Bio-101 Exam 3!

Exam 4/27 - work in progress

Source: Quiz - Cell Division & Mitosis

Cell division is necessary for _____.

a. growth and development

b. repairing damaged cells and tissues

c. reproduction (e.g. unicellular organisms)

d. all of the above

d. all of the above

Source: Quiz - Cell Division & Mitosis

Cell division - the cycle of interphase, mitosis, and cytokinesis - results in:

a. cells that are identical to the parent cell

b. cells that differ from the parent cell

c. eggs and sperm

d. none of the above

a. cells that are identical to the parent cell

Source: Quiz - Cell Division & Mitosis

During interphase of cell division, which cell activities occur?

a. the cell grows

b. the cell replicates its DNA

c. the cell makes preparations for divisions

d. all of these happen in interphase

d. all of these happen in interphase

Source: Quiz - Cell Division & Mitosis

What term (and its designation) refers to a cell that has two sets of every chromosome?

a. Diploid (n)

b. Diploid (2n)

c. Haploid (n)

d. Haploid (2n)

b. Diploid (2n)

Source: Quiz - Cell Division & Mitosis

Which answer correctly represents the order in which mitosis occurs?

prophase, metaphase, anaphase, telophase

Source: Quiz - Cell Division & Mitosis

Which of the following phases of mitosis is where sister chromatids separate?

a. anaphase

b. metaphase

c. prophase

d. telophase

a. anaphase

Source: Quiz - Cell Division & Mitosis

Cytokinesis in animals and plants differs because plants have cell walls and animals do not. Because of this difference, cytokinesis in animals occurs by ______ while plants _____.

a. cleaving… create cell plates

b. creating cell plates… cleave

c. crenation… create cell plates

d. crenation… cleave

a. cleaving… create cell plates

Source: Quiz - Cell Division & Mitosis

In which stage of cell division would apoptosis occur, if necessary?

interphase

Source: The Cell Cycle Lab

Reasons for cell division

• support growth and development & repair injuries (multicellular organisms)

• replacing dead cells

• serves as form of reproduction (unicellular organisms)

• allows organisms to produce new cells identical to existing cells

Source: The Cell Cycle Lab

Three phases of interphase

G1 - cell recovers from its previous division and begins to double the number of organelles

S - DNA is replicated

G2 - Sister chromatids are synthesized

Source: The Cell Cycle Lab

Prophase

Chromatin condenses and becomes visible as chromosomes. The nuclear envelope breaks up and the mitotic spindle forms

Source: The Cell Cycle Lab

Metaphase

Chromosomes line up along the center of the cell (equatorial plane). The spindle fibers attack to the kinetochore of the chromosomes

Source: The Cell Cycle Lab

Anaphase

Pairs of sister chromatids separate at the centromere and the members of each pair move toward the opposite poles

Source: The Cell Cycle Lab

Telophase

Groups of chromatids at each pole begin to condense. The nuclear envelopes from around each group and 2 nuclei are formed.

Source: The Cell Cycle Lab

Outcomes

Interphase occurs much longer than other phases. Most of the cells under the microscope are seen in interphase.

This is because the cell must go through several checks for apoptosis before duplication.

Source: The Cell Cycle Lab

Cell Theory

All living things are composed of cells and cells come from cells

Source: The Cell Cycle Lab

Explain the reason why cells divide

To replace dead cells or cells that need repaired

Source: The Cell Cycle Lab

Why are Alliumroot tips ideal specimens for the study of mitosis?

Different cell types have different rates of division. Alliumroot tips have quicker rates.

Source: The Cell Cycle Lab

Why are there check points during the cell cycle?

To check for apoptosis to get rid of “faulty” cells.

Source: The Cell Cycle Lab

Where is the genetic material during interphase, and why can’t we see the chromosomes?

They have condensed

Source: The Cell Cycle Lab

How do the structural differences between plant and animal cells influence the process of cytokinesis (division of the cytoplasm)?

During anaphase, spindle fibers separate chromatids in preparation for telophase.

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Purpose of cell division

• increase in body size

• replace dead and worn-out cells

• repair damaged tissue

• reproduce (for unicellular organisms)

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

What is cell division?

Division into two identical cells; a cloning process

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

3 stages of cell division

• interphase - cell growth, dna replication, prepares for divison

• mitosis - nuclear division

• cytokinesis - cytoplasmic division

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Cells that divide at frequent rates

• Skin (2-3 weeks)

• stomach lining (every few days)

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Cells that divide at infrequent rates or do not at all

• nerve cells (100 years if at all)

• red blood cells (can’t divide)

• muscle cells (can’t divide)

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

DNA (definition)

Genetic material

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Chromosome (definition)

DNA & associated proteins

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Chromatin (definition)

DNA in a “relaxed” state

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Chromatid (definition)

½ of a replicated chromosome, particularly when connected at the centromere

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Centromere (definition)

Locations where chromatids connect

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Diploid - 2n (definition)

Chromosomes exist in matching pairs

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Haploid - n (definition)

Chromosomes exist w/out pair

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Somatic cell (definition)

“Body cells”; diploid cells that can undergo cell division

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Gametic cell (definition)

Haploid cell produced from a germ cell going through meiosis (sperm & egg)

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Germ cell (definition)

Diploid; undergoes cell division and meiosis; results in gametes

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Subphases and differences (definition)

Interphase

• G1 = gap 1

• S = synthesis

• G2 = gap 2

Mitosis

• Prophase, metaphase, anaphase, telophase

Cytokinesis

• Animals = cleavage furrow

• Plants = cell plate formation

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Cancer

Abnormal, unregulated cell growth; lack contact inhibition (e.g. tumors)

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Characteristics of cancer cells

• lack differentiation

• have abnormal nuclei

• do not undergo apoptosis

• form tumors (lack of contact inhibition)

• undergo metastasis and angiogenesis

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Origins of cancer

• Heredity - brocca gene (breast cancer)

• Pesticides and herbicides - kidney cancer

• Radiation sources - sun, x-rays, tanning

• Viruses - associated with mutations that can cause cancer

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Diff types of cloning

• Reproductive

• Therapeutic - taking cells to grow into different cells (stem cells manipulated into other organs)

Source: Ch 9 - The Cell Cycle and Cellular Reproduction Notes

Cell division in summary

• cloning process

• diploid (2n) —> diploid (2n)

• Many functions

• Not used for sexv4l reproduction (had to censor or I couldn’t share…)

Source: Meiosis and Sexual Reproduction Notes

Defining meiosis

Reduction in the # of chromosomes by one half

Source: Meiosis and Sexual Reproduction Notes

Homologues (definition)

Matching chromosomes

Source: Meiosis and Sexual Reproduction Notes

Dyad (definition)

Replicated chromosomes (i.e. 2 sister chromatids connected @ centromere)

Source: Meiosis and Sexual Reproduction Notes

Tetrad (definition)

Replicated, homologous chromosomes

Source: Meiosis and Sexual Reproduction Notes

Gonads (definition)

Location of germ cells (ovaries adn testes)

Source: Meiosis and Sexual Reproduction Notes

Gametogenesis (definition)

Production of gametes (meiosis)

• Spermatogenesis and oogenesis

Source: Meiosis and Sexual Reproduction Notes

Spermatogenesis (definition)

Production of sperm in testes

Source: Meiosis and Sexual Reproduction Notes

Oogenesis (definition)

Production of oocytes (eggs) in ovaries

Source: Meiosis and Sexual Reproduction Notes

Germ cell (definition)

Diploid (2n) cell located in gonads that can undergo mitosis & meiosis

Source: Meiosis and Sexual Reproduction Notes

Euploid (definition)

Cell/organism with the “normal” expected chromosomal number

Source: Meiosis and Sexual Reproduction Notes

Aneuploid (definition)

without expected chromosomal number

Source: Meiosis and Sexual Reproduction Notes

Meiosis I

Prophase I

Metaphase I

Anaphase I

Telophase I

Cytokinesis

* Homologues pair, homologues separate (most important difference than mitosis)

Source: Meiosis and Sexual Reproduction Notes

Meiosis II

Prophase II

Metaphase II

Anaphase II

Telophase II

Cytokinesis

*Sister chromatids separate

Source: Meiosis and Sexual Reproduction Notes

How does meiosis result in variation of offspring?

• Crossing over

• Independent assortment

Source: Meiosis and Sexual Reproduction Notes

Male meiosis

• production of 4 haploid sperm per germ cell

• timing: from sexual maturity onwards

Source: Meiosis and Sexual Reproduction Notes

Female meiosis

• production of 1 haploid oocyte per germ cells and 2-3 polar bodies

• timing: meiosis I happens before birth; meiosis II happens after fertilization

Source: Meiosis and Sexual Reproduction Notes

Summary of meiosis

• Halves the number of chromosomes

• 2n —> n

• Produces gametes

• Increases genetic variabillity

• Used in sexual reproduction

• Happens in germ cells only