclei appear

How can we determine probabilities of transmission of traits?

***knowing the frequencies of alleles (using the Punnett square or branch-line method) and assuming that each pair of alleles is assorted randomly and inherited independently of other allele pairs during meiosis

What is the difference between epistasis and polygenic inheritance?

Polygenic inheritance is when multiple genes affect a phenotype. The phenotype is continuous, such as the different pigmentation of human skin - the alleles are usually additive. For example, for skin color in humans, the more "dark" alleles one has in total, the darker their skin will be. Epistasis is the masking of the phenotypic effect of either one or both members of a pair of alleles by a gene or genes of a different pair of allele; for instance, one locus determines the color of the flower, however, the other locus controls whether or not the flower-color locus is masked or expressed. This causes gradation of two different colors.

What does the telomere tell about the chromosome?

the age of the chromosome

What is polygenic inheritance?

involves the expression from three genes with different loci; within a population, the phenotypes span a gradient of color (vs. just two possible phenotypes of genes that display simple patterns of inheritance)

What is incomplete dominance?

involves the expression from three genes with different loci; within a population, the phenotypes span a gradient of color (cf just two possible phenotypes of genes that display simple patterns of inheritance)

What is epistasis?

expression of one set of alleles is influenced by another independently inherited set; it is the interaction between these sets of alleles that collectively determines the phenotype

What are the cellular events of prophase?

chromatin condensation to form shortened chromosomes; break-down of nucleolus,

breakdown of nuclear membrane; movement of centrioles to begin formation of the spindle

apparatus.

What are the cellular events of metaphase?

chromosomes attached (via the kinetochore/centromere) to fully formed spindle fibers (microtubules), move towards the metaphase (equatorial plate) by the end of metaphase.

What are the cellular events of anaphase?

as microtubules depolymerize, chromosomes are pulled to opposite poles of what will

become the new daughter cells; by late anaphase, the beginnings of cytokinesis: movement of

cytoplasm and organelles into what will become the new daughter cells

What are the cellular events of telophase?

chromosomes begin to decondense, reappearance of nuclear membrane; reappearance of

nucleoli; partition between daughter cells is formed: in plants, this involves the coalescence of

Golgi-derived vesicles (aligning at the equator) to form the primary cell plate that divides the two

cells; in animals, this involves the contraction of an actin derived ring (aligned at the equator) to seal

off the two cells; the aster (spindle apparatus) fades away.

What are the cellular landmarks of prophase?

shortened, thickened, recognizable chromosomes appear; nuclear membrane not

as prominent as in interphase cells; nucleoli absent

What are the cellular landmarks of metaphase?

chromosomes aligned along the equator

What are the cellular landmarks of anaphase?

"V"-shaped chromosomes, being partitioned to opposite poles of the cell.

What are the cellular landmarks of telophase?

prominent nucleoli, nuclear membrane; chromosomes less distinct; cell partition between the two daughters is distinct.

Sort the phases of the cell cycle by their (typical) length - longest to shortest. (The phases of the cell cycle are interphase, prophase, metaphase, anaphase, and telophase.)

Interphase, prophase, anaphase, telophase, metaphase.

What is the G0 phase?

the phase for terminally differentiated cells that are no longer cycling

anaphase

stage of mitosis during which sister chromatids are separated from each other

binary fission

prokaryotic cell division process

cell cycle checkpoint

mechanism that monitors the preparedness of a eukaryotic cell to advance through the various cell cycle stages

cell cycle

ordered sequence of events that a cell passes through between one cell division and the next

cell plate

structure formed during plant cell cytokinesis by Golgi vesicles, forming a temporary structure (phragmoplast) and fusing at the metaphase plate; ultimately leads to the formation of cell walls that separate the two daughter cells

centriole

rod-like structure constructed of microtubules at the center of each animal cell centrosome

centromere

region at which sister chromatids are bound together; a constricted area in condensed chromosomes

chromatid

single DNA molecule of two strands of duplicated DNA and associated proteins held together at the centromere

cleavage furrow

constriction formed by an actin ring during cytokinesis in animal cells that leads to cytoplasmic division

condensin

proteins that help sister chromatids coil during prophase

cyclin-dependent kinase

one of a group of protein kinases that helps to regulate the cell cycle when bound to cyclin; it functions to phosphorylate other proteins that are either activated or inactivated by phosphorylation

cyclin

one of a group of proteins that act in conjunction with cyclin-dependent kinases to help regulate the cell cycle by phosphorylating key proteins; the concentrations of cyclins fluctuate throughout the cell cycle

cytokinesis

division of the cytoplasm following mitosis that forms two daughter cells.

diploid

cell, nucleus, or organism containing two sets of chromosomes (2n)

G0 phase

distinct from the G1 phase of interphase; a cell in G0 is not preparing to divide

G1 phase

(also, first gap) first phase of interphase centered on cell growth during mitosis