BIS 2A- Cell Cycle (Mitosis and Meiosis)

G1 phase

(first gap) First phase of interphase where the cell undergoes the final preparations (growing/making new proteins) for division and mitosis

Cytokinesis

1. It is the division of cytoplasm that occurs after the karyokinesis. 2. Here diassembled micro-tubles are used but no chromosomal movement occurs. 3. It can not occur without karyokinesis.

Karyokinesis

1. It is the division of nucleus, which occurs in a specific sequence of chromosomal events during cell division. 2. It involves formation of spindle and movement of chromosomes. 3. It may occur without being followed by cytokinesis.

What are the phases of Mitosis?

1.Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase (think of PMAT)

Meiosis I

1st round of meiotic division; ploidy level is reduced from diploid to haploid

tetrad

2 duplicated homologous chromosomes (4 chromatids) bound together by chiasmata during prophase I.

Meiosis II

2nd round of meiotic division; sister chromatids are separated into individual chromosomes. Result = 4 unique haploid cells

Haploid

A haploid cell is a cell that contains one complete set of chromosomes. Gametes are haploid cells that are produced by meiosis.

Sister chromatids

A sister chromatid refers to either of the two identical copies (chromatids) formed by the replication of a single chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said as 'one-half' of the duplicated chromosome.

Describe how the duplicated bacterial (prokaryotic) chromosomes are distributed into new daughter cells without the direction of the mitotic spindle.

As the chromosome is being duplicated, each origin moves away from the starting point of replication. The chromosomes are attached to the cell membrane via proteins; the growth of the membrane as the cell elongates aids in their movement.

Gamete

Gametes are reproductive cells (sex cells) that unite during sexual reproduction to form a new cell called a zygote.

Binary Fission

Happens in prokaryotic cells; cell division process.

Homologous chromosomes

Homologous chromosomes are chromosome pairs, one from each parent, that are similar in length, gene position, and centromere location. The position of the genes on each homologous chromosome is the same, however the genes may contain different alleles.

Compare and contrast a human somatic cell to a human gamete.

Human somatic cells have 46 chromosomes : 22 pairs and 2 sex chromosomes that may or may not form a pair. This is the 2n or diploid condition. Human gametes have 23 chromosomes, one each of the 23 unique unique chromosomes, one of which is a sex chromosome. This is the n or haploid condition.

chromatin

Mass of genetic material composed of DNA and proteins that condense to form chromosomes during eukaryotic cell division. Chromatin is located in the nucleus of a cell.

What would happen if anaphase proceeded even though the sister chromatids were not properly attached to their respective microtubules and lined up at the metaphase plate?

One or both of the new daughter cells would accidentally receive duplicate chromosomes and/or would be missing certain chromosomes.

Eukaryotic chromosomes are thousands of times longer than a typical cell. Explain how chromosomes can fit inside a eukaryotic nucleus.

The DNA double helix is wrapped around histone proteins to form structures called nucleosomes. Nucleosomes and the linker DNA in between them are coiled. During cell division, chromatin is further condensed by packing proteins.

Cytokinesis

The division of the cytoplasm following mitosis to form 2 daughter cells

Interphase

The period of the cell cycle leading up to mitosis; includes G(o), G1, G2

Metaphase

The stage of mitosis during which chromosomes are lined up at the metaphase plate

Telophase

The stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by new nuclear envelopes

Prophase

The stage of mitosis during which chromosomes condense and the miotic spindle begins to form

Prometaphase

The stage of mitosis during which miotic spindle fibers attach to kinetochores

Anaphase

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

allele

Variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome. Humans are called diploid organisms because they have two alleles at each genetic locus, with one allele inherited from each parent.

G(o) phase

a cell cycle phase distinct from G1 phase of interphase; not yet preparing to divide

Diploid cell

a cell that contains two sets of chromosomes. One set of chromosomes is donated from each parent. (Humans have 2 sets of 23 chromosomes for a total of 46 chromosomes)

kinetochore

a protein structure in the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase

At metaphase I, homologous chromosomes are connected only at what structures? a. chiasmata b. recombination nodules c. microtubules d. kinetochores

a.

Which is the correct sequence of stages in the cell cycle that produces a differentiated cell? (D = cell differentiation) a.G1, S, G2, M, D. b.G1, G2, S, M, D. c.S, G1, G2, M, D. d.G1, M, G2, S, D.

a.

Which of the following is correct? a.The chromosomes shorten and thicken during prophase. b.The nucleolus reappears following telophase. c.Interphase is characterized by little cellular activity, as the cell is resting to prepare for the next mitotic event. d.All of the above.

a.

The individual chromosomes become visible with a light microscope during which stage of mitosis? a. prophase b. prometaphase c. metaphase d. anaphase

a. prophase

somatic cell

all the cells of a multicellular organism except the gametes or reproductive cells

FtsZ proteins direct the formation of a _______ that will eventually form the new cell walls of the daughter cells. a. contractlile ring b. cell plate c. cytoskeleton d. septum

b.

