Chapter 8 (cell division)

Question 1

Why do cells divide?

Answer 1

Growth- increasing the number of somatic (body) cells
Repair- replace cells that are damaged
Reproduce- asexual reproduction

Question 2

How does a non-duplicated chromosome compare physically to a duplicated chromosome?

Answer 2

Unduplicated chromosomes are single linear strands. Duplicated chromosomes contain two identical copies (sister chromatids) joined by a centromere, that result from DNA replication .

Question 3

Why do you think DNA coils tightly into chromosomes before mitosis occurs?

Answer 3

Condensing DNA into chromosomes prevents DNA tangling and damage during cell division (prepares for efficient separation)

Question 4

homologous chromosomes

Answer 4

Two chromosomes in a pair – normally one inherited from the mother and one from the father.

Question 5

diploid

Answer 5

containing two sets of chromosomes, one set from each parent (humans are diploids)

Question 6

haploid

Answer 6

containing a single set of chromosomes

Question 7

sister chromatids

Answer 7

either of the two identical chromatids that are formed by replication of a chromosome during the S phase of the cell cycle, are joined by a centromere, and segregate into separate daughter cells during anaphase.

Question 8

centromere

Answer 8

The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm and a long arm on the chromatids. During mitosis, spindle fibers attach to the centromere

Question 9

meiosis

Answer 9

A type of cell division that produces gametes (sperm and egg). Makes 4 genetically unique haploid cells

Question 10

mitosis

Answer 10

Cell division that produces body cells (repairs and grows) Makes 2 genetically identical diploid cells

Question 11

cytokinesis

Answer 11

the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.

Question 12

What is the difference between chromatin and chromosome?

Answer 12

Chromatin is the DNA and proteins that make up a chromosome. Chromosomes are the separate pieces of DNA in a cell.

Question 13

What directs the movement of chromosomes during the division process?

Answer 13

Spindle fibers made by the centrioles

Question 14

Draw the cell cycle and label Interphase (G1, S, G2) and mitosis. Briefly describe what is
occurring during G1, S, G2 and mitosis. Name the phases of mitosis. Draw phases.
Describe the major events of each phase and be able to recognize the phases in a
picture.

Answer 14

PMAT
G1- cells grow and divide
S- DNA doubles (synthesis)
G2 - cells grow more and organize contents to prep for mitosis
Mitosis- division of nucleus

Question 15

Name 4 differences between mitosis and meiosis.

Answer 15

Mitosis:
-has one stage of cell division
- produces diploid cells
-makes body cells
-genetically identical cells
Meiosis:
-has two stages of cell division
-produces haploid cells
-makes sperm and egg cells (sexual)
-genetically unique cells

Question 16

How many cells are produced after mitosis? Are the cells identical or non-identical?

Answer 16

2 identical diploid cells

Question 17

How many cells are produced after meiosis? Are the cells identical or non-identical?

Answer 17

4 genetically unique haploid cells

Question 18

How does crossing over and independent assortment contribute to genetic diversity?

Answer 18

In meiosis I, crossing over during prophase and independent assortment during anaphase creates sets of chromosomes with new combinations of alleles that can be different from both parents.

Question 19

If a sperm fertilizes an egg, what is made?

Answer 19

diploid zygote

Question 20

How are cancer cells different from normal cells?

Answer 20

cancer cells keep multiplying uncontrollably; each cell created has the same defect

Question 21

Define nondisjunction.

Answer 21

the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

Question 22

How are gametes produced from nondisjunction different from normal gametes?

Answer 22

they are either missing or have an extra chromosome

Question 23

What type of disease can result from fertilization of gametes produced from nondisjunction?

Answer 23

Down Syndrome

Question 24

Which cells go through binary fission, mitotic division, meiosis and what is the function
of these types of cell division?

Answer 24

Binary- Asexual (prokaryotes: bacteria and archae)
Mitotic- Eukaryotes: multi-cellular- growth of the individual; repair and replacement of cells and tissues (asexual)
Meiosis- Eukaryotes single-celled or multicellular (sexual)