Meosis/Mitosis

What is the difference between a bivalent and a chromatid pair?

A bivalent is a pair of homologous chromosomes, or two homologous chromatid pairs. A single chromatid pair are two identical chromosomes bound by a centromere.

Which of the following best describe the term "crossing over"?

An exchange of information between two homologous chromosomes

During which stage does the following occur Daughter chromosomes arrive at the poles

Anaphase

Name the phase of mitosis in which chromatids separate and move to opposite ends of the cell

Anaphase

Chromosomes move to separate poles:

Anaphase I

What is crossing over? When does it happen?

Crossing over is when genes from homologous chromosomes swap places in a bivalent. This creates genetic diversity in gametes during prophase I of meiosis I in meiosis.

What is the difference between a haploid cell, diploid cell, and a zygote?

Haploid: A haploid cell contains one set of chromosomes. Diploid: A diploid cell contains two sets of homologous chromosomes. Zygote: A zygote is a fertilized egg, formed after two haploid gametes fuse after fertilization. It is a diploid cell.

Name the phase in which a nucleus is visible and the DNA is spread out as chromatin

Interphase

What is the phase of the cell cycle in which cells stop dividing

Interphase

Why is it necessary to have two separate divisions during meiosis?

The first division, meiosis I, creates genetic variation (crossing over). The second division creates four daughter cells with 23 chromosomes in each cell.

What is the ultimate goal/purpose of mitosis? What term do we use to describe the new cells?

The goal of mitosis is to create new, genetically identical cells with a larger surface area to volume ratio. These are called daughter cells.

Are chromatids of a chromosome identical?

Yes

When a sperm cell and an ovum/egg merge, they undergo the process of fertilization, and give rise to a __________, which is ______.

Zygote, diploid

Phase in which chromosomes spread out into chromatin

telophase

Chromosomes that are the same size, same shape, and carry genes for the same traits are called ________

homologous chromosomes

During meiosis, the chromosome number

is reduced

Is DNA copied before Meiosis II?

no

Which stage of meiosis does cross over happen.

prophase 1

Homologous chromosomes pair and form bivalents:

prophase I

Nuclear membrane disappears:

prophase I

If a cell has 34 chromosomes how many chromatids does it have.

34

If a cell has 26 chromosomes before meiosis begins, how many bivalents will it contain after prophase 1 and anaphase 1

13, 0

What is the diploid chromosome number for humans?

46

If the diploid number in a liver cell is 52, how many chromosomes are there in the egg of this organism?

26

Describe cancer.

Cancer is the uncontrollable mitotic dividing of somatic cells.

The structures where the spindle gibers grow from

Centrioles

Spot that holds the chromatid arms together

Centromere

DNA that is spread out in the nucleus of a non dividing cell is called

Chromatin

How are DNA and chromosomes related?

Chromosomes are made of supercoiled DNA.

What is the difference between chromosomes, chromatids, and homologous chromosomes?

Chromosomes: DNA supercoiled during cell division. Chromaids: Two identical chromosomes held together by a centromere. Homologous chromosomes: Two chromosomes that contain the same genes in the same locations, but may contain different alleles for those traits.

Cells starting mitosis & meiosis begin with a (haploid or diploid) set of chromosomes

Diploid

How many cells are created after meiosis?

Four

What is the final result of the meiotic process?

Four genetically different haploid gametes

What does Meiosis create? Haploid or Diploid cells? Somatic cells or gametes?

Four haploid gametes.

What are the parts of a bivalent? What phase do you first see this in?

Four sister chromatids (or two chromosomes) held together by two centromeres prophase II

How many cells form at the end of Meiosis II and how many chromosomes do they contain?

Four, a haploid number (23 in humans)

Name the phase of the cell cycle in which cells spend the most of their time doing their job.

G1 Interphase

3 phases to make up interphase

G1,S,G2

Phase of the cell cycle in which the cell makes organelles needed for the new cell

G2

What type of cell undergoes meiosis?