If a muscle cell of a typical organism has 32 chromosomes, how many chromosomes will be in a gamete of that same organism? a. 8 b. 16 c. 32 d. 64

b.

In prophase, the nuclear membrane disappears. a.True, it occurs early in prophase. b.True, it occurs late in prophase. c.False, it is not associated with prophase.

b.

What is the primary function of tumor supressor genes? a. stop all cells from dividing b. stop certain cells from dividing c. help oncogenes produce oncoproteins d. allow the cell to skip certain phases of the cell cycle

b.

What structure is most important in forming the tetrads? a. centromere b. synaptomenal complex c. chiasma d. kinetochore

b.

Which of the following is NOT correct? a.Mitosis is produces genetically identical cells. b.Cytokinesis is a part of mitosis c.Metaphase occurs before anaphase. d.All somatic cells are produced by mitosis.

b.

Which of the following phases is characterized by preparation for DNA synthesis? a. Go b. G1 c. G2 d. S

b.

An organism's traits are determined by the specific combination of inherited ______________. a. cells b. genes c. proteins d. chromatids

b. genes

Interkinesis (Interphase II)

brief period of rest between meiosis I and II.

A diploid cell has ____the number of chromosomes than a haploid cell. a. 1/4 b. half c. twice d. four times

c.

Meiosis produces __________daughter cells. a. two haploid b. two diploid c. four haploid d. four diploid

c.

The part of meiosis that is similar to mitosis is: a. meiosis I b. anaphase I c. meiosis II d. interkenesis

c.

What phase of mitotic interphase is missing from meiotic interkenesis? a. Go phase b. G1 phase c. S phase d. G2 phase

c.

Which eukaryotic cell cycle event is missing in binary fission? a. cell growth b. DNA duplication c. karyokinesis d. cytokinesis

c.

Separation of the sister chromatids is a characteristic of which stage in mitosis? a. prometaphase b. metaphase c. anaphase d. telophase

c. anaphase

A mutation in the gene for cyclin protein might result in which of the following? a. stop all cells from dividing b. stop certain cells from dividing c. help oncogenes produce oncoproteins d. any of the above

d.

At which stage of meiosis are sister chromatids separated from one another? a. prophase I b. prophase II c. anaphase I d. anaphase II

d.

What is the function of centrioles? a.To cause cytokinesis via the concentric shortening of microtubules. b.They are required for DNA replication. c.They are the structure which hold the 2 daughter chromatids together at the centromere. d.They produce microtubules for the chromosomes to migrate along as they move to opposite poles of the cell.

d.

The first level of DNA organization in a eukaryotic cell is maintained by which molecule? a. cohesin b. condensin c. chromatin d. histone

d. histone

Chromosomes are duplicated during which portion of the cycle? a. prometaphase b. metaphase c. anaphase d. telophase

d. prometaphase

Identical copies of chromatin held together by cohesin at the centromere are called ______. a. histones b. nucleosomes c. chromatin d. sister chromatids

d. sister chromatids

quiescent

describes a cell that is performing normal cell functions and has not initiated preparations for cell division yet

Crossover

exchange of genetic material between non-sister chromatids resulting in chromosomes that incorporate genes from both parents of the organism.

synapsis

formation of a close association between homologous chromosomes during prophase I

Gene

functional units of chromosomes that determine specific characteristics by coding for specific proteins

histone

histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes.

reductive devision

nuclear division that produces daughter nuclei each having 1/2 as many chromosome sets as their parental nucleus. (Meiosis I is a reduction division)

locus

position of a gene on a chromosome

synaptomenal complex

protein lattice that forms between 2 homologous chromosomes during prophase I, supporting crossover.

Cohesin

proteins that form a complex that seals sister chromatids together at their centromeres until anaphase II of meiosis

centromere

region at which sister chromatids are bound together

Meiosis

results in 4 haploid cells

chromatid

single DNA molecule of 2 strands of of duplicated DNA and associated proteins held together at the centromere

septum

structure formed in a bacterial cell as a precursor to the seperation of the cell into 2 daughter cells

nucleosome

subunit of chromatin composed of a short length of DNA wrapped around a core of histone proteins

Zygote

the cell produced by the union of two gametes (sex cells)

mitotic spindle

the microtubule apparatus that orchestrates the movement of chromosomes during mitosis

Ploidy level

the number of sets of chromosomes in a cell

chiasmata

the structure that forms the crossover points after genetic material is exchanged

FtsZ

tubulin-like protein component of the prokaryotic cytoskeleton that is important in prokaryotic cytokinesis.

fertilization

union of 2 haploid cells from two individual organisms

Trait

variations of characteristics from genes (ex: hair color is a characteristic with traits blonde, brown, black, red, etc.)