Chapter 6 Chromosomes and Cell Reproduction

Chapter 6 Chromosomes and Cell Reproduction

I.  Chromosomes

A.  Formation of New Cells by Cell Division

-About ______are produced by an adult human body every day.

-______– cell reproduction for purposes of ______,______,______or ______.

-______– an organisms reproductive cells such as ______cells

-______must be present in each cell that is produced.

-DNA stores the information that tells ______

______.This information directs a cells activities and determines its ______.

1.  Prokaryotic Cell Reproduction

-single ______DNA molecule

-prokaryotes reproduce by ______.

-binary fission – a form of ______that

produces ______offspring.

In asexual reproduction a single parent passes all of its DNA to its offspring.

a. Binary fission occurs in ______stages

- DNA is ______

- The cell ______

2.  Eukaryotic Cell Reproduction

-Gene - ______

______. Genes code for specific traits, ex. ______.

-a single molecule of DNA has ______of genes. Prior to cell division in ______the chromosomes are copied first then become clearly visible.

-chromosomes – ______

______

-______- the 2 exact copies of DNA that make up each chromosomes.

-______– the point at which the 2 chromatids attach.

The chromatid become ______during cell division and place into each new cell.

Draw the structure of a chromosomes and label its three parts (2 chromatids and centromere).

II. How Chromosome Number and Structure Affect Development

1.  In humans ______cells (body cells) have ______of 23 chromosomes for a total of _____chromosomes. The 23 chromosome pairs differ in ______. Each chromosome contains ______of genes important for development and survival.

A.  Sets of Chromosomes

1.  ______– are pairs of chromosomes that are similar in size, shape and genetic content. You get one of each pair from your two parents.

Draw Figure 3

2.  Diploid cells –______

Body cells – example-______

3.  ______– contain one set of chromosomes. Ex sperm and egg cells (gametes). The symbol ____ is used to represent one set of chromosomes. n=23 in humans, 2n=46.

4.  ______– fusion of two haploid gametes

5.  Zygote – ______

6.  All organisms have a characteristic number of chromosomes,

Chromosome number of Various Organisms / Diploid number (2n) / Haploid number (n)
Orangutan / 48
Adder’s Tongue Fern
Dog / 39
Mosquito
Frog

B.  Sex Chromosomes

1.  Autosomes – ______

______

2.  ______– chromosomes that are involved in determining gender. Ex X and Y Chromosomes. Genes that cause a fertilized egg to develop into a male are located on the ______. Males have an X and Y chromosome. Females have two X chromosomes.

C.  Change in Chromosome Number

1.  The presence of all 46 chromosomes is essential for normal development and function.

2.  ______– when a humans has 3 copies of a chromosome .

3.  ______– photo of the chromosomes in a dividing cell that shows the chromosomes arranged by size. Used to detect abnormal chromosome numbers in cells.

4.  Trisomy 21 = ______

5.  ______– used to detect abnormal chromosome numbers in a fetus. Ex. ______and ______(CVS).

D.  Change in Chromosome Structure

1.  ______– change in an organisms chromosome structure.

2.  ______mutation – a piece of a chromosome breaks off completely.

3.  ______mutation – a chromosome fragment attaches to its homologous chromosome, which will then carry 2 copies of a certain set of genes.

4.  ______mutation – the chromosome piece reattaches to the original chromosome but in reverse orientation.

5.  ______- when the piece attaches to a non-homologous chromosome.

Section 2 The Cell Cycle

I. The Life of a Eukaryotic Cell

A. The Cell Cycle

1.______- the repeating sequence of cellular growth and division during the life of an organism.

2. cells spend ______of their time in the first 3 phases of the cell cycle, called ______.

3. Phases of the cell cycle:

- First growth (G1) Phase – a cell grows and ______

______. Some______cells such as ______and ______never divide. When these cells die the body ______replace them.

-______- a cell’s DNA is copied or replicated . At the end of this phase a chromosome consists of ______.

- Second growth (G2) Phase - ______

______. The mitochondria are replicated.

-Mitosis – the process during cell division in which ______.

-Cytokinesis - ______

______.

4. ______and ______produce new cells that are identical to the original cells and allow organisms to ______, ______and in some organisms ______.

II. Control of the cell Cycle

1.  the cell cycle in eukaryotes is controlled by many ______.

a.  Cell growth (G1) checkpoint – this checkpoint makes the ______. If conditions are favorable for division and the cell is ______and ______certain proteins will stimulate the cell to begin the ______.

b.  DNA synthesis (G2) checkpoint – ______is checked at this point by DNA repair enzymes. If this checkpoint is passed proteins trigger mitosis.

c.  Mitosis checkpoint – this checkpoint triggers the ______

______.

1. When control is lost: cancer

2. What causes cancer? ______

3. What is it called when cancer spreads from one area of the body to another?______

4. What are the treatments for cancer? ______

______