Chapter 8 Mitosis and Meosis, Biology

What is cellular division?

Reproduction at the cellular level

What does cell division require?

The duplication of all the DNA

Where is the duplication of DNA organized?

Into structures called chromosomes

What is the purpose of cell division?

Sorts two new sets of chromosomes into a new pair of daughter cells

How do prokaryotic cells divide?

Through Binary Fission

What is the term for dividing in half (prokaryotic cells)

Binary Fission

How many stages are in binary fission?

3

What is the first stage of binary fission?

Duplication of the chromosomes and separation of the copies

What occurs in the second stage of binary fission?

Continued elongation of the cell and movement of the copies away from each other

What occurs in the third stage of binary fission?

Division into two daughter cells that are “clones” of the “mother” cell

What is going on in the blue portion?

Interphase of a cell

What is Mitosis? (The Green)

Active Cell Division

Are there different phases of interphase?

Yes

What happens in the G1 interphase?

Growth phase

In which part of interphase is extra organelles and proteins produced?

G1 aka the growth phase

What is the second phase in the interphase of a cell?

The S phase aka the synthesis phase

What happens in the synthesis phase during the interphase of a cell?

DNA is replicated, 23 pairs of chromosomes are replicated to make 46 pairs

When does a cell go into the G0 phase of interphase?

When a cell doesn’t need to divide. Like a neuron

What is the third step of interphase

G2, another growth phase where the cell is preparing for mitosis

How does the G2 phase prepare for mitosis?

Make microtubules

What are microtubules used for?

Used to pull chromatids apart

How many stages are in Mitosis?

5 (PPMAT) Cytokinesis is often apart of Telophase

What is the first stage of Mitosis?

Prophase

What happens in the cytoplasm during prophase?

Mircrotubes being to emerge from centrosomes, forming the spindle as the centrioles being to move to opposite sides of the cell called the poles

What happens in the nucleus during prophase?

Chromosomes coil and become compact, nucleolus disappears, clear envelope begins to disingigrate.

What is the second stage of Mitosis?

Prometaphase

What happens during prometaphase in mitosis?

Spindle microtubules reach out to the chromosomes where they attach to fibers from the Kinetochores on the centromeres of the sister chromatids.

What happens in the cytoplasm during prometaphase? (Mitosis)

Begin to move chromosomes to the center of the cell

What is the third phase of Mitosis?

Metaphase

What is Apoptosis

How a cell dies without causing a unnecessary reaction in the body

What happens in Metaphase during mitosis?

The nuclear membrane breaks apart, spindle fibers attach to the chromosomes then chromosomes line up at the equator of the cell.

What is the equator called in cells where chromosomes line up (During metaphase)

Metaphase Plate

What is the forth phase of mitosis?

Anaphase

What happens in Anaphase during mitosis?

Spindle fibers shorten and the centromere divides (chromosomes divide)

Why does the centromere divide during Anaphase in Mitosis?

So that each chromosome becomes two separate chromatids.

What is the fifth phase of Mitosis?

Telophase

What happens during Telophase during Mitosis?

Nuclear membrane forms around each set of chromosomes then spread out to the new nucleus.

What happens to spindle fibers during Telophase?

They are broken down

What step of Mitosis goes along with Telophase?

Cytokinesis

What happens during Cytokinesis in Mitosis?

The cell membrane pinches into two separate sets of chromatids, two identical cells are produced.

What are Homologous chromosomes?

Similar but not identical chromosomes, same shape just different gene variation

Define ploidy

Refers to the NUMBER OF SETS of chromosomes

Define haploid

1 set of chromosomes = 1n or n

Define diploid

2 sets of chromosomes = 2n

What are somatic cells?

Cells that are found everywhere in the body except for testes and ovaries

Where are Gamete Cells found?

Only in ovaries and testes

What is cytokinesis?

Cell content division and splitting of 1 cell into 2 cells

What happens during cytokinesis?

The cytoplasm is divided and the process of separating the cells into two separate cells continues

When does cytokinesis occur in Animal Cells?

As a cleavage furrow forms a contacting ring of microfilaments

When does cytokinesis occur in Plant cells?

As a cell plate forms in the middle, form vesicles containing cell wall materials

Apoptosis is caused by enzymes called

Caspases

What are benign tumors?

Non cancerous tumors, encapsulated / do not invade neighboring tissue / do not spread

What are malignant tumors?

Cancerous tumors, not encapsulated, rapidly invade neighboring tissue

Do malignant tumors result from a mutation of genes regulated in the cell cycle?

Yes

Characteristics of Cancer Cells

non- specialized, are immortal (can enter cell cycle repeatedly)

Have abnormal nuclei, may be enlarged, abnormal number of chromosomes, extra copies of genes

What is Meiosis?

A process that converts diploid nuclei to haploid nuclei - 2n to n

Where does Meiosis occur?

Only in Sex Organs - Ovaries and testes

What they of cells does Meiosis produce?

Gametes

What are Gametes?

Eggs and sperm

The initial cell formed when two gamete cells are joined is called …

Zygote

Does a Zygoat have a diploid or haploid chromosome number?

A diploid (2n) one set of chromosomes from each parent

A special cell division that will reduce the number of sets of chromosomes in the egg and sperm is called …

Meiosis

What happens in Interphase during Meiosis

DNA is replicated in preparation for Meiosis 1

What is the first step of meiosis 1?

Prophase 1

What happens during prophase 1? (Meiosis)

The nuclear membrane dissolves and the centrioles move to the poles.

What are the duplicated homologous chromosomes called?

Tetrad

What is it called when the tetrad pairs up?

Synapsis

What happens as a result of tetrad’s pairing up (synapsis)?

Genes are recombined by crossing over

What happens after crossing over during prophase 1? (meiosis)

Spindle fibers attach to the chromosomes

What happens during metaphase 1? (meiosis)

The homologous chromosomes move and line up in the center

What happens during anaphase 1? (meiosis)

Homologous chromosomes separate

What happens in telophase 1? (Meiosis)

The nuclei reform and the chromosomes unwind into chromatin

What happens during cytokinesis? (meiosis)

The rest of the cytoplasm divides

What happens during prophase 2? (Meiosis)

The chromosomes reform and the two nuclei break apart, then the centrioles send out spindle fibers that connect to the centromeres of the chromosomes.

What happens during metaphase 2? (Meiosis)

The chromosomes line up at the center

What happens in Anaphase 2? (Meiosis)

The chromatids separate into chromosomes as spindle fibers pull them to each side

When does the cytoplasm divide into 4 haploid cells that are all different? (Meiosis)

During cytokinesis

At what point during meiosis does the ploidy change from diploid to haploid?

Meiosis 1, specifically during Anaphase 1, finalized by telophase 1 and cytokinesis

What happens in telophase 2? (Meiosis)

The chromosomes unwind into chromatin and the nuclei reform