Gamete cells

Copy/Paste diagrams of Meiosis 1 and Meiosis 2. What are the differences between these two diagrams.

In meiosis I, bivalents form and crossing over takes place. Two genetically different haploid cells form. In meiosis II, we start with two genetically different haploid cells, the chromosomes already paired as genetically different sister chromatids. We end with four genetically different gamete haploid cells.

How, specifically, do the resulting cells of mitosis and meiosis differ?

In mitosis, the nuclei of one cell copies itself exactly into two identical nuclei, usually resulting in two identical diploid nuclei of the same genetic code. In meiosis, the nucleus of one diploid cell splits twice to become four haploid nuclei, all of which contain a different set of alleles due to crossing over. Meiosis: four cells, genetically different, haploid nuclei Mitosis: two cells, genetically identical, diploid nuclei

During which stage does the following occur This is the longest part of the cell cycle

Interphase

What are the stages of meiosis called?

Meiosis I: __prophase I_, ____metaphse I__, __anaphase I______, ____telophase I___/cytokinesis Meiosis II: ___prophase II___, ___ metaphase II____, ___ anaphase II__, ___ telophase II_____/cytokinesis

How does Meiosis differ from Mitosis? Be specific!

Meiosis is the formation of four, genetically different haploid gametes. Mitosis is the formation of two genetically identical somatic cells.

During which stage does the following occur Chromosomes align in center of cell

Metaphase

Bivalents align at metaphase plate:

Metaphase I

Name two errors that can occur during meiosis

Nondisjunction, and Translocation/deletion (the first, nondisjunction, is far more important for you to know!)

During what stage(s) of mitosis do we find bivalents? (list any/all that apply):

None! Bivalents do not form during mitosis!

During which stage does the following occur Chromatin condenses into chromosomes

Prophase

During which stage does the following occur Nuclear envelope breaks down

Prophase

Phase in which the nuclear membrane and nucleolus disappear and spindle fibers and centrioles appear.

Prophase

Crossing-over can be found in the stage of

Prophase I

During which stage(s) of meiosis do we find bivalents? (list any/all that apply)

Prophase I and Metaphase I (when listing phases of meiosis, never forget to list the number next to the phase!)

List the stages of mitosis.

Prophase, Metaphase, Anaphase, Telophase

Name the stage of interphase in which cells copy their DNA

S-phase

Phase of the cell cycle that follows G1

S-phase

What is a gamete? How do we represent the chromosome number: 2n or n?

Sex cell, egg or sperm. n

The microtubule fibers that pull the chromosomes are called the

Spindle fibers

Name the phase in which spindle fibers and centrioles disappear

Telophase

Name the phase of mitosis that follows anaphase

Telophase

Phase of the cell cycle in which the nuclear membrane and nucleolus return.

Telophase

Nuclear membrane reforms:

Telophase I

Two complete daughter cells form:

Telophase I/cytokinesis

During which stage does the following occur Cell is cleaved into two new daughter cells

Telophase/Cytokinesis

How many times do cells divide during meiosis?

Twice

How many cells are created after mitosis?

Two

What are homologous chromosomes?

Two chromosomes that contain the same genes at the same places, but may contain different alleles for those traits.

What would happen to the final cells if one chromatid pair did not separate in Anaphase II of meiosis?

Two gametes would have the normal haploid number of chromosomes (n, or 23 chromosomes in humans), one gamete would have one too many chromosomes (n + 1, or 24 chromosomes in humans) and one gamete would have one too few chromosomes (n - 1, or 22 chromosomes in humans)

What is the final result of the mitotic process?

Two genetically identical daughter cells

Egg and sperm cells are (haploid or diploid?):

haploid (23 chromosomes)

Phase in which the cytoplasm splits

cytokinesis

What event pulled the two chromosomes next to each other in crossing over.

forming of bivalents

A sperm cell is a ____ and is ______

gamete, haploid