Chapter 8

Question 1

(2)What organelles are important for cell division?

Answer 1

Nucleus, Nucleolus, Chromatin(Chromosomes), Centrosomes (+Microtubules)

Question 2

(3)What is cell division?

Answer 2

Maintaining the continuity of life, the organism’s ability to reproduce

Question 3

(5) What is the role of cell division?

Answer 3

1. Reproduction
2. Growth and Developpement
3. Tissue Renewal/Repair

Question 4

(6) What are the different arrangements of DNA?

Answer 4

1. Chromatin (base state): Long thin threads
2. Chromosomes (cell division): Chromatin tightly coiled around histones (proteins)

Question 5

(7) What is the genome?

Answer 5

All the genetic material contained in the cell

Question 6

(7) What is a chromosome?

Answer 6

1. A molecule of DNA made up of nucleotides
2. Contains a large amount of genes

Question 7

(7) What is a gene

Answer 7

1. Located on the chromosome
2. Contains the genetic code for characteristics like hair, skin, flower color

Question 8

(8) What is the gene locus?

Answer 8

1. The predetermined placed on a chromosome where a gene is located
2. Each gene occurs on a specific chromosome in a specific region/site

Question 9

(9) What are the characteristics of Chromosome number?

Answer 9

1. Each species has a characteristic number of chromosomes
2. Humans have 23 different pairs of chromosomes, 2 sets of 23 chromosomes from each parent

Question 10

(10) What is a karyotype?

Answer 10

1. An organized profile of a person’s chromosomes
2. Stained, photographed chromosomes arranged from largest to smallest
3. Identify irregularities in number or structure of chromosomes (genetic disorders caused by chromosomal alterations)

Question 11

(13) What are the types of chromosomes (organization,role)?

Answer 11

1. Individual chromosomes = Haploid, Chromosomes in pairs = Diploid
2. Sex chromosomes - Code for sex characteristics
   Autosomes - Non-reproductive chromosomes that do not code for sex characteristics

Question 12

(14) What happens at conception between the two somatic cells?

Answer 12

The sperm cell and egg unite to form a zygote (fertilized egg), fusing the nuclei together to form a single nucleus. The zygote has 1 set of 23 chromosomes from each parent (46 tot). Genetically unique individual(Miosis)

Question 13

(15) What happens after fertilization, the process from zygote to fetus?

Answer 13

The individual grows by increasing cell number exponentially (2,4,8,16…). The genetic information in these cells are copied exactly prior to cell division, each new cell gets a copy of each chromosome.

Question 14

(17) What is the cell cycle?

Answer 14

It describes the life cycle of almost every cell, between the time it forms and divides, forming 2 daughter cells

Question 15

(18) What are the different types of cell cycles a human body requires?

Answer 15

Mitosis and Miosis

Question 16

(19) What is mitosis

Answer 16

Cell division of somatic cells that results in 2 daughter cells that have the same # of chromosomes as the parent cell

Question 17

(21,30) What are the different stages in the cell cycle?

Answer 17

1. Interphase: Occurs between the time a cell is formed and when the division process begins
2. Miotic Phase: steps that result in distribution of exact copies of chromosomes to each daughter cell

Question 18

(22) What are the stages of Interphase?

Answer 18

1. Growth 1
2. DNA synthesis
3. Growth 2

Question 19

(23) Describe what happens during Growth 1 phase?

Answer 19

Begins as soon as the daughter cell is formed. Non dividing cells are in this phase
Period of active growth, increase in size
Extensive synthesis of new organelles : normal metabolism eventually reaches mature size for cell type

Question 20

(24) Explain what happens during the DNA synthesis phase?

Answer 20

Genetic information contained on chromosomes is copied.
An exact copy of each chromosome is produced

Question 21

(25) In S phase, describe the copied chromosomes. Are they attached?

Answer 21

They are called sister chromatids. They both contain the same genetic information. They are attached by centromeres. They are not in condensed form, they are simply attached together.

Question 22

(26) How many chromosomes are after the S phase?

Answer 22

Cells briefly have 2 chromatids for each chromosome. 23 pairs of chromosomes becomes 46 pairs of chromatids and then each daughter cell receives a chromosome copy. 46 unpaired chromosomes become 46 pairs of sister chromatids.

Question 23

(28) Explain what happens during Growth 2 phase?

Answer 23

2nd growth phase, cell size increases slightly.
Begins to prepare for the miotic phase: centrosomes duplicate , mature, microtubules form

Question 24

(30) What are the different phases of the mitotic phase?

Answer 24

a) Mitosis
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase

b) Cytokinesis

Question 25

(31) What happens during Prophase?

Answer 25

1. Condensation of DNA, still sister chromatids, stays in chromosome form after telophase 2. Nuclear envelope breaks 3. Duplicated Centrosomes separate 4. Microtubule extend between the centrosomes to form the mitotic spindle 5. Microtubules attach to chromosomes

Question 26

(32) What happens during prometaphase?

Answer 26

1. Nuclear membrane breaks 2. Centrosomes place themselves on opposite sides of the cell 3. Microtubules attach to kinetochores (centromeres) 4. Nucleoli disappears

Question 27

(34) What happens during Metaphase?

Answer 27

1. Chromosomes line up along the cell midline 2. Each chromosome is now attached to microtubules coming from opposite centrosomes

Question 28

(35) What happens during Anaphase?

Answer 28

1. Separation of Sister chromatids as centromeres break. The chromatids become chromosomes. 2. They are pulled to opposite sides of the cell by microtubules acting as tracks 3. Cell elongates, preparing to separate 4. Each pole has a set of 23 pairs of chromosomes

Question 29

(38) What happens during telophase?

Answer 29

End of mitosis, one copy of each chromosome on each pole of the cell 1. Spindle fibers disappear 2. Nuclear membrane forms around chromosomes 3. Nucleolus reappear 4. Chromosomes return to chromatin form

Question 30

(39) What happens during cytokinesis?

Answer 30

1. Cell pinches along the middle, to form the cleavage furrow 2. Separates the cell into two daughter cells with identic genetic information 3. Cell can repeat cell cycle

Question 31

(42) Describe the cell cycles within the plant cells?

Answer 31

Mitosis in plants is similar (no centrioles but have microtubules) Differences: Cells can't pinch in half daughter cells are separated by cell plate, Vesicles from Golgi carry cell wall components and travel to the center to divide the cells. Cell plate forms at the center and develops into cell membrane.

Question 32

(44) Describes the cell cycles within prokaryotic cells

Answer 32

Binary fission most bacteria only have one chromosome that forms nucleotide Chromosome replicates, 2 chromosomes migrate to polar ends of the cells, and cell elongates to provide room for both chromosomes Plasma membrane grow inward at the center of the cell. New cell wall deposited in between cells until 2 daughter calls are created.

Question 33

(45) What is a checkpoint

Answer 33

At specific times, cell checks itself and make an assessment if everything is going to plan. if everything is ok, than the cycle continues to the next stage. If something is wrong, the cycle does not continue until the error is fixed. If the error cannot be fixed, the cell will undergo aptosis, programmed cell death. Do no want to copy a damaged cell. Cancer prevention: a cancerous cell is one that multiplies out of control, the checkpoints are ignored.

Question 34

(50) What is cancer?

Answer 34

Results from genetic changes called mutations. cancer is a disease in which cells escape normal control methods, that regulate growth and division Spontaneous mutations can occur during DNA replication Mutagens can occur by: Various agents(chemical, radiation, etc.) that changes the genetic information of an organism that increases the frequency of mutations anything that can bring about a mutation in DNA is called a mutagen

Question 35

(51) What is a benign tumor

Answer 35

Benign Tumors: mass of cell (lump) that do not invade neighboring tissues, can grow very large. Not considered cancer. Can be removed.

Question 36

(51) What is a malignant tumor?

Answer 36

Mass of cells that invade neighboring tissues. Can impair the functioning of one or more organs. Considered cancerous. Spread of cancer cells to locations distant from their original site = metastasis. Only malignant tumor cells have the capacity to metastasize. Metastasis is the release of cancerous cells in the blood stream

Question 37

(53) What is the treatment for cancer

Answer 37

1. Surgery 2. A localized tumor can be treated with high-energy radiation: Non-specific DNA damage, cancer cells lose their ability to repair DNA 3. Metastatic tumors treated with chemotherapy: Damage to actively dividing cells, Taxol freezes the mitotic spindle by preventing microtubule formation. Side effect: nausea, immune suppression, hair loss, dividing cells